WorldWideScience

Sample records for cosmic growth history

  1. Conjoined constraints on modified gravity from the expansion history and cosmic growth

    Science.gov (United States)

    Basilakos, Spyros; Nesseris, Savvas

    2017-09-01

    In this paper we present conjoined constraints on several cosmological models from the expansion history H (z ) and cosmic growth f σ8. The models we study include the CPL w0wa parametrization, the holographic dark energy (HDE) model, the time-varying vacuum (ΛtCDM ) model, the Dvali, Gabadadze and Porrati (DGP) and Finsler-Randers (FRDE) models, a power-law f (T ) model, and finally the Hu-Sawicki f (R ) model. In all cases we perform a simultaneous fit to the SnIa, CMB, BAO, H (z ) and growth data, while also following the conjoined visualization of H (z ) and f σ8 as in Linder (2017). Furthermore, we introduce the figure of merit (FoM) in the H (z )-f σ8 parameter space as a way to constrain models that jointly fit both probes well. We use both the latest H (z ) and f σ8 data, but also LSST-like mocks with 1% measurements, and we find that the conjoined method of constraining the expansion history and cosmic growth simultaneously is able not only to place stringent constraints on these parameters, but also to provide an easy visual way to discriminate cosmological models. Finally, we confirm the existence of a tension between the growth-rate and Planck CMB data, and we find that the FoM in the conjoined parameter space of H (z )-f σ8(z ) can be used to discriminate between the Λ CDM model and certain classes of modified gravity models, namely the DGP and f (T ).

  2. Vortical Motions of Baryonic Gas in the Cosmic Web: Growth History and Scaling Relation

    CERN Document Server

    Zhu, Weishan

    2015-01-01

    The vortical motions of the baryonic gas residing in large scale structures are investigated by cosmological hydrodynamic simulations. Proceeding in the formation of the cosmic web, the vortical motions of baryonic matter are pumped up by baroclinity in two stages, i.e., the formation of sheets, and filaments. The mean curl velocity are about $< 1$, 1-10, 10-150, 5-50 km/s in voids, sheets, filaments and knots at $z=0$, respectively. The scaling of the vortical velocity of gas can be well described by the She-Leveque hierarchical turbulence model in the range of $l<0.65(1.50) h^{-1}$ Mpc in simulation of box size 25(100) $h^{-1}$ Mpc. The fractal Hausdorff dimension of vortical motions, $d$, revealed by velocity structure functions, is $\\sim 2.1-2.3$($\\sim 1.8-2.1$). It is slightly larger than the fractal dimension of mass distribution in filaments, $\\textit{D}^f \\sim 1.9-2.2$, and smaller than the fractal dimension of sheets, $\\textit{D}^s \\sim 2.4-2.7$. The vortical kinetic energy of baryonic gas is m...

  3. The imprint of the cosmic supermassive black hole growth history on the 21 cm background radiation

    CERN Document Server

    Tanaka, Takamitsu L; Perna, Rosalba

    2015-01-01

    The redshifted 21 cm transition line of hydrogen tracks the thermal evolution of the neutral intergalactic medium (IGM) at "cosmic dawn," during the emergence of the first luminous astrophysical objects (~100 Myr after the Big Bang) but before these objects ionized the IGM (~400-800 Myr after the Big Bang). Because X-rays, in particular, are likely to be the chief energy courier for heating the IGM, measurements of the 21 cm signature can be used to infer knowledge about the first astrophysical X-ray sources. Using analytic arguments and a numerical population synthesis algorithm, we argue that the progenitors of supermassive black holes (SMBHs) should be the dominant source of hard astrophysical X-rays---and thus the primary driver of IGM heating and the 21 cm signature---at redshifts $z 20$. An absence of such a signature in the forthcoming observational data would imply that SMBH formation occurred later (e.g. via so-called direct collapse scenarios), that it was not a common occurrence in early galaxies ...

  4. History of cosmic ray research in Finland

    Science.gov (United States)

    Usoskin, I. G.; Valtonen, E.; Vainio, R.; Tanskanen, P. J.; Aurela, A. M.

    2009-11-01

    The history of cosmic ray research in Finland can be traced back to the end of 1950s, when first ground-based cosmic ray measurements started in Turku. The first cosmic ray station was founded in Oulu in 1964 performing measurements of cosmic rays by a muon telescope, which was later complemented by a neutron monitor. Since the 1990s, several research centers and universities, such as The Finnish Meteorological Institute, Helsinki University of Technology, University of Oulu, University of Turku and University of Helsinki have been involved in space science projects, such as SOHO, AMS, Cluster, Cassini, BepiColombo, etc. At the same time, ground-based cosmic ray measurements have reached a new level, including a fully automatic on-line database in Oulu and a new muon measuring underground site in Pyhäsalmi. Research groups in Helsinki, Oulu and Turku have also extensive experience in theoretical investigations of different aspects of cosmic ray physics. Cosmic ray research has a 50-year long history in Finland, covering a wide range from basic long-running ground-based observations to high-technology space-borne instrumentation and sophisticated theoretical studies. Several generations of researchers have been involved in the study ensuring transfer of experience and building the recognized Finnish research school of cosmic ray studies.

  5. Cosmic Growth and Expansion Conjoined

    CERN Document Server

    Linder, Eric V

    2016-01-01

    Cosmological measurements of both the expansion history and growth history have matured, and the two together provide an important test of general relativity. We consider their joint evolutionary track, showing that this has advantages in distinguishing cosmologies relative to considering them individually or at isolated redshifts. In particular, the joint comparison relaxes the shape degeneracy that makes $f\\sigma_8(z)$ curves difficult to separate from the overall growth amplitude. The conjoined method further helps visualization of which combinations of redshift ranges provide the clearest discrimination. We examine standard dark energy cosmologies, modified gravity, and "stuttering" growth, each showing distinct signatures.

  6. Probes of Cosmic Star Formation History

    Indian Academy of Sciences (India)

    Pranab Ghosh

    2002-03-01

    I summarize X-ray diagnostic studies of cosmic star formation history in terms of evolutionary schemes for X-ray binary evolution in normal galaxies with evolving star formation. Deep X-ray imaging studies by Chandra and XMM-Newton are now beginning to constrain both the X-ray luminosity evolution of galaxies and the log – log diagnostics of the X-ray background. I discuss these in the above context, summarizing current understanding and future prospects.

  7. Key scientific problems from Cosmic Ray History

    Science.gov (United States)

    Lev, Dorman

    2016-07-01

    Recently was published the monograph "Cosmic Ray History" by Lev Dorman and Irina Dorman (Nova Publishers, New York). What learn us and what key scientific problems formulated the Cosmic Ray History? 1. As many great discoveries, the phenomenon of cosmic rays was discovered accidentally, during investigations that sought to answer another question: what are sources of air ionization? This problem became interesting for science about 230 years ago in the end of the 18th century, when physics met with a problem of leakage of electrical charge from very good isolated bodies. 2. At the beginning of the 20th century, in connection with the discovery of natural radioactivity, it became apparent that this problem is mainly solved: it was widely accepted that the main source of the air ionization were α, b, and γ - radiations from radioactive substances in the ground (γ-radiation was considered as the most important cause because α- and b-radiations are rapidly absorbed in the air). 3. The general accepted wrong opinion on the ground radioactivity as main source of air ionization, stopped German meteorologist Franz Linke to made correct conclusion on the basis of correct measurements. In fact, he made 12 balloon flights in 1900-1903 during his PhD studies at Berlin University, carrying an electroscope to a height of 5500 m. The PhD Thesis was not published, but in Thesis he concludes: "Were one to compare the presented values with those on ground, one must say that at 1000 m altitude the ionization is smaller than on the ground, between 1 and 3 km the same amount, and above it is larger with values increasing up to a factor of 4 (at 5500 m). The uncertainties in the observations only allow the conclusion that the reason for the ionization has to be found first in the Earth." Nobody later quoted Franz Linke and although he had made the right measurements, he had reached the wrong conclusions, and the discovery of CR became only later on about 10 years. 4. Victor Hess, a

  8. Growth of cosmic structure: Probing dark energy beyond expansion

    Energy Technology Data Exchange (ETDEWEB)

    Huterer, Dragan; Kirkby, David; Bean, Rachel; Connolly, Andrew; Dawson, Kyle; Dodelson, Scott; Evrard, August; Jain, Bhuvnesh; Jarvis, Michael; Linder, Eric; Mandelbaum, Rachel; May, Morgan; Raccanelli, Alvise; Reid, Beth; Rozo, Eduardo; Schmidt, Fabian; Sehgal, Neelima; Slosar, Anže; van Engelen, Alex; Wu, Hao-Yi; Zhao, Gongbo

    2015-03-01

    The quantity and quality of cosmic structure observations have greatly accelerated in recent years, and further leaps forward will be facilitated by imminent projects. These will enable us to map the evolution of dark and baryonic matter density fluctuations over cosmic history. The way that these fluctuations vary over space and time is sensitive to several pieces of fundamental physics: the primordial perturbations generated by GUT-scale physics; neutrino masses and interactions; the nature of dark matter and dark energy. We focus on the last of these here: the ways that combining probes of growth with those of the cosmic expansion such as distance-redshift relations will pin down the mechanism driving the acceleration of the Universe.

  9. Cosmic R-string in thermal history

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kobayashi, Tatsuo [Kyoto Univ. (Japan). Dept. of Physics; Ohashi, Keisuke [Osaka City Univ. (Japan). Dept. of Mathematics and Physics; Ookouchi, Yutaka [Kyoto Univ. (Japan). Dept. of Physics; Kyoto Univ. (Japan). The Hakubi Center for Advanced Research

    2013-03-15

    We study stabilization of an unstable cosmic string associated with spontaneously broken U(1){sub R} symmetry, which otherwise causes a dangerous roll-over process. We demonstrate that in a gauge mediation model, messengers can receive enough corrections from the thermal plasma of the supersymmetric standard model particles to stabilize the unstable modes of the string.

  10. Cosmic Evolution: The History of an Idea

    Science.gov (United States)

    Dick, S. J.

    2004-12-01

    Cosmic evolution has become the conceptual framework within which modern astronomy is undertaken, and is the guiding principle of major NASA programs such as Origins and Astrobiology. While there are 19th- and early 20th century antecedents, as in the work of Robert Chambers, Herbert Spencer and Lawrence Henderson, it was only at mid-20th century that full-blown cosmic evolution began to be articulated and accepted as a research paradigm extending from the Big Bang to life, intelligence and the evolution of culture. Harlow Shapley was particularly important in spreading the idea to the public in the 1950s, and NASA embraced the idea in the 1970s as part of its SETI program and later its exobiology and astrobiology programs. Eric Chaisson, Carl Sagan and others were early proponents of cosmic evolution, and it continues to be elaborated in ever more subtle form as a research program and a philosophy. It has even been termed "Genesis for the 21st century." This paper documents the origin and development of the idea and offers a glimpse of where it could lead if cultural evolution is taken seriously, possibly leading to the concept of a postbiological universe.

  11. Cosmic Supernova Rate History and Type Ia Supernova Progenitors

    OpenAIRE

    Kobayashi, Chiaki; Nomoto, Ken'ichi; Tsujimoto, Takuji

    2001-01-01

    Adopting a single degenerate scenario for Type Ia supernova progenitors with the metallicity effect, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in spiral and elliptical galaxies, and compare with the recent observational data up to z ~ 0.55.

  12. Unveiling the cosmic history of light

    Science.gov (United States)

    Desai, Abhishek; Ajello, Marco; Hartmann, Dieter; Sharan Paliya, Vaidehi; Finke, Justin; Omodei, Nicola; Dominguez, Alberto; Helgason, Kári; Meyer, Manuel

    2017-08-01

    The extragalactic background light (EBL) is the collective emission of all the stars and galaxies over the history of the universe. The most efficient method to study the EBL is through the imprint it leaves via photon-photon annihilation in the spectra of distant gamma-ray sources. Here we present a combined analysis of gamma-ray data from GRBs and blazars detected by Fermi Large Area Telescope. This analysis allows us to probe the EBL up to much higher redshifts (z>4) and over a larger wavelength range. The details of this work and its implications will be discussed.

  13. The enrichment history of cosmic metals

    CERN Document Server

    Wiersma, Robert P C; Vecchia, Claudio Dalla; Booth, C M; Theuns, Tom; Aguirre, Anthony

    2010-01-01

    We use a suite of cosmological, hydrodynamical simulations to investigate the chemical enrichment history of the Universe. Specifically, we trace the origin of the metals back in time to investigate when various gas phases were enriched and by what halo masses. We find that the age of the metals decreases strongly with the density of the gas in which they end up. At least half of the metals that reside in the diffuse intergalactic medium (IGM) at redshift zero (two) were ejected from galaxies above redshift two (three). The mass of the haloes that last contained the metals increases rapidly with the gas density. More than half of the mass in intergalactic metals was ejected by haloes with total masses less than 1e11 solar masses and stellar masses less than 1e9 solar masses. The range of halo masses that contributes to the enrichment is wider for the hotter part of the IGM. By combining the `when' and `by what' aspects of the enrichment history, we show that metals residing in lower density gas were typically...

  14. Growth of cosmic structure: Probing dark energy beyond expansion

    Science.gov (United States)

    Huterer, Dragan; Kirkby, David; Bean, Rachel; Connolly, Andrew; Dawson, Kyle; Dodelson, Scott; Evrard, August; Jain, Bhuvnesh; Jarvis, Michael; Linder, Eric; Mandelbaum, Rachel; May, Morgan; Raccanelli, Alvise; Reid, Beth; Rozo, Eduardo; Schmidt, Fabian; Sehgal, Neelima; Slosar, Anže; van Engelen, Alex; Wu, Hao-Yi; Zhao, Gongbo

    2015-03-01

    The quantity and quality of cosmic structure observations have greatly accelerated in recent years, and further leaps forward will be facilitated by imminent projects. These will enable us to map the evolution of dark and baryonic matter density fluctuations over cosmic history. The way that these fluctuations vary over space and time is sensitive to several pieces of fundamental physics: the primordial perturbations generated by GUT-scale physics; neutrino masses and interactions; the nature of dark matter and dark energy. We focus on the last of these here: the ways that combining probes of growth with those of the cosmic expansion such as distance-redshift relations will pin down the mechanism driving the acceleration of the Universe. One way to explain the acceleration of the Universe is invoke dark energy parameterized by an equation of state w. Distance measurements provide one set of constraints on w, but dark energy also affects how rapidly structure grows; the greater the acceleration, the more suppressed the growth of structure. Upcoming surveys are therefore designed to probe w with direct observations of the distance scale and the growth of structure, each complementing the other on systematic errors and constraints on dark energy. A consistent set of results will greatly increase the reliability of the final answer. Another possibility is that there is no dark energy, but that General Relativity does not describe the laws of physics accurately on large scales. While the properties of gravity have been measured with exquisite precision at stellar system scales and densities, within our solar system and by binary pulsar systems, its properties in different environments are poorly constrained. To fully understand if General Relativity is the complete theory of gravity we must test gravity across a spectrum of scales and densities. Rapid developments in gravitational wave astronomy and numerical relativity are directed at testing gravity in the high

  15. Cosmic update dark puzzles : arrow of time : future history

    CERN Document Server

    Adams, Fred; Mersini-Houghton, Laura; Nekoogar, Farzad

    2012-01-01

    "...The Multiversal book series is equally unique, providing book-length extensions of the lectures with enough additional depth for those who truly want to explore these fields, while also providing the kind of clarity that is appropriate for interested lay people to grasp the general principles involved." - Lawrence M. Krauss Cosmic Update covers: A novel approach to uncover the dark faces of the Standard Model of cosmology. The possibility that Dark Energy and Dark Matter are manifestations of the inhomogeneous geometry of our Universe. The history of cosmological model building and the general architecture of cosmological models. Illustrations of the Large Scale Structure of the Universe. A new perspective on the classical static Einstein Cosmos. Global properties of World Models including their Topology. The Arrow of Time in a Universe with a Positive Cosmological Constant. The exploration of the consequences of a fundamental Cosmological Constant for our Universe. The exploration of why the current ob...

  16. The physics driving the cosmic star formation history

    CERN Document Server

    Schaye, Joop; Booth, C M; Wiersma, Robert P C; Theuns, Tom; Haas, Marcel R; Bertone, Serena; Duffy, Alan R; McCarthy, I G; van de Voort, Freeke

    2009-01-01

    We investigate the physics driving the cosmic star formation (SF) history using the more than fifty large, cosmological, hydrodynamical simulations that together comprise the OverWhelmingly Large Simulations (OWLS) project. We systematically vary the parameters of the model to determine which physical processes are dominant and which aspects of the model are robust. Generically, we find that SF is limited by the build-up of dark matter haloes at high redshift, reaches a broad maximum at intermediate redshift, then decreases as it is quenched by lower cooling rates in hotter and lower density gas, gas exhaustion, and self-regulated feedback from stars and black holes. The higher redshift SF is therefore mostly determined by the cosmological parameters and to a lesser extent by photo-heating from reionization. The location and height of the peak in the SF history, and the steepness of the decline towards the present, depend on the physics and implementation of stellar and black hole feedback. Mass loss from int...

  17. Interactions of Cosmic Rays in the Atmosphere: Growth Curves Revisited

    CERN Document Server

    Obermeier, A; Hörandel, J; Müller, D

    2013-01-01

    Measurements of cosmic-ray abundances on balloons are affected by interactions in the residual atmosphere above the balloon. Corrections for such interactions are particularly important for observations of rare secondary particles such as boron, antiprotons and positrons. These corrections can either be calculated if the relevant cross sections in the atmosphere are known, or may be empirically determined by extrapolation of the "growth curves", i. e. the individual particle intensities as functions of atmospheric depth. The growth-curve technique is particularly attractive for long-duration balloon flights where the periodic daily altitude variations permit rather precise determinations of the corresponding particle intensity variations. We determine growth curves for nuclei from boron (Z=5) to iron (Z=26), using data from the 2006 Arctic balloon flight of the TRACER detector for cosmic-ray nuclei, and we compare the growth curves with predictions from published cross section values. In general, good agreeme...

  18. The Growth of Supermassive Black Holes Across Cosmic Time

    CERN Document Server

    Nandra, K; Alexander, D M; Ballantyne, D R; Barcons, X; Bauer, F E; Boller, T; Brandt, W N; Brusa, M; Cattaneo, A; Chartas, G; Coil, A L; Comastri, A; Croton, D J; Della Ceca, R; Dickinson, M; Fabian, A C; Fazio, G G; Fiore, F; Flanagan, K A; Forman, W R; Gehrels, N; Georgakakis, A; Georgantopoulos, I; Gilli, R; Hasinger, G; Hopkins, P F; Hornschemeier, A E; Ivison, R J; Kauffmann, G; King, A R; Koekemoer, A M; Koo, D C; Kunieda, H; Laird, E S; Levenson, N A; Li, Y; Madau, P; Ohashi, T; Pounds, K A; Primack, J R; Ranalli, P; Ricker, G R; Rossi, E M; Shemmer, O; Somerville, R S; Stern, D; Stiavelli, M; Tananbaum, H; Terashima, Y; Treister, E; Ueda, Y; Vignali, C; Volonteri, M; Watson, M G; White, N E; White, S D M

    2009-01-01

    One of the main themes in extragalactic astronomy for the next decade will be the evolution of galaxies over cosmic time. Many future observatories, including JWST, ALMA, GMT, TMT and E-ELT will intensively observe starlight over a broad redshift range, out to the dawn of the modern Universe when the first galaxies formed. It has, however, become clear that the properties and evolution of galaxies are intimately linked to the growth of their central black holes. Understanding the formation of galaxies, and their subsequent evolution, will therefore be incomplete without similarly intensive observations of the accretion light from supermassive black holes (SMBH) in galactic nuclei. To make further progress, we need to chart the formation of typical SMBH at z>6, and their subsequent growth over cosmic time, which is most effectively achieved with X-ray observations. Recent technological developments in X-ray optics and instrumentation now bring this within our grasp, enabling capabilities fully matched to those...

  19. The rise and fall of cosmical physics: notes for a history, ca. 1850-1920

    CERN Document Server

    Kragh, Helge

    2013-01-01

    In the period from about 1890 to 1915 an interdisciplinary and unifying research programme known as "cosmical physics" attracted much scientific and public attention. It typically included aspects of the earth sciences (such as magnetic storms and atmospheric electricity) combined with astronomical subjects (such as the solar corona and cometary tails), but there was no unanimity as to the precise meaning of cosmical physics, which collapsed after World War I. The essay covers the history of cosmical physics as it unfolded in particular in Germany, Austria, England and Scandinavia. Among the scientists who contributed to the development of cosmical physics were Wilhelm Foerster from Germany, Wilhelm Trabert from Austria, Kristian Birkeland from Norway and Svante Arrhenius from Sweden. While cosmical physics did not usually involve a cosmological dimension, both Birkeland and Arrhenius constructed cosmologies based on their work on auroral and other phenomena.

  20. A snapshot from the history of cosmic ray research: a Japanese scientist view

    CERN Document Server

    Muraki, Yasushi

    2010-01-01

    This short note describes the history of cosmic ray research. A part of this document was presented orally at the international conference of CRIS 2010 held in Catania, Italy. The document is written being based on the English translation of a Japanese article entitled "One Hundred Years of Research on Cosmic Rays". The document was published in 2008 by the Japan Astronomy Society as a series of books on "Modern Astronomy" (Volume 17).

  1. Reconstruction of cosmic history from a simple parametrization of H

    CERN Document Server

    Pacif, S K J; Myrzakul, S

    2016-01-01

    In this paper, we propose a simple parametrization of the Hubble parameter H in order to explain the late time cosmic acceleration. We show that our proposal covers many models obtained in different schemes of parametrization under one umbrella. We demonstrate that a simple modification in the functional form of Hubble parameter can give rise to interesting cosmological phenomena such as big rip singularity, bounce and others. We have also constrained the model parameters using the latest 28 points of H(z) data for three cases which admit transition from deceleration to acceleration.

  2. Negative feedback effects on star formation history and cosmic reionization

    CERN Document Server

    Wang, Lei; Xiang, Shouping; Yuan, Ye-Fei

    2008-01-01

    After considering the effects of negative feedback on the process of star formation, we explore the relationship between star formation process and the associated feedback, by investigating how the mechanical feedback from supernovae(SNe) and radiative feedback from luminous objects regulate the star formation rate and therefore affect the cosmic reionization.Based on our present knowledge of the negative feedback theory and some numerical simulations, we construct an analytic model in the framework of the Lambda cold dark matter model. In certain parameter regions, our model can explain some observational results properly. In large halos(T_vir>10000 K), both mechanical and radiative feedback have a similar behavior: the relative strength of negative feedback reduces as the redshift decreases. In contrast, in small halos (T_vir<10000 K$) that are thought to breed the first stars at early time, the radiative feedback gets stronger when the redshift decreases. And the star formation rate in these small halos...

  3. Spectral distortion of the CMB by the cumulative CO emission from galaxies throughout cosmic history

    Science.gov (United States)

    Mashian, Natalie; Loeb, Abraham; Sternberg, Amiel

    2016-05-01

    We show that the cumulative CO emission from galaxies throughout cosmic history distorts the spectrum of the cosmic microwave background at a level that is well above the detection limit of future instruments, such as the Primordial Inflation Explorer. The modelled CO signal has a prominent bump in the frequency interval 100-200 GHz, with a characteristic peak intensity of ˜2 × 10-23 W m-2 Hz-1 sr-1. Most of the CO foreground originates from modest redshifts, z ˜ 2-5, and needs to be efficiently removed for more subtle distortions from the earlier Universe to be detected.

  4. A meta-analysis of cosmic star-formation history

    CERN Document Server

    Hogg, D W

    2001-01-01

    A meta-analysis is performed of the literature on evolution in cosmic star-formation rate density from redshift unity to the present day. The measurements are extremely diverse, including radio, infrared, and ultraviolet broad-band photometric indicators, and visible and near-ultraviolet line-emission indicators. Although there is large scatter among indicators at any given redshift, virtually all studies find a significant decrease from redshift unity to the present day. This is the most heterogeneously confirmed result in the study of galaxy evolution. When comoving star-formation rate density is treated as being proportional to $(1+z)^{\\beta}$, the meta-analysis gives a best-fit exponent and conservative confidence interval of $\\beta= 3.1\\pm 0.7$ in a world model with $(\\Omega_M,\\Omega_{\\Lambda})=(0.3,0.7)$ and $\\beta= 3.8\\pm 0.8$ in $(\\Omega_M,\\Omega_{\\Lambda})=(1.0,0.0)$. In either case these evolutionary trends are strong enough that the bulk of the stellar mass at the present day ought to be in old ($>...

  5. The Lunar Regolith as a Recorder of Cosmic History

    Science.gov (United States)

    Cooper, Bonnie; McKay, D.; Riofrio, L.

    2012-01-01

    The Moon can be considered a giant tape recorder containing the history of the solar system and Universe. The lunar regolith (soil) has recorded the early history of the Moon, Earth, the solar system and Universe. A major goal of future lunar exploration should be to find and play back existing fragments of that tape . By reading the lunar tape, we can uncover a record of planetary bombardment, as well as solar and stellar variability. The Moon can tell us much about our place in the Universe. The lunar regolith has likely recorded the original meteoritic bombardment of Earth and Moon, a violent cataclysm that may have peaked around 4 Gyr, and the less intense bombardment occurring since that time. This impact history is preserved on the Moon as regolith layers, ejecta layers, impact melt rocks, and ancient impact breccias. The impact history of the Earth and Moon possibly had profound effects on the origin and development of life. Decrease in meteor bombardment allowed life to develop on Earth. Life may have developed first on another body, such as Mars, then arrived via meteorite on Earth. The solar system may have experienced bursts of severe radiation from the Sun, other stars, or from unknown sources. The lunar regolith has recorded this radiation history in the form of implanted solar wind, solar flare materials and radiation damage. Lunar soil can be found sandwiched between layers of basalt or pyroclastic deposits. This filling constitutes a buried time capsule that is likely to contain well-preserved ancient regolith. Study of such samples will show us how the solar system has evolved and changed over time. The lunar tape recorder can provide detailed information on specific portions of solar and stellar variability. Data from the Moon also offers clues as to whether so-called fundamental constants have changed over time.

  6. Cosmic reionization on computers. II. Reionization history and its back-reaction on early galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Gnedin, Nickolay Y. [Particle Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Kaurov, Alexander A., E-mail: gnedin@fnal.gov, E-mail: kaurov@uchicago.edu [Department of Astronomy and Astrophysics, The University of Chicago, Chicago, IL 60637 (United States)

    2014-09-20

    We compare the results from several sets of cosmological simulations of cosmic reionization, produced under the Cosmic Reionization On Computers project, with existing observational data on the high-redshift Lyα forest and the abundance of Lyα emitters. We find good consistency with the observational measurements and previous simulation work. By virtue of having several independent realizations for each set of numerical parameters, we are able to explore the effect of cosmic variance on observable quantities. One unexpected conclusion we are forced into is that cosmic variance is unusually large at z > 6, with both our simulations and, most likely, observational measurements still not fully converged for even such basic quantities as the average Gunn-Peterson optical depth or the volume-weighted neutral fraction. We also find that reionization has little effect on the early galaxies or on global cosmic star formation history, because galaxies whose gas content is affected by photoionization contain no molecular (i.e., star-forming) gas in the first place. In particular, measurements of the faint end of the galaxy luminosity function by the James Webb Space Telescope are unlikely to provide a useful constraint on reionization.

  7. Cosmic expansion history from SNe Ia data via information field theory: the charm code

    Science.gov (United States)

    Porqueres, Natàlia; Enßlin, Torsten A.; Greiner, Maksim; Böhm, Vanessa; Dorn, Sebastian; Ruiz-Lapuente, Pilar; Manrique, Alberto

    2017-03-01

    We present charm (cosmic history agnostic reconstruction method), a novel inference algorithm that reconstructs the cosmic expansion history as encoded in the Hubble parameter H(z) from SNe Ia data. The novelty of the approach lies in the usage of information field theory, a statistical field theory that is very well suited for the construction of optimal signal recovery algorithms. The charm algorithm infers non-parametrically s(a) = ln(ρ(a) /ρcrit0), the density evolution which determines H(z), without assuming an analytical form of ρ(a) but only its smoothness with the scale factor a = (1 + z)-1. The inference problem of recovering the signal s(a) from the data is formulated in a fully Bayesian way. In detail, we have rewritten the signal as the sum of a background cosmology and a perturbation. This allows us to determine the maximum a posteriory estimate of the signal by an iterative Wiener filter method. Applying charm to the Union2.1 supernova compilation, we have recovered a cosmic expansion history that is fully compatible with the standard ΛCDM cosmological expansion history with parameter values consistent with the results of the Planck mission.

  8. On The History and Future of Cosmic Planet Formation

    CERN Document Server

    Behroozi, Peter

    2015-01-01

    We combine constraints on galaxy formation histories with planet formation models, yielding the Earth-like and giant planet formation histories of the Milky Way and the Universe as a whole. In the Hubble Volume (10^13 Mpc^3), we expect there to be ~10^20 Earth-like and ~10^20 giant planets; our own galaxy is expected to host ~10^9 and ~10^10 Earth-like and giant planets, respectively. Proposed metallicity thresholds for planet formation do not significantly affect these numbers. However, the metallicity dependence for giant planets results in later typical formation times and larger host galaxies than for Earth-like planets. The Solar System formed at the median age for existing giant planets in the Milky Way, and consistent with past estimates, formed after 80% of Earth-like planets. However, if existing gas within virialised dark matter haloes continues to collapse and form stars and planets, the Universe will form over 10 times more planets than currently exist. We show that this would imply at least a 92%...

  9. Matching the Local and Cosmic Star Formation Histories

    CERN Document Server

    Drozdovsky, Igor; Aparicio, Antonio; Gallart, Carme

    2008-01-01

    Given the many recent advances in our understanding of the star formation history (SFH) of the Local Group and other nearby galaxies, and in the evolution of star formation with redshift, we present a new comparison of the comoving space density of the star formation rate as a function of look-back time for the Local and Distant Universe. We update the Local SFH derived from the analysis of resolved stellar populations (``fossil records'') in individual nearby galaxies, based on our own estimations as well as available in the literature. While the preliminary comparison of SFHs is found to be broadly consistent, some discrepancies still remain, including an excess of the Local SFR density in the most recent epoch.

  10. Cosmology with hybrid expansion law: scalar field reconstruction of cosmic history and observational constraints

    Energy Technology Data Exchange (ETDEWEB)

    Akarsu, Özgür [Department of Physics, Koç University, 34450 Sariyer, İstanbul (Turkey); Kumar, Suresh [Department of Mathematics, BITS Pilani, Pilani Campus, Rajasthan-333031 (India); Myrzakulov, R.; Sami, M. [Centre of Theoretical Physics, Jamia Millia Islamia, New Delhi-110025 (India); Xu, Lixin, E-mail: oakarsu@ku.edu.tr, E-mail: sukuyd@gmail.com, E-mail: rmyrzakulov@gmail.com, E-mail: samijamia@gmail.com, E-mail: lxxu@dlut.edu.cn [Institute of Theoretical Physics, Dalian University of Technology, Dalian, 116024 (China)

    2014-01-01

    In this paper, we consider a simple form of expansion history of Universe referred to as the hybrid expansion law - a product of power-law and exponential type of functions. The ansatz by construction mimics the power-law and de Sitter cosmologies as special cases but also provides an elegant description of the transition from deceleration to cosmic acceleration. We point out the Brans-Dicke realization of the cosmic history under consideration. We construct potentials for quintessence, phantom and tachyon fields, which can give rise to the hybrid expansion law in general relativity. We investigate observational constraints on the model with hybrid expansion law applied to late time acceleration as well as to early Universe a la nucleosynthesis.

  11. Star formation and gas phase history of the cosmic web

    Science.gov (United States)

    Snedden, Ali; Coughlin, Jared; Phillips, Lara Arielle; Mathews, Grant; Suh, In-Saeng

    2016-01-01

    We present a new method of tracking and characterizing the environment in which galaxies and their associated circumgalactic medium evolve. We have developed a structure finding algorithm that uses the rate of change of the density gradient to self-consistently parse and follow the evolution of groups/clusters, filaments and voids in large-scale structure simulations. We use this to trace the complete evolution of the baryons in the gas phase and the star formation history within each structure in our simulated volume. We vary the structure measure threshold to probe the complex inner structure of star-forming regions in poor clusters, filaments and voids. We find that the majority of star formation occurs in cold, condensed gas in filaments at intermediate redshifts (z ˜ 3). We also show that much of the star formation above a redshift z = 3 occurs in low-contrast regions of filaments, but as the density contrast increases at lower redshift, star formation switches to the high-contrast regions, or inner parts, of filaments. Since filaments bridge the void and cluster regions, it suggests that the majority of star formation occurs in galaxies in intermediate density regions prior to the accretion on to groups/clusters. We find that both filaments and poor clusters are multiphase environments distinguishing themselves by different distributions of gas phases.

  12. Can f(T) gravity theories mimic ΛCDM cosmic history

    Energy Technology Data Exchange (ETDEWEB)

    Setare, M.R.; Mohammadipour, N., E-mail: rezakord@ipm.ir, E-mail: N.Mohammadipour@uok.ac.ir [Department of Science, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

    2013-01-01

    Recently the teleparallel Lagrangian density described by the torsion scalar T has been extended to a function of T. The f(T) modified teleparallel gravity has been proposed as the natural gravitational alternative for dark energy to explain the late time acceleration of the universe. In order to reconstruct the function f(T) by demanding a background ΛCDM cosmology we assume that, (i) the background cosmic history provided by the flat ΛCDM (the radiation ere with ω{sub eff} = (1/3), matter and de Sitter eras with ω{sub eff} = 0 and ω{sub eff} = −1, respectively) (ii) the radiation dominate in the radiation era with Ω{sub 0r} = 1 and the matter dominate during the matter phases when Ω{sub 0m} = 1. We find the cosmological dynamical system which can obey the ΛCDM cosmic history. In each era, we find a critical lines that, the radiation dominated and the matter dominated are one points of them in the radiation and matter phases, respectively. Also, we drive the cosmologically viability condition for these models. We investigate the stability condition with respect to the homogeneous scalar perturbations in each era and we obtain the stability conditions for the fixed points in each eras. Finally, we reconstruct the function f(T) which mimics cosmic expansion history.

  13. Cosmic expansion histories in doubly-coupled, ghost-free massive bigravity

    CERN Document Server

    Enander, Jonas; Akrami, Yashar; Mortsell, Edvard

    2015-01-01

    We study the cosmic expansion history of massive bigravity with a ghost-free matter coupling which treats both metrics on equal footing. We derive the Friedmann equation for the effective metric through which matter couples to the two metrics, and study its solutions. For certain parameter choices, the background cosmology is identical to that of $\\Lambda$CDM. More general parameters yield dynamical dark energy, which can still be in agreement with observations of the expansion history. We study specific parameter choices of interest, including minimal models, maximally-symmetric models, and a candidate partially-massless theory.

  14. From spontaneous ionization to subatomic physics: Some vignettes from cosmic ray history

    Science.gov (United States)

    Cronin, James W.

    2014-01-01

    In 1879 Crookes discovered that air seemed to ionize spontaneously. With the discovery in 1896 of radioactivity by Henri Becquerel, it appeared that the mystery was solved. However a number of physicists sought a quantitative agreement between the ”spontaneous ionization” and the radioactivity in the earth. The persistence of these physicists led to the discovery of another source of radiation which appeared to come from the heavens. The nature of this ”cosmic radiation” involved phenomena that were completely unknown. Coming to an understanding of the nature of this cosmic radiation took about 40 years between 1912 and 1953. This history involves extraordinary scientists and the invention of dramatic new detection techniques. This story finishes with a remarkable conference organized by Patrick Blackett and Louis Leprince-Ringuet (1953) in the Pyrenees town of Bagnères de Bigorre. Following 1953 the cosmic ray researchers divided into two groups, those who continued the investigation of the new particles with the accelerators and those who continued with the search for the origin and the astrophysics of the cosmic rays.

  15. Virtual impact: visualizing the potential effects of cosmic impact in human history

    Energy Technology Data Exchange (ETDEWEB)

    Masse, W Bruce [Los Alamos National Laboratory; Janecky, David R [Los Alamos National Laboratory; Forte, Maurizio [UC MERCED; Barrientos, Gustavo [UNIV OF LA PLATA, ARG.

    2009-01-01

    Current models indicate that catastrophic impacts by asteroids and comets capable of killing more than one quarter of Earth's human population have occurred on average once every million years; smaller impacts, such the 1908 Tunguska impact that leveled more than 2,000 square km of Siberian forest, occur every 200-300 years. Therefore, cosmic impact likely significantly affected hominine evolution and conceivably played a role in Holocene period human culture history. Regrettably, few archaeologists are trained to appreciate the nature and potential effects of cosmic impact. We have developed a conceptual model for an extensible set of educational and research tools based on virtual reality collaborative environments to engage archaeologists and the general public on the topic of the role of cosmic impact in human history. Our initial focus is on two documented asteroid impacts in Argentina during the period of 4000 to 1000 B.C. Campo del Cicio resulted in an energy release of around 2-3 megatons (100-150 times the Hiroshima atomic weapon), and left several craters and a strewn field covering 493 km{sup 2} in northeastern Argentina. Rio Cuarto was likely more than 1000 megatons and may have devastated an area greater than 50,000 km{sup 2} in central Argentina. We are focusing on reconstructions of these events and their potential effects on contemporary hunter and gatherers. Our vinual reality tools also introduce interactive variables (e.g., impactor physical properties, climate, vegetation, topography, and social complexity) to allow researchers and students to better investigate and evaluate the factors that significantly influence cosmic impact effects.

  16. Detecting massive black hole binaries and unveiling their cosmic history with gravitational wave observations

    CERN Document Server

    Sesana, A

    2012-01-01

    Space based gravitational wave astronomy will open a completely new window on the Universe and massive black holes binaries are expected to be among the primary actors on this upcoming stage. The New Gravitational-wave Observatory (NGO) is a space interferometer proposal derived from the former Laser Interferometer Space Antenna (LISA) concept. We describe here its capabilities of observing massive black hole binaries throughout the Universe, measuring their relevant parameters (masses, spins, distance to the observer) to high precision. The statistical properties of the population of detected systems can be used to constrain the massive black hole cosmic history, providing deep insights into the faint, high redshift Universe.

  17. The formation and evolution of dark matter halos early in cosmic history

    Science.gov (United States)

    Ernest, Alllan David; Collins, Matthew P.

    2015-08-01

    Observational evidence points to the formation of super-massive black holes, heavy elements and halo structure much earlier in cosmic history than expected [1], and this is challenging for Lambda Cold Dark Matter (LCDM) theory. However, if photon scattering cross sections were less than expected it becomes possible for halos to form at earlier times and relax the tensions that exist with LCDM theory. This may indeed be the case: it has recently been shown [2,3] that photon-particle scattering cross sections vary significantly with the eigenspectral distribution of the scattering particle in deep gravity wells, an effect that depends on the degree of localization of the particle wavefunction and the proximity of the halo to thermal equilibrium. Cross sections tend to be lower the larger and deeper the gravitational well. This purely quantum effect means that accepted cross sections, as measured on Earth and used to determine the rate and timing of halo formation, may not be applicable to deep gravity wells, not only at the present epoch but throughout cosmic history.By combining reduced photon scattering cross sections with Carr’s primordial black hole mass spectrum formulation[4] calculated at the last phase transition (t = 1 s), it is possible to provide a scenario of halo formation that enables galaxies and halos to form much earlier in cosmic history, yet maintain consistency with cosmic microwave background observations and primordial nucleosynthesis. In addition this scenario provides a unified model relating globular clusters, dwarf spheroidal galaxies and bulges, enables an understanding of the black hole-bulge/black hole-dark halo relations, and enables prediction of dark to visible matter, based on the physical parameters of a halo. This scenario will be presented and discussed.[1] Xue-Bing Wu et al, 2015, Nature, 518,512-515 doi: 10.1038/nature14241[2] Ernest A. D., 2009, J. Phys. A: Math. Theor. 42 115207, 115208[3] Ernest A. D, 2012, in Advances in

  18. Cosmic expansion history from SN Ia data via information field theory

    CERN Document Server

    Porqueres, Natàlia; Greiner, Maksim; Böhm, Vanessa; Dorn, Sebastian; Ruiz-Lapuente, Pilar; Manrique, Alberto

    2016-01-01

    We present a novel inference algorithm that reconstructs the cosmic expansion history as encoded in the Hubble parameter $H(z)$ from SNe Ia data. The novelty of the approach lies in the usage of information field theory, a statistical field theory that is very well suited for the construction of optimal signal recovery algorithms. The algorithm infers non-parametrically $s(a)=\\ln(\\rho(a)/\\rho_{\\mathrm{crit}0})$, the density evolution which determines $H(z)$, without assuming an analytical form of $\\rho(a)$ but only its smoothness with the scale factor $a=(1+z)^{-1}$. The inference problem of recovering the signal $s(a)$ from the data is formulated in a fully Bayesian way. In detail, we rewrite the signal as the sum of a background cosmology and a perturbation. This allows to determine the maximum a posteriory estimate of the signal by an iterative Wiener filter method. Applying this method to the Union2.1 supernova compilation, we recover a cosmic expansion history that is fully compatible with the standard $...

  19. Annama H chondrite—Mineralogy, physical properties, cosmic ray exposure, and parent body history

    Science.gov (United States)

    Kohout, TomáÅ.¡; Haloda, Jakub; Halodová, Patricie; Meier, Matthias M. M.; Maden, Colin; Busemann, Henner; Laubenstein, Matthias; Caffee, Marc. W.; Welten, Kees C.; Hopp, Jens; Trieloff, Mario; Mahajan, Ramakant R.; Naik, Sekhar; Trigo-Rodriguez, Josep M.; Moyano-Cambero, Carles E.; Oshtrakh, Michael I.; Maksimova, Alevtina A.; Chukin, Andrey V.; Semionkin, Vladimir A.; Karabanalov, Maksim S.; Felner, Israel; Petrova, Evgeniya V.; Brusnitsyna, Evgeniia V.; Grokhovsky, Victor I.; Yakovlev, Grigoriy A.; Gritsevich, Maria; Lyytinen, Esko; Moilanen, Jarmo; Kruglikov, Nikolai A.; Ishchenko, Aleksey V.

    2017-08-01

    The fall of the Annama meteorite occurred early morning (local time) on April 19, 2014 on the Kola Peninsula (Russia). Based on mineralogy and physical properties, Annama is a typical H chondrite. It has a high Ar-Ar age of 4.4 Ga. Its cosmic ray exposure history is atypical as it is not part of the large group of H chondrites with a prominent 7-8 Ma peak in the exposure age histograms. Instead, its exposure age is within uncertainty of a smaller peak at 30 ± 4 Ma. The results from short-lived radionuclides are compatible with an atmospheric pre-entry radius of 30-40 cm. However, based on noble gas and cosmogenic radionuclide data, Annama must have been part of a larger body (radius >65 cm) for a large part of its cosmic ray exposure history. The 10Be concentration indicates a recent (3-5 Ma) breakup which may be responsible for the Annama parent body size reduction to 30-35 cm pre-entry radius.

  20. A bridge between unified cosmic history by $f(R)$-gravity and BIonic system

    CERN Document Server

    Sepehri, Alireza; Setare, Mohammad Reza

    2015-01-01

    Recently, the cosmological deceleration-acceleration transition redshift in $f(R)$ gravity has been considered in order to address consistently the problem of cosmic evolution. It is possible to show that the deceleration parameter changes sign at a given redshift according to observational data. Furthermore, a $f(R)$ gravity cosmological model can be constructed in brane-antibrane system starting from the very early universe and accounting for the cosmological redshift at all phases of cosmic history, from inflation to late time acceleration. Here we propose a $f(R)$ model where transition redshifts correspond to inflation-deceleration and deceleration-late time acceleration transitions starting froma BIon system. At the point where the universe was born, due to the transition of $k$ black fundamental strings to the BIon configuration, the redshift is approximately infinity and decreases with reducing temperature ($z\\sim T^{2}$). The BIon is a configuration in flat space of a universe-brane and a parallel an...

  1. Active Galactic Nuclei - the Physics of Individual Sources and the Cosmic History of Formation and Evolution

    CERN Document Server

    Treister, Ezequiel

    2013-01-01

    In this paper we give a brief review of the astrophysics of active galactic nuclei (AGN). After a general introduction motivating the study of AGNs, we discuss our present understanding of the inner workings of the central engines, most likely accreting black holes with masses between a million and ten billion solar masses. We highlight recent results concerning the jets (collimated outflows) of AGNs derived from X-ray observations (Chandra) of kpc-scale jets and gamma-ray observations of AGNs (Fermi, Cherenkov telescopes) with jets closely aligned with the lines of sight (blazars), and discuss the interpretation of these observations. Subsequently, we summarize our knowledge about the cosmic history of AGN formation and evolution. We conclude with a description of upcoming observational opportunities.

  2. Cosmic Star Formation History from Local Observations and an Outline for Galaxy Formation and Evolution

    CERN Document Server

    Hartwick, F D A

    2004-01-01

    The goal of this investigation is to reconstruct the cosmic star formation rate density history from local observations and in doing so to gain insight into how galaxies might have formed and evolved. A new chemical evolution model is described which accounts for the formation of globular clusters as well as the accompanying field stars. When this model is used in conjunction with the observed age metallicity relations for the clusters and with input which allows for the formation of the nearly universally observed bimodal distribution of globular clusters, star formation rates are obtained. By confining attention to a representative volume of the local universe, these rates allow a successful reconstruction of the Madau plot while complementary results similtaneously satisfy many local cosmological constraints. A physical framework for galaxy formation is presented which incorporates the results from this chemical evolution model and assumes an anisotropic collapse. In addition to providing the `classical' h...

  3. The WiggleZ Dark Energy Survey: measuring the cosmic growth rate with the two-point galaxy correlation function

    CERN Document Server

    Contreras, Carlos; Poole, Gregory B; Marin, Felipe; Brough, Sarah; Colless, Matthew; Couch, Warrick; Croom, Scott; Croton, Darren; Davis, Tamara M; Drinkwater, Michael J; Forster, Karl; Gilbank, David; Gladders, Mike; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J; Li, I-hui; Madore, Barry; Martin, D Christopher; Pimbblet, Kevin; Pracy, Michael; Sharp, Rob; Wisnioski, Emily; Woods, David; Wyder, Ted K; Yee, H K C; 10.1093/mnras/sts608

    2013-01-01

    The growth history of large-scale structure in the Universe is a powerful probe of the cosmological model, including the nature of dark energy. We study the growth rate of cosmic structure to redshift $z = 0.9$ using more than $162{,}000$ galaxy redshifts from the WiggleZ Dark Energy Survey. We divide the data into four redshift slices with effective redshifts $z = [0.2,0.4,0.6,0.76]$ and in each of the samples measure and model the 2-point galaxy correlation function in parallel and transverse directions to the line-of-sight. After simultaneously fitting for the galaxy bias factor we recover values for the cosmic growth rate which are consistent with our assumed $\\Lambda$CDM input cosmological model, with an accuracy of around 20% in each redshift slice. We investigate the sensitivity of our results to the details of the assumed model and the range of physical scales fitted, making close comparison with a set of N-body simulations for calibration. Our measurements are consistent with an independent power-spe...

  4. A bridge between unified cosmic history by f( R)-gravity and BIonic system

    Science.gov (United States)

    Sepehri, Alireza; Capozziello, Salvatore; Setare, Mohammad Reza

    2016-04-01

    Recently, the cosmological deceleration-acceleration transition redshift in f( R) gravity has been considered in order to address consistently the problem of cosmic evolution. It is possible to show that the deceleration parameter changes sign at a given redshift according to observational data. Furthermore, a f( R) gravity cosmological model can be constructed in brane-antibrane system starting from the very early universe and accounting for the cosmological redshift at all phases of cosmic history, from inflation to late time acceleration. Here we propose a f( R) model where transition redshifts correspond to inflation-deceleration and deceleration-late time acceleration transitions starting froma BIon system. At the point where the universe was born, due to the transition of k black fundamental strings to the BIon configuration, the redshift is approximately infinity and decreases with reducing temperature (z˜ T2). The BIon is a configuration in flat space of a universe-brane and a parallel anti-universe-brane connected by a wormhole. This wormhole is a channel for flowing energy from extra dimensions into our universe, occurring at inflation and decreasing with redshift as z˜ T^{4+1/7}. Dynamics consists with the fact that the wormhole misses its energy and vanishes as soon as inflation ends and deceleration begins. Approaching two universe branes together, a tachyon is originated, it grows up and causes the formation of a wormhole. We show that, in the framework of f( R) gravity, the cosmological redshift depends on the tachyonic potential and has a significant decrease at deceleration-late time acceleration transition point (z˜ T^{2/3}). As soon as today acceleration approaches, the redshift tends to zero and the cosmological model reduces to the standard Λ CDM cosmology.

  5. Measuring the growth rate of structure around cosmic voids

    Science.gov (United States)

    Hawken, A. J.; Michelett, D.; Granett, B.; Iovino, A.; Guzzo, L.

    2016-10-01

    Using an algorithm based on searching for empty spheres we identified 245 voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS). We show how by modelling the anisotropic void-galaxy cross correlation function we can probe the growth rate of structure.

  6. Growth of Structure in Theories of Cosmic Acceleration

    DEFF Research Database (Denmark)

    Cataneo, Matteo

    , and is currently associated with the energy density of the vacuum. Cold dark matter is the second most abundant constituent of the universe, even though it has not been detected yet. This slowly moving collection of particles forms the scaffolding of the stunning, luminous structures we see with our telescopes...... on the largest scales, eliminating the need for dark energy. Moreover, modifications to General Relativity lead to changes in the formation of structures compared to standard gravity. In particular, the accretion history of collapsed objects, as well as their abundance as a function of mass and time are key...

  7. ZOMG - I. How the cosmic web inhibits halo growth and generates assembly bias

    Science.gov (United States)

    Borzyszkowski, Mikolaj; Porciani, Cristiano; Romano-Díaz, Emilio; Garaldi, Enrico

    2017-07-01

    The clustering of dark matter haloes with fixed mass depends on their formation history, an effect known as assembly bias. We use zoom N-body simulations to investigate the origin of this phenomenon. For each halo at redshift z = 0, we determine the time in which the physical volume containing its final mass becomes stable. We consider five examples for which this happens at z ˜ 1.5 and two that do not stabilize by z = 0. The zoom simulations show that early-collapsing haloes do not grow in mass at z = 0 while late-forming ones show a net inflow. The reason is that 'accreting' haloes are located at the nodes of a network of thin filaments feeding them. Conversely, each 'stalled' halo lies within a prominent filament that is thicker than the halo size. Infalling material from the surroundings becomes part of the filament while matter within it recedes from the halo. We conclude that assembly bias originates from quenching halo growth due to tidal forces following the formation of non-linear structures in the cosmic web, as previously conjectured in the literature. Also the internal dynamics of the haloes change: the velocity anisotropy profile is biased towards radial (tangential) orbits in accreting (stalled) haloes. Our findings reveal the cause of the yet unexplained dependence of halo clustering on the anisotropy. Finally, we extend the excursion-set theory to account for these effects. A simple criterion based on the ellipticity of the linear tidal field combined with the spherical-collapse model provides excellent predictions for both classes of haloes.

  8. Cosmic star formation history and AGN evolution near and far: from AKARI to SPICA

    CERN Document Server

    Goto, Tomotsugu; Matsuhara, Hideo

    2015-01-01

    Infrared (IR) luminosity is fundamental to understanding the cosmic star formation history and AGN evolution, since their most intense stages are often obscured by dust. Japanese infrared satellite, AKARI, provided unique data sets to probe these both at low and high redshifts. The AKARI performed an all sky survey in 6 IR bands (9, 18, 65, 90, 140, and 160$\\mu$m) with 3-10 times better sensitivity than IRAS, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can measure the total infrared luminosity ($L_{TIR}$) of individual galaxies much more precisely, and thus, the total infrared luminosity density of the local Universe. In the AKARI NEP deep field, we construct restframe 8$\\mu$m, 12$\\mu$m, and total infrared (TIR) luminosity functions (LFs) at 0.15$

  9. Probing the physics and history of cosmic reionization with the Sunyaev-Zel'dovich Effect

    CERN Document Server

    Colafrancesco, S; Emritte, M S

    2016-01-01

    We study here an alternative technique to probe the Dark Ages (DA) and the Epoch of Reonization (EoR) that makes use of the Comptonization of the CMB spectrum modified by physical effects occurring during this epoch related to the emergence of the 21-cm radiation background. Inverse Compton scattering of 21-cm photon background by thermal and non-thermal electrons residing in the atmospheres of cosmic structures like galaxy clusters, radiogalaxy lobes and galaxy halos, produces a specific form of Sunyaev-Zel'dovich effect (SZE) that we refer to as SZE-21cm. We derive the SZE-21cm in a general relativistic approach which is required to describe the correct spectral features of this astrophysical effect. We calculate the spectral features of the thermal and non-thermal SZE-21cm in galaxy clusters and in radiogalaxy lobes, and their dependence on the history of physical mechanisms occurring during the DA and EoR. We study how the spectral shape of the SZE-21cm can be used to establish the global features in the ...

  10. Cosmic Star-Formation History Since Z 5 And Faint Radio Populations

    Science.gov (United States)

    Novak, Mladen

    2017-06-01

    We make use of the deep VLA-COSMOS radio observations at 3 GHz to infer radio luminosity functions using approximately 6000 star-forming galaxies and 1800 AGN hosts up to redshift of z 5. This is currently the largest radio-selected sample available out to such high redshift across an area of 2 square degrees with a sensitivity of rms=2.3 ujy/beam. For both populations we find a strong redshift trend that can be fitted with a two-parameter pure luminosity evolution model. We estimate star formation rates (SFR) from our radio luminosities using an IR-radio correlation that is redshift dependent. Our data suggest that the cosmic SFR density (SFRD) history peaks about z 2.5 and that the ultraluminous infrared galaxies contribute up to 25% to the total SFRD at the same redshift. We find evidence of a potential underestimation of SFRD based on UV rest-frame observations of Lyman break galaxies. Finally, we use our evolution models to calculate the radio source counts down to SKA sensitivity limits thus providing better constraints for the next generation radio surveys.

  11. Cosmic star formation history and AGN evolution near and far: AKARI reveals both

    CERN Document Server

    Goto, Tomotsugu

    2015-01-01

    Understanding infrared (IR) luminosity is fundamental to understanding the cosmic star formation history and AGN evolution, since their most intense stages are often obscured by dust. Japanese infrared satellite, AKARI, provided unique data sets to probe this both at low and high redshifts. The AKARI performed all sky survey in 6 IR bands (9, 18, 65, 90, 140, and 160$\\mu$m) with 3-10 times better sensitivity than IRAS, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can much more precisely measure the total infrared luminosity ($L_{TIR}$) of individual galaxies, and thus, the total infrared luminosity density of the local Universe. In the AKARI NEP deep field, we construct restframe 8$\\mu$m, 12$\\mu$m, and total infrared (TIR) luminosity functions (LFs) at 0.15$

  12. Precision growth index using the clustering of cosmic structures

    CERN Document Server

    Pouri, Athina; Plionis, Manolis

    2014-01-01

    We use the clustering properties of Luminous Red Galaxies (LRGs) and of SDSS rich galaxy clusters in order to constrain the growth index ($\\gamma$) of the linear matter fluctuations. We perform a standard $\\chi^2$-minimization procedure between theoretical expectations and data, followed by a joint likelihood analysis and we find a value of $\\gamma=0.54\\pm 0.03$, perfectly consistent with the expectations of the $\\Lambda$CDM model, and $\\Omega_{m0} =0.30\\pm 0.01$, in excellent agreement with the latest Planck results. Our analysis provides significantly more stringent growth index constraints with respect to previous studies, as indicated by the fact that the corresponding uncertainty is only $\\sim 0.06 \\gamma$. Finally, allowing $\\gamma$ to vary with redshift we find degeneracies among the model parameters, as other similar studies. In order to alleviate the degeneracy we utilize a combined statistical analysis between our clustering and literature growth data and obtain more stringent constraints with respe...

  13. Lunar Meteorite QUE 93069: History Derived from Cosmic-Ray-Produced and Trapped Noble Gases

    Science.gov (United States)

    Thalmann, Ch.; Eugster, O.

    1995-09-01

    We obtained lunar meteorite QUE 93069,7 (0.304 g) from the NASA/MWG for the determination of its noble gas isotopic abundances and exposure history. The data relevant for the discussion of the exposure history and trapped noble gases are given in Tables 1 and 2. Exposure history: The duration of Moon-Earth transfer was determined by Nishiizumi et al. [1]. Based on 10Be these authors obtained 1.9 +/- 0.4 Ma for a 4 pi model (all radionuclides produced in 4 pi space) and MAC 88105 and ALHA 81005). QUE 93069 shows the longest exposure to cosmic rays (1100 +/- 400 Ma) of all lunar meteorites if we compare the T38 values. Based on 21Nec we obtain 420 +/- 60 Ma. Typically for lunar surface material the T21 are lower than those based on 38Arc, 83Krc, and 126Xec due to 21Ne loss. This effect is also observed for MAC 88105 and ALHA 81005. Characteristics of the trapped noble gases: The long lunar surface residence time and the shallow shielding depth are consistent with the very large amounts of trapped solar wind particles (20Ne and 36Ar, Table 1) for QUE 93069. The concentration of trapped 36Ar is quite similar to that of Y-791197: Takaoka [3] and Ostertag et al. [4] obtained 33900 and 36600 x 10-8 cm3 STP/g, respectively. The trapped ratio 40Ar/36Ar, an antiquity indicator for lunar soil, yields information on the time when the breccia was compacted from regolith material [5]. For QUE 93069 we obtain (40Ar/36Ar)trapped = 1.9 +/- 0.1 indicating exposure of the breccia material on the lunar surface about 600 Ma ago. Conclusions: Based on 38Arc the lunar surface exposure to cosmic rays for QUE 93069 lasted about 1100 +/- 400 Ma, similar to Y-791197, about twice as long as for ALHA 81005, and about seven times longer than for MAC 88104/5. The trapped 40Ar/36Ar ratio of 1.9 +/- 0.1 suggests that exposure to solar particles occured around 600 Ma ago. Since relatively large amounts of solar wind particles were accumulated, it is reasonable to assume that most cosmogenic noble

  14. A Brief History of Bacterial Growth Physiology

    Directory of Open Access Journals (Sweden)

    Moselio eSchaechter

    2015-04-01

    Full Text Available Arguably, microbial physiology started when Leeuwenhoek became fascinated by observing a Vorticella beating its cilia, my point being that almost any observation of microbes has a physiological component. With the advent of modern microbiology in the mid 19th century, the field became recognizably distinctive with such discoveries as anaerobiosis, fermentation as a biological phenomenon, and the nutritional requirements of microbes. Soon came the discoveries of Winogradsky and his followers of the chemical changes in the environment that result from microbial activities. Later, during the first half of the 20th century, microbial physiology became the basis for much of the elucidation of central metabolism.Bacterial physiology then became a handmaiden of molecular biology and was greatly influenced by the discovery of cellular regulatory mechanisms. Microbial growth, which had come of age with the early work of Hershey, Monod, and others, was later pursued by studies on a whole cell level by what became known as the Copenhagen School. During this time, the exploration of physiological activities became coupled to modern inquiries into the structure of the bacterial cell.Recent years have seen the development of a further phase in microbial physiology, one seeking a deeper quantitative understanding of phenomena on a whole cell level. This pursuit is exemplified by the emergence of systems biology, which is made possible by the development of technologies that permit the gathering of information in huge amounts. As has been true through history, the research into microbial physiology continues to be guided by the development of new methods of analysis. Some of these developments may well afford the possibility of making stunning breakthroughs.

  15. A brief history of bacterial growth physiology.

    Science.gov (United States)

    Schaechter, Moselio

    2015-01-01

    Arguably, microbial physiology started when Leeuwenhoek became fascinated by observing a Vorticella beating its cilia, my point being that almost any observation of microbes has a physiological component. With the advent of modern microbiology in the mid-19th century, the field became recognizably distinctive with such discoveries as anaerobiosis, fermentation as a biological phenomenon, and the nutritional requirements of microbes. Soon came the discoveries of Winogradsky and his followers of the chemical changes in the environment that result from microbial activities. Later, during the first half of the 20th century, microbial physiology became the basis for much of the elucidation of central metabolism. Bacterial physiology then became a handmaiden of molecular biology and was greatly influenced by the discovery of cellular regulatory mechanisms. Microbial growth, which had come of age with the early work of Hershey, Monod, and others, was later pursued by studies on a whole cell level by what became known as the "Copenhagen School." During this time, the exploration of physiological activities became coupled to modern inquiries into the structure of the bacterial cell. Recent years have seen the development of a further phase in microbial physiology, one seeking a deeper quantitative understanding of phenomena on a whole cell level. This pursuit is exemplified by the emergence of systems biology, which is made possible by the development of technologies that permit the gathering of information in huge amounts. As has been true through history, the research into microbial physiology continues to be guided by the development of new methods of analysis. Some of these developments may well afford the possibility of making stunning breakthroughs.

  16. Probing the interstellar dust in galaxies over >10 Gyr of cosmic history

    Science.gov (United States)

    Kulkarni, Varsha P.; Aller, Monique C.; York, Donald G.; Welty, Daniel E.; Vladilo, Giovanni; Som, Debopam

    2016-11-01

    Dust has a profound effect on the physics and chemistry of the interstellar gas in galaxies and on the appearance of galaxies. Understanding the cosmic evolution of dust with time is therefore crucial for understanding the evolution of galaxies. Despite the importance of interstellar dust, very little is known about its nature and composition in distant galaxies. We summarize the results of our ongoing programs using observations of distant quasars to obtain better constraints on dust grains in foreground galaxies that happen to lie along the quasar sightlines. These observations consist of a combination of mid-infrared data obtained with the Spitzer Space Telescope and optical/UV data obtained with ground-based telescopes and/or the Hubble Space Telescope. The mid-IR data target the 10 μm and 18 μm silicate absorption features, while the optical/UV data allow determinations of element depletions, extinction curves, 2175 Å bumps, etc. Measurements of such properties in absorption-selected galaxies with redshifts ranging from z 0 to z > 2 provide constraints on the evolution of interstellar dust over the past > 10 Gyr . The optical depth of the 10 μm silicate absorption feature (τ10) in these galaxies is correlated with the amount of reddening along the sightline. But there are indications (e.g., based on the τ10 / E(B - V) ratio and possible grain crystallinity) that the dust in these distant galaxies differs in structure and composition from the dust in the Milky Way and the Magellanic Clouds. We briefly discuss the implications of these results for the evolution of galaxies and their star formation history.

  17. History of cosmic evolution with modified Gauss-Bonnet-dilatonic coupled term

    CERN Document Server

    Debnath, Subhra; Mandal, Ranajit; Sanyal, Abhik Kumar

    2016-01-01

    Gauss-Bonnet-dilatonic coupling in four dimension plays an important role to explain late time cosmic evolution. However, this term is an outcome of low energy string effective action and thus ought to be important in the early universe too. Unfortunately, phase-space formulation of such a theory does not exist in the literature due to branching. We therefore consider a modified theory of gravity, which contains a nonminimally coupled scalar-tensor sector in addition to higher order scalar curvature invariant term with Gauss-Bonnet-dilatonic coupling. Such an action unifies early inflation with late-time cosmic acceleration. Quantum version of the theory is also well-behaved.

  18. The History of the Limits to Growth

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen; Ragnarsdóttir, Kristín Vala; Peet, John

    2010-01-01

    The report The Limits to Growth was in many ways a breakthrough in the way the future was debated and analysed as far as the physical economy was concerned. The paper describes how the very title seems to have offended many people, leading a cohort of critics to reject the report as a doomsday...

  19. The WiggleZ Dark Energy Survey: the growth rate of cosmic structure since redshift z=0.9

    OpenAIRE

    Blake, Chris; Brough, Sarah; Colless, Matthew; Contreras, Carlos; Couch, Warrick; Croom, Scott; Davis, Tamara; Drinkwater, Michael J.; Forster, Karl; Gilbank, David; Gladders, Mike; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J; Li, I-hui

    2011-01-01

    We present precise measurements of the growth rate of cosmic structure for the redshift range 0.1 < z < 0.9, using redshift-space distortions in the galaxy power spectrum of the WiggleZ Dark Energy Survey. Our results, which have a precision of around 10% in four independent redshift bins, are well-fit by a flat LCDM cosmological model with matter density parameter Omega_m = 0.27. Our analysis hence indicates that this model provides a self-consistent description of the growth of cosmic struc...

  20. History of cosmic evolution with modified Gauss-Bonnet-dilatonic coupled term

    Energy Technology Data Exchange (ETDEWEB)

    Debnath, Subhra; Sanyal, Abhik Kumar [Jangipur College, Department of Physics, Murshidabad (India); Ruz, Soumendra Nath [Ramananda Centenary College, Department of Physics, Purulia (India); Mandal, Ranajit [University of Kalyani, Department of Physics, Nadia (India)

    2017-05-15

    Gauss-Bonnet-dilatonic coupling in four dimensions plays an important role to explain late-time cosmic evolution. However, this term is an outcome of the low energy string effective action and thus ought to be important in the early universe too. Unfortunately, a phase-space formulation of such a theory does not exist in the literature due to branching. We therefore consider a modified theory of gravity, which contains a nonminimally coupled scalar-tensor sector in addition to a higher-order scalar curvature invariant term with Gauss-Bonnet-dilatonic coupling. Such an action unifies early inflation with late-time cosmic acceleration. The quantum version of the theory is also well behaved. (orig.)

  1. Cosmic ray produced Be-10 and Al-26 in Antarctic rocks - Exposure and erosion history

    Science.gov (United States)

    Nishiizumi, K.; Kohl, C. P.; Arnold, J. R.; Klein, J.; Fink, D.

    1991-01-01

    Cosmic-ray produced Be-10 and Al-26 were measured in purified quartz fractions of selected rock samples from Antarctic mountains. From these data, mean erosion rates were calculated for the limiting case of steady-state surface exposure to cosmic rays, and minimum exposure ages, for the limiting case of no erosion. Calculated mean erosion rates are very low, on the order of a few times 0.00001 cm/yr; the sampling is believed to be sufficient to generalize this result to exposed bedrock in Antarctica. In favorable cases it is possible to distinguish between the limiting cases; steady-state erosion seems a better description in such cases. Most samaples, including some taken a few meters above the present ice level, seem to have been exposed for millions of years, without major episodes of burial or abrasion by ice.

  2. The Formation of Supermassive Black Holes from Population III Seeds. I. Cosmic Formation Histories

    CERN Document Server

    Banik, Nilanjan; Monaco, Pierluigi

    2016-01-01

    We model the cosmic distributions in space and time of the formation sites of the first stars that may be the progenitors of supermassive black holes (SMBHs). Pop III.1 stars are defined to form in dark matter minihalos (i.e., with masses $\\sim10^6\\:M_\\odot$) that are isolated from neighboring astrophysical sources by a given isolation distance, $d_{\\rm iso}$. We assume these sources are the seeds for the cosmic population of SMBHs, based on a model of protostellar support by dark matter annihilation heating that allows these objects to accrete most of the baryonic content of their minihalos, i.e., $\\gtrsim10^5\\:M_\\odot$. Exploring a range of $d_{\\rm iso}$ from 10 to 100~kpc (proper distances), we predict the evolution with redshift of the number density of these Pop III.1 sources and their SMBH remnants. In the context of this model, the local, $z=0$ density of SMBHs constrains $d_{\\rm iso}\\gtrsim100$~kpc (i.e., a comoving distance of 3~Mpc at $z\\simeq30$). In our simulated ($\\sim$40.96 $h^{-1}$~Mpc)$^3$ com...

  3. Probing the Interstellar Dust in Galaxies over > 10 Gyr of Cosmic History

    CERN Document Server

    Kulkarni, Varsha P; York, Donald G; Welty, Daniel E; Vladilo, Giovanni; Som, Debopam

    2016-01-01

    This article is based on an invited talk given by V. P. Kulkarni at the 8th Cosmic Dust meeting. Dust has a profound effect on the physics and chemistry of the interstellar gas in galaxies and on the appearance of galaxies. Understanding the cosmic evolution of dust with time is therefore crucial for understanding the evolution of galaxies. Despite the importance of interstellar dust, very little is known about its nature and composition in distant galaxies. We summarize the results of our ongoing programs using observations of distant quasars to obtain better constraints on dust grains in foreground galaxies that happen to lie along the quasar sightlines. These observations consist of a combination of mid-infrared data obtained with the Spitzer Space Telescope and optical/UV data obtained with ground-based telescopes and/or the Hubble Space Telescope. The mid-IR data target the 10 $\\mu$m and 18 $\\mu$m silicate absorption features, while the optical/UV data allow determinations of element depletions, extincti...

  4. Precision growth index using the clustering of cosmic structures and growth data

    Energy Technology Data Exchange (ETDEWEB)

    Pouri, Athina; Basilakos, Spyros [Academy of Athens, Research Center for Astronomy and Applied Mathematics, Soranou Efesiou 4, 11527, Athens (Greece); Plionis, Manolis, E-mail: athpouri@phys.uoa.gr, E-mail: svasil@academyofathens.gr, E-mail: mplionis@physics.auth.gr [Physics Dept., Sector of Astrophysics, Astronomy and Mechanics, Aristotle Univ. of Thessaloniki, Thessaloniki 54124 (Greece)

    2014-08-01

    We use the clustering properties of Luminous Red Galaxies (LRGs) and the growth rate data provided by the various galaxy surveys in order to constrain the growth index γ) of the linear matter fluctuations. We perform a standard χ{sup 2}-minimization procedure between theoretical expectations and data, followed by a joint likelihood analysis and we find a value of γ=0.56± 0.05, perfectly consistent with the expectations of the ΛCDM model, and Ω{sub m0} =0.29± 0.01, in very good agreement with the latest Planck results. Our analysis provides significantly more stringent growth index constraints with respect to previous studies, as indicated by the fact that the corresponding uncertainty is only ∼ 0.09 γ. Finally, allowing γ to vary with redshift in two manners (Taylor expansion around z=0, and Taylor expansion around the scale factor), we find that the combined statistical analysis between our clustering and literature growth data alleviates the degeneracy and obtain more stringent constraints with respect to other recent studies.

  5. Lifetime growth in wild meerkats: incorporating life history and environmental factors into a standard growth model.

    Science.gov (United States)

    English, Sinéad; Bateman, Andrew W; Clutton-Brock, Tim H

    2012-05-01

    Lifetime records of changes in individual size or mass in wild animals are scarce and, as such, few studies have attempted to model variation in these traits across the lifespan or to assess the factors that affect them. However, quantifying lifetime growth is essential for understanding trade-offs between growth and other life history parameters, such as reproductive performance or survival. Here, we used model selection based on information theory to measure changes in body mass over the lifespan of wild meerkats, and compared the relative fits of several standard growth models (monomolecular, von Bertalanffy, Gompertz, logistic and Richards). We found that meerkats exhibit monomolecular growth, with the best model incorporating separate growth rates before and after nutritional independence, as well as effects of season and total rainfall in the previous nine months. Our study demonstrates how simple growth curves may be improved by considering life history and environmental factors, which may be particularly relevant when quantifying growth patterns in wild populations.

  6. Cosmic-ray exposure histories of the lunar meteorites AaU 012 and Shişr 166

    Science.gov (United States)

    Mészáros, Marianna; Leya, Ingo; Hofmann, Beda A.

    2017-09-01

    We measured the concentrations and isotopic compositions of the stable isotopes of He, Ne, Ar, Kr, and Xe in the two lunar impact-melt breccias Abar al' Uj (AaU) 012 and Shişr 166 to obtain information on their cosmic-ray exposure histories and possible launch pairing; the latter was suggested because of their similar chemical composition. AaU 012 has higher gas concentrations than Shişr 166 and clearly contains implanted solar wind gases, indicating a shallow to moderate shielding for this meteorite in the lunar regolith. The maximum shielding depth of AaU 012 was most likely ≤310 g cm-2 and its lunar regolith residence time was ≥420 ± 70 Ma. Our results indicate that in Shişr 166 the trapped component is a mixture of air and solar wind. The low concentration of cosmogenic and solar wind gases indicate substantial diffusive gas loss and a shielding depth of exposure history on the Moon does not exclude the possibility that the two meteorites were ejected by a single, large impact event.

  7. Petrology, mineralogy, porosity, and cosmic-ray exposure history of Huaxi ordinary chondrite

    Science.gov (United States)

    Li, Shijie; Wang, Shijie; Leya, Ingo; Li, Yang; Li, Xiongyao; Smith, Thomas

    2017-05-01

    A meteorite fall was heard and collected on July 13, 2010 at about 18:00 (local time) in the Shibanjing village of the Huaxi district of Guiyang, Guizhou province, China. The total mass of the fall is estimated to be at least 1.6 kg; some fragments are missing. The meteorite consists mainly of olivine, low-Ca pyroxene, high-Ca pyroxene, plagioclase, kamacite, taenite, and troilite. Minor phases include chromite and apatite. Various textural types of chondrules exist in this meteorite: most chondrule textures can be easily defined. The grain sizes of secondary plagioclase in this meteorite range from 2 to 50 μm. The chemical composition of olivine and low-Ca pyroxene are uniform; Fa in olivine and Fs in low-Ca pyroxene are, respectively, 19.6 ± 0.2 and 17.0 ± 0.3 (mole%). Huaxi has been classified as an H5 ordinary chondrite, with a shock grade S2, and weathering W0. The weak shock features, rare fractures, and the high porosity (17.6%) indicates that Huaxi is a less compacted meteorite. The preatmospheric radius of Huaxi is 11 cm, corresponding to 21 kg. The meteorite experienced a relatively short cosmic-ray exposure of about 1.6 ± 0.1 Ma. The 4He and 40Ar retention ages are older than 4.6 Ga implying that Huaxi did not degas after thermal metamorphism on its parent body.

  8. Intensity Mapping of the History of Stellar Emission with the Cosmic Infrared Background ExpeRiment-2

    Science.gov (United States)

    Lanz, Alicia E.; Arai, Toshiaki; Battle, John; Bock, James; Cooray, Asantha R.; Hristov, Viktor; Korngut, Phillip; Lee, Dae Hee; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Onishi, Yosuke; Shirahata, Mai; Tsumurai, Kohji; Wada, Takehiko; Zemcov, Michael B.

    2016-01-01

    Recent measurements of the near-infrared Extragalactic Background Light (EBL) anisotropy find excess spatial power above the level predicted by known galaxy populations at large angular scales. These anisotropies trace spatial variations in integrated photon production, so measurements of EBL surface brightness fluctuations provide a complete census of the emission from stars summed over cosmic history. As a result, EBL fluctuations contain contributions from objects forming during the Epoch of Reionization (EOR), from the integrated galactic light (IGL), and faint, extended components such as intra-halo light (IHL) from stars tidally stripped from galaxies during merger events. Additional measurements with greater sensitivity, spectral range, and spectral resolution are required to disentangle these contributions.The Cosmic Infrared Background ExpeRiment 2 (CIBER-2) is an instrument optimized for the measurement of near-infrared EBL anisotropies. As the Earth's atmosphere generates time-varying near-infrared emission, CIBER-2 is launched on a sounding rocket from which it will carry out multiwavelength imaging in six spectral bands that span the visible to near-infrared. The 2.4 square degree images allow CIBER-2 to produce measurements of EBL fluctuations with high fidelity on large angular scales. The Lyman break feature from EOR sources provides a unique spectral feature which can be used to disentangle the high from the low redshift contributions to the anisotropy signal. Measurement in six independent wavebands allows detailed cross-correlation studies to constrain the source of the excess fluctuations at large angular scales. We provide an overview of the CIBER-2 instrument and explain CIBER-2 spectral feature identification and cross-correlation study methodologies.

  9. DISSECTING THE PROPERTIES OF OPTICALLY THICK HYDROGEN AT THE PEAK OF COSMIC STAR FORMATION HISTORY

    Energy Technology Data Exchange (ETDEWEB)

    Fumagalli, Michele [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); O' Meara, John M. [Department of Chemistry and Physics, Saint Michael' s College, Colchester, VT 05439 (United States); Prochaska, J. Xavier [University of California Observatories-Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Worseck, Gabor, E-mail: mfumagalli@obs.carnegiescience.edu [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)

    2013-09-20

    We present the results of a blind survey of Lyman limit systems (LLSs) detected in absorption against 105 quasars at z ∼ 3 using the blue sensitive MagE spectrograph at the Magellan Clay telescope. By searching for Lyman limit absorption in the wavelength range λ ∼ 3000-4000 Å, we measure the number of LLSs per unit redshift l(z) = 1.21 ± 0.28 at z ∼ 2.8. Using a stacking analysis, we further estimate the mean free path of ionizing photons in the z ∼ 3 universe λ{sub mfp}{sup 912} = 100 ± 29 h{sub 70.4}{sup -1} Mpc. Combined with our LLS survey, we conclude that systems with log N{sub HI} ≥ 17.5 cm{sup –2} contribute only ∼40% to the observed mean free path at these redshifts. Furthermore, with the aid of photoionization modeling, we infer that a population of ionized and metal poor systems is likely required to reproduce the metal line strengths observed in a composite spectrum of 20 LLSs with log N{sub HI} ∼ 17.5-19 cm{sup –2} at z ∼ 2.6-3.0. Finally, with a simple toy model, we deduce that gas in the halos of galaxies can alone account for the totality of LLSs at z ∼< 3, but a progressively higher contribution from the intergalactic medium is required beyond z ∼ 3.5. We also show how the weakly evolving number of LLSs per unit redshift at z ∼< 3 can be modeled either by requiring that the spatial extent of the circumgalactic medium is redshift invariant in the last ∼10 Gyr of cosmic evolution or by postulating that LLSs arise in halos that are rare fluctuations in the density field at each redshift.

  10. The WiggleZ Dark Energy Survey: the growth rate of cosmic structure since redshift z=0.9

    CERN Document Server

    Blake, Chris; Colless, Matthew; Contreras, Carlos; Couch, Warrick; Croom, Scott; Davis, Tamara; Drinkwater, Michael J; Forster, Karl; Gilbank, David; Gladders, Mike; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J; Li, I-hui; Madore, Barry; Martin, Chris; Pimbblet, Kevin; Poole, Gregory; Pracy, Michael; Sharp, Rob; Wisnioski, Emily; Woods, David; Wyder, Ted; Yee, Howard

    2011-01-01

    We present precise measurements of the growth rate of cosmic structure for the redshift range 0.1 < z < 0.9, using redshift-space distortions in the galaxy power spectrum of the WiggleZ Dark Energy Survey. Our results, which have a precision of around 10% in four independent redshift bins, are well-fit by a flat LCDM cosmological model with matter density parameter Omega_m = 0.27. Our analysis hence indicates that this model provides a self-consistent description of the growth of cosmic structure through large-scale perturbations and the homogeneous cosmic expansion mapped by supernovae and baryon acoustic oscillations. We achieve robust results by systematically comparing our data with several different models of the quasi-linear growth of structure including empirical models, fitting formulae calibrated to N-body simulations, and perturbation theory techniques. We extract the first measurements of the power spectrum of the velocity divergence field, P_vv(k), as a function of redshift (under the assump...

  11. The dust un-biased cosmic star formation history from the 20 cm VLA-COSMOS survey

    CERN Document Server

    Smolcic, V; Zamorani, G; Bell, E F; Bondi, M; Carilli, C L; Ciliegi, P; Mobasher, B; Paglione, T; Scodeggio, M; Scoville, N

    2008-01-01

    We derive the cosmic star formation history (CSFH) out to z=1.3 using a sample of ~350 radio-selected star-forming galaxies, a far larger sample than in previous, similar studies. We attempt to differentiate between radio emission from AGN and star-forming galaxies, and determine an evolving 1.4 GHz luminosity function based on these VLA-COSMOS star forming galaxies. We precisely measure the high-luminosity end of the star forming galaxy luminosity function (SFR>100 M_Sol/yr; equivalent to ULIRGs) out to z=1.3, finding a somewhat slower evolution than previously derived from mid-infrared data. We find that more stars are forming in luminous starbursts at high redshift. We use extrapolations based on the local radio galaxy luminosity function; assuming pure luminosity evolution, we derive $L_* \\propto (1+z)^{2.1 \\pm 0.2}$ or $L_* \\propto (1+z)^{2.5 \\pm 0.1}$, depending on the choice of the local radio galaxy luminosity function. Thus, our radio-derived results independently confirm the ~1 order of magnitude de...

  12. From Haloes to Galaxies - I: The dynamics of the gas regulator model and the implied cosmic sSFR-history

    CERN Document Server

    Peng, Yingjie

    2014-01-01

    We explore the basic parameters that drive the evolution of the fundamental properties of star forming galaxies within the gas regulator model, or bathtub-model. We derive the general analytic form of the evolution of the key galaxy properties, i.e. gas mass, star formation rate (SFR), stellar mass, specific SFR, gas fraction, gas phase metallicity and stellar metallicity, without assuming that galaxies live in the equilibrium state. We find that the timescale required to reach equilibrium, tau_eq, which is determined by the product of star-formation efficiency and mass-loading factor, is the central parameter in the gas regulator model that is essentially in control of the evolution of all key galaxy properties. The scatters in most of the key scaling relations are primarily governed by tau_eq. Most strikingly, the predicted sSFR evolution is controlled solely by tau_eq (apart from the cosmic time). Although the precise evolution of the sSFR depends on tau_eq, the sSFR history is largely insensitive to diffe...

  13. Background history and cosmic perturbations for a general system of self-conserved dynamical dark energy and matter

    CERN Document Server

    Gomez-Valent, Adria; Sola, Joan

    2015-01-01

    We determine the Hubble expansion and the general cosmic perturbations equations for a general system consisting of self-conserved matter and self-conserved dark energy (DE). While at the background level the two components are non-interacting, they do interact at the perturbations level. We show that the coupled system of matter and DE perturbations can be transformed into a single, third order, matter perturbation equation, which reduces to the (derivative of the) standard one in the case that the DE is just a cosmological constant. As a nontrivial application we analyze a class of dynamical models whose DE density $\\rho_D$ consists of a constant term, $C_0$, and a series of powers of the Hubble rate. These models were previously analyzed from the point of view of dynamical vacuum models, but here we treat them as self-conserved DE models with a dynamical equation of state. We fit them to the wealth of expansion history and linear structure formation data and compare the obtained fit quality with that of th...

  14. The growth of typical star-forming galaxies and their supermassive black holes across cosmic time since z ˜ 2

    Science.gov (United States)

    Calhau, João; Sobral, David; Stroe, Andra; Best, Philip; Smail, Ian; Lehmer, Bret; Harrison, Chris; Thomson, Alasdair

    2017-01-01

    Understanding galaxy formation and evolution requires studying the interplay between the growth of galaxies and the growth of their black holes across cosmic time. Here, we explore a sample of Hα-selected star-forming galaxies from the High Redshift Emission Line Survey and use the wealth of multiwavelength data in the Cosmic Evolution Survey field (X-rays, far-infrared and radio) to study the relative growth rates between typical galaxies and their central supermassive black holes, from z = 2.23 to z = 0. Typical star-forming galaxies at z ˜ 1-2 have black hole accretion rates (dot{M}_BH) of 0.001-0.01 M⊙ yr-1 and star formation rates (SFRs) of ˜10-40 M⊙ yr-1, and thus grow their stellar mass much quicker than their black hole mass (3.3±0.2 orders of magnitude faster). However, ˜3 per cent of the sample (the sources detected directly in the X-rays) show a significantly quicker growth of the black hole mass (up to 1.5 orders of magnitude quicker growth than the typical sources). dot{M}_BH falls from z = 2.23 to z = 0, with the decline resembling that of SFR density or the typical SFR (SFR*). We find that the average black hole to galaxy growth (dot{M}_BH/SFR) is approximately constant for star-forming galaxies in the last 11 Gyr. The relatively constant dot{M}_BH/SFR suggests that these two quantities evolve equivalently through cosmic time and with practically no delay between the two.

  15. The rise and fall of stellar discs across the peak of cosmic star formation history: mergers versus smooth accretion

    CERN Document Server

    Welker, Charlotte; Devriendt, Julien; Pichon, Christophe; Kaviraj, Sugata; Peirani, Sebastien

    2015-01-01

    Building galaxy merger trees from a state-of-the-art cosmological hydrodynamics simulation, Horizon-AGN, we perform a statistical study of how mergers and smooth accretion drive galaxy morphologic properties above $z > 1$. More specifically, we investigate how stellar densities, effective radii and shape parameters derived from the inertia tensor depend on mergers of different mass ratios. We find strong evidence that smooth accretion tends to flatten small galaxies over cosmic time, leading to the formation of disks. On the other hand, mergers, and not only the major ones, exhibit a propensity to puff up and destroy stellar disks, confirming the origin of elliptical galaxies. We also find that elliptical galaxies are more susceptible to grow in size through mergers than disc galaxies with a size-mass evolution $r \\prop M^{1.2}$ instead of $r \\prop M^{-0.5} - M^{0.5}$ depending on the merger mass ratio. The gas content drive the size-mass evolution due to merger with a faster size growth for gas-poor galaxies...

  16. Impaired Perinatal Growth and Longevity: A Life History Perspective

    Directory of Open Access Journals (Sweden)

    Deborah M. Sloboda

    2009-01-01

    Full Text Available Life history theory proposes that early-life cues induce highly integrated responses in traits associated with energy partitioning, maturation, reproduction, and aging such that the individual phenotype is adaptively more appropriate to the anticipated environment. Thus, maternal and/or neonatally derived nutritional or endocrine cues suggesting a threatening environment may favour early growth and reproduction over investment in tissue reserve and repair capacity. These may directly affect longevity, as well as prioritise insulin resistance and capacity for fat storage, thereby increasing susceptibility to metabolic dysfunction and obesity. These shifts in developmental trajectory are associated with long-term expression changes in specific genes, some of which may be underpinned by epigenetic processes. This normative process of developmental plasticity may prove to be maladaptive in human environments in transition towards low extrinsic mortality and energy-dense nutrition, leading to the development of an inappropriate phenotype with decreased potential for longevity and/or increased susceptibility to metabolic disease.

  17. The WiggleZ Dark Energy Survey: Joint measurements of the expansion and growth history at z < 1

    CERN Document Server

    Blake, Chris; Colless, Matthew; Contreras, Carlos; Couch, Warrick; Croom, Scott; Croton, Darren; Davis, Tamara; Drinkwater, Michael J; Forster, Karl; Gilbank, David; Gladders, Mike; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J; Li, I-hui; Madore, Barry; Martin, Chris; Pimbblet, Kevin; Poole, Gregory B; Pracy, Michael; Sharp, Rob; Wisnioski, Emily; Woods, David; Wyder, Ted; Yee, Howard

    2012-01-01

    We perform a joint determination of the distance-redshift relation and cosmic expansion rate at redshifts z = 0.44, 0.6 and 0.73 by combining measurements of the baryon acoustic peak and Alcock-Paczynski distortion from galaxy clustering in the WiggleZ Dark Energy Survey, using a large ensemble of mock catalogues to calculate the covariance between the measurements. Further combining our results with other baryon acoustic oscillation and distant supernovae datasets, we use a Monte Carlo Markov Chain technique to determine the evolution of the Hubble parameter H(z) as a stepwise function in 9 redshift bins of width dz = 0.1, also marginalizing over the spatial curvature. Our measurements of H(z), which have precision better than 7% in most redshift bins, are consistent with the expansion history predicted by a cosmological-constant dark-energy model, in which the expansion accelerates at redshift z < 0.7. We also measure the normalized cosmic growth rate at z = 0.44, 0.6 and 0.73, together with its covarian...

  18. Cosmic-ray history derived from the {sup 54}Mn, {sup 56}Ni and {sup 144}Pm chronometers

    Energy Technology Data Exchange (ETDEWEB)

    Zaerpoor, K.; Chan, Y.D.; DiGregorio, D.E.; Dragowsky, M.R.; Hindi, M.M.; Isaac, M.C.P.; Krane, K.S.; Larimer, R.-M.; Macchiavelli, A.O.; Macleod, R. W.; Miocinovic, P.; Norman, E.B.; Robinson, S.J

    1999-07-26

    Sources of {sup 54}Mn, {sup 56}Ni, and {sup 144}Pm were placed at the center of the Gammasphere array and searches were made for the astrophysically interesting {beta}{sup +} decay modes of these isotopes. The results of these searches are presented and the implications for cosmic-ray physics are discussed.

  19. The growth of typical star-forming galaxies and their super massive black holes across cosmic time since z~2

    CERN Document Server

    Calhau, João; Stroe, Andra; Best, Philip; Smail, Ian; Lehmer, Bret; Harrison, Chris; Thomson, Alasdair

    2016-01-01

    Understanding galaxy formation and evolution requires studying the interplay between the growth of galaxies and the growth of their black holes across cosmic time. Here we explore a sample of Ha-selected star-forming galaxies from the HiZELS survey and use the wealth of multi-wavelength data in the COSMOS field (X-rays, far-infrared and radio) to study the relative growth rates between typical galaxies and their central supermassive black holes, from z=2.23 to z=0. Typical star-forming galaxies at z~1-2 have black hole accretion rates (BHARs) of 0.001-0.01 Msun/yr and star formation rates (SFRs) of ~10-40 Msun/yr, and thus grow their stellar mass much quicker than their black hole mass (~3.3 orders of magnitude faster). However, ~3% of the sample (the sources detected directly in the X-rays) show a significantly quicker growth of the black hole mass (up to 1.5 orders of magnitude quicker growth than the typical sources). BHARs fall from z=2.23 to z=0, with the decline resembling that of star formation rate de...

  20. Reconstructing the Chronology of Supernovae: Determining Major Variations in the History of the Cosmic-ray Flux Incident on the Earth's Surface by Measuring the Concentration of 22Ne in Halite

    Science.gov (United States)

    Nahill, N. D.; Giegengack, R.; Lande, K.; Omar, G.

    2008-12-01

    We plan to measure the inventory of cosmogenically produced 22Ne atoms preserved in the mineral lattice of halite in deposits of rock salt, and to use that inventory to measure variations in the cosmic-ray flux to enable us to reconstruct the history of supernovae. Bedded rock salt consists almost entirely of the mineral halite (NaCl). Any neon trapped in the halite crystals during precipitation is primarily 20Ne, with a 22Ne concentration of 9% or less. Any neon resulting from cosmic-ray interactions with 23Na is solely 22Ne; therefore, 22Ne atoms in excess of 9% of the total neon are cosmogenic in origin. Measurement of the 22Ne inventory in halite from deposits covering a range of geologic ages may enable us to document the systematic growth of 22Ne through geologic time and, thus, establish the cosmic-ray flux and a chronology of supernovae. The cosmic-ray flux is attenuated in direct proportion to the mass of material overlying a halite deposit. To adjust the 22Ne inventory to account for that attenuation, we must reconstruct the post-depositional history of accumulation and removal of superjacent sediment for each halite deposit we study. As an example of our procedure, we reconstruct here the shielding history of the Permian halite deposit, the Salado Formation, Delaware Basin, New Mexico. The stratigraphy of the Delaware Basin has been well documented via exploration and production wells drilled in search of oil and gas, exploration boreholes associated with potash mining, and comprehensive geologic site assessment of the DOE Waste Isolation Pilot Plant (WIPP). WIPP is a subsurface repository for the permanent disposal of transuranic wastes, located in southeastern New Mexico, 42 km east of Carlsbad and approximately 655 m beneath the surface in the Salado Fm. The Salado Fm is part of the Late Permian Ochoan Series, and consists of 1) a lower member, 2) the McNutt Potash Zone, and 3) an upper member. WIPP lies between marker bed (MB)139 and MB136 in the

  1. Evolution of Infrared Luminosity functions of Galaxies in the AKARI NEP-Deep field: Revealing the cosmic star formation history hidden by dust

    CERN Document Server

    Goto, Tomotsugu; Matsuhara, H; Takeuchi, T T; Pearson, C; Wada, T; Nakagawa, T; Ilbert, O; Le Floc'h, E; Oyabu, S; Ohyama, Y; Malkan, M; Lee, H M; Lee, M G; Inami, H; Hwang, N; Hanami, H; Im, M; Imai, K; Ishigaki, T; Serjeant, S; Shim, H

    2010-01-01

    Dust-obscured star-formation becomes much more important with increasing intensity, and increasing redshift. We aim to reveal cosmic star-formation history obscured by dust using deep infrared observation with the AKARI. We construct restframe 8um, 12um, and total infrared (TIR) luminosity functions (LFs) at 0.15cosmic infrared luminosity density (Omega_IR), which was obtained by integrating analytic fits to the LFs, we found a good agreement with previous work at z<1.2, and that ...

  2. Galaxy And Mass Assembly (GAMA): Stellar mass growth of spiral galaxies in the cosmic web

    CERN Document Server

    Alpaslan, Mehmet; Marcum, Pamela M; Popescu, Cristina; Tuffs, Richard; Bland-Hawthorn, Joss; Brough, Sarah; Brown, Michael J I; Davies, Luke J M; Driver, Simon P; Holwerda, Benne W; Kelvin, Lee S; Lara-López, Maritza A; López-Sánchez, Ángel R; Loveday, Jon; Moffett, Amanda; Taylor, Edward N; Owers, Matt; Robotham, Aaron S G

    2016-01-01

    We look for correlated changes in stellar mass and star formation rate along filaments in the cosmic web by examining the stellar masses and UV-derived star formation rates (SFR) of 1,799 ungrouped and unpaired spiral galaxies that reside in filaments. We devise multiple distance metrics to characterise the complex geometry of filaments, and find that galaxies closer to the cylindrical centre of a filament have higher stellar masses than their counterparts near the periphery of filaments, on the edges of voids. In addition, these peripheral spiral galaxies have higher specific star formation rates (SSFR) at a given mass. Complementing our sample of filament spiral galaxies with spiral galaxies in tendrils and voids, we find that the average SFR of these objects in different large scale environments are similar to each other with the primary discriminant in SFR being stellar mass, in line with previous works. However, the distributions of SFRs are found to vary with large-scale environment. Our results thus su...

  3. Cosmic Strings and Superstrings

    CERN Document Server

    Copeland, Edmund J

    2009-01-01

    Cosmic strings are predicted by many field-theory models, and may have been formed at a symmetry-breaking transition early in the history of the universe, such as that associated with grand unification. They could have important cosmological effects. Scenarios suggested by fundamental string theory or M-theory, in particular the popular idea of brane inflation, also strongly suggest the appearance of similar structures. Here we review the reasons for postulating the existence of cosmic strings or superstrings, the various possible ways in which they might be detected observationally, and the special features that might discriminate between ordinary cosmic strings and superstrings.

  4. Cosmic-ray exposure histories of two Antarctic meteorites from Chinese collections and the Guangmingshan and Zhuanghe chondrites

    Institute of Scientific and Technical Information of China (English)

    王道德; 林杨挺; 刘小汉; 琚宜太

    2003-01-01

    Concentrations of noble gases of two Antarctic meteorites (GRV 98002, 98004) from Chinese collections, and the Guangmingshan and Zhuanghe chondrites were measured. Based on the petrography and mineralogy of these meteorites, and production rates of the cosmogenic nuclides, we calculated cosmic-ray exposure and gas retention ages of the four chondrites. Exposure ages of the four chondrites are 0.052 Ma ± 0.008 Ma (GRV 98004, H5), 17.0 Ma ± 2.5 Ma (GRV98002, L5), 3.8 Ma ± 0.6 Ma (Zhuanghe, H5), and 68.9 Ma ± 10 Ma (Guangmingshan, H5), respectively. The exposure age of GRV 98004 is the lowest value of Antarctic meteorites reported up to date; while that of Guangmingshan is higher than other Chinese meteorites of H-group. Both GRV 98002 and Zhuanghe have low 4He concentrations, probably due to shock effects or solar heating at orbits with small perihelion distances during cosmic-ray exposure. On the other hand, losses of cosmogenic 3He and 4He are correlated with both GRV 98002 and Guangmingshan.

  5. Review article: Cosmology with cosmic shear observations

    CERN Document Server

    Kilbinger, Martin

    2014-01-01

    Cosmic shear is the distortion of images of distant galaxies due to weak gravitational lensing by the large-scale structure in the Universe. Such images are coherently deformed by the tidal field of matter inhomogeneities along the line of sight. By measuring galaxy shape correlations, we can study the properties and evolution of structure on large scales as well as the geometry of the Universe. Thus, cosmic shear has become a powerful probe into the nature of dark matter and the origin of the current accelerated expansion of the Universe. Over the last years, cosmic shear has evolved into a reliable and robust cosmological probe, providing measurements of the expansion history of the Universe and the growth of its structure. We review here the principles of weak gravitational lensing and show how cosmic shear is interpreted in a cosmological context. Then we give an overview of weak-lensing measurements, and present the main observational cosmic-shear results since it was discovered 15 years ago, as well as ...

  6. Torque-Limited Growth of Massive Black Holes in Galaxies Across Cosmic Time

    CERN Document Server

    Anglés-Alcázar, Daniel; Davé, Romeel; Katz, Neal; Kollmeier, Juna A; Oppenheimer, Benjamin D

    2013-01-01

    We combine cosmological hydrodynamic simulations with analytic models to evaluate the role of galaxy-scale gravitational torques on the evolution of massive black holes at the centres of star-forming galaxies. We confirm and extend our earlier results to show that torque-limited growth yields black holes and host galaxies evolving on average along the Mbh-Mbulge relation from early times down to z = 0 and that convergence onto the scaling relation occurs independent of the initial conditions and with no need for mass averaging through mergers or additional self-regulation processes. Smooth accretion dominates the long-term evolution, with black hole mergers with mass ratios >1:5 representing typically a small fraction of the total growth. Winds from the accretion disk are required to eject significant mass to suppress black hole growth, but there is no need for coupling this wind to galactic-scale gas to regulate black holes in a non-linear feedback loop. Torque-limited growth yields a close-to-linear relatio...

  7. Balance of payments constrained growth models: history and overview

    Directory of Open Access Journals (Sweden)

    Anthony P. Thirlwall

    2011-12-01

    Full Text Available Thirlwall’s 1979 balance of payments constrained growth model predicts that a country’s long run growth of GDP can be approximated by the ratio of the growth of real exports to the income elasticity of demand for imports assuming negligible effects from real exchange rate movements. The paper surveys developments of the model since then, allowing for capital flows, interest payments on debt, terms of trade movements, and disaggregation of the model by commodities and trading partners. Various tests of the model are discussed, and an extensive list of papers that have examined the model is presented.

  8. The history effect in bubble growth and dissolution. Part 1. Theory

    NARCIS (Netherlands)

    Peñas, P.; Parrales, M.A.; Rodriguez-Rodriguez, J.; van der Meer, Roger M.

    2016-01-01

    The term ‘history effect’ refers to the contribution of any past mass transfer events between a gas bubble and its liquid surroundings towards the current diffusion-driven growth or dissolution dynamics of that same bubble. The history effect arises from the (non-instantaneous) development of the di

  9. Reconstructing cosmic growth with kinetic Sunyaev-Zel'dovich observations in the era of stage IV experiments

    Science.gov (United States)

    Alonso, David; Louis, Thibaut; Bull, Philip; Ferreira, Pedro G.

    2016-08-01

    Future ground-based cosmic microwave background (CMB) experiments will generate competitive large-scale structure data sets by precisely characterizing CMB secondary anisotropies over a large fraction of the sky. We describe a method for constraining the growth rate of structure to sub-1% precision out to z ≈1 , using a combination of galaxy cluster peculiar velocities measured using the kinetic Sunyaev-Zel'dovich (kSZ) effect, and the velocity field reconstructed from galaxy redshift surveys. We consider only thermal SZ-selected cluster samples, which will consist of O (1 04- 1 05) sources for Stage 3 and 4 CMB experiments respectively. Three different methods for separating the kSZ effect from the primary CMB are compared, including a novel blind "constrained realization" method that improves signal-to-noise by a factor of ˜2 over a commonly-used aperture photometry technique. Assuming a correlation between the integrated tSZ y -parameter and the cluster optical depth, it should then be possible to break the kSZ velocity-optical depth degeneracy. The effects of including CMB polarization and SZ profile uncertainties are also considered. In the absence of systematics, a combination of future Stage 4 experiments should be able to measure the product of the growth and expansion rates, α ≡f H , to better than 1% in bins of Δ z =0.1 out to z ≈1 —competitive with contemporary redshift-space distortion constraints from galaxy surveys. We conclude with a discussion of the likely impact of various systematics.

  10. The evolution of CNO isotopes: a new window on cosmic star formation history and the stellar IMF in the age of ALMA

    Science.gov (United States)

    Romano, D.; Matteucci, F.; Zhang, Z.-Y.; Papadopoulos, P. P.; Ivison, R. J.

    2017-09-01

    We use state-of-the-art chemical models to track the cosmic evolution of the CNO isotopes in the interstellar medium of galaxies, yielding powerful constraints on their stellar initial mass function (IMF). We re-assess the relative roles of massive stars, asymptotic giant branch (AGB) stars and novae in the production of rare isotopes such as 13C, 15N, 17O and 18O, along with 12C, 14N and 16O. The CNO isotope yields of super-AGB stars, novae and fast-rotating massive stars are included. Having reproduced the available isotope enrichment data in the solar neighbourhood, and across the Galaxy, and having assessed the sensitivity of our models to the remaining uncertainties, e.g. nova yields and star formation history, we show that we can meaningfully constrain the stellar IMF in galaxies using C, O and N isotope abundance ratios. In starburst galaxies, where data for multiple isotopologue lines are available, we find compelling new evidence for a top-heavy stellar IMF, with profound implications for their star formation rates and efficiencies, perhaps also their stellar masses. Neither chemical fractionation nor selective photodissociation can significantly perturb globally averaged isotopologue abundance ratios away from the corresponding isotope ones, as both these processes will typically affect only small mass fractions of molecular clouds in galaxies. Thus, the Atacama Large Millimeter Array now stands ready to probe the stellar IMF, and even the ages of specific starburst events in star-forming galaxies across cosmic time unaffected by the dust obscuration effects that plague optical/near-infrared studies.

  11. ZOMG I: How the cosmic web inhibits halo growth and generates assembly bias

    CERN Document Server

    Borzyszkowski, Mikolaj; Romano-Diaz, Emilio; Garaldi, Enrico

    2016-01-01

    The clustering of dark-matter haloes with fixed mass depends on their formation history, an effect known as assembly bias. We investigate the origin of this phenomenon using zoom N-body simulations. We follow the formation of seven galaxy-sized haloes selected using a definition of collapse time that generates strong assembly bias. Haloes at redshift zero are classified according to the time in which the physical volume containing their final mass becomes stable. For `stalled' haloes this happens at z~1.5 while for `accreting' haloes this has not happened yet. The zoom simulations confirm that stalled haloes do not grow in mass while accreting haloes show a net inflow. The reason is that accreting haloes are located at the nodes of a network of thin filaments which feed them. Conversely, each stalled halo lies within a prominent filament that is thicker than the halo size. Infalling material from the surroundings becomes part of the filament while matter within it recedes from the halo. We conclude that assem...

  12. Complex fringes around magnetite porphyroclasts: growth and deformation history.

    OpenAIRE

    Lagoeiro, Leonardo Evangelista; Barbosa, Paola Ferreira; Fueten, Frank

    2011-01-01

    Deformed strain fringes in iron formation rocks show complex quartz fiber patterns that grew alongside magnetite porphyroclasts embedded in a matrix of quartz and iron oxides during coaxial to non-coaxial deformation. These rocks have been deformed by a combination of processes involving microfracturing, pressure solution and dislocation glide at temperatures of approximately 300 °C. Detailed microstructural observation and crystallographic analysis show that quartz fiber growth is not contro...

  13. Cosmic Dawn Intensity Mapper

    CERN Document Server

    Cooray, Asantha; Burgarella, Denis; Chary, Ranga; Chang, Tzu-Ching; Doré, Olivier; Fazio, Giovanni; Ferrara, Andrea; Gong, Yan; Santos, Mario; Silva, Marta; Zemcov, Michael

    2016-01-01

    Cosmic Dawn Intensity Mapper is a "Probe Class" mission concept for reionization studies of the universe. It will be capable of spectroscopic imaging observations between 0.7 to 6-7 microns in the near-Infrared. The primary observational objective is pioneering observations of spectral emission lines of interest throughout the cosmic history, but especially from the first generation of distant, faint galaxies when the universe was less than 800 million years old. With spectro-imaging capabilities, using a set of linear variable filters (LVFs), CDIM will produce a three-dimensional tomographic view of the epoch of reionization (EoR). CDIM will also study galaxy formation over more than 90% of the cosmic history and will move the astronomical community from broad-band astronomical imaging to low-resolution (R=200-300) spectro-imaging of the universe.

  14. Reconstructing cosmic growth with kSZ observations in the era of Stage IV experiments

    CERN Document Server

    Alonso, David; Bull, Philip; Ferreira, Pedro G

    2016-01-01

    Future ground-based CMB experiments will generate competitive large-scale structure datasets by precisely characterizing CMB secondary anisotropies over a large fraction of the sky. We describe a method for constraining the growth rate of structure to sub-1% precision out to $z\\approx 1$, using a combination of galaxy cluster peculiar velocities measured using the kinetic Sunyaev-Zel'dovich (kSZ) effect, and the velocity field reconstructed from galaxy redshift surveys. We consider only thermal SZ-selected cluster samples, which will consist of $\\mathcal{O}(10^4-10^5)$ sources for Stage 3 and 4 CMB experiments respectively. Three different methods for separating the kSZ effect from the primary CMB are compared, including a novel blind "constrained realization" method that improves signal-to-noise by a factor of $\\sim 2$ over a commonly-used aperture photometry technique. Measurements of the integrated tSZ $y$-parameter are used to break the kSZ velocity-optical depth degeneracy, and the effects of including C...

  15. The VIMOS Public Extragalactic Redshift Survey: Measuring the growth rate of structure around cosmic voids

    CERN Document Server

    Hawken, A J; Iovino, A; Guzzo, L; Peacock, J A; de la Torre, S; Garilli, B; Bolzonella, M; Scodeggio, M; Abbas, U; Adami, C; Bottini, D; Cappi, A; Cucciati, O; Davidzon, I; Fritz, A; Franzetti, P; Krywult, J; Brun, V Le; Fevre, O Le; Maccagni, D; Małek, K; Marulli, F; Polletta, M; Pollo, A; Tasca, L A M; Tojeiro, R; Vergani, D; Zanichelli, A; Arnouts, S; Bel, J; Branchini, E; De Lucia, G; Ilbert, O; Moscardini, L; Percival, W J

    2016-01-01

    We identified voids in the completed VIMOS Public Extragalactic Redshift Survey (VIPERS), using an algorithm based on searching for empty spheres. We measured the cross-correlation between the centres of voids and the complete galaxy catalogue. The cross-correlation function exhibits a clear anisotropy in both VIPERS fields (W1 and W4), which is characteristic of linear redshift space distortions. By measuring the projected cross-correlation and then deprojecting it we are able to estimate the undistorted cross-correlation function. We propose that given a sufficiently well measured cross-correlation function one should be able to measure the linear growth rate of structure by applying a simple linear Gaussian streaming model for the redshift space distortions (RSD). Our study of voids in 306 mock galaxy catalogues mimicking the VIPERS fields would suggest that VIPERS is capable of measuring $\\beta$ with an error of around $25\\%$. Applying our method to the VIPERS data, we find a value for the redshift space ...

  16. Supermassive Black Hole Growth During The Peak Of Cosmic Star Formation

    Science.gov (United States)

    Ross, Nathaniel Robert

    2016-01-01

    Massive galaxies in the nearby universe all show evidence of a central Supermassive Black Hole. The black holes are seen to grow over time by accretion of gas from their host galaxy, a phenomenon referred to as an Active Galactic Nucleus. This process is believed to be fundamental to the observed correlations between black hole mass and properties of the host galaxies. We have a more limited and biased understanding of the growth of supermassive black holes in more 'typical' galaxies at z ˜ 1 -- 2. In this work, we search for Active Galactic Nuclei in a population of star-forming galaxies spanning a mass range of M* ˜ 107 -- 1012 M[special character omitted] at 0.62 Parallels (WISP) survey, for which we designed and implemented a suite of data analysis routines for discovering and measuring star-forming galaxies and active galactic nuclei. We find a sample of 50 active galactic nuclei, identified by their strong, rest-frame optical, emission-line ratios. We find that growing supermassive black holes in low-mass galaxies at z [special character omitted] 1 either make up a greater fraction of their galaxies' masses than those in massive galaxies, or perhaps emit a greater fraction of their energy in [O III].

  17. The Formation of Supermassive Black Holes from Population III.1 Seeds. I. Cosmic Formation Histories and Clustering Properties

    Energy Technology Data Exchange (ETDEWEB)

    Banik, Nilanjan; Tan, Jonathan C.; Monaco, Pierluigi

    2016-08-15

    We calculate the cosmic distributions in space and time of the formation sites of the first, "Pop III.1" stars, exploring a model in which these are the progenitors of all supermassive black holes (SMBHs). Pop III.1 stars are defined to form from primordial composition gas in dark matter minihalos with $\\sim10^6\\:M_\\odot$ that are isolated from neighboring astrophysical sources by a given isolation distance, $d_{\\rm{iso}}$. We assume Pop III.1 sources are seeds of SMBHs, based on protostellar support by dark matter annihilation heating that allows them to accrete a large fraction of their minihalo gas, i.e., $\\sim 10^5\\:M_\\odot$. Exploring $d_{\\rm{iso}}$ from 10--$100\\:\\rm{kpc}$ (proper distances), we predict the redshift evolution of Pop III.1 source and SMBH remnant number densities. The local, $z=0$ density of SMBHs constrains $d_{\\rm{iso}}\\lesssim 100\\:\\rm{kpc}$ (i.e., $3\\:\\rm{Mpc}$ comoving distance at $z\\simeq30$). In our simulated ($\\sim60\\:\\rm{Mpc}$)$^3$ comoving volume, Pop III.1 stars start forming just after $z=40$. Their formation is largely complete by $z\\simeq25$ to 20 for $d_{\\rm{iso}}=100$ to $50\\:\\rm{kpc}$. We follow source evolution to $z=10$, by which point most SMBHs reside in halos with $\\gtrsim10^8\\:M_\\odot$. Over this period, there is relatively limited merging of SMBHs for these values of $d_{\\rm{iso}}$. We also predict SMBH clustering properties at $z=10$: feedback suppression of neighboring sources leads to relatively flat angular correlation functions. Finally, we consider a simple "Str\\"omgren" model for $d_{\\rm iso}$, based on ionizing feedback from zero age main sequence supermassive Pop III.1 stars that may be the direct progenitors of SMBHs in this scenario. Such models naturally produce feedback effects on scales of $\\sim100\\:$kpc and thus self-consistently generate a SMBH number density similar to the observed value.

  18. A peek into the history of sapphire crystal growth

    Science.gov (United States)

    Harris, Daniel C.

    2003-09-01

    After the chemical compositions of sapphire and ruby were unraveled in the middle of the 19th century, chemists set out to grow artificial crystals of these valuable gemstones. In 1885 a dealer in Geneva began to sell ruby that is now believed to have been created by flame fusion. Gemnologists rapidly concluded that the stones were artificial, but the Geneva ruby stimulated A. V. L. Verneuil in Paris to develop a flame fusion process to produce higher quality ruby and sapphire. By 1900 there was brisk demand for ruby manufactured by Verneuil's method, even though Verneuil did not publicly announce his work until 1902 and did not publish details until 1904. The Verneuil process was used with little alteration for the next 50 years. From 1932-1953, S. K. Popov in the Soviet Union established a capability for manufacturing high quality sapphire by the Verneuil process. In the U.S., under government contract, Linde Air Products Co. implemented the Verneuil process for ruby and sapphire when European sources were cut off during World War II. These materials were essential to the war effort for jewel bearings in precision instruments. In the 1960s and 1970s, the Czochralski process was implemented by Linde and its successor, Union Carbide, to make higher crystal quality material for ruby lasers. Stimulated by a government contract for structural fibers in 1966, H. LaBelle invented edge-defined film-fed growth (EFG). The Saphikon company, which is currently owned by Saint-Gobain, evolved from this effort. Independently and simultaneously, Stepanov developed edge-defined film-fed growth in the Soviet Union. In 1967 F. Schmid and D. Viechnicki at the Army Materials Research Lab grew sapphire by the heat exchanger method (HEM). Schmid went on to establish Crystal Systems, Inc. around this technology. Rotem Industries, founded in Israel in 1969, perfected the growth of sapphire hemispheres and near-net-shape domes by gradient solidification. In the U.S., growth of near

  19. The history of doping and growth hormone abuse in sport.

    Science.gov (United States)

    Holt, Richard I G; Erotokritou-Mulligan, Ioulietta; Sönksen, Peter H

    2009-08-01

    The earliest records of doping in sport come from the Ancient Olympics games when athletes are reported to have taken figs to improve their performance. With the advent of modern pharmacology in the 19th century, many athletes began to experiment with cocktails of drugs to improve strength and overcome fatigue. As this practice was not illegal, there are good records of the lengths athletes would go to in order to win. Alongside the benefits, came the dangers and following several fatalities, a code to ban performance enhancing drugs was gradually developed. Growth hormone was first isolated from the human pituitary gland in the 1950s. Its anabolic effects were soon recognised and athletes had begun to abuse it by the early 1980s, at least a decade before it was used therapeutically by adult endocrinologists. A number of high profile athletes have admitted using growth hormone. Detection of its abuse has been challenging and the lack of an effective test has undoubtedly encouraged its abuse. Only now are methodologies being developed that should stem this tide.

  20. Strong Cosmic Censorship

    Science.gov (United States)

    Isenberg, James

    2017-01-01

    The Hawking-Penrose theorems tell us that solutions of Einstein's equations are generally singular, in the sense of the incompleteness of causal geodesics (the paths of physical observers). These singularities might be marked by the blowup of curvature and therefore crushing tidal forces, or by the breakdown of physical determinism. Penrose has conjectured (in his `Strong Cosmic Censorship Conjecture`) that it is generically unbounded curvature that causes singularities, rather than causal breakdown. The verification that ``AVTD behavior'' (marked by the domination of time derivatives over space derivatives) is generically present in a family of solutions has proven to be a useful tool for studying model versions of Strong Cosmic Censorship in that family. I discuss some of the history of Strong Cosmic Censorship, and then discuss what is known about AVTD behavior and Strong Cosmic Censorship in families of solutions defined by varying degrees of isometry, and discuss recent results which we believe will extend this knowledge and provide new support for Strong Cosmic Censorship. I also comment on some of the recent work on ``Weak Null Singularities'', and how this relates to Strong Cosmic Censorship.

  1. Life-history and spatial determinants of somatic growth dynamics in Komodo dragon populations.

    Directory of Open Access Journals (Sweden)

    Rebecca J Laver

    Full Text Available Somatic growth patterns represent a major component of organismal fitness and may vary among sexes and populations due to genetic and environmental processes leading to profound differences in life-history and demography. This study considered the ontogenic, sex-specific and spatial dynamics of somatic growth patterns in ten populations of the world's largest lizard the Komodo dragon (Varanus komodoensis. The growth of 400 individual Komodo dragons was measured in a capture-mark-recapture study at ten sites on four islands in eastern Indonesia, from 2002 to 2010. Generalized Additive Mixed Models (GAMMs and information-theoretic methods were used to examine how growth rates varied with size, age and sex, and across and within islands in relation to site-specific prey availability, lizard population density and inbreeding coefficients. Growth trajectories differed significantly with size and between sexes, indicating different energy allocation tactics and overall costs associated with reproduction. This leads to disparities in maximum body sizes and longevity. Spatial variation in growth was strongly supported by a curvilinear density-dependent growth model with highest growth rates occurring at intermediate population densities. Sex-specific trade-offs in growth underpin key differences in Komodo dragon life-history including evidence for high costs of reproduction in females. Further, inverse density-dependent growth may have profound effects on individual and population level processes that influence the demography of this species.

  2. Cosmic Strings

    CERN Document Server

    Vachaspati, Tanmay; Steer, Daniele

    2015-01-01

    This article, written for Scolarpedia, provides a brief introduction into the subject of cosmic strings, together with a review of their main properties, cosmological evolution and observational signatures.

  3. Overview: early history of crop growth and photosynthesis modeling.

    Science.gov (United States)

    El-Sharkawy, Mabrouk A

    2011-02-01

    As in industrial and engineering systems, there is a need to quantitatively study and analyze the many constituents of complex natural biological systems as well as agro-ecosystems via research-based mechanistic modeling. This objective is normally addressed by developing mathematically built descriptions of multilevel biological processes to provide biologists a means to integrate quantitatively experimental research findings that might lead to a better understanding of the whole systems and their interactions with surrounding environments. Aided with the power of computational capacities associated with computer technology then available, pioneering cropping systems simulations took place in the second half of the 20th century by several research groups across continents. This overview summarizes that initial pioneering effort made to simulate plant growth and photosynthesis of crop canopies, focusing on the discovery of gaps that exist in the current scientific knowledge. Examples are given for those gaps where experimental research was needed to improve the validity and application of the constructed models, so that their benefit to mankind was enhanced. Such research necessitates close collaboration among experimentalists and model builders while adopting a multidisciplinary/inter-institutional approach.

  4. Evolution of infrared luminosity functions of galaxies in the AKARI NEP-deep field. Revealing the cosmic star formation history hidden by dust

    Science.gov (United States)

    Goto, T.; Takagi, T.; Matsuhara, H.; Takeuchi, T. T.; Pearson, C.; Wada, T.; Nakagawa, T.; Ilbert, O.; Le Floc'h, E.; Oyabu, S.; Ohyama, Y.; Malkan, M.; Lee, H. M.; Lee, M. G.; Inami, H.; Hwang, N.; Hanami, H.; Im, M.; Imai, K.; Ishigaki, T.; Serjeant, S.; Shim, H.

    2010-05-01

    Aims: Dust-obscured star-formation increases with increasing intensity and increasing redshift. We aim to reveal the cosmic star-formation history obscured by dust using deep infrared observation with AKARI. Methods: We constructed restframe 8 μm, 12 μm, and total infrared (TIR) luminosity functions (LFs) at 0.15 < z < 2.2 using 4128 infrared sources in the AKARI NEP-deep field. A continuous filter coverage in the mid-IR wavelength (2.4, 3.2, 4.1, 7, 9, 11, 15, 18, and 24 μm) by the AKARI satellite allowed us to estimate restframe 8 μm and 12 μm luminosities without using a large extrapolation based on an SED fit, which was the largest uncertainty in previous work. Results: We find that all 8 μm (0.38 < z < 2.2), 12 μm (0.15 < z < 1.16), and TIR LFs (0.2 < z <1.6) show continuous and strong evolution toward higher redshift. Our direct estimate of 8 μm LFs is useful since previous work often had to use a large extrapolation from the Spitzer 24 μm to 8 μm, where SED modeling is more difficult because of the PAH emissions. In terms of cosmic infrared luminosity density (Ω_IR), which was obtained by integrating analytic fits to the LFs, we find good agreement with previous work at z<1.2. We find the Ω_IR evolves as propto(1 + z)4.4± 1.0. When we separate contributions to Ω_IR by LIRGs and ULIRGs, we found more IR luminous sources are increasingly more important at higher redshift. We find that the ULIRG (LIRG) contribution increases by a factor of 10 (1.8) from z = 0.35 to z = 1.4. This research is based on the observations with AKARI, a JAXA project with the participation of ESA.Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  5. Cosmic expansion in extended quasidilaton massive gravity

    Science.gov (United States)

    Kahniashvili, Tina; Kar, Arjun; Lavrelashvili, George; Agarwal, Nishant; Heisenberg, Lavinia; Kosowsky, Arthur

    2015-02-01

    Quasidilaton massive gravity offers a physically well-defined gravitational theory with nonzero graviton mass. We present the full set of dynamical equations governing the expansion history of the Universe, valid during radiation domination, matter domination, and a late-time self-accelerating epoch related to the graviton mass. The existence of self-consistent solutions constrains the amplitude of the quasidilaton field and the graviton mass, as well as other model parameters. We point out that the effective mass of gravitational waves can be significantly larger than the graviton mass, opening the possibility that a single theory can explain both the late-time acceleration of cosmic expansion and modifications of structure growth leading to the suppression of large-angle correlations observed in the cosmic microwave background.

  6. Cosmic Expansion in Extended Quasidilaton Massive Gravity

    CERN Document Server

    Kahniashvili, Tina; Lavrelashvili, George; Agarwal, Nishant; Heisenberg, Lavinia; Kosowsky, Arthur

    2014-01-01

    Quasidilaton massive gravity offers a physically well-defined gravitational theory with non-zero graviton mass. We present the full set of dynamical equations governing the expansion history of the universe, valid during radiation domination, matter domination, and a late-time self-accelerating epoch related to the graviton mass. The existence of self-consistent solutions constrains the amplitude of the quasi-dilaton field and the graviton mass, as well as other model parameters. We point out that the effective mass of gravitational waves can be significantly larger than the graviton mass, opening the possibility that a single theory can explain both the late-time acceleration of the cosmic expansion and modifications of structure growth leading to the suppression of large-angle correlations observed in the cosmic microwave background.

  7. Historie

    DEFF Research Database (Denmark)

    Poulsen, Jens Aage

    Historie i serien handler om læreplaner og læremidler og deres brug i skolefaget historie. Bogen indeholder nyttige redskaber til at analysere og vurdere læremidler......Historie i serien handler om læreplaner og læremidler og deres brug i skolefaget historie. Bogen indeholder nyttige redskaber til at analysere og vurdere læremidler...

  8. The rise and fall of stellar across the peak of cosmic star formation history: effects of mergers versus diffuse stellar mass acquisition

    Science.gov (United States)

    Welker, C.; Dubois, Y.; Devriendt, J.; Pichon, C.; Kaviraj, S.; Peirani, S.

    2017-02-01

    Building galaxy merger trees from a state-of-the-art cosmological hydrodynamics simulation, Horizon-AGN, we perform a statistical study of how mergers and smooth accretion drive galaxy morphologic properties above $z > 1$. More specifically, we investigate how stellar densities, effective radii and shape parameters derived from the inertia tensor depend on mergers of different mass ratios. We find strong evidence that smooth accretion tends to flatten small galaxies over cosmic time, leading to the formation of disks. On the other hand, mergers, and not only the major ones, exhibit a propensity to puff up and destroy stellar disks, confirming the origin of elliptical galaxies. We also find that elliptical galaxies are more susceptible to grow in size through mergers than disc galaxies with a size-mass evolution $r \\prop M^{1.2}$ instead of $r \\prop M^{-0.5} - M^{0.5}$ depending on the merger mass ratio. The gas content drive the size-mass evolution due to merger with a faster size growth for gas-poor galaxies $r \\prop M^2$ than for gas-rich galaxies $r \\prop M$.

  9. Why, indeed, in America? Theory, History, and the Origins of Modern Economic Growth

    OpenAIRE

    ROMER, Paul M.

    1996-01-01

    When they are used together, economic history and new growth theory give a more complete picture of technological change than either can give on its own. An empirical strategy for studying growth that does not use historical evidence is likely to degenerate into sterile model testing exercises. Historical analysis that uses the wrong kind of theory or no theory may not emphasize the lessons about technology that generalize. The complementarity between these fields is illustrated by an analysi...

  10. Cosmic Magnification

    CERN Document Server

    Ménard, B

    2002-01-01

    I present the current status of the cosmic magnification produced by systematic amplification of background sources by large-scale structures. After introducing its principle, I focus on its interests for cosmology and underline its complementary aspect to cosmic shear and galaxy auto-correlations. I finally discuss recent investigations using higher-order statistics.

  11. Cosmic superstrings.

    Science.gov (United States)

    Sakellariadou, Mairi

    2008-08-28

    Cosmic superstrings are expected to be formed at the end of brane inflation, within the context of brane-world cosmological models inspired from string theory. By studying the properties of cosmic superstring networks and comparing their phenomenological consequences against observational data, we aim to pin down the successful and natural inflationary model and get an insight into the stringy description of our Universe.

  12. The Cosmic History of Hot Gas Cooling and Radio AGN Activity in Massive Early-Type Galaxies

    Science.gov (United States)

    Danielson, A. L. R.; Lehmer, B. D.; Alexander, D. M.; Brandt, W. M.; Luo, B.; Miller, N.; Xue, Y. Q.; Stott, J. P.

    2012-01-01

    We study the X-ray properties of 393 optically selected early-type galaxies (ETGs) over the redshift range of z approx equals 0.0-1.2 in the Chandra Deep Fields. To measure the average X-ray properties of the ETG population, we use X-ray stacking analyses with a subset of 158 passive ETGs (148 of which were individually undetected in X-ray). This ETG subset was constructed to span the redshift ranges of z = 0.1-1.2 in the approx equals 4 Ms CDF-S and approx equals 2 Ms CDF-N and z = 0.1-0.6 in the approx equals 250 ks E-CDF-S where the contribution from individually undetected AGNs is expected to be negligible in our stacking. We find that 55 of the ETGs are detected individually in the X-rays, and 12 of these galaxies have properties consistent with being passive hot-gas dominated systems (i.e., systems not dominated by an X-ray bright Active Galactic Nucleus; AGN). On the basis of our analyses, we find little evolution in the mean 0.5-2 keY to B-band luminosity ratio (L(sub x) /L(sub Beta) varies as [1 +z]) since z approx equals 1.2, implying that some heating mechanism prevents the gas from cooling in these systems. We consider that feedback from radio-mode AGN activity could be responsible for heating the gas. We select radio AGNs in the ETG population using their far-infrared/radio flux ratio. Our radio observations allow us to constrain the duty cycle history of radio AGN activity in our ETG sample. We estimate that if scaling relations between radio and mechanical power hold out to z approx equals 1.2 for the ETG population being studied here, the average mechanical power from AGN activity is a factor of approx equals1.4 -- 2.6 times larger than the average radiative cooling power from hot gas over the redshift range z approx equals 0-1.2. The excess of inferred AGN mechanical power from these ETGs is consistent with that found in the local Universe for similar types of galaxies.

  13. Observational Probes of Cosmic Acceleration

    CERN Document Server

    Weinberg, David H; Eisenstein, Daniel J; Hirata, Christopher; Riess, Adam G; Rozo, Eduardo

    2012-01-01

    The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious experimental efforts to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit "Stage IV" dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock-Paczynski test, and direct meas...

  14. Mapping the Cosmic Dawn

    Science.gov (United States)

    Furlanetto, Steven

    The following sections are included: * A Brief History of Our Universe: From Soup to Galaxies * The Hidden Cosmic Dawn * The Solution: Flipping Spins * The Spin-Flip Transition as an Astronomical Tool * Foiled!: Early Cosmology with the Spin-Flip Transition * Spin-Flip Radiation Holds the Key to Observing the Cosmic Dawn * The Spin-Flip Background: The First Stars * The Spin-Flip Background: The First Black Holes * The Spin-Flip Background: The Epoch of Reionization * FM Radio Antennae as Cosmic Observatories * Piles and Tiles of Antennae: Mapping the Spin-Flip Background * Mountains to Scale: Challenges to Observing the Spin-Flip Background * Sound and Fury, Signifying Statistics * An Explosion of Telescopes * Dreams for the Future * An Unfinished Story

  15. Growth and life history variability of the grey reef shark (Carcharhinus amblyrhynchos) across its range

    Science.gov (United States)

    Bradley, Darcy; Conklin, Eric; Papastamatiou, Yannis P.; McCauley, Douglas J.; Pollock, Kydd; Kendall, Bruce E.; Gaines, Steven D.; Caselle, Jennifer E.

    2017-01-01

    For broadly distributed, often overexploited species such as elasmobranchs (sharks and rays), conservation management would benefit from understanding how life history traits change in response to local environmental and ecological factors. However, fishing obfuscates this objective by causing complex and often mixed effects on the life histories of target species. Disentangling the many drivers of life history variability requires knowledge of elasmobranch populations in the absence of fishing, which is rarely available. Here, we describe the growth, maximum size, sex ratios, size at maturity, and offer a direct estimate of survival of an unfished population of grey reef sharks (Carcharhinus amblyrhynchos) using data from an eight year tag-recapture study. We then synthesized published information on the life history of C. amblyrhynchos from across its geographic range, and for the first time, we attempted to disentangle the contribution of fishing from geographic variation in an elasmobranch species. For Palmyra’s unfished C. amblyrhynchos population, the von Bertalanffy growth function (VBGF) growth coefficient k was 0.05 and asymptotic length L∞ was 163.3 cm total length (TL). Maximum size was 175.5 cm TL from a female shark, length at maturity was estimated at 116.7–123.2 cm TL for male sharks, maximum lifespan estimated from VBGF parameters was 18.1 years for both sexes combined, and annual survival was 0.74 year-1. Consistent with findings from studies on other elasmobranch species, we found significant intraspecific variability in reported life history traits of C. amblyrhynchos. However, contrary to what others have reported, we did not find consistent patterns in life history variability as a function of biogeography or fishing. Ultimately, the substantial, but not yet predictable variability in life history traits observed for C. amblyrhynchos across its geographic range suggests that regional management may be necessary to set sustainable harvest

  16. Rate of head circumference growth as a function of autism diagnosis and history of autistic regression.

    Science.gov (United States)

    Webb, Sara Jane; Nalty, Theresa; Munson, Jeff; Brock, Catherine; Abbott, Robert; Dawson, Geraldine

    2007-10-01

    Several reports indicate that autism spectrum disorder is associated with increased rate of head growth in early childhood. Increased rate of growth may index aberrant processes during early development, may precede the onset of symptoms, and may predict severity of the disease course. We examined rate of change in occipitofrontal circumference measurements (abstracted from medical records) in 28 boys with autism spectrum disorder and in 8 boys with developmental delay without autism from birth to age 36 months. Only children who had more than 3 occipitofrontal circumference measurements available during this age period were included. All data were converted to z scores based on the Centers for Disease Control and Prevention norms. Rate of growth from birth to age 36 months was statistically significantly higher for the autism spectrum disorder group than the developmental delay group, with children with autism spectrum disorder showing a statistically significant increase in occipitofrontal circumference relative to norms between 7 and 10 months; this group difference in rate of growth was more robust when height was used as a covariate. Rate of growth was not found to be different for children with autism spectrum disorder whose parents reported a history of loss of skills (regression) vs those whose parents reported early onset of autism symptoms. Findings from this study suggest that the aberrant growth is present in the first year of life and precedes the onset and diagnosis in children with autism spectrum disorder with and without a history of autistic regression.

  17. Effect of sow history features on growth and feed intake in grow-finish pigs

    OpenAIRE

    Sell-Kubiak, E.B.; Knol, E.F.; Bijma, P

    2012-01-01

    The sow provides a specific environment to her offspring during gestation and lactation. Certain features in the early life of the sow (sow history features) may affect her ability to deliver and feed a healthy litter. In genetic analyses of grow-finish traits, these effects are estimated as common litter or permanent sow effects. The objective of this research was to identify sow history features that affect the growth rate (GR) and feed intake (FI) of her offspring during the grow-finish st...

  18. Galaxy Formation Spanning Cosmic History

    CERN Document Server

    Benson, Andrew J

    2010-01-01

    Over the past several decades, galaxy formation theory has met with significant successes. In order to test current theories thoroughly we require predictions for as yet unprobed regimes. To this end, we describe a new implementation of the Galform semi-analytic model of galaxy formation. Our motivation is the success of the model described by Bower et al. in explaining many aspects of galaxy formation. Despite this success, the Bower et al. model fails to match some observational constraints and certain aspects of its physical implementation are not as realistic as we would like. The model described in this work includes substantially updated physics, taking into account developments in our understanding over the past decade, and removes certain limiting assumptions made by this (and most other) semi-analytic models. This allows it to be exploited reliably in high-redshift and low mass regimes. Furthermore, we have performed an exhaustive search of model parameter space to find a particular set of model para...

  19. THE COSMIC STAR FORMATION HISTORY

    Directory of Open Access Journals (Sweden)

    M. A. Muñoz-Gutiérrez

    2011-01-01

    Full Text Available Se presenta y compara con observaciones un modelo para calcular la historia de la densidad de la tasa de formación estelar cósmica en un universo ACDM jerárquico. Se discuten el rol de diferentes procesos astrofísicos como la función de la masa y época, así como potenciales problemas.

  20. Life history of Rhamphorhynchus inferred from bone histology and the diversity of pterosaurian growth strategies.

    Science.gov (United States)

    Prondvai, Edina; Stein, Koen; Osi, Attila; Sander, Martin P

    2012-01-01

    Rhamphorhynchus from the Solnhofen Limestones is the most prevalent long tailed pterosaur with a debated life history. Whereas morphological studies suggested a slow crocodile-like growth strategy and superprecocial volant hatchlings, the only histological study hitherto conducted on Rhamphorhynchus concluded a relatively high growth rate for the genus. These controversial conclusions can be tested by a bone histological survey of an ontogenetic series of Rhamphorhynchus. Our results suggest that Bennett's second size category does not reflect real ontogenetic stage. Significant body size differences of histologically as well as morphologically adult specimens suggest developmental plasticity. Contrasting the 'superprecocial hatchling' hypothesis, the dominance of fibrolamellar bone in early juveniles implies that hatchlings sustained high growth rate, however only up to the attainment of 30-50% and 7-20% of adult wingspan and body mass, respectively. The early fast growth phase was followed by a prolonged, slow-growth phase indicated by parallel-fibred bone deposition and lines of arrested growth in the cortex, a transition which has also been observed in Pterodaustro. An external fundamental system is absent in all investigated specimens, but due to the restricted sample size, neither determinate nor indeterminate growth could be confirmed in Rhamphorhynchus. The initial rapid growth phase early in Rhamphorhynchus ontogeny supports the non-volant nature of its hatchlings, and refutes the widely accepted 'superprecocial hatchling' hypothesis. We suggest the onset of powered flight, and not of reproduction as the cause of the transition from the fast growth phase to a prolonged slower growth phase. Rapidly growing early juveniles may have been attended by their parents, or could have been independent precocial, but non-volant arboreal creatures until attaining a certain somatic maturity to get airborne. This study adds to the understanding on the diversity of

  1. Growth, life history, and species interactions of bluegill sunfish (Lepomis macrochirus) under heavy predation

    Energy Technology Data Exchange (ETDEWEB)

    Belk, M.C. [Georgia Univ., Athens, GA (United States)

    1992-12-31

    The purpose of this study was, first, to compare growth and life history characteristics of an unfished population of bluegill sunfish (Lepomis macrochirus) in the presence of an abundant predator population to characteristic exhibited by bluegills in typical southeastern US reservoirs where the abundance of predators is reduced, but fishing is increased. The second objective was to determine if differences observed between populations were determined genetically or environmentally.

  2. Association with pathogenic bacteria affects life-history traits and population growth in Caenorhabditis elegans.

    Science.gov (United States)

    Diaz, S Anaid; Mooring, Eric Q; Rens, Elisabeth G; Restif, Olivier

    2015-04-01

    Determining the relationship between individual life-history traits and population dynamics is an essential step to understand and predict natural selection. Model organisms that can be conveniently studied experimentally at both levels are invaluable to test the rich body of theoretical literature in this area. The nematode Caenorhabditis elegans, despite being a well-established workhorse in genetics, has only recently received attention from ecologists and evolutionary biologists, especially with respect to its association with pathogenic bacteria. In order to start filling the gap between the two areas, we conducted a series of experiments aiming at measuring life-history traits as well as population growth of C. elegans in response to three different bacterial strains: Escherichia coli OP50, Salmonella enterica Typhimurium, and Pseudomonas aeruginosa PAO1. Whereas previous studies had established that the latter two reduced the survival of nematodes feeding on them compared to E. coli OP50, we report for the first time an enhancement in reproductive success and population growth for worms feeding on S. enterica Typhimurium. Furthermore, we used an age-specific population dynamic model, parameterized using individual life-history assays, to successfully predict the growth of populations over three generations. This study paves the way for more detailed and quantitative experimental investigation of the ecology and evolution of C. elegans and the bacteria it interacts with, which could improve our understanding of the fate of opportunistic pathogens in the environment.

  3. Growth and resilience of pioneering nonprofit human service organizations: a cross-case analysis of organizational histories.

    Science.gov (United States)

    Kimberlin, Sara E; Schwartz, Sara L; Austin, Michael J

    2011-01-01

    Knowledge of organizational history is important for recognizing patterns in effective management and understanding how organizations respond to internal and external challenges. This cross-case analysis of 12 histories of pioneering nonprofit human service organizations contributes an important longitudinal perspective on organizational history, complementing the cross-sectional case studies that dominate the existing research on nonprofit organizations. The literature on organizational growth, including lifecycle models and growth management, is reviewed, along with the literature on organizational resilience. Based on analysis of the 12 organizational histories, a conceptual model is presented that synthesizes key factors in the areas of leadership, internal operations, and external relations that influence organizational growth and resilience to enable nonprofit organizations to survive and thrive over time. Both cross-sectional and longitudinal examples from the organizational histories illustrate the conceptual map. The paper concludes with a discussion of directions for future research on nonprofit organizational history.

  4. The LEGACY Girls Study: Growth and development in the context of breast cancer family history

    Science.gov (United States)

    John, Esther M.; Terry, Mary Beth; Keegan, Theresa H.M.; Bradbury, Angela R.; Knight, Julia A.; Chung, Wendy K.; Frost, Caren J.; Lilge, Lothar; Patrick-Miller, Linda; Schwartz, Lisa A.; Whittemore, Alice S.; Buys, Saundra S.; Daly, Mary B.; Andrulis, Irene L.

    2017-01-01

    Background Although the timing of pubertal milestones has been associated with breast cancer risk, few studies of girls’ development include girls at increased breast cancer risk due to their family history. Methods The LEGACY (Lessons in Epidemiology and Genetics of Adult Cancer from Youth) Girls Study was initiated in 2011 in the USA and Canada to assess the relation between early-life exposures and intermediate markers of breast cancer risk (e.g., pubertal development, breast tissue characteristics) and to investigate psychosocial well-being and health behaviors in the context of family history. We describe the methods used to establish and follow a cohort of 1,040 girls ages 6–13 years at baseline, half with a breast cancer family history, and the collection of questionnaire data (family history, early-life exposures, growth and development, psychosocial and behavioral), anthropometry, biospecimens, and breast tissue characteristics using optical spectroscopy. Results During this initial 5-year phase of the study, follow-up visits are conducted every six months for repeated data and biospecimen collection. Participation in baseline components was high (98% for urine, 97.5% for blood or saliva, and 98% for anthropometry). At enrollment, 77% of girls were pre-menarcheal and 49% were at breast Tanner stage T1. Conclusions This study design allows thorough examination of events affecting girls’ growth and development and how they differ across the spectrum of breast cancer risk. A better understanding of early-life breast cancer risk factors will be essential to enhance prevention across the lifespan for those with and without a family history of the disease. PMID:26829160

  5. Cosmic-ray history derived from the sup 5 sup 4 Mn, sup 5 sup 6 Ni and sup 1 sup 4 sup 4 Pm chronometers

    CERN Document Server

    Zaerpoor, K; Di Gregorio, D E; Dragowsky, M R; Hindi, M M; Isaac, M C P; Krane, Kenneth S; Larimer, R M; Macchiavelli, A O; MacLeod, R W; Miocinovic, P; Norman, E B; Robinson, S J

    1999-01-01

    Sources of sup 5 sup 4 Mn, sup 5 sup 6 Ni, and sup 1 sup 4 sup 4 Pm were placed at the center of the Gammasphere array and searches were made for the astrophysically interesting beta sup + decay modes of these isotopes. The results of these searches are presented and the implications for cosmic-ray physics are discussed.

  6. Evolution of cosmic star formation in the SCUBA-2 Cosmology Legacy Survey

    CERN Document Server

    Bourne, N; Merlin, E; Parsa, S; Schreiber, C; Castellano, M; Conselice, C J; Coppin, K E K; Farrah, D; Fontana, A; Geach, J E; Halpern, M; Knudsen, K K; Michalowski, M J; Mortlock, A; Santini, P; Scott, D; Shu, X W; Simpson, C; Simpson, J M; Smith, D J B; van der Werf, P

    2016-01-01

    We present a new exploration of the cosmic star-formation history and dust obscuration in massive galaxies at redshifts $0.510^{10}M_\\odot$ galaxies at $0.510$. One third of this is accounted for by 450$\\mu$m-detected sources, while one fifth is attributed to UV-luminous sources (brighter than $L^\\ast_{UV}$), although even these are largely obscured. By extrapolating our results to include all stellar masses, we estimate a total SFRD that is in good agreement with previous results from IR and UV data at $z\\lesssim3$, and from UV-only data at $z\\sim5$. The cosmic star-formation history undergoes a transition at $z\\sim3-4$, as predominantly unobscured growth in the early Universe is overtaken by obscured star formation, driven by the build-up of the most massive galaxies during the peak of cosmic assembly.

  7. Cosmic Forms

    CERN Document Server

    Kleman, Maurice

    2011-01-01

    The continuous 1D defects of an isotropic homogeneous material in an Euclidean 3D space are classified by a construction method, the Volterra process (VP). We employ the same method to classify the continuous 2D defects (which we call \\textit{cosmic forms}) of a vacuum in a 4D maximally symmetric spacetime. These defects fall into three different classes: i)- $m$-forms, akin to 3D space disclinations, related to ordinary rotations and analogous to Kibble's global cosmic strings (except that being continuous any deficit angle is allowed); ii)- $t$-forms, related to Lorentz boosts (hyperbolic rotations); iii)- $r$-forms, never been considered so far, related to null rotations. A detailed account of their metrics is presented. Their inner structure in many cases appears as a non-singular \\textit{core} separated from the outer part by a timelike hypersurface with distributional curvature and/or torsion, yielding new types of geometrical interactions with cosmic dislocations and other cosmic disclinations. Whereas...

  8. Cosmic Rays Astrophysics: The Discipline, Its Scope, and Its Applications

    Science.gov (United States)

    Barghouty, A. F.

    2009-01-01

    This slide presentation gives an overview of the discipline surrounding cosmic ray astrophysics. It includes information on recent assertions surrounding cosmic rays, exposure levels, and a short history with specific information on the origin, acceleration, transport, and modulation of cosmic rays.

  9. Eye size at birth in prosimian primates: life history correlates and growth patterns.

    Directory of Open Access Journals (Sweden)

    Joshua R Cummings

    Full Text Available BACKGROUND: Primates have large eyes relative to head size, which profoundly influence the ontogenetic emergence of facial form. However, growth of the primate eye is only understood in a narrow taxonomic perspective, with information biased toward anthropoids. METHODOLOGY/PRINCIPAL FINDINGS: We measured eye and bony orbit size in perinatal prosimian primates (17 strepsirrhine taxa and Tarsius syrichta to infer the extent of prenatal as compared to postnatal eye growth. In addition, multiple linear regression was used to detect relationships of relative eye and orbit diameter to life history variables. ANOVA was used to determine if eye size differed according to activity pattern. In most of the species, eye diameter at birth measures more than half of that for adults. Two exceptions include Nycticebus and Tarsius, in which more than half of eye diameter growth occurs postnatally. Ratios of neonate/adult eye and orbit diameters indicate prenatal growth of the eye is actually more rapid than that of the orbit. For example, mean neonatal transverse eye diameter is 57.5% of the adult value (excluding Nycticebus and Tarsius, compared to 50.8% for orbital diameter. If Nycticebus is excluded, relative gestation age has a significant positive correlation with relative eye diameter in strepsirrhines, explaining 59% of the variance in relative transverse eye diameter. No significant differences were found among species with different activity patterns. CONCLUSIONS/SIGNIFICANCE: The primate developmental strategy of relatively long gestations is probably tied to an extended period of neural development, and this principle appears to apply to eye growth as well. Our findings indicate that growth rates of the eye and bony orbit are disassociated, with eyes growing faster prenatally, and the growth rate of the bony orbit exceeding that of the eyes after birth. Some well-documented patterns of orbital morphology in adult primates, such as the enlarged orbits

  10. Diamond growth history from in situ measurement of Pb and S isotopic compositions of sulfide inclusions

    Science.gov (United States)

    Rudnick, Roberta L.; Eldridge, C. Stewart; Bulanova, Galina P.

    1993-01-01

    In a continuing effort to understand crust-mantle dynamics, we have determined the S and Pb isotopic compositions of mantle sulfides encapsulated within diamonds from under the Siberian craton and compared these results to those of previously investigated African counterparts. Because diamond inclusions are isolated from exchange with surrounding mantle, they may preserve the history of diamond growth and act as direct tracers of the origins of mantle materials. Study of these inclusions may thus offer the best chance of recognizing global-scale interaction between Earth's crust and mantle. Although δ34S values of the Siberian sulfides do not deviate significantly from the mantle value of 0‰ ± 3‰, Pb isotopic compositions are highly variable. Pb isotopic compositions of sulfides from peridotitic suite diamonds generally plot near the terrestrial Pb growth curve, with model ages ranging between 0 and 2 Ga, whereas sulfides from eclogitic suite diamonds have radiogenic compositions, plotting beyond the growth curve. These results, which are similar to those for sulfides in African diamonds, suggest that the sulfides from eclogitic suite diamonds were derived from a source with an unusually high U/Pb ratio and may indicate a common process (such as subduction of crystal materials into the mantle) operating beneath Africa and Siberia. The absence of extremely radiogenic Pb in sulfides from eclogite xenoliths suggests that the radiogenic material from which eclogitic suite diamonds grew was a transient feature of the mantle, associated with diamond growth. The ultimate origin of this high U/Pb signature, however, remains enigmatic. Large variations in Pb isotopic composition of sulfides from different zones in a single peridotitic suite diamond document (1) crystallization of the diamond's core near 2.0 Ga, (2) growth of its outer zone in an environment with a high U/Pb ratio similar to the growth environment of eclogitic suite diamonds, and (3) growth of the

  11. One century of cosmic rays – A particle physicist's view

    Directory of Open Access Journals (Sweden)

    Sutton Christine

    2015-01-01

    Full Text Available Experiments on cosmic rays and the elementary particles share a common history that dates back to the 19th century. Following the discovery of radioactivity in the 1890s, the paths of the two fields intertwined, especially during the decades after the discovery of cosmic rays. Experiments demonstrated that the primary cosmic rays are positively charged particles, while other studies of cosmic rays revealed various new sub-atomic particles, including the first antiparticle. Techniques developed in common led to the birth of neutrino astronomy in 1987 and the first observation of a cosmic γ-ray source by a ground-based cosmic-ray telescope in 1989.

  12. The simplest model of galaxy formation I: A formation history model of galaxy stellar mass growth

    CERN Document Server

    Mutch, Simon J; Poole, Gregory B

    2013-01-01

    We introduce a simple model to self-consistently connect the growth of galaxies to the formation history of their host dark matter halos. Our model is defined by two simple functions: the "baryonic growth function" which controls the rate at which new baryonic material is made available for star formation, and the "physics function" which controls the efficiency with which this material is converted into stars. Using simple, phenomenologically motivated forms for both functions that depend only on a single halo property, we demonstrate the model's ability to reproduce the z=0 red and blue stellar mass functions. Furthermore, by adding redshift as a second input variable to the physics function we show that the reproduction of the global stellar mass function out to z=3 is improved. We conclude by discussing the general utility of our new model, highlighting its usefulness for creating mock galaxy samples which have a number of key advantages over those generated by other techniques.

  13. The cosmic growth of the active black hole population at 1

    CERN Document Server

    Schulze, A; Gavignaud, I; Schramm, M; Silverman, J; Merloni, A; Zamorani, G; Hirschmann, M; Mainieri, V; Wisotzki, L; Shankar, F; Fiore, F; Koekemoer, A M; Temporin, G

    2014-01-01

    We present a census of the active black hole population at 1cosmic evolution of the AGN population as a function of AGN luminosity, black hole mass and accretion rate. Compared to z = 0 we find a distinct change in the shape of the BHMF and the ERDF, consistent with downsizing in black hole mass. The active fraction or duty cycle of type 1 AGN at z~1.5 is almost flat as...

  14. Cosmic confusion

    CERN Document Server

    Magueijo, J

    1994-01-01

    We propose to minimise the cosmic confusion between Gaussian and non Gaussian theories by investigating the structure in the m's for each multipole of the cosmic radiation temperature anisotropies. We prove that Gaussian theories are (nearly) the only theories which treat all the m's equally. Hence we introduce a set of invariant measures of ``m-preference'' to be seen as non-Gaussianity indicators. We then derive the distribution function for the quadrupole ``m-preference'' measure in Gaussian theories. A class of physically motivated toy non Gaussian theories is introduced as an example. We show how the quadrupole m-structure is crucial in reducing the confusion between these theories and Gaussian theories.

  15. External public indebtedness in Mexico: recent history and future oil-bounded optimal growth

    Energy Technology Data Exchange (ETDEWEB)

    Zedillo Ponce De Leon, E.

    1981-01-01

    The Phenomenon of the growth of the external public debt in Mexico since 1954 is studied. Chapter 1 provides a review of a few preliminary topics such as the history of the debt prior to 1954 and the evoluton of the Mexican economy and the total inflow of foreign capital since 1954. Chapter 2 provides a detailed description of the growth of the foreign public debt during 1954-1979, paying attention to a number of debt-management aspects. At this point it is clear that the external debt began to grow well over its historic trend in 1973. An analysis of the short-run direct macroeconomic impacts of the net flow of the debt from the mid-fifties to the mid-seventies is presented in Chapter 3. Through the specification and estimation of a small econometric model, the direct impact of such variable on different components of the aggregate demand is estimated. In Chapter 4, the causes of the growth of the debt during 1973-1977 are studied. An analytical framework that distinguishes between external and internal debt-inducing factors is presented. Its application reveals that, unlike the case of other LDC's, the growth of the debt during such period was more the result of internal than external phenomena. In the final chapter, Mexico's indebtedness outlook for the 1980's is considered. The analysis focuses on the interaction that should exist between oil exports and indebtedness.

  16. Supermassive Black-Hole Growth Over Cosmic Time: Active Galaxy Demography, Physics, and Ecology from Chandra Surveys

    CERN Document Server

    Brandt, W N

    2010-01-01

    Extragalactic X-ray surveys over the past decade have dramatically improved understanding of the majority populations of active galactic nuclei (AGNs) over most of the history of the Universe. Here we briefly highlight some of the exciting discoveries about AGN demography, physics, and ecology with a focus on results from Chandra. We also discuss some key unresolved questions and future prospects.

  17. Life-history plasticity and sustainable exploitation: a theory of growth compensation applied to walleye management.

    Science.gov (United States)

    Lester, Nigel P; Shuter, Brian J; Venturelli, Paul; Nadeau, Daniel

    2014-01-01

    A simple population model was developed to evaluate the role of plastic and evolutionary life-history changes on sustainable exploitation rates. Plastic changes are embodied in density-dependent compensatory adjustments to somatic growth rate and larval/juvenile survival, which can compensate for the reductions in reproductive lifetime and mean population fecundity that accompany the higher adult mortality imposed by exploitation. Evolutionary changes are embodied in the selective pressures that higher adult mortality imposes on age at maturity, length at maturity, and reproductive investment. Analytical development, based on a biphasic growth model, led to simple equations that show explicitly how sustainable exploitation rates are bounded by each of these effects. We show that density-dependent growth combined with a fixed length at maturity and fixed reproductive investment can support exploitation-driven mortality that is 80% of the level supported by evolutionary changes in maturation and reproductive investment. Sustainable fishing mortality is proportional to natural mortality (M) times the degree of density-dependent growth, as modified by both the degree of density-dependent early survival and the minimum harvestable length. We applied this model to estimate sustainable exploitation rates for North American walleye populations (Sander vitreus). Our analysis of demographic data from walleye populations spread across a broad latitudinal range indicates that density-dependent variation in growth rate can vary by a factor of 2. Implications of this growth response are generally consistent with empirical studies suggesting that optimal fishing mortality is approximately 0.75M for teleosts. This approach can be adapted to the management of other species, particularly when significant exploitation is imposed on many, widely distributed, but geographically isolated populations.

  18. Cosmic Ether

    CERN Document Server

    Tomaschitz, R

    1998-01-01

    A prerelativistic approach to particle dynamics is explored in an expanding Robertson-Walker cosmology. The receding galactic background provides a distinguished frame of reference and a unique cosmic time. In this context the relativistic, purely geometric space-time concept is criticized. Physical space is regarded as a permeable medium, the cosmic ether, which effects the world-lines of particles and rays. We study in detail a Robertson-Walker universe with linear expansion factor and negatively curved, open three-space; we choose the permeability tensor of the ether in such a way that the semiclassical approximation is exact. Galactic red-shifts depend on the refractive index of the ether. In the local Minkowskian limit the ether causes a time variation of mass, which scales inversely proportional to cosmic time. In the globally geodesic rest frames of galactic observers the ether manifests itself in an unbounded speed of signal transfer, in bifurcations of world-lines, and in time inversion effects.

  19. Intelligence Quotient (IQ and Growth Indices in Children with the History of Low Birth Weight

    Directory of Open Access Journals (Sweden)

    Amin-Gooran Urimei

    2009-12-01

    Full Text Available Objective: In two groups of children with and without the history of LBW, Intelligence Quotient (IQ and growth indices including weight and height are compared.Methods: In this historical cohort study performed in Zanjan City (Iran, 130 six-year-old children of both sexes in two equal groups, 65 with LBW history and 65 with normal birth weight (NBW, were selected randomly to be assessed for IQ, utilizing Wechsler Intelligence Scale for Children-Revised (WISC-R and physical growth indices, including weight and height. The results were analyzed statistically and P-values less than 0.05 were considered as significant.Findings: Verbal, non-verbal and total IQ, all were significantly different between LBW and NBW groups (P=0.02, P=0.04 and P=0.01, respectively. Mean total IQ was 93.66±8.27 and 99.32±11.05, respectively. Weight and height between case and control groups showed significant differences, too (P=0.001 and P= 0.005, respectively.Conclusion: The results of this study and similar studies emphasize paying special attention to the problem of low birth weight deliveries, recognizing related risk factors and trying to reduce them.

  20. Note on cosmic censorship

    Science.gov (United States)

    Tipler, F. J.

    1985-05-01

    A number of recent theorems by Krolak (1983) and Newman (1983) purport to prove cosmic censorship by showing that strong-curvature singularities must be hidden behind horizons. It is shown that the 'null strong-curvature' condition which Newman imposes on certain classes of null geodesics to restrict curvature growth in the space-time does not hold in many physically realistic space-times: it is not satisfied by any null geodesic in the relevant class in any open Friedmann cosmological model, nor does it hold for any null geodesic in the relevant class in maximal Schwarzschild space. More generally it is argued that the singularity predicted by the Penrose singularity theorem is unlikely to be of the type eliminated by Newman. Thus the Newman theorems are probably without physical significance. The Krolak theorems, although based on a physically significant definition of strong curvature singularity, are mathematically invalid, and this approach cannot be used to obtain a cosmic-censorship theorem.

  1. Discovery of cosmic fractals

    CERN Document Server

    Baryshev, Yuri

    2002-01-01

    This is the first book to present the fascinating new results on the largest fractal structures in the universe. It guides the reader, in a simple way, to the frontiers of astronomy, explaining how fractals appear in cosmic physics, from our solar system to the megafractals in deep space. It also offers a personal view of the history of the idea of self-similarity and of cosmological principles, from Plato's ideal architecture of the heavens to Mandelbrot's fractals in the modern physical cosmos. In addition, this invaluable book presents the great fractal debate in astronomy (after Luciano Pi

  2. The Natural Science Underlying Big History

    CERN Document Server

    Chaisson, Eric J

    2014-01-01

    Nature's many varied complex systems (including galaxies, stars, planets, life, and society) are islands of order within the increasingly disordered universe. All organized systems are subject to physical, biological or cultural evolution, which together comprise the grander interdisciplinary subject of cosmic evolution. This is global history greatly extended, big history with a scientific basis, and natural history broadly portrayed across 14 billion years of time. Such evolution writ large has significant potential to unify the natural sciences into a holistic understanding of who we are and whence we came. No new science (beyond frontier, non-equilibrium thermodynamics) is needed to describe cosmic evolution's major milestones at a deep and empirical level. Quantitative models and experimental tests imply that a remarkable simplicity underlies the emergence and growth of complexity for a wide spectrum of known and diverse systems. In particular, energy rate density is an objective metric suitable to gauge...

  3. Postnatal long bone growth in terrestrial placental mammals: allometry, life history, and organismal traits.

    Science.gov (United States)

    Kilbourne, Brandon M; Makovicky, Peter J

    2012-10-01

    The ontogenetic allometry of long bone proportions is poorly understood in Mammalia. It has previously been suggested that during mammalian ontogeny long bone proportions grow more slender (positive allometry; length ∝ circumference(>1.0) ), although this conclusion was based upon data from a few small-bodied taxa. It remains unknown how ontogenetic long bone allometry varies across Mammalia in terms of both taxonomy and body size. We collected long bone length and circumference data for ontogenetic samples of 22 species of mammals spanning six major clades and three orders of magnitude in body mass. Using reduced major axis bivariate regressions to compare bone length to circumference, we found that isometry and positive allometry are the most widespread patterns of growth across mammals. Negative allometry (i.e., bones growing more robust during ontogeny) occurs in mammals but is largely restricted to cetartiodactyls. Using regression slope as a proxy for long bone allometry, we compared long bone allometry to life history and organismal traits. Neonatal body mass, adult body mass, and growth rate have a negative relationship with long bone allometry. At an adult mass of roughly 15-20 kg, long bone growth shifts from positive allometry to mainly isometry and negative allometry. There were no significant relationships between ontogenetic long bone allometry and either cursoriality or basal metabolic rate. Copyright © 2012 Wiley Periodicals, Inc.

  4. Elemental markers in elasmobranchs: effects of environmental history and growth on vertebral chemistry.

    Science.gov (United States)

    Smith, Wade D; Miller, Jessica A; Heppell, Selina S

    2013-01-01

    Differences in the chemical composition of calcified skeletal structures (e.g. shells, otoliths) have proven useful for reconstructing the environmental history of many marine species. However, the extent to which ambient environmental conditions can be inferred from the elemental signatures within the vertebrae of elasmobranchs (sharks, skates, rays) has not been evaluated. To assess the relationship between water and vertebral elemental composition, we conducted two laboratory studies using round stingrays, Urobatis halleri, as a model species. First, we examined the effects of temperature (16°, 18°, 24°C) on vertebral elemental incorporation (Li/Ca, Mg/Ca, Mn/Ca, Zn/Ca, Sr/Ca, Ba/Ca). Second, we tested the relationship between water and subsequent vertebral elemental composition by manipulating dissolved barium concentrations (1x, 3x, 6x). We also evaluated the influence of natural variation in growth rate on elemental incorporation for both experiments. Finally, we examined the accuracy of classifying individuals to known environmental histories (temperature and barium treatments) using vertebral elemental composition. Temperature had strong, negative effects on the uptake of magnesium (DMg) and barium (DBa) and positively influenced manganese (DMn) incorporation. Temperature-dependent responses were not observed for lithium and strontium. Vertebral Ba/Ca was positively correlated with ambient Ba/Ca. Partition coefficients (DBa) revealed increased discrimination of barium in response to increased dissolved barium concentrations. There were no significant relationships between elemental incorporation and somatic growth or vertebral precipitation rates for any elements except Zn. Relationships between somatic growth rate and DZn were, however, inconsistent and inconclusive. Variation in the vertebral elemental signatures of U. halleri reliably distinguished individual rays from each treatment based on temperature (85%) and Ba exposure (96%) history. These

  5. Origin of cosmic magnetic fields

    Science.gov (United States)

    Rees, M. J.

    2006-06-01

    The first significant cosmic fields, and the seed field for galactic dynamos probably developed after the formation of the first non-linear structures. The history of star formation and the intergalactic medium is controlled, at least in part, by how and when galaxies and their precursors acquired their fields. The amplification of fields behind shocks, and the diffusivity of the magnetic flux, are crucial to the interpretation of radio sources, gamma ray burst afterglows, and other energetic cosmic phenomena. The build-up of magnetic fields is an important aspect of the overall cosmogonic process.

  6. Cosmic radioactivities

    CERN Document Server

    Arnould, M; Arnould, Marcel; Prantzos, Nikos

    1999-01-01

    Radionuclides with half-lives ranging from some years to billions of years presumably synthesized outside of the solar system are now recorded in ``live'' or ``fossil'' form in various types of materials, like meteorites or the galactic cosmic rays. They bring specific astrophysical messages the deciphering of which is briefly reviewed here, with special emphasis on the contribution of Dave Schramm and his collaborators to this exciting field of research. Short-lived radionuclides are also present in the Universe today, as directly testified by the gamma-ray lines emitted by the de-excitation of their daughter products. A short review of recent developments in this field is also presented.

  7. Cosmic radioactivities

    Science.gov (United States)

    Arnould, Marcel; Prantzos, Nikos

    1999-07-01

    Radionuclides with half-lives ranging from some years to billions of years presumably synthesized outside of the solar system are now recorded in "live" or "fossil" form in various types of materials, like meteorites or the galactic cosmic rays. They bring specific astrophysical messages, the deciphering of which is briefly reviewed here, with special emphasis on the contribution of Dave Schramm and his collaborators to this exciting field of research. Short-lived radionuclides are also present in the Universe today, as directly testified by the γ-ray lines emitted by the de-excitation of their daughter products. A short review of recent developments in this field is also presented.

  8. On Strong Cosmic Censorship

    CERN Document Server

    Isenberg, James

    2015-01-01

    For almost half of the one hundred year history of Einstein's theory of general relativity, Strong Cosmic Censorship has been one of its most intriguing conjectures. The SCC conjecture addresses the issue of the nature of the singularities found in most solutions of Einstein's gravitational field equations: Are such singularities generically characterized by unbounded curvature? Is the existence of a Cauchy horizon (and the accompanying extensions into spacetime regions in which determinism fails) an unstable feature of solutions of Einstein's equations? In this short review article, after briefly commenting on the history of the SCC conjecture, we survey some of the progress made in research directed either toward supporting SCC or toward uncovering some of its weaknesses. We focus in particular on model versions of SCC which have been proven for restricted families of spacetimes (e.g., the Gowdy spacetimes), and the role played by the generic presence of Asymptotically Velocity Term Dominated behavior in th...

  9. Cosmic Ray transport in turbulent magnetic field

    CERN Document Server

    Yan, Huirong

    2013-01-01

    Cosmic ray (CR) transport and acceleration is determined by the properties of magnetic turbulence. Recent advances in MHD turbulence call for revisions in the paradigm of cosmic ray transport. We use the models of magnetohydrodynamic turbulence that were tested in numerical simulation, in which turbulence is injected at large scale and cascades to to small scales. We shall address the issue of the transport of CRs, both parallel and perpendicular to the magnetic field. We shall demonstrate compressible fast modes are dominant cosmic ray scatterer from both quasilinear and nonlinear theories. We shall also show that the self-generated wave growth by CRs are constrained by preexisting turbulence and discuss the process in detail in the context of shock acceleration at supernova remnants and their implications. In addition, we shall dwell on the nonlinear growth of kinetic gyroresonance instability of cosmic rays induced by large scale compressible turbulence. This gyroresonance of cosmic rays on turbulence is d...

  10. Long bone histology and growth patterns in ankylosaurs: implications for life history and evolution.

    Directory of Open Access Journals (Sweden)

    Martina Stein

    Full Text Available The ankylosaurs are one of the major dinosaur groups and are characterized by unique body armor. Previous studies on other dinosaur taxa have revealed growth patterns, life history and evolutionary mechanisms based on their long bone histology. However, to date nothing is known about long bone histology in the Ankylosauria. This study is the first description of ankylosaurian long bone histology based on several limb elements, which were sampled from different individuals from the Ankylosauridae and Nodosauridae. The histology is compared to that of other dinosaur groups, including other Thyreophora and Sauropodomorpha. Ankylosaur long bone histology is characterized by a fibrolamellar bone architecture. The bone matrix type in ankylosaurs is closest to that of Stegosaurus. A distinctive mixture of woven and parallel-fibered bone together with overall poor vascularization indicates slow growth rates compared to other dinosaurian taxa. Another peculiar characteristic of ankylosaur bone histology is the extensive remodeling in derived North American taxa. In contrast to other taxa, ankylosaurs substitute large amounts of their primary tissue early in ontogeny. This anomaly may be linked to the late ossification of the ankylosaurian body armor. Metabolically driven remodeling processes must have liberated calcium to ossify the protective osteodermal structures in juveniles to subadult stages, which led to further remodeling due to increased mechanical loading. Abundant structural fibers observed in the primary bone and even in remodeled bone may have improved the mechanical properties of the Haversian bone.

  11. Long bone histology and growth patterns in ankylosaurs: implications for life history and evolution.

    Science.gov (United States)

    Stein, Martina; Hayashi, Shoji; Sander, P Martin

    2013-01-01

    The ankylosaurs are one of the major dinosaur groups and are characterized by unique body armor. Previous studies on other dinosaur taxa have revealed growth patterns, life history and evolutionary mechanisms based on their long bone histology. However, to date nothing is known about long bone histology in the Ankylosauria. This study is the first description of ankylosaurian long bone histology based on several limb elements, which were sampled from different individuals from the Ankylosauridae and Nodosauridae. The histology is compared to that of other dinosaur groups, including other Thyreophora and Sauropodomorpha. Ankylosaur long bone histology is characterized by a fibrolamellar bone architecture. The bone matrix type in ankylosaurs is closest to that of Stegosaurus. A distinctive mixture of woven and parallel-fibered bone together with overall poor vascularization indicates slow growth rates compared to other dinosaurian taxa. Another peculiar characteristic of ankylosaur bone histology is the extensive remodeling in derived North American taxa. In contrast to other taxa, ankylosaurs substitute large amounts of their primary tissue early in ontogeny. This anomaly may be linked to the late ossification of the ankylosaurian body armor. Metabolically driven remodeling processes must have liberated calcium to ossify the protective osteodermal structures in juveniles to subadult stages, which led to further remodeling due to increased mechanical loading. Abundant structural fibers observed in the primary bone and even in remodeled bone may have improved the mechanical properties of the Haversian bone.

  12. Leaf and life history traits predict plant growth in a green roof ecosystem.

    Science.gov (United States)

    Lundholm, Jeremy; Heim, Amy; Tran, Stephanie; Smith, Tyler

    2014-01-01

    Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth) to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime's C-S-R strategies) for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that favor less

  13. Leaf and life history traits predict plant growth in a green roof ecosystem.

    Directory of Open Access Journals (Sweden)

    Jeremy Lundholm

    Full Text Available Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime's C-S-R strategies for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that

  14. Beyond the growth rate of cosmic structure: Testing modified gravity models with an extra degree of freedom

    CERN Document Server

    Burrage, Clare; Seery, David

    2015-01-01

    In 'modified' gravity the observed acceleration of the universe is explained by changing the gravitational force law or the number of degrees of freedom in the gravitational sector. Both possibilities can be tested by measurements of cosmological structure formation. In this paper we elaborate the details of such tests using the Galileon model as a case study. We pay attention to the possibility that each new degree of freedom may have stochastically independent initial conditions, generating different types of potential well in the early universe and breaking complete correlation between density and velocity power spectra. This 'stochastic bias' can confuse schemes to parametrize the predictions of modified gravity models, such as the use of the growth parameter f alone. Using data from the WiggleZ Dark Energy Survey we show that it will be possible to obtain constraints using information about the cosmological-scale force law embedded in the multipole power spectra of redshift-space distortions. As an examp...

  15. Beyond the growth rate of cosmic structure: Testing modified gravity models with an extra degree of freedom

    Science.gov (United States)

    Burrage, Clare; Parkinson, David; Seery, David

    2017-08-01

    In "modified" gravity the observed acceleration of the universe is explained by changing the gravitational force law or the number of degrees of freedom in the gravitational sector. Both possibilities can be tested by measurements of cosmological structure formation. In this paper we elaborate the details of such tests using the Galileon model as a case study. We pay attention to the possibility that each new degree of freedom may have stochastically independent initial conditions, generating different types of potential well in the early universe and breaking complete correlation between density and velocity power spectra. This "stochastic bias" can confuse schemes to parametrize the predictions of modified gravity models, such as the use of the growth parameter f alone. Using data from the WiggleZ Dark Energy Survey we show that it will be possible to obtain constraints using information about the cosmological-scale force law embedded in the multipole power spectra of redshift-space distortions. As an example, we obtain an upper limit on the strength of the conformal coupling to matter in the cubic Galileon model, giving |1 /M |≲200 /MP . This allows the fifth-force to be stronger than gravity, but is consistent with zero coupling.

  16. Life histories have a history: effects of past and present conditions on adult somatic growth rates in wild Trinidadian guppies.

    Science.gov (United States)

    Auer, Sonya K; Lopez-Sepulcre, Andrés; Heatherly, Thomas; Kohler, Tyler J; Bassar, Ronald D; Thomas, Steven A; Reznick, David N

    2012-07-01

    1. Environmental conditions in the present, more recent past and during the juvenile stage can have significant effects on adult performance and population dynamics, but their relative importance and potential interactions remain unexplored. 2. We examined the influence of food availability at the time of sampling, 2 months prior and during the juvenile stage on adult somatic growth rates in wild Trinidadian guppies (Poecilia reticulata). 3. We found that food availability during both the early and later parts of an individual's ontogeny had important consequences for adult growth strategies, but the direction of these effects differed among life stages and their magnitude, in some cases, depended on food levels experienced during other life stages. Current food levels and those 2 months prior to growth measurements had positive effects on adult growth rate; though, food levels 2 months prior had a greater effect on growth than current food levels. In contrast, the effects of food availability during the juvenile stage were higher in magnitude but opposite in direction to current food levels and those 2 months prior to growth rate measurements. Individuals recruiting under low food levels grew faster as adults than individuals recruiting during periods of high food availability. There was also a positive interaction between food levels experienced during the juvenile stage and 2 months prior such that the effects of juvenile food level diminished as the food level experienced 2 months prior increased. 4. These results suggest that the similar conditions occurring at different life stages can have different effects on short- and long-term growth strategies of individuals within a population. They also demonstrate that, while juvenile conditions can have lasting effects on adult performance, the strength of that effect can be dampened by environmental conditions experienced as an adult. 5. A simultaneous consideration of past events in both the

  17. Effect of sow history features on growth and feed intake in grow-finish pigs.

    Science.gov (United States)

    Sell-Kubiak, E; Knol, E F; Bijma, P

    2012-01-01

    The sow provides a specific environment to her offspring during gestation and lactation. Certain features in the early life of the sow (sow history features) may affect her ability to deliver and feed a healthy litter. In genetic analyses of grow-finish traits, these effects are estimated as common litter or permanent sow effects. The objective of this research was to identify sow history features that affect the growth rate (GR) and feed intake (FI) of her offspring during the grow-finish stage. Data from 17,743 grow-finish pigs, coming from 604 sires and 681 crossbred sows, were recorded between May 2001 and February 2010 at the experimental farm of the Institute for Pig Genetics (Beilen, the Netherlands). The grow-finish stage was divided into 2 phases (phase 1: 26 to 75 kg; phase 2: 75 to 115 kg). The sow history features were birth litter size, birth year and season, birth farm, weaning age, age of transfer to the experimental farm, and age at first insemination. The sow features were added to the basic model one at a time to study their effect on the grow-finish traits of the pigs. Subsequently, significant sow features (P finish pigs by 0.1 g/d. The heritability estimates for GR and FI (only in phase 2 of the grow-finish stage) decreased after adding the sow features to the model. No differences were found in estimates of the common litter effects between the basic model and the model with all significant sow features. The estimates of the permanent sow effect changed for FI from 0.03 (basic model) to 0.00 (model with sow features), and for FI in phase 1, the permanent sow effect decreased from 0.03 (basic model) to 0.01 (model with sow features). In conclusion, selected sow features do affect the grow-finish traits of the pigs, but their estimates are small and explain only a small proportion of the differences in the GR and FI of grow-finish pigs. The sow features partially explained the permanent sow effect of FI-related traits and did not explain the

  18. Slow Crack Growth and Fatigue Life Prediction of Ceramic Components Subjected to Variable Load History

    Science.gov (United States)

    Jadaan, Osama

    2001-01-01

    Present capabilities of the NASA CARES/Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code include probabilistic life prediction of ceramic components subjected to fast fracture, slow crack growth (stress corrosion), and cyclic fatigue failure modes. Currently, this code has the capability to compute the time-dependent reliability of ceramic structures subjected to simple time-dependent loading. For example, in slow crack growth (SCG) type failure conditions CARES/Life can handle the cases of sustained and linearly increasing time-dependent loads, while for cyclic fatigue applications various types of repetitive constant amplitude loads can be accounted for. In real applications applied loads are rarely that simple, but rather vary with time in more complex ways such as, for example, engine start up, shut down, and dynamic and vibrational loads. In addition, when a given component is subjected to transient environmental and or thermal conditions, the material properties also vary with time. The objective of this paper is to demonstrate a methodology capable of predicting the time-dependent reliability of components subjected to transient thermomechanical loads that takes into account the change in material response with time. In this paper, the dominant delayed failure mechanism is assumed to be SCG. This capability has been added to the NASA CARES/Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code, which has also been modified to have the ability of interfacing with commercially available FEA codes executed for transient load histories. An example involving a ceramic exhaust valve subjected to combustion cycle loads is presented to demonstrate the viability of this methodology and the CARES/Life program.

  19. The ACS LCID Project : V. The Star Formation History of the Dwarf Galaxy LGS-3: Clues to Cosmic Reionization and Feedback

    NARCIS (Netherlands)

    Hidalgo, Sebastian L.; Aparicio, Antonio; Skillman, Evan; Monelli, Matteo; Gallart, Carme; Cole, Andrew; Dolphin, Andrew; Weisz, Daniel; Bernard, Edouard J.; Cassisi, Santi; Mayer, Lucio; Stetson, Peter; Tolstoy, Eline; Ferguson, Henry

    2011-01-01

    We present an analysis of the star formation history (SFH) of the transition-type (dIrr/dSph) Local Group galaxy LGS-3 (Pisces) based on deep photometry obtained with the Advanced Camera for Surveys onboard the Hubble Space Telescope. Our observations reach the oldest main-sequence turnoffs at high

  20. The ACS LCID Project. V. The Star Formation History of the Dwarf Galaxy LGS-3: Clues to Cosmic Reionization and Feedback

    NARCIS (Netherlands)

    Hidalgo, Sebastian L.; Aparicio, Antonio; Skillman, Evan; Monelli, Matteo; Gallart, Carme; Cole, Andrew; Dolphin, Andrew; Weisz, Daniel; Bernard, Edouard J.; Cassisi, Santi; Mayer, Lucio; Stetson, Peter; Tolstoy, Eline; Ferguson, Henry

    We present an analysis of the star formation history (SFH) of the transition-type (dIrr/dSph) Local Group galaxy LGS-3 (Pisces) based on deep photometry obtained with the Advanced Camera for Surveys onboard the Hubble Space Telescope. Our observations reach the oldest main-sequence turnoffs at high

  1. The 7 Ms Chandra Deep Field-South Survey: Cosmic Black-Hole Growth is Mainly Linked to Host-Galaxy Stellar Mass

    Science.gov (United States)

    Brandt, W. Niel; Yang, Guang; Chen, Chien-Ting; Vito, Fabio

    2017-08-01

    The Chandra exposure on the Chandra Deep Field-South (CDF-S) has recently been increased to 7 Ms, allowing unmatched X-ray and multiwavelength characterization of cosmic black-hole growth in active galactic nuclei (AGNs). We have used these data to investigate the dependence of black-hole accretion rate (BHAR) on host-galaxy star formation rate (SFR) and stellar mass (M*) at z = 0.5-2. Our sample consists of 18,000 galaxies with SFR and M* measurements, and we use sample-mean BHAR for these galaxies to approximate their long-term average BHAR. Our sample-mean BHARs are derived from the CDF-S observations via both direct spectral analysis and stacking. The average BHAR is correlated positively with both SFR and M*, and the BHAR-SFR and BHAR-M* relations can both be described acceptably by linear models with a slope of unity. However, according to partial-correlation analyses, BHAR is correlated more strongly with M* than SFR. This result indicates that M* is the primary host-galaxy property related to black-hole growth, and the well-known BHAR-SFR relation is largely a secondary effect due to the "star-forming main sequence". Among our sources, massive galaxies have significantly higher BHAR/SFR ratios than less-massive galaxies, indicating the former have higher black-hole fueling efficiency and/or higher SMBH occupation fraction than the latter; e.g., the deeper potential wells in higher mass galaxies may promote black-hole accretion and counteract AGN/supernova feedback. Our results can naturally explain the observed proportionality between MBH and M* for local giant ellipticals, and suggest their MBH/M* ratios are higher than those of local star-forming galaxies. Finally, prospects for extending this work will be discussed; e.g., by further investigating the redshift evolution of the primary BHAR-M* relation and measuring this relation for even higher values of M*, above ~ 1011 solar masses, using wide-field X-ray surveys.

  2. Determining individual variation in growth and its implication for life-history and population processes using the empirical Bayes method.

    Directory of Open Access Journals (Sweden)

    Simone Vincenzi

    2014-09-01

    Full Text Available The differences in demographic and life-history processes between organisms living in the same population have important consequences for ecological and evolutionary dynamics. Modern statistical and computational methods allow the investigation of individual and shared (among homogeneous groups determinants of the observed variation in growth. We use an Empirical Bayes approach to estimate individual and shared variation in somatic growth using a von Bertalanffy growth model with random effects. To illustrate the power and generality of the method, we consider two populations of marble trout Salmo marmoratus living in Slovenian streams, where individually tagged fish have been sampled for more than 15 years. We use year-of-birth cohort, population density during the first year of life, and individual random effects as potential predictors of the von Bertalanffy growth function's parameters k (rate of growth and L∞ (asymptotic size. Our results showed that size ranks were largely maintained throughout marble trout lifetime in both populations. According to the Akaike Information Criterion (AIC, the best models showed different growth patterns for year-of-birth cohorts as well as the existence of substantial individual variation in growth trajectories after accounting for the cohort effect. For both populations, models including density during the first year of life showed that growth tended to decrease with increasing population density early in life. Model validation showed that predictions of individual growth trajectories using the random-effects model were more accurate than predictions based on mean size-at-age of fish.

  3. Determining Individual Variation in Growth and Its Implication for Life-History and Population Processes Using the Empirical Bayes Method

    Science.gov (United States)

    Vincenzi, Simone; Mangel, Marc; Crivelli, Alain J.; Munch, Stephan; Skaug, Hans J.

    2014-01-01

    The differences in demographic and life-history processes between organisms living in the same population have important consequences for ecological and evolutionary dynamics. Modern statistical and computational methods allow the investigation of individual and shared (among homogeneous groups) determinants of the observed variation in growth. We use an Empirical Bayes approach to estimate individual and shared variation in somatic growth using a von Bertalanffy growth model with random effects. To illustrate the power and generality of the method, we consider two populations of marble trout Salmo marmoratus living in Slovenian streams, where individually tagged fish have been sampled for more than 15 years. We use year-of-birth cohort, population density during the first year of life, and individual random effects as potential predictors of the von Bertalanffy growth function's parameters k (rate of growth) and (asymptotic size). Our results showed that size ranks were largely maintained throughout marble trout lifetime in both populations. According to the Akaike Information Criterion (AIC), the best models showed different growth patterns for year-of-birth cohorts as well as the existence of substantial individual variation in growth trajectories after accounting for the cohort effect. For both populations, models including density during the first year of life showed that growth tended to decrease with increasing population density early in life. Model validation showed that predictions of individual growth trajectories using the random-effects model were more accurate than predictions based on mean size-at-age of fish. PMID:25211603

  4. The life and death of cosmic voids

    CERN Document Server

    Sutter, P M; Falck, Bridget; Onions, Julian; Hamaus, Nico; Knebe, Alexander; Srisawat, Chaichalit; Schneider, Aurel

    2014-01-01

    We investigate the formation, growth, merger history, movement, and destruction of cosmic voids detected via the watershed transform in a cosmological N-body dark matter {\\Lambda}CDM simulation. By adapting a method used to construct halo merger trees, we are able to trace individual voids back to their initial appearance and record the merging and evolution of their progenitors at high redshift. For the scales of void sizes captured in our simulation, we find that the void formation rate peaks at scale factor 0.3, which coincides with a growth in the void hierarchy and the emergence of dark energy. Voids of all sizes appear at all scale factors, though the median initial void size decreases with time. When voids become detectable they have nearly their present-day volumes. Almost all voids have relatively stable growth rates and suffer only infrequent minor mergers. Dissolution of a void via merging is very rare. Instead, most voids maintain their distinct identity as annexed subvoids of a larger parent. The...

  5. Note on cosmic censorship

    Energy Technology Data Exchange (ETDEWEB)

    Tipler, F.J.

    1985-05-01

    A number of recent theorems by Krolak and Newman purport to prove cosmic censorship by showing that ''strong curvature'' singularities must be hidden behind horizons. It is proved that Newman's ''null, strong curvature'' condition, which is imposed on certain classes of null geodesics to restrict curvature growth in the space-time, does not hold in many physically realistic space-times: it is not satisfied by any null geodesic in the relevant class in any open Friedmann cosmological model, nor does it hold for any null geodesic in the relevant class in maximal Schwarzschild space. More generally, it is argued that the singularity predicted by the Penrose singularity theorem is unlikely to be of the type eliminated by Newman. Thus the Newman theorems are probably without physical significance. The Krolak theorems, although based on a physically significant definition of strong curvature singularity, are mathematically invalid, and this approach cannot be used to obtain a cosmic censorship theorem. (author).

  6. Cosmic particle acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Zimbardo, Gaetano; Perri, Silvia [Universita della Calabria, Dipartimento di Fisica, 87036 Rende (Italy)

    2014-07-01

    The most popular mechanism for the acceleration of cosmic rays, which is thought to operate in supernova remnant shocks as well as at heliospheric shocks, is the diffusive shock acceleration, which is a Fermi mechanism based on normal diffusion. On the other hand, in the last few years it has been shown that the transport of plasma particles in the presence of electric and magnetic turbulence can be superdiffusive rather than normal diffusive. The term 'superdiffusive' refers to the mean square displacement of particle positions growing superlinearly with time, as compared to the normal linear growth. In particular, superdiffusion is characterized by a non Gaussian statistical process called Levy random walk. We show how diffusive shock acceleration is modified by superdiffusion, and how this yields new predictions for the cosmic ray spectral index, for the acceleration time, and for the spatial profile of energetic particles. A comparison with observations of particle acceleration at heliospheric shocks and at supernova remnant shocks is done. We discuss how superdiffusive shock acceleration allows to explain the observations of hard ion spectra at the solar wind termination shock detected by Voyager 2, of hard radio spectra due to synchrotron emission of electrons accelerated at supernova remnant shocks, and how it can help to explain the observations of 'thin rims' in the X-ray synchrotron emission.

  7. ALICE Cosmic Ray Detector

    CERN Multimedia

    Fernandez Tellez, A; Martinez Hernandez, M; Rodriguez Cahuantzi, M

    2013-01-01

    The ALICE underground cavern provides an ideal place for the detection of high energy atmospheric muons coming from cosmic ray showers. ACORDE detects cosmic ray showers by triggering the arrival of muons to the top of the ALICE magnet.

  8. History of the "Detector Materials Engineering" Crystal Growth Process for Bulk Hg1- x Cd x Te

    Science.gov (United States)

    Higgins, W. M.; Nelson, D. A.; Roy, R. G.; Murosako, R. P.; Lancaster, R. A.; Tower, J.; Norton, P.

    2013-11-01

    This paper reviews the history and technology of a bulk Hg1- x Cd x Te crystal growth process that was developed in the early 1980s at Honeywell Electro-Optics Division (presently BAE Systems, Electronic Solutions). The crystal growth process name, DME, was an acronym for the department name: Detector Materials Engineering. This was an accelerated crucible rotation technique (ACRT) vertical traveling heater method growth process. Crystal growth occurred in the pseudobinary Hg1- x Cd x Te system. ACRT mixing allowed the lower-density, higher- x-value Hg1- x Cd x Te growth nutrient in the upper region of the ampoule to replenish the depleted melt and allowed the growth of constant- x-value, higher-density Hg1- x Cd x Te. The material grown by this research and production growth process yielded single crystals that had improved purity, compositional uniformity, precipitate density, and reproducibility in comparison with solid-state recrystallization and other bulk Hg1- x Cd x Te growth techniques. Radial and longitudinal nonuniformities in x-value for Hg1- x Cd x Te were reduced to DME material had highly desired performance characteristics.

  9. Cosmic rays on earth.

    Science.gov (United States)

    Allkofer, O. C.; Grieder, P. K. F.

    Contents: Cosmic rays in the atmosphere: Charged hadron data. Neutron data. Gamma-ray data. Electron data. Muon data. Data on nuclei. Data on antiparticles. Cosmic rays at sea level: Muon data. Charged hadron data.Neutron data. Electron data. Gamma-ray data. Data on nuclei. Cosmic rays underground: Muon data. Neutrino data.

  10. Development of the cosmic ray techniques

    Science.gov (United States)

    Rossi, B.

    1982-12-01

    It has been found that most advances of cosmic-ray physics have been directly related to the development of observational techniques. The history of observational techniques is discussed, taking into account ionization chambers, refinements applied to ionization chambers to make them suitable for an effective use in the study of cosmic radiation, the Wulf-type electrometer, the electrometer designed by Millikan and Neher, the Geiger-Mueller counter, the experiment of Bothe and Kolhoerster, the coincidence circuit, and a cosmic-ray 'telescope'. Attention is given to a magnetic lens for cosmic rays, a triangular arrangement of Geiger-Mueller counters used to demonstrate the production of a secondary radiation, a stereoscopic cloud-chamber photograph of showers, the cloud-chamber picture which provided the first evidence of the positive electron, and arrangements for studying photon components, mu-mesons, and air showers.

  11. Fibroblast Growth Factor 21 (FGF-21 in Peritoneal Dialysis Patients: Natural History and Metabolic Implications.

    Directory of Open Access Journals (Sweden)

    Elena González

    Full Text Available Human fibroblast growth factor 21 (FGF-21 is an endocrine liver hormone that stimulates adipocyte glucose uptake independently of insulin, suppresses hepatic glucose production and is involved in the regulation of body fat. Peritoneal dialysis (PD patients suffer potential interference with FGF-21 status with as yet unknown repercussions.The aim of this study was to define the natural history of FGF-21 in PD patients, to analyze its relationship with glucose homeostasis parameters and to study the influence of residual renal function and peritoneal functional parameters on FGF-21 levels and their variation over time.We studied 48 patients with uremia undergoing PD. Plasma samples were routinely obtained from each patient at baseline and at 1, 2 and 3 years after starting PD therapy.Plasma FGF-21 levels substantially increased over the first year and were maintained at high levels during the remainder of the study period (253 pg/ml (59; 685 at baseline; 582 pg/ml (60.5-949 at first year and 647 pg/ml (120.5-1116.6 at third year (p<0.01. We found a positive correlation between time on dialysis and FGF-21 levels (p<0.001, and also, those patients with residual renal function (RRF had significantly lower levels of FGF-21 than those without RRF (ρ -0.484, p<0.05. Lastly, there was also a significant association between FGF-21 levels and peritoneal protein losses (PPL, independent of the time on dialysis (ρ 0.410, p<0.05.Our study shows that FGF-21 plasma levels in incident PD patients significantly increase during the first 3 years. This increment is dependent on or is associated with RRF and PPL (higher levels in patients with lower RRF and higher PPL. FGF-21 might be an important endocrine agent in PD patients and could act as hormonal signaling to maintain glucose homeostasis and prevent potential insulin resistance. These preliminary results suggest that FGF-21 might play a protective role as against the development of insulin resistance over

  12. The ACS LCID project. V. The Star Formation History of the Dwarf Galaxy \\objectname[]{LGS-3}: Clues for Cosmic Reionization and Feedback

    CERN Document Server

    Hidalgo, Sebastian L; Skillman, Evan; Monelli, Matteo; Gallart, Carme; Cole, Andrew; Dolphin, Andrew; Weisz, Daniel; Bernard, Edouard; Cassisi, Santi; Mayer, Lucio; Stetson, Peter; Tolstoy, Eline; Ferguson, Henry

    2011-01-01

    We present an analysis of the star formation history (SFH) of the transition-type (dIrr/dSph) Local Group galaxy \\objectname[]{LGS-3} (Pisces) based on deep photometry obtained with the {\\it Advanced Camera for Surveys} onboard the {\\it Hubble Space Telescope}. Our analysis shows that the SFH of \\objectname[]{LGS-3} is dominated by a main episode $\\sim 11.7$ Gyr ago with a duration of $\\sim$ 1.4 Gyr which formed $\\sim 90%$ of the stars. Subsequently, \\objectname[]{LGS-3} continued forming stars until the present, although at a much lower rate. The lack of early chemical enrichment is in contrast to that observed in the isolated dSph galaxies of comparable luminosity, implying that the dSphs were more massive and subjected to more tidal stripping. We compare the SFH of \\objectname[]{LGS-3} with expectations from cosmological models. Most or all the star formation was produced in \\objectname[]{LGS-3} after the reionization epoch, assumed to be completed at $z\\sim6$ or $\\sim 12.7$ Gyr ago. The total mass of the ...

  13. Cosmic Humanity: Utopia, Realities, Prospects

    Directory of Open Access Journals (Sweden)

    Sergey Krichevsky

    2017-07-01

    characteristics and tendencies of the development of the world cosmonaut community for 55 years of spaceflight, indicators of national competitions in selecting cosmonauts as indicators of the society’s attitude to cosmonautics and the cosmic future of humanity are given. The main results, consequences and prospects of spacewalk in the context of the evolution of technology, human and humanity, including the main potentialities, challenges and threats caused by technical development, the creation of a posthuman, etc., are considered. The description and analysis of the social mega-project of the new space state ASGARDIA, which is created since October 2016 and is the institutional basis of cosmic humanity, is given. In fact, it is a state for the future of cosmic humanity, which has already begun (itself to be organized on Earth. There is a process of transformation of the almost fantastic and superglobal utopia of the first in the history of the earthly civilization of the cosmic state of people — the “cosmic international” — into the reality of a fundamentally new social contract. The idea and the project of the space state is exactly what was lacking for the process of space expansion to go seriously: a new geocosmopolitan subject and an actor who is interested in space exploration (including resettlement in it in the long run as in its main goal and overarching goal, and Focused on this process. The first results of the project are encouraging. An interesting sociological model is being created, based on an analysis of the statistical relationships of the present earthly and promising cosmic humanity. The first, unique, but important and unique “cosmic referendum” on the Earth is being held. The characteristics of the state being created are shown, citizens of which expressed a desire to become about 600 thousand people from more than 200 states, of which over 170 thousand people are certified as citizens and the process continues. A “cosmic” coefficient was

  14. Seismic slip history of the Aterno-Sulmona fault system in central Apennines (Italy) using in situ produced 36Cl cosmic ray exposure dating.

    Science.gov (United States)

    Jim, T.; Benedetti, L. C.; Bruno, P.; Visini, F.; Aumaitre, G.; Bourles, D. L.

    2014-12-01

    Acquiring long records of past earthquakes on a large population of faults is a key step to understand how strain release along those fault systems varies spatially and temporally.In central Italy, NE-SW extension (~4 mm/yr) is accommodated on a wide normal fault system (50 x 100km). Benedetti et al. (2013) found that 7 of these faults, belonging to the Fucino fault system, have their seismic activity synchronized during short (less than 1 ka) paroxysmal phases of activity. 36Cl measurements and rare earth elements (REE) concentrations were used to reconstruct the seismic slip history of four major faults belonging to an adjacent 30-km-long fault system, the Aterno-Sulmona fault system, at the southeastward tip of the Paganica fault that ruptured during the 2009 L'Aquila earthquake.The preliminary results suggest that 3-7 seismic events have occurred on each fault over the last 11 ka (from NE to SW the Roccapreturo, the Castel di Ieri, the Roccacasale and the Pizzalto faults), with 50 cm to 2 m of associated slip per event. These events appear clustered within intense period of seismic activity lasting less than 1ka (2 to 4 seismic events) separated by 2 to 3 ka periods with no seismic events. The most recent recorded paroxysmal activity occurred about 2.5 ka ago with all four studied faults rupturing in more than 15 earthquakes over a period lasting less than 1ka. These results thus suggest that, as already observed on the Fucino fault system, the seismic activity of the Aterno-Sulmona fault system is also synchronized during short periods of paroxysmal seismic activity.When clustering periods are compared, the seismic activity of the Fucino and the Aterno-Sulmona fault system, are, however, apparently unsynchronized since the most recent clustering period for the Aterno-Sulmona system corresponds to a quiescent period for the Fucino fault system.

  15. Establishing the natural history and growth rate of ameloblastoma with implications for management: systematic review and meta-analysis.

    Science.gov (United States)

    Chae, Michael P; Smoll, Nicolas R; Hunter-Smith, David J; Rozen, Warren Matthew

    2015-01-01

    Ameloblastoma is the second most common odontogenic tumor, known to be slow-growing, persistent, and locally aggressive. Recent data suggests that ameloblastoma is best treated with wide resection and adequate margins. Following primary excision, bony reconstruction is often necessary for a functional and aesthetically satisfactory outcome, making early diagnosis paramount. Despite earlier diagnosis potentially limiting the extent of resection and reconstruction, an understanding of the growth rate and natural history of ameloblastoma has been notably lacking from the literature. A systematic review of the literature was conducted by reviewing relevant articles from PubMed and Web of Science databases. Each article's level of evidence was formally appraised according to the Centre of Evidence Based Medicine (CEBM), with data from each utilized in a meta-analysis of growth rates for ameloblastoma. Literature regarding the natural history of ameloblastoma is limited since the tumor is immediately acted upon at its initial detection, unless the patient voluntarily refuses a surgical intervention. From the limited data, it is derived that the highest estimated growth rate is associated with solid, multicystic type and the lowest rate with peripheral ameloblastomas. After meta-analysis, the calculated mean specific grow rate is 87.84% per year. The growth rate of ameloblastoma has been demonstrated, offering prognostic and management information, particularly in cases where a delay in management is envisaged.

  16. Cosmic Complexity

    Science.gov (United States)

    Mather, John C.

    2012-01-01

    neutrons, liberating a little energy and creating complexity. Then, the expanding universe cooled some more, and neutrons and protons, no longer kept apart by immense temperatures, found themselves unstable and formed helium nuclei. Then, a little more cooling, and atomic nuclei and electrons were no longer kept apart, and the universe became transparent. Then a little more cooling, and the next instability began: gravitation pulled matter together across cosmic distances to form stars and galaxies. This instability is described as a "negative heat capadty" in which extracting energy from a gravitating system makes it hotter -- clearly the 2nd law of thermodynamics does not apply here! (This is the physicist's part of the answer to e e cummings' question: what is the wonder that's keeping the stars apart?) Then, the next instability is that hydrogen and helium nuclei can fuse together to release energy and make stars burn for billions of years. And then at the end of the fuel source, stars become unstable and explode and liberate the chemical elements back into space. And because of that, on planets like Earth, sustained energy flows support the development of additional instabilities and all kinds of complex patterns. Gravitational instability pulls the densest materials into the core of the Earth, leaving a thin skin of water and air, and makes the interior churn incessantly as heat flows outwards. And the heat from the sun, received mostly near the equator and flowing towards the poles, supports the complex atmospheric and oceanic circulations. And because or that, the physical Earth is full of natural chemical laboratories, concentrating elements here, mixing them there, raising and lowering temperatures, ceaselessly experimenting with uncountable events where new instabilities can arise. At least one of them was the new experiment called life. Now that we know that there are at least as many planets as there are stars, it is hard to imagine that nature's ceasess

  17. Cosmic Complexity

    Science.gov (United States)

    Mather, John C.

    2012-01-01

    neutrons, liberating a little energy and creating complexity. Then, the expanding universe cooled some more, and neutrons and protons, no longer kept apart by immense temperatures, found themselves unstable and formed helium nuclei. Then, a little more cooling, and atomic nuclei and electrons were no longer kept apart, and the universe became transparent. Then a little more cooling, and the next instability began: gravitation pulled matter together across cosmic distances to form stars and galaxies. This instability is described as a "negative heat capadty" in which extracting energy from a gravitating system makes it hotter -- clearly the 2nd law of thermodynamics does not apply here! (This is the physicist's part of the answer to e e cummings' question: what is the wonder that's keeping the stars apart?) Then, the next instability is that hydrogen and helium nuclei can fuse together to release energy and make stars burn for billions of years. And then at the end of the fuel source, stars become unstable and explode and liberate the chemical elements back into space. And because of that, on planets like Earth, sustained energy flows support the development of additional instabilities and all kinds of complex patterns. Gravitational instability pulls the densest materials into the core of the Earth, leaving a thin skin of water and air, and makes the interior churn incessantly as heat flows outwards. And the heat from the sun, received mostly near the equator and flowing towards the poles, supports the complex atmospheric and oceanic circulations. And because or that, the physical Earth is full of natural chemical laboratories, concentrating elements here, mixing them there, raising and lowering temperatures, ceaselessly experimenting with uncountable events where new instabilities can arise. At least one of them was the new experiment called life. Now that we know that there are at least as many planets as there are stars, it is hard to imagine that nature's ceasess

  18. Early life-history consequences of growth-hormone transgenesis in rainbow trout reared in stream ecosystem mesocosms.

    Science.gov (United States)

    Crossin, Glenn T; Sundström, L Fredrik; Vandersteen, Wendy E; Devlin, Robert H

    2015-01-01

    There is persistent commercial interest in the use of growth modified fishes for shortening production cycles and increasing overall food production, but there is concern over the potential impact that transgenic fishes might have if ever released into nature. To explore the ecological consequences of transgenic fish, we performed two experiments in which the early growth and survival of growth-hormone transgenic rainbow trout (Oncorhynchus mykiss) were assessed in naturalized stream mesocosms that either contained predators or were predator-free. We paid special attention to the survival bottleneck that occurs during the early life-history of salmonids, and conducted experiments at two age classes (first-feeding fry and 60 days post-first-feeding) that lie on either side of the bottleneck. In the late summer, the first-feeding transgenic trout could not match the growth potential of their wild-type siblings when reared in a hydrodynamically complex and oligotrophic environment, irrespective of predation pressure. Furthermore, overall survival of transgenic fry was lower than in wild-type (transgenic = 30% without predators, 8% with predators; wild-type = 81% without predators, 31% with predators). In the experiment with 60-day old fry, we explored the effects of the transgene in different genetic backgrounds (wild versus domesticated). We found no difference in overwinter survival but significantly higher growth by transgenic trout, irrespective of genetic background. We conclude that the high mortality of GH-transgenic trout during first-feeding reflects an inability to sustain the basic metabolic requirements necessary for life in complex, stream environments. However, when older, GH-transgenic fish display a competitive advantage over wild-type fry, and show greater growth and equal survival as wild-type. These results demonstrate how developmental age and time of year can influence the response of genotypes to environmental conditions. We therefore urge

  19. Quasar Mass Functions Across Cosmic Time

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2010-01-01

    I present mass functions of actively accreting black holes detected in different quasar surveys which in concert cover a wide range of cosmic history. I briefly address what we learn from these mass functions. I summarize the motivation for such a study and the methods by which we determine black...

  20. GAMA/H-ATLAS: a meta-analysis of SFR indicators - comprehensive measures of the SFR-M* relation and cosmic star formation history at z < 0.4

    Science.gov (United States)

    Davies, L. J. M.; Driver, S. P.; Robotham, A. S. G.; Grootes, M. W.; Popescu, C. C.; Tuffs, R. J.; Hopkins, A.; Alpaslan, M.; Andrews, S. K.; Bland-Hawthorn, J.; Bremer, M. N.; Brough, S.; Brown, M. J. I.; Cluver, M. E.; Croom, S.; da Cunha, E.; Dunne, L.; Lara-López, M. A.; Liske, J.; Loveday, J.; Moffett, A. J.; Owers, M.; Phillipps, S.; Sansom, A. E.; Taylor, E. N.; Michalowski, M. J.; Ibar, E.; Smith, M.; Bourne, N.

    2016-09-01

    We present a meta-analysis of star formation rate (SFR) indicators in the Galaxy And Mass Assembly (GAMA) survey, producing 12 different SFR metrics and determining the SFR-M* relation for each. We compare and contrast published methods to extract the SFR from each indicator, using a well-defined local sample of morphologically selected spiral galaxies, which excludes sources which potentially have large recent changes to their SFR. The different methods are found to yield SFR-M* relations with inconsistent slopes and normalizations, suggesting differences between calibration methods. The recovered SFR-M* relations also have a large range in scatter which, as SFRs of the targets may be considered constant over the different time-scales, suggests differences in the accuracy by which methods correct for attenuation in individual targets. We then recalibrate all SFR indicators to provide new, robust and consistent luminosity-to-SFR calibrations, finding that the most consistent slopes and normalizations of the SFR-M* relations are obtained when recalibrated using the radiation transfer method of Popescu et al. These new calibrations can be used to directly compare SFRs across different observations, epochs and galaxy populations. We then apply our calibrations to the GAMA II equatorial data set and explore the evolution of star formation in the local Universe. We determine the evolution of the normalization to the SFR-M* relation from 0 < z < 0.35 - finding consistent trends with previous estimates at 0.3 < z < 1.2. We then provide the definitive z < 0.35 cosmic star formation history, SFR-M* relation and its evolution over the last 3 billion years.

  1. Life-history trait of the Mediterranean keystone species Patella rustica: growth and microbial bioerosion

    Directory of Open Access Journals (Sweden)

    I. PRUSINA

    2015-05-01

    Full Text Available The age and shell growth patterns in populations of Patella rustica of the Adriatic Sea were determined by analyzing the inner growth lines visible in shell sections. Marginal increment analysis showed annual periodicity with annual growth line being deposited in May. The growth analysis of 120 individual shells showed that 90.8 % of collected individuals were less than 4 years of age and only two individuals (1.6 % were older than 6 years. Population structure was described and the generalized von Bertalanffy growth parameters were calculated: asymptotic length (L∞ was 38.22 mm and the growth constant (K was 0.30 year-1. Growth performance index value of P. rustica (Ø’ was 2.64 and is among the lowest ranges reported for limpet species. Patella rustica shells were degraded to different degrees by microbial bioerosion. Microboring organisms identified were pseudofilamentous and filamentous cyanobacteria Hormathonema paulocellulare, Hyella caespitosa, Mastigocoleus testarum and Leptolyngbya sp. The overall intensity of infestation was relatively low, but increased in severity with shell length. The damage was most often restricted to the oldest parts of the shell, i.e. apex of the shell, posing difficulties in determining the exact position of the first growth line. The present study is first to introduce the use of inner growth lines in Patella rustica shell sections as a reliable method for age determination and it provides the first insight into the growth patterns of this keystone species while taking the interference of microbial shell bioerosion in consideration.

  2. Life-history trait of the Mediterranean keystone species Patella rustica: growth and microbial bioerosion

    Directory of Open Access Journals (Sweden)

    I. PRUSINA

    2015-07-01

    Full Text Available The age and shell growth patterns in populations of Patella rustica of the Adriatic Sea were determined by analyzing the inner growth lines visible in shell sections. Marginal increment analysis showed annual periodicity with annual growth line being deposited in May. The growth analysis of 120 individual shells showed that 90.8 % of collected individuals were less than 4 years of age and only two individuals (1.6 % were older than 6 years. Population structure was described and the generalized von Bertalanffy growth parameters were calculated: asymptotic length (L∞ was 38.22 mm and the growth constant (K was 0.30 year-1. Growth performance index value of P. rustica (Ø’ was 2.64 and is among the lowest ranges reported for limpet species. Patella rustica shells were degraded to different degrees by microbial bioerosion. Microboring organisms identified were pseudofilamentous and filamentous cyanobacteria Hormathonema paulocellulare, Hyella caespitosa, Mastigocoleus testarum and Leptolyngbya sp. The overall intensity of infestation was relatively low, but increased in severity with shell length. The damage was most often restricted to the oldest parts of the shell, i.e. apex of the shell, posing difficulties in determining the exact position of the first growth line. The present study is first to introduce the use of inner growth lines in Patella rustica shell sections as a reliable method for age determination and it provides the first insight into the growth patterns of this keystone species while taking the interference of microbial shell bioerosion in consideration.

  3. Roles of density-dependent growth and life history evolution in accounting for fisheries-induced trait changes.

    Science.gov (United States)

    Eikeset, Anne Maria; Dunlop, Erin S; Heino, Mikko; Storvik, Geir; Stenseth, Nils C; Dieckmann, Ulf

    2016-12-27

    The relative roles of density dependence and life history evolution in contributing to rapid fisheries-induced trait changes remain debated. In the 1930s, northeast Arctic cod (Gadus morhua), currently the world's largest cod stock, experienced a shift from a traditional spawning-ground fishery to an industrial trawl fishery with elevated exploitation in the stock's feeding grounds. Since then, age and length at maturation have declined dramatically, a trend paralleled in other exploited stocks worldwide. These trends can be explained by demographic truncation of the population's age structure, phenotypic plasticity in maturation arising through density-dependent growth, fisheries-induced evolution favoring faster-growing or earlier-maturing fish, or a combination of these processes. Here, we use a multitrait eco-evolutionary model to assess the capacity of these processes to reproduce 74 y of historical data on age and length at maturation in northeast Arctic cod, while mimicking the stock's historical harvesting regime. Our results show that model predictions critically depend on the assumed density dependence of growth: when this is weak, life history evolution might be necessary to prevent stock collapse, whereas when a stronger density dependence estimated from recent data is used, the role of evolution in explaining fisheries-induced trait changes is diminished. Our integrative analysis of density-dependent growth, multitrait evolution, and stock-specific time series data underscores the importance of jointly considering evolutionary and ecological processes, enabling a more comprehensive perspective on empirically observed stock dynamics than previous studies could provide.

  4. Can backcalculation models unravel complex larval growth histories in a tropical freshwater fish?

    Science.gov (United States)

    Starrs, D; Ebner, B C; Fulton, C J

    2013-07-01

    This experimental study compared the precision and accuracy of the biological intercept (BI), modified fry (MF) and time-varying growth (TVG) backcalculation models in estimating the early growth of the tropical freshwater purple-spotted gudgeon Mogurnda adspersa. Larvae were reared up to 41 days post hatching under two temperatures and four different feeding regimes. Food and temperature treatments induced complex growth profiles among fish, and although total length (LT ) and otolith radius were related under all conditions, some uncoupling was evident in the otolith-somatic-growth (OSG) relationship of fish subjected to periods of changing food availability. Furthermore, otolith growth was found to be significantly influenced by temperature, but not by food availability. Analysis of backcalculation residuals by linear mixed effects modelling revealed that BI and TVG were equally precise in predicting somatic growth, with the highest accuracy provided by TVG. The performance of all the three models declined as the OSG relationship weakened under low-food conditions, with maximum errors estimated to be 39, 60 and 36% of observed LT for the BI, MF and TVG models, respectively. The need for careful validation of backcalculation models is emphasized when examining fishes subjected to variable environmental conditions, and when exploring the differential influence of temperature and food on fish LT and otolith growth.

  5. Effect of sow history features on growth and feed intake in grow-finish pigs

    NARCIS (Netherlands)

    Sell-Kubiak, E.B.; Knol, E.F.; Bijma, P.

    2012-01-01

    The sow provides a specific environment to her offspring during gestation and lactation. Certain features in the early life of the sow (sow history features) may affect her ability to deliver and feed a healthy litter. In genetic analyses of grow-finish traits, these effects are estimated as common

  6. How resource competition shapes individual life history for nonplastic growth: ungulates in seasonal food environments

    NARCIS (Netherlands)

    Roos, de A.; Galic, N.G.; Heesterbeek, H.

    2009-01-01

    We analyze an age-, size- and sex-structured model to investigate how the interplay between individual-level energy budget dynamics and the feedback of population grazing on resources shapes the individual life history and the dynamics of ungulate populations, living in a predator-free, seasonal res

  7. Association with pathogenic bacteria affects life-history traits and population growth in Caenorhabditis elegans

    NARCIS (Netherlands)

    Anaid Rens, S.; Mooring, E.Q.; Rens, E.G.; Restif, O.

    2015-01-01

    Determining the relationship between individual life-history traits and population dynamics is an essential step to understand and predict natural selection. Model organisms that can be conveniently studied experimentally at both levels are invaluable to test the rich body of theoretical literature

  8. How resource competition shapes individual life history for nonplastic growth: Ungulates in seasonal food environments

    NARCIS (Netherlands)

    A.M. de Roos; N. Galic; H. Heesterbeek

    2009-01-01

    We analyze an age-, size- and sex-structured model to investigate how the interplay between individual-level energy budget dynamics and the feedback of population grazing on resources shapes the individual life history and the dynamics of ungulate populations, living in a predator-free, seasonal res

  9. How resource competition shapes individual life history for nonplastic growth: ungulates in seasonal food environments

    NARCIS (Netherlands)

    Roos, de A.; Galic, N.G.; Heesterbeek, H.

    2009-01-01

    We analyze an age-, size- and sex-structured model to investigate how the interplay between individual-level energy budget dynamics and the feedback of population grazing on resources shapes the individual life history and the dynamics of ungulate populations, living in a predator-free, seasonal

  10. Effect of sow history features on growth and feed intake in grow-finish pigs

    NARCIS (Netherlands)

    Sell-Kubiak, E.B.; Knol, E.F.; Bijma, P.

    2012-01-01

    The sow provides a specific environment to her offspring during gestation and lactation. Certain features in the early life of the sow (sow history features) may affect her ability to deliver and feed a healthy litter. In genetic analyses of grow-finish traits, these effects are estimated as common

  11. Testicular Growth During Puberty in Boys With and Without a History of Congenital Cryptorchidism

    DEFF Research Database (Denmark)

    Sadov, Sergey; Koskenniemi, Jaakko J; Virtanen, Helena E

    2016-01-01

    CONTEXT: The pattern of testicular growth during puberty may provide important information about early testicular damage and reproductive potential in adulthood. OBJECTIVE: To evaluate pubertal testicular growth in boys with congenital cryptorchidism and controls. DESIGN: Longitudinal case...... mL by orchidometer and 25 mm by ruler as cut-offs in definition of the onset of puberty. An orchidometer size of 3 mL and ruler length of 25 mm corresponded to 1.6 and 1.7 mL by ultrasound (with Lambert's formula), respectively. CONCLUSIONS: Testicular growth in puberty was impaired in congenitally...

  12. Plasma effects on extragalactic ultra-high-energy cosmic ray hadron beams in cosmic voids

    Energy Technology Data Exchange (ETDEWEB)

    Krakau, Steffen; Schlickeiser, Reinhard [Institut fur Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universitaet Bochum (Germany)

    2015-05-01

    The linear instability of an ultrarelativistic hadron beam (Γ{sub b} ∼ 10{sup 6}) in the unmagnetized intergalactic medium is investigated with respect to the excitation of collective electrostatic and aperiodic electromagnetic fluctuations. This analysis is important for the propagation of extragalactic ultrarelativistic cosmic rays (E > 10{sup 15} eV) from their distant sources to Earth. We calculate minimum instability growth times which are orders of magnitude shorter than the cosmic ray propagation time in the IGM. Due to nonlinear effects, especially the modulation instability, the cosmic ray beam stabilize and can propagate with nearly no energy loss through the intergalactic medium.

  13. Disturbance history and tree establishment in old-growth Pinus koraiensis hardwood forests in the Russian Far East

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Yukio [Senshu Univ., Bibai (Japan). Dept. of Forestry and Landscape Architecture; Krestov, Pavel [Inst. of Biology and Pedology, Vladivostok (Russian Federation). Lab. of Geobotany; Namikawa, Kanji [Hokkaido Univ. of Education, Sapporo (Japan). Sapporo College, Biological Lab.

    1999-08-01

    Dendro-ecological studies were undertaken to document the disturbance history in two old-growth mixed Pinus koraiensis hardwood forests in the southern part of the Sikhote-Alin mountains in the Russian Far East. Establishment of four common canopy conifers, Abies holophylla, A. nephrolepis, P. koraiensis and Picea ajanensis, and three common canopy hardwoods, Acer mono, Betula costata and Tilia amurensis, were also inferred from population age structures and spatial dispersion patterns. Growth releases on increment cores suggested that peak periods of growth releases indicating partial canopy disturbances have repeatedly occurred over the past 230 yr at intervals from ca. 35 to 100 yr. Slight releases and suppressions other than the peak releases occurred in many years of both histories, suggesting the formation of smaller-scale canopy gaps. Despite the predominance of anthropogenic fires in Primorskiy Kray at present, destructive fires had not affected either forest. Wind disturbances and low intensity fires are likely factors controlling the dynamics of the forests. Under the disturbance regime, P. koraiensis has maintained its populations through its dependence on canopy gaps for establishment. Age distribution and gap dependence of P. ajanensis, A. nephrolepis and A. mono suggested continuous establishment of these species under a closed canopy, whereas occasional establishment of T. amurensis was derived largely from vegetative reproduction. Restricted establishment of A. holophylla and B. costata suggested a variety in kinds of disturbance throughout the histories. Continuous habitation of the study area by P. koraiensis is likely under the disturbance regime without destructive fires 59 refs, 3 figs, 4 tabs

  14. AFSC/ABL: 1996 Brood year Steelhead growth and early life-history transitions

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Heritabilities of growth, precocious maturation and smolting were measured in 75 families of juvenile steelhead or rainbow trout Oncorhynchus mykiss, progeny of...

  15. Cosmic ray-driven winds in the Galactic environment and the cosmic ray spectrum

    Science.gov (United States)

    Recchia, S.; Blasi, P.; Morlino, G.

    2017-09-01

    Cosmic rays escaping the Galaxy exert a force on the interstellar medium directed away from the Galactic disc. If this force is larger than the gravitational pull due to the mass embedded in the Galaxy, then galactic winds may be launched. Such outflows may have important implications for the history of star formation of the host galaxy, and in turn affect in a crucial way the transport of cosmic rays, both due to advection with the wind and to the excitation of waves by the same cosmic rays, through streaming instability. The possibility to launch cosmic ray-induced winds and the properties of such winds depend on environmental conditions, such as the density and temperature of the plasma at the base of the wind and the gravitational potential, especially the one contributed by the dark matter halo. In this paper, we make a critical assessment of the possibility to launch cosmic ray-induced winds for a Milky Way-like galaxy and how the properties of the wind depend upon the conditions at the base of the wind. Special attention is devoted to the implications of different conditions for wind launching on the spectrum of cosmic rays observed at different locations in the disc of the galaxy. We also comment on how cosmic ray-induced winds compare with recent observations of Oxygen absorption lines in quasar spectra and emission lines from blank sky, as measured by XMM-Newton/EPIC-MOS.

  16. High energy cosmic rays

    CERN Document Server

    Stanev, Todor

    2010-01-01

    Offers an accessible text and reference (a cosmic-ray manual) for graduate students entering the field and high-energy astrophysicists will find this an accessible cosmic-ray manual Easy to read for the general astronomer, the first part describes the standard model of cosmic rays based on our understanding of modern particle physics. Presents the acceleration scenario in some detail in supernovae explosions as well as in the passage of cosmic rays through the Galaxy. Compares experimental data in the atmosphere as well as underground are compared with theoretical models

  17. Energy budgets, growth rates, and thermal constraints: toward an integrative approach to the study of life-history variation.

    Science.gov (United States)

    Niewiarowski, P H

    2001-04-01

    Variation in thermal constraints on activity has been hypothesized to be an important ecological source of geographic variation in growth rates of juvenile eastern fence lizards Sceloporus undulatus. However, most of the evidence to support this hypothesis is either inferential or indirect. In this study, I quantitatively compared thermal constraints on activity and their relationship to growth rates of free-ranging juvenile fence lizards from two extremes of the range of variation in growth rate (Nebraska and New Jersey) used in a reciprocal transplant experiment. I also examined energy allocation made to growth and storage by yearling lizards. Reduced growth rates in New Jersey of normally fast-growing hatchlings from Nebraska were associated with a more stringent thermal constraint on activity corresponding to a 2-3-h shorter predicted daily activity period in New Jersey compared to Nebraska. The thermal constraint on activity was particularly strong (24% less time available in New Jersey compared to Nebraska) during the period when hatchling lizards emerge (August-October). An 8% reduction in total activity time available over the course of a single year was associated with a 7% reduction in the total amount of energy accumulated by lizards in New Jersey. Differences in the total amount of energy available for allocation were also accompanied by differences in how energy was allocated. Lizards from New Jersey had an allocatable energy pool of approximately 40.34 kJ (88% to growth, 12% to storage, and 0% to reproduction). Lizards from Nebraska had an allocatable pool of 43.44 kJ (22% to growth, 18% to storage, and 60% to reproduction). This study joins others in advocating and illustrating an integrative approach to determining the causes and consequences of life-history variation by combining experimental, comparative, and phylogenetic methods in a single system.

  18. Alternative life histories in Xiphophorus multilineatus: evidence for different ages at sexual maturity and growth responses in the wild.

    Science.gov (United States)

    Bono, L M; Rios-Cardenas, O; Morris, M R

    2011-05-01

    In order to examine potential trade-offs in alternative life histories of the high-backed pygmy swordtail Xiphophorus multilineatus, otoliths were used from wild-caught males to determine if sneaker males had the advantage of maturing earlier in natural environments. The sneakers matured significantly earlier than courters, but there was no difference among the three courter variants. In addition, analyses suggested that the effect of the pituitary locus on size at sexual maturity and growth rates was a consequence of age at sexual maturity. Finally, one of the courter variants had a significantly different relationship between age and size at sexual maturity than the other variants, suggesting that in this variant, age at sexual maturity may be more closely related to size and therefore may be less plastic in its growth responses.

  19. EFFECT OF GROWTH HORMONE REPLACEMENT THERAPY ON THE QUALITY OF LIFE IN WOMEN WITH GROWTH HORMONE DEFICIENCY WHO HAVE A HISTORY OF ACROMEGALY VERSUS OTHER DISORDERS

    Science.gov (United States)

    Valassi, Elena; Brick, Danielle J.; Johnson, Jessica C.; Biller, Beverly M. K.; Klibanski, Anne; Miller, Karen K.

    2013-01-01

    Objective To compare the response in quality of life (QoL) to growth hormone (GH) replacement in women with GH deficiency (GHD) and a history of acromegaly with that in women with GHD of other causes. Methods Fifty-five women with GHD were studied: 17 with prior acromegaly and 38 with other causes of GHD. We compared two 6-month, randomized, placebo-controlled studies of GH therapy in women with hypopituitarism conducted with use of the same design—one in women with a history of acromegaly and one in women with no prior acromegaly. QoL was assessed with the following questionnaires: the QoL-Assessment of Growth Hormone deficiency in Adults (AGHDA), the Symptom Questionnaire, and the 36-Item Short-Form Health Survey (SF-36). Results The 2 groups had comparable mean pretreatment age, body mass index, and QoL scores and comparable mean GH dose at 6 months (0.61 ± 0.30 versus 0.67 ± 0.27 mg daily). After 6 months of GH replacement therapy, women with GHD and prior acromegaly demonstrated a greater improvement in AGHDA score, four SF-36 subscales (Role Limitations due to Physical Health, Energy or Fatigue, Emotional Well-Being, and Social Functioning), and the Somatic Symptoms subscale of the Symptom Questionnaire than did women with GHD of other causes. Poorer pretreatment QoL was associated with a greater improvement in QoL after administration of GH. Conclusion In this study, GH replacement therapy improved QoL in women with GHD and a history of acromegaly but not in women with GHD due to other hypothalamic and pituitary disorders. Further studies are needed to determine the long-term risks versus benefits of GH replacement in patients who develop GHD after definitive treatment for acromegaly. PMID:22440981

  20. Onset of oligarchic growth and implication for accretion histories of dwarf planets

    CERN Document Server

    Morishima, Ryuji

    2016-01-01

    We investigate planetary accretion that starts from equal-mass planetesimals using an analytic theory and numerical simulations. We particularly focus on how the planetary mass $M_{\\rm oli}$ at the onset of oligarchic growth depends on the initial mass $m_0$ of a planetesimal. Oligarchic growth commences when the velocity dispersion relative to the Hill velocity of the protoplanet takes its minimum. We find that if $m_0$ is small enough, this normalized velocity dispersion becomes as low as unity during the intermediate stage between the runaway and oligarchic growth stages. In this case, $M_{\\rm oli}$ is independent of $m_0$. If $m_0$ is large, on the other hand, oligarchic growth commences directly after runaway growth, and $M_{\\rm oli} \\propto m_0^{3/7}$. The planetary mass $M_{\\rm oli}$ for the solid surface density of the Minimum Mass Solar Nebula is close to the masses of the dwarf planets in a reasonable range of $m_0$. This indicates that they are likely to be the largest remnant planetesimals that fa...

  1. Maria Montessori's Cosmic Vision, Cosmic Plan, and Cosmic Education

    Science.gov (United States)

    Grazzini, Camillo

    2013-01-01

    This classic position of the breadth of Cosmic Education begins with a way of seeing the human's interaction with the world, continues on to the grandeur in scale of time and space of that vision, then brings the interdependency of life where each growing human becomes a participating adult. Mr. Grazzini confronts the laws of human nature in…

  2. Cosmic Rays: studies and measurements before 1912

    Energy Technology Data Exchange (ETDEWEB)

    De Angelis, Alessandro [INFN and Università di Udine, Via delle Scienze 206, I-33100 Udine (Italy); LIP/IST Lisboa (Portugal)

    2013-06-15

    The discovery of cosmic rays, a milestone in science, was based on the work by scientists in Europe and the New World and took place during a period characterised by nationalism and lack of communication. Many scientists that took part in this research a century ago were intrigued by the penetrating radiation and tried to understand the origin of it. Several important contributions to the discovery of the origin of cosmic rays have been forgotten; historical, political and personal facts might have contributed to their substantial disappearance from the history of science.

  3. Natural history of the classical form of primary growth hormone (GH) resistance (Laron syndrome).

    Science.gov (United States)

    Laron, Z

    1999-04-01

    A description of the clinical, biochemical and endocrinological features of the classical form of the syndrome of primary growth hormone (GH) resistance (Laron syndrome) is presented including the progressive changes during follow-up from infancy into adulthood. The main diagnostic features are: severe growth retardation, acromicria, small gonads and genitalia, and obesity. Serum GH levels are elevated and insulin-like growth factor-I (IGF-I) values are low and do not rise upon stimulation by exogenous hGH. The pathogenesis of this syndrome is due to various molecular defects from exon deletion to nonsense, frameshift, splice and missense mutations in the GH receptor (GH-R) gene or in its post-receptor pathways.

  4. Population growth through history and the escape from the Malthusian trap: a homeostatic simulation model.

    Science.gov (United States)

    Artzrouni, M; Komlos, J

    1985-01-01

    "A Malthusian simulation model is proposed to describe the growth of human population from the Neolithic through the Industrial Revolution. The economy is composed of a subsistence sector and a capital-producing sector. Our model captures the 'incessant contest' between population growth and the means of subsistence. When the per capita agricultural output falls below a biological minimum, the growth rate of the population is subject, in a random fashion, to perturbations that can take on disastrous proportions." It is suggested that "the slow accumulation of capital (and the buildup of the population of the capital-producing sector) eventually enables the population to overcome the constraints of the hostile economic environment. Our simulations (complete with confidence intervals) yield numerically realistic estimates of the population that eventually escapes from the Malthusian menace and grows unhindered during the Industrial Revolution." (summary in FRE, ITA)

  5. The basis for cosmic ray feedback: Written on the wind.

    Science.gov (United States)

    Zweibel, Ellen G

    2017-05-01

    Star formation and supermassive black hole growth in galaxies appear to be self-limiting. The mechanisms for self-regulation are known as feedback. Cosmic rays, the relativistic particle component of interstellar and intergalactic plasma, are among the agents of feedback. Because cosmic rays are virtually collisionless in the plasma environments of interest, their interaction with the ambient medium is primarily mediated by large scale magnetic fields and kinetic scale plasma waves. Because kinetic scales are much smaller than global scales, this interaction is most conveniently described by fluid models. In this paper, I discuss the kinetic theory and the classical theory of cosmic ray hydrodynamics (CCRH) which follows from assuming cosmic rays interact only with self-excited waves. I generalize CCRH to generalized cosmic ray hydrodynamics, which accommodates interactions with extrinsic turbulence, present examples of cosmic ray feedback, and assess where progress is needed.

  6. Elevated CO2 impacts bell pepper growth with consequences to Myzus persicae life history, feeding behaviour and virus transmission ability

    Science.gov (United States)

    Dáder, Beatriz; Fereres, Alberto; Moreno, Aránzazu; Trębicki, Piotr

    2016-01-01

    Increasing atmospheric carbon dioxide (CO2) impacts plant growth and metabolism. Indirectly, the performance and feeding of insects is affected by plant nutritional quality and resistance traits. Life history and feeding behaviour of Myzus persicae were studied on pepper plants under ambient (aCO2, 400 ppm) or elevated CO2 (eCO2, 650 ppm), as well as the direct impact on plant growth and leaf chemistry. Plant parameters were significantly altered by eCO2 with a negative impact on aphid’s life history. Their pre-reproductive period was 11% longer and fecundity decreased by 37%. Peppers fixed significantly less nitrogen, which explains the poor aphid performance. Plants were taller and had higher biomass and canopy temperature. There was decreased aphid salivation into sieve elements, but no differences in phloem ingestion, indicating that the diminished fitness could be due to poorer tissue quality and unfavourable C:N balance, and that eCO2 was not a factor impeding feeding. Aphid ability to transmit Cucumber mosaic virus (CMV) was studied by exposing source and receptor plants to ambient (427 ppm) or elevated (612 ppm) CO2 before or after virus inoculation. A two-fold decrease on transmission was observed when receptor plants were exposed to eCO2 before aphid inoculation when compared to aCO2.

  7. Crustal growth history of the Korean Peninsula:Constraints from detrital zircon ages in modern river sediments

    Institute of Scientific and Technical Information of China (English)

    Taejin Choi; Yong Il Lee; Yuji Orihashi

    2016-01-01

    U-Pb analyses were carried out on detrital zircon grains from major river-mouth sediments draining South Korea to infer provenance characteristics and the crustal growth history of the southern Korean Peninsula, using a laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS). The Korean Peninsula is located in the East Asian continental margin and mainly comprises three Precambrian massifs and two metamorphic belts in between them. We obtained 515 concordant to slightly discordant zircon ages ranging from ca. 3566 to ca. 48 Ma. Regardless of river-mouth location, predominance of Mesozoic (249e79 Ma) and Paleoproterozoic (2491e1691 Ma) ages with subordinate Archean ages in-dicates that the zircon ages reflect present exposures of plutonic/metamorphic rocks in the drainage basins of the South Korean rivers and the crustal growth of the southern Korean Peninsula was focused in these two periods. Comparison of detrital zircon-age data between the North and South Korean river sediments reveals that the Paleoproterozoic zircon age distributions of both regions are nearly identical, while the NeoproterozoicePaleozoic ages exist and the Mesozoic ages are dominant in southern Korean Peninsula. This result suggests that Precambrian terrains in Korea record the similar pre-Mesozoic magmatic history and that the influence of Mesozoic magmatism was mainly focused in South Korea.

  8. Influence of life history strategies on sensitivity, population growth and response to climate for sympatric alpine birds

    Directory of Open Access Journals (Sweden)

    Wilson Scott

    2012-06-01

    Full Text Available Abstract Background The life history strategy of a species can influence how populations of that species respond to environmental variation. In this study, we used a matrix modeling approach to examine how life history differences among sympatric rock and white-tailed ptarmigan affect the influence of demographic rates on population growth (λ and the potential response to a changing climate. Rock ptarmigan have a slower life history strategy than white-tailed ptarmigan in the study region with lower annual reproductive effort but higher adult survival. Results Based on data from a 5-year field study, deterministic estimates of λ indicated that populations were stable for rock ptarmigan (λ = 1.01, but declining for white-tailed ptarmigan (λ = 0.96. The demographic rates with the highest elasticity for rock ptarmigan were the survival of after-second year females, followed by juvenile survival and success of the first nest. For white-tailed ptarmigan, juvenile survival had the highest elasticity followed by success of the first nest and survival of second-year females. Incorporating stochasticity into the demographic rates led to a 2 and 4% drop in λ for rock and white-tailed ptarmigan respectively. Using data from the first three years we also found that population growth rates of both species were depressed following an increased frequency of severe years, but less so for rock ptarmigan which showed greater resilience under these conditions. Conclusions Our results provide evidence that populations of closely related species can vary in their response to environmental change as a consequence of life history differences. Rock ptarmigan, with a slower life history, are more responsive to demographic rates that influence survival and older life stages but this response is tempered by the extent of variability in each of the rates. Thus, predictions need to consider both aspects in modeling population response to a varying climate

  9. The Role of Education in Economic Growth: Theory, History and Current Returns

    Science.gov (United States)

    Breton, Theodore R.

    2013-01-01

    Background: This paper was prepared to address the issue of whether current levels of public expenditures on education are cost-effective in countries with widely differing average levels of education. Purpose: The paper examines the role of education in economic growth from a theoretical and historic perspective, addresses why education has been…

  10. Gastrostomy placement favorably alters the natural history of growth failure and undernutrition in Rett syndrome

    Science.gov (United States)

    Growth failure and undernutrition complicate the clinical course of girls with Rett syndrome (RTT). These abnormalities are, in part, the consequence of oral motor dysfunction and inadequate dietary intake. Our objective was to determine if gastrostomy placement for nutritional therapy alters the na...

  11. Telomere attrition and growth : A life-history framework and case study in common terns

    NARCIS (Netherlands)

    Vedder, O.; Verhulst, S.; Bauch, C.; Bouwhuis, S.

    The relationship between growth and age-specific telomere length, as a proxy of somatic state, is increasingly investigated, but observed patterns vary and a predictive framework is lacking. We outline expectations based on the assumption that telomere maintenance is costly and argue that individual

  12. Interactions of cosmic superstrings

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Mark G.; /Fermilab

    2007-06-01

    We develop methods by which cosmic superstring interactions can be studied in detail. These include the reconnection probability and emission of radiation such as gravitons or small string loops. Loop corrections to these are discussed, as well as relationships to (p; q)-strings. These tools should allow a phenomenological study of string models in anticipation of upcoming experiments sensitive to cosmic string radiation.

  13. Cosmic rays on earth

    Energy Technology Data Exchange (ETDEWEB)

    Allkofer, O.C.; Grieder, P.K.F.

    1984-01-01

    A data collection is presented that covers cosmic rays on earth. Included are all relevant data on flux and intensity measurements, energy spectra, and related data of all primary and secondary components of the cosmic radiation at all levels in the atmosphere, at sea level and underground. In those cases where no useful experimental data have been available, theoretical predictions were substituted.

  14. Onset of oligarchic growth and implication for accretion histories of dwarf planets

    Science.gov (United States)

    Morishima, Ryuji

    2017-01-01

    We investigate planetary accretion that starts from equal-mass planetesimals using an analytic theory and numerical simulations. We particularly focus on how the planetary mass Moli at the onset of oligarchic growth depends on the initial mass m0 of a planetesimal. Oligarchic growth commences when the velocity dispersion relative to the Hill velocity of the protoplanet takes its minimum. We find that if m0 is small enough, this normalized velocity dispersion becomes as low as unity during the intermediate stage between the runaway and oligarchic growth stages. In this case, Moli is independent of m0. If m0 is large, on the other hand, oligarchic growth commences directly after runaway growth, and Moli ∝ m03/7. The planetary mass Moli for the solid surface density of the Minimum Mass Solar Nebula is close to the masses of the dwarf planets in a reasonable range of m0. This indicates that they are likely to be the largest remnant planetesimals that failed to become planets. The power-law exponent q of the differential mass distribution of remnant planetesimals is typically - 2.0 and - 2.7 to - 2.5 for small and large m0. The slope, q ≃ - 2.7 , and the bump at 1021 g (or 50 km in radius) for the mass distribution of hot Kuiper belt objects are reproduced if m0 is the bump mass. On the other hand, small initial planetesimals with m0 ∼ 1013 g or less are favored to explain the slope of large asteroids, q ≃ - 2.0 , while the bump at 1021 g can be reproduced by introducing a small number of asteroid seeds each with mass of 1019 g.

  15. Lessons from the life history of natural fertility societies on child growth and maturation.

    Science.gov (United States)

    Gawlik, Aneta; Hochberg, Ze'ev

    2012-06-19

    During the evolution of hominids, childhood and adolescence have been added as new life-history phases. The transition from infancy to childhood (ICT) confers a predictive adaptive response to energetic cues that strongly influence adult height, whereas the transition from juvenility to adolescence establishes longevity and the age of fertility. Evolutionary short-term adaptations to energy crises apparently use epigenetic mechanisms that defer the ICT, culminating in short stature. The study of hunter-gatherers gives us an indication of pre-demographic transition populations and their life style that prevailed for 99% of homo's evolution. The secular trend for receding age of pubertal development has been an adaptive response to positive environmental cues in terms of energy balance. In natural fertility preindustrial societies with limited access to modern contraception and health care, and whose economies are primarily subsistence-based, most resources are invested as somatic capital in human body size and fertility. Here we review results from databases for natural fertility societies, with the information on life history, population density, height and body mass, indices of adolescence and fertility. By using them it was possible to verify the ICT model as well as to explore pubertal parameters that are related to evolutionary fitness. They confirmed that body size was adaptively smaller in hostile environments, and was tightly associated with reproductive fitness.

  16. How Cosmic Web Detachment Drives Galaxy Quenching

    CERN Document Server

    Aragon-Calvo, Miguel A; Silk, Joseph

    2016-01-01

    We present the Cosmic Web Detachment (CWD) model, a conceptual framework to interpret galaxy evolution in a cosmological context, providing a direct link between the star formation history of galaxies and the cosmic web. The CWD model unifies several mechanism known to disrupt or stop star formation into one single physical process and provides a natural explanation for a wide range of galaxy properties. Galaxies begin accreting star-forming gas at early times via a network of primordial highly coherent filaments. The efficient star formation phase ends when non-linear interactions with other galaxies or elements of the cosmic web detach the galaxy from its network of primordial filaments, thus ending the efficient accretion of cold gas. The stripping of the filamentary web around galaxies is the physical process responsible of star formation quenching in gas stripping, harassment, strangulation and starvation. Being a purely gravitational/mechanical process CWD acts at a more fundamental level than internal ...

  17. Insulin-like signaling (IIS) responses to temperature, genetic background, and growth variation in garter snakes with divergent life histories.

    Science.gov (United States)

    Reding, Dawn M; Addis, Elizabeth A; Palacios, Maria G; Schwartz, Tonia S; Bronikowski, Anne M

    2016-07-01

    The insulin/insulin-like signaling pathway (IIS) has been shown to mediate life history trade-offs in mammalian model organisms, but the function of this pathway in wild and non-mammalian organisms is understudied. Populations of western terrestrial garter snakes (Thamnophis elegans) around Eagle Lake, California, have evolved variation in growth and maturation rates, mortality senescence rates, and annual reproductive output that partition into two ecotypes: "fast-living" and "slow-living". Thus, genes associated with the IIS network are good candidates for investigating the mechanisms underlying ecological divergence in this system. We reared neonates from each ecotype for 1.5years under two thermal treatments. We then used qPCR to compare mRNA expression levels in three tissue types (brain, liver, skeletal muscle) for four genes (igf1, igf2, igf1r, igf2r), and we used radioimmunoassay to measure plasma IGF-1 and IGF-2 protein levels. Our results show that, in contrast to most mammalian model systems, igf2 mRNA and protein levels exceed those of igf1 and suggest an important role for igf2 in postnatal growth in reptiles. Thermal rearing treatment and recent growth had greater impacts on IGF levels than genetic background (i.e., ecotype), and the two ecotypes responded similarly. This suggests that observed ecotypic differences in field measures of IGFs may more strongly reflect plastic responses in different environments than evolutionary divergence. Future analyses of additional components of the IIS pathway and sequence divergence between the ecotypes will further illuminate how environmental and genetic factors influence the endocrine system and its role in mediating life history trade-offs.

  18. Update History of This Database - The Rice Growth Monitoring for The Phenotypic Functional Analysis | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available abase Date Update contents 2014/10/20 The URLs of the database maintenance site and the portal site are changed. 2014/02/10 The... Rice Growth Monitoring for the Phenotypic Functional Analysis English archive site is opened. 2003/10/01 The...switchLanguage; BLAST Search Image Search Home About Archive Update History Data List Contact us The... Rice Growth Monitoring for The Phenotypic Functional Analysis Update History of This Dat... Rice Growth Monitoring System for the Phenotypic Functional

  19. Case history: improved maxillary growth and development following digit sucking elimination and orofacial myofunctional therapy.

    Science.gov (United States)

    Green, Shari

    2013-11-01

    Orofacial myologists are frequently called upon to address retained oral habit concerns. During this process, current I.A.O.M. recommended treatment includes addressing tongue, lip, and jaw rest posture concerns. Following digit sucking remediation, we may also be called upon to address these rest posture issues, and tongue thrust more aggressively together. In this process, facial growth and development and jaw structure may coincidentally improve as a result of 'nature taking its course' by addressing both swallow AND rest posture. In a select subset of clients, dramatic improvements may occur if the timing is right. This article discusses one such case that appears to have yielded a significant improvement in oral postures influencing improved facial and oral growth and development.

  20. Gravitational entropy of cosmic expansion

    CERN Document Server

    Sussman, Roberto A

    2014-01-01

    We apply a recent proposal to define "gravitational entropy" to the expansion of cosmic voids within the framework of non-perturbative General Relativity. By considering CDM void configurations compatible with basic observational constraints, we show that this entropy grows from post-inflationary conditions towards a final asymptotic value in a late time fully non-linear regime described by the Lemaitre-Tolman-Bondi (LTB) dust models. A qualitatively analogous behavior occurs if we assume a positive cosmological constant consistent with a $\\Lambda$-CDM background model. However, the $\\Lambda$ term introduces a significant suppression of entropy growth with the terminal equilibrium value reached at a much faster rate.

  1. Growth history of hydrothermal chimneys at EPR 9―10°N: A structural and mineralogical study

    Institute of Scientific and Technical Information of China (English)

    PENG Xiaotong; ZHOU Huaiyang

    2005-01-01

    Based on structural and mineralogical characteristics of four hydrothermal chimney samples collected by submersible Alvin, growth history and formation environment of hydrothermal chimney at EPR 9―10°N are established. It is shown that there occur two types of hydrothermal chimney with different deposition environments at EPR 9―10°N according to differences in their shape, structure and mineral assemblage: type I chimney forms in an environment with high temperature, low pH and strong reducing hydrothermal focus flow and type II chimney forms in a relatively low temperature, high pH and rich Zn hydrothermal environment. Growth of type I chimney begins with the formation of anhydrite. Subsequently deposition of Cu-Fe-Zn sulphide in various directions of chimneys decides the final structure of this type of chimney. According to observation and analysis of mineral assemblages, the formation process of type I chimney could be divided into three stages from early, middle to late. Changes of temperature and major chemical reaction type in the process of hydrothermal chimney formation are also deduced. Different from type I chimney, quenching crystalline of pyrite and/or crystalline of sphalerite provide the growth foundation of type II chimney in the early stage of chimney formation.

  2. Xenia: A Probe of Cosmic Chemical Evolution

    Science.gov (United States)

    Kouveliotou, Chryssa; Piro, L.

    2008-01-01

    Xenia is a concept study for a medium-size astrophysical cosmology mission addressing the Cosmic Origins key objective of NASA's Science Plan. The fundamental goal of this objective is to understand the formation and evolution of structures on various scales from the early Universe to the present time (stars, galaxies and the cosmic web). Xenia will use X-and y-ray monitoring and wide field X-ray imaging and high-resolution spectroscopy to collect essential information from three major tracers of these cosmic structures: the Warm Hot Intergalactic Medium (WHIM), Galaxy Clusters and Gamma Ray Bursts (GRBs). Our goal is to trace the chemo-dynamical history of the ubiquitous warm hot diffuse baryon component in the Universe residing in cosmic filaments and clusters of galaxies up to its formation epoch (at z =0-2) and to map star formation and galaxy metal enrichment into the re-ionization era beyond z 6. The concept of Xenia (Greek for "hospitality") evolved in parallel with the Explorer of Diffuse Emission and GRB Explosions (EDGE), a mission proposed by a multinational collaboration to the ESA Cosmic Vision 2015. Xenia incorporates the European and Japanese collaborators into a U.S. led mission that builds on the scientific objectives and technological readiness of EDGE.

  3. Environmental changes and growth history of a cold-water carbonate mound (Propeller Mound, Porcupine Seabight)

    Science.gov (United States)

    Rüggeberg, Andres; Dullo, Christian; Dorschel, Boris; Hebbeln, Dierk

    2007-02-01

    On- and off-mound sediment cores from Propeller Mound (Hovland Mound province, Porcupine Seabight) were analysed to understand better the evolution of a carbonate mound. The evaluation of benthic foraminiferal assemblages from the off-mound position helps to determine the changes of the environmental controls on Propeller Mound in glacial and interglacial times. Two different assemblages describe the Holocene and Marine Isotope Stage (MIS) 2 and late MIS 3 (˜31 kyr BP). The different assemblages are related to changes in oceanographic conditions, surface productivity and the waxing and waning of the British Irish Ice Sheet (BIIS) during the last glacial stages. The interglacial assemblage is related to a higher supply of organic material and stronger current intensities in water depth of recent coral growth. During the last glaciation the benthic faunas showed high abundances of cassidulinid species, implying cold bottom waters and a reduced availability of organic matter. High sedimentation rates and the domination of Elphidium excavatum point to shelf erosion related to sea-level lowering (˜50 m) and the progradation of the BIIS onto the shelf. A different assemblage described for the on-mound core is dominated by Discanomalina coronata, Gavelinopsis translucens, Planulina ariminensis, Cibicides lobatulus and to a lower degree by Hyrrokkin sarcophaga. These species are only found or show significantly higher relative abundances in on-mound samples and their maximum contribution in the lower part of the record indicates a higher coral growth density on Propeller Mound in an earlier period. They are less abundant during the Holocene, however. This dataset portrays the boundary conditions of the habitable range for the cold-water coral Lophelia pertusa, which dominates the deep-water reefal ecosystem on the upper flanks of Propeller Mound. The growth of this ecosystem occurs during interglacial and interstadial periods, whereas a retreat of corals is documented in

  4. Cosmic Rays in Magnetospheres of the Earth and other Planets

    CERN Document Server

    Dorman, Lev

    2009-01-01

    This monograph describes the behaviour of cosmic rays in the magnetosphere of the Earth and of some other planets. Recently this has become an important topic both theoretically, because it is closely connected with the physics of the Earth’s magnetosphere, and practically, since cosmic rays determine a significant part of space weather effects on satellites and aircraft. The book contains eight chapters, dealing with – The history of the discovery of geomagnetic effects caused by cosmic rays and their importance for the determination of the nature of cosmic rays or gamma rays – The first explanations of geomagnetic effects within the framework of the dipole approximation of the Earth’s magnetic field – Trajectory computations of cutoff rigidities, transmittance functions, asymptotic directions, and acceptance cones in the real geomagnetic field taking into account higher harmonics – Cosmic ray latitude-longitude surveys on ships, trains, tracks, planes, balloons and satellites for determining the...

  5. The Tribal Perspective of Old Growth in Frequent-fire Forests—Its History

    Directory of Open Access Journals (Sweden)

    Victoria Yazzie

    2007-12-01

    Full Text Available Anyone who has not lived in “Indian country” cannot understand just how extensively the United States government and its laws affect Native Americans and their natural resource management. These effects are sobering, and touch upon sensitive issues that all Native Americans hold within us. In this article, I outline the historic cycle of tribal entities, and characterize today’s tribal self-determination in forest management. I provide an historical account from the “colonial” period and its use of the Doctrine of Discovery to the relations between the United States government and Native Americans from the 18th through the 20th centuries, during which time Native Americans struggled to establish their legal status as tribes, and solidify their land base to sustain and conserve culturally important lands, including areas of old-growth forests, to the current self-determination and self-governance potential of Indian tribes. More importantly, I discuss the cultural connectivity that Native Americans have to the land, and address the unique inherent right of tribes to integrate this cultural view into current forest management, including the protection of old-growth forests, on their reservations.

  6. Eleventh European Cosmic Ray Symposium

    Science.gov (United States)

    1988-08-01

    The biannual Symposium includes all aspects of cosmic ray research. The scientific program was organized under three main headings: cosmic rays in the heliosphere, cosmic rays in the interstellar and extragalactic space, and properties of high-energy interactions as studied by cosmic rays. Selected short communications out of 114 contributed papers were indexed separately for the INIS database.

  7. Light scattering by cosmic particles

    NARCIS (Netherlands)

    Hovenier, J.W.; Min, M.

    2008-01-01

    We define cosmic particles as particles outside the Earth. Two types of cosmic particles can be distinguished, namely liquid and solid particles. The solid particles are often called grains or cosmic dust particles. Cosmic particles occur in a great variety of astronomical objects and environments.

  8. Supermassive cosmic string compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Blanco-Pillado, Jose J.; Reina, Borja; Sousa, Kepa; Urrestilla, Jon, E-mail: josejuan.blanco@ehu.es, E-mail: borja.reina@ehu.es, E-mail: kepa.sousa@ehu.es, E-mail: jon.urrestilla@ehu.es [Department of Theoretical Physics and History of Science, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain)

    2014-06-01

    The space-time dimensions transverse to a static straight cosmic string with a sufficiently large tension (supermassive cosmic strings) are compact and typically have a singularity at a finite distance form the core. In this paper, we discuss how the presence of multiple supermassive cosmic strings in the 4d Abelian-Higgs model can induce the spontaneous compactification of the transverse space and explicitly construct solutions where the gravitational background becomes regular everywhere. We discuss the embedding of this model in N = 1 supergravity and show that some of these solutions are half-BPS, in the sense that they leave unbroken half of the supersymmetries of the model.

  9. Supermassive Cosmic String Compactifications

    CERN Document Server

    Blanco-Pillado, Jose J; Sousa, Kepa; Urrestilla, Jon

    2014-01-01

    The space-time dimensions transverse to a static straight cosmic string with a sufficiently large tension (supermassive cosmic strings) are compact and typically have a singularity at a finite distance form the core. In this paper, we discuss how the presence of multiple supermassive cosmic strings in the 4D Abelian-Higgs model can induce the spontaneous compactification of the transverse space and explicitly construct solutions where the gravitational background becomes regular everywhere. We discuss the embedding of this model in N=1 supergravity and show that some of these solutions are half-BPS, in the sense that they leave unbroken half of the supersymmetries of the model.

  10. Natural history of de novo High Grade Glioma: first description of growth parabola.

    Science.gov (United States)

    Altieri, Roberto; Hirono, Seiichiro; Duffau, Hugues; Ducati, Alessandro; Fontanella, Marco; LA Rocca, Giuseppe; Melcarne, Antonio; Panciani, Pier P; Spena, Giannantonio; Garbossa, Diego

    2017-07-26

    Etiopathogenesis and physiopathology of gliomas are largely unknown. Recently, many authors have proved a strict correlation between the velocity of diametric expansion (VDE) on the Magnetic Resonance Imaging (MRI) and the biological behavior of these tumors, especially in Low Grade Gliomas (LGGs). Unfortunately, natural history of High Grade Gliomas (HGGs) has not been well clarified because of its fast progression, late diagnoses and early surgical intervention. We describe, for the first time to our knowledge, the case of asymptomatic patient with an incidentally discovered de novo HGG with a total of 17 months of follow-up. A male patient was referred to our consultation for routinely follow-up after meningioma resection 5 years before. He underwent MRI every year without any neuroradiological alterations. A new MRI image presented a non-enhancing lesion in the right temporal lobe with 3.55 cm of Mean Tumor Diameter (MTD) and 35.6 mm/year of VDE. After two months interval, the lesion had 3.97 cm of MTD and 27.8 mm/year of VDE. Although we have strongly suggested surgical resection, patient have delayed the operation for personal issues. After other 3 months, the tumor showed enhancement with 4.5 of MTD and 17.4 mm/year of VDE. We speculate that the descending parabola is due to initial mass effect and hypoxia of the tumor core. We also underline the crucial role of the VDE determining, in order to predict the nature of the lesion and address the most effective treatment for each patient.

  11. Habitability and cosmic catastrophes

    CERN Document Server

    Hanslmeier, Arnold; McKay, Christopher P

    2008-01-01

    Catastrophic cosmic events such as asteroid impacts appear in the range of some 100 million years and have drastically affected evolution. The author discusses whether and how such events could have occurred in recently found extrasolar planetary systems.

  12. Astrophysics: Cosmic jet engines

    Science.gov (United States)

    Young, Andy

    2010-02-01

    In some galaxies, matter falling onto a supermassive black hole is ejected in narrow jets moving at close to the speed of light. New observations provide insight into the workings of these cosmic accelerators.

  13. Establishing the Post-Inflationary History from Fundamental Theory Through Cosmological Observations

    Science.gov (United States)

    Watson, Scott

    Big Bang Nucleosynthesis (BBN) was an early success of the Big Bang model of cosmology. Cosmic inflation provides an origin for the initial conditions necessary for the growth of structure in the universe. However, little is known observationally about the cosmic epoch in between - despite expectations from fundamental theory for a rich amount of phenomenology. The objective of the proposed research is to establish the history of the universe during this cosmic epoch by exploring the connection between particle theory and observations today. A strictly thermal history is a well-motivated possibility for the evolution during this epoch. However, other alternatives are possible. One example is if dark matter were produced not only in thermal equilibrium, but also from the decay of heavier matter following thermal "freeze-out". This non-thermal history often arises from fundamental theories that invoke Supersymmetry to address the hierarchy between the strength of gravity and the electroweak scale. In such a history a secondary source for the origin of dark matter leads to different predictions for both its composition and interaction strength. In some cases dark matter can interact as much as 1000 times more strongly than anticipated from a strictly thermal history. These enhanced interactions lead to a plethora of new predictions for the physics of the Cosmic Microwave Background (CMB), the growth of cosmic structure on all scales, and the flux of particles coming from dark matter annihilations within galaxies For a non-thermal history it has already been demonstrated that stringent constraints can be placed on model building by combining data from observations on various scales. As an example, a non-thermal history resulting from heavy particle decay is found to lead to a faster rate for dark matter annihilations, which results in an extended period of reionization compared to that predicted by a thermal history. Observations from the NASA Wilkinson Microwave

  14. Highest Energy Cosmic Rays

    CERN Document Server

    Frampton, Paul H

    1998-01-01

    It is proposed that the highest energy $\\sim 10^{20}$eV cosmic ray primaries are protons, decay products of a long-lived progenitor whose high kinetic energy arises from decay of a distant (cosmological) superheavy particle, G. Such a scenario can occur in e.g. SU(15) grand unification and in some preon models, but is more generic; if true, these unusual cosmic rays provide a window into new physics.

  15. The co-evolution of black hole growth and star formation from a cross-correlation analysis between quasars and the cosmic infrared background

    CERN Document Server

    Wang, Lingyu; Ross, Nicholas P; Asboth, Viktoria; Bethermin, Matthieu; Bock, Jamie; Clements, Dave; Conley, Alex; Cooray, Asantha; Farrah, Duncan; Hajian, Amir; Han, Jiaxin; Lagache, Guilaine; Marsden, Gaelen; Myers, Adam; Norberg, Peder; Oliver, Seb; Page, Mat; Symeonidis, Myrto; Schulz, Bernhard; Wang, Wenting; Zemcov, Mike

    2014-01-01

    We present the first cross-correlation measurement between Sloan Digital Sky Survey (SDSS) Type 1 quasars and the cosmic infrared background (CIB) measured by Herschel. The distribution of the quasars at 0.15=1.4) is $11.1^{+1.6}_{-1.4}$, $7.1^{+1.6}_{-1.3}$ and $3.6^{+1.4}_{-1.0}$ mJy at 250, 350 and 500 microns, respectively, while the mean sub-mm flux densities of the DR9 quasars (=2.5) is $5.7^{+0.7}_{-0.6}$, $5.0^{+0.8}_{-0.7}$ and $1.8^{+0.5}_{-0.4}$ mJy. We find that the correlated sub-mm emission includes both the emission from satellite DSFGs in the same halo as the central quasar and the emission from DSFGs in separate halos (correlated with the quasar-hosting halo). The amplitude of the one-halo term is ~10 times smaller than the sub-mm emission of the quasars, implying the the satellites have a lower star-formation rate than the quasars. The satellite fraction for the DR7 quasars is $0.008^{+0.008}_{-0.005}$ and the host halo mass scale for the central and satellite quasars is $10^{12.36\\pm0.87}$ ...

  16. Life History Traits and Population Growth of Greenhouse Whitefly (Trialeurodes vaporariorum Westwood on Different Tomato Genotypes

    Directory of Open Access Journals (Sweden)

    Mirjana Prijović

    2013-12-01

    Full Text Available The effects of five tomato genotypes (cv. Narvik and hybrids NS-6, Tamaris, Alliance and Marko on the survival, reproduction, development and population growth of the greenhouse whitefly Trialeurodes vaporariorum were examined. A laboratory population of T. vaporariorum had been reared on tobacco plants for three years before the study. Females that laid eggs on the genotype Marko lived significantly longer and their offspring needed significantly shorter periods to develop than females on the genotype Narvik. The highest gross and net fecundity rates were found in females on the genotype Marko (36.74 eggs/ female and 27.93 eggs/female, respectively and they differed significantly from the corresponding rates of females living on the genotype NS-6 (18.55 eggs/female and 15.33 eggs/ female, who had the lowest fecundity rates. The highest gross and net fertility rates were also found in females on the genotype Marko (31.24 adults/female and 23.73 adults/female, and they were significantly higher than those of females living on NS-6 (14.85 adults/female and 12.53 adults/female. Besides, net fertility rate of the females living on the genotype Narvik (13.80 adults/female was also significantly lower than the rate of females on Marko. The instantaneous rates of increase showed no significant difference over a 10-day interval following the start of oviposition, while the increase rate was significantly higher on the genotype Marko after 12, 14 and 16 days, compared to the genotype NS-6. Eighteen, 20 and 22 days after the beginning of oviposition, the instantaneous rate of increase on the genotype Marko was significantly higher than it was on NS-6 and Narvik. Our data provide a basis for further research aiming to improve programs of integrated management of greenhouse whitefly.

  17. Acoustic instability driven by cosmic-ray streaming

    Science.gov (United States)

    Begelman, Mitchell C.; Zweibel, Ellen G.

    1994-01-01

    We study the linear stability of compressional waves in a medium through which cosmic rays stream at the Alfven speed due to strong coupling with Alfven waves. Acoustic waves can be driven unstable by the cosmic-ray drift, provided that the streaming speed is sufficiently large compared to the thermal sound speed. Two effects can cause instability: (1) the heating of the thermal gas due to the damping of Alfven waves driven unstable by cosmic-ray streaming; and (2) phase shifts in the cosmic-ray pressure perturbation caused by the combination of cosmic-ray streaming and diffusion. The instability does not depend on the magnitude of the background cosmic-ray pressure gradient, and occurs whether or not cosmic-ray diffusion is important relative to streaming. When the cosmic-ray pressure is small compared to the gas pressure, or cosmic-ray diffusion is strong, the instability manifests itself as a weak overstability of slow magnetosonic waves. Larger cosmic-ray pressure gives rise to new hybrid modes, which can be strongly unstable in the limits of both weak and strong cosmic-ray diffusion and in the presence of thermal conduction. Parts of our analysis parallel earlier work by McKenzie & Webb (which were brought to our attention after this paper was accepted for publication), but our treatment of diffusive effects, thermal conduction, and nonlinearities represent significant extensions. Although the linear growth rate of instability is independent of the background cosmic-ray pressure gradient, the onset of nonlinear eff ects does depend on absolute value of DEL (vector differential operator) P(sub c). At the onset of nonlinearity the fractional amplitude of cosmic-ray pressure perturbations is delta P(sub C)/P(sub C) approximately (kL) (exp -1) much less than 1, where k is the wavenumber and L is the pressure scale height of the unperturbed cosmic rays. We speculate that the instability may lead to a mode of cosmic-ray transport in which plateaus of uniform cosmic

  18. Natural histroy of trisomy 18 and trisomy 13: I. Growth, physical assessment, medical histories, survival, and recurrence risk

    Energy Technology Data Exchange (ETDEWEB)

    Baty, B.J.; Blackburn, B.L.; Carey, J.C. [Univ. of Utah School of Medicine, Salt Lake City, UT (United States)

    1994-01-15

    The natural history of trisomy 18 and trisomy 13 was investigated using data derived from parent questionnaires and medical records from 98 families with an index case of trisomy 18 and 32 families with an index case of trisomy 13. Data are presented on pregnancy, delivery, survival, medical complications, immunizations, growth, cause of death, cytogenetics, and recurrence risk. Half of the trisomy 18 babies were delivered by C-section. Fetal distress was a factor in half, and the only reason in a third of C-section deliveries. One minute Apgar scores were significantly lower in C-section and breech deliveries. There were more small-for-gestational-age babies than in the general population, but most of the low-birth-weight newborns were small for gestational age, unlike the general population. Survival in this group of children was better than in other studies due to ascertainment bias. There were more girls than boys at all ages for both conditions, and the sex ratio decreased with time. Growth curves for length, weight, head circumference, and weight vs height are provided. Long-term survival did not appear to be due to mosaicism. There were no adverse reactions attributable to immunizations. At age 1 year there was an average of approximately 2 operations per living child. The authors report the second case of successful major cardiac surgery in a trisomy 18 child. Almost 70% of deaths were attributed to cardiopulmonary arrest. The sibling recurrence risk for trisomy 18 or trisomy 13 was 0.55%. 86 refs., 5 figs., 5 tabs.

  19. Molecular hydrogen in the cosmic recombination epoch

    CERN Document Server

    Alizadeh, Esfandiar

    2010-01-01

    The advent of precise measurements of the cosmic microwave background (CMB) anisotropies has motivated correspondingly precise calculations of the cosmic recombination history. Cosmic recombination proceeds far out of equilibrium because of a "bottleneck" at the $n=2$ level of hydrogen: atoms can only reach the ground state via slow processes: two-photon decay or Lyman-$\\alpha$ resonance escape. However, even a small primordial abundance of molecules could have a large effect on the interline opacity in the recombination epoch and lead to an additional route for hydrogen recombination. Therefore, this paper computes the abundance of the H$_2$ molecule during the cosmic recombination epoch. Hydrogen molecules in the ground electronic levels X$^1\\Sigma^+_g$ can either form from the excited H$_2$ electronic levels B$^1\\Sigma^+_u$ and C$^1\\Pi_u$ or through the charged particles H$_2^+$, HeH$^+$ and H$^-$. We follow the transitions among all of these species, resolving the rotational and vibrational sub-levels. Si...

  20. Neutrino mass without cosmic variance

    CERN Document Server

    LoVerde, Marilena

    2016-01-01

    Measuring the absolute scale of the neutrino masses is one of the most exciting opportunities available with near-term cosmological datasets. Two quantities that are sensitive to neutrino mass, scale-dependent halo bias $b(k)$ and the linear growth parameter $f(k)$ inferred from redshift-space distortions, can be measured without cosmic variance. Unlike the amplitude of the matter power spectrum, which always has a finite error, the error on $b(k)$ and $f(k)$ continues to decrease as the number density of tracers increases. This paper presents forecasts for statistics of galaxy and lensing fields that are sensitive to neutrino mass via $b(k)$ and $f(k)$. The constraints on neutrino mass from the auto- and cross-power spectra of spectroscopic and photometric galaxy samples are weakened by scale-dependent bias unless a very high density of tracers is available. In the high density limit, using multiple tracers allows cosmic-variance to be beaten and the forecasted errors on neutrino mass shrink dramatically. In...

  1. Cosmic Rays and Climate

    CERN Document Server

    Kirkby, Jasper

    2007-01-01

    Among the most puzzling questions in climate change is that of solar-climate variability, which has attracted the attention of scientists for more than two centuries. Until recently, even the existence of solar-climate variability has been controversial—perhaps because the observations had largely involved correlations between climate and the sunspot cycle that had persisted for only a few decades. Over the last few years, however, diverse reconstructions of past climate change have revealed clear associations with cosmic ray variations recorded in cosmogenic isotope archives, providing persuasive evidence for solar or cosmic ray forcing of the climate. However, despite the increasing evidence of its importance, solar-climate variability is likely to remain controversial until a physical mechanism is established. Although this remains a mystery, observations suggest that cloud cover may be influenced by cosmic rays, which are modulated by the solar wind and, on longer time scales, by the geomagnetic fiel...

  2. Constraints On Cosmic Dynamics

    CERN Document Server

    Mbonye, M R

    2003-01-01

    Observationally, the universe appears virtually critical. Yet, there is no simple explanation for this state. In this article we advance and explore the premise that the dynamics of the universe always seeks equilibrium conditions. Vacuum-induced cosmic accelerations lead to creation of matter-energy modes at the expense of vacuum energy. Because they gravitate, such modes constitute inertia against cosmic acceleration. On the other extreme, the would-be ultimate phase of local gravitational collapse is checked by a phase transition in the collapsing matter fields leading to a de Sitter-like fluid deep inside the black hole horizon, and at the expense of the collapsing matter fields. As a result, the universe succumbs to neither vacuum-induced run-away accelerations nor to gravitationally induced spacetime curvature singularities. Cosmic dynamics is self-regulating. We discuss the physical basis for these constraints and the implications, pointing out how the framework relates and helps resolve standing puzzl...

  3. A cosmic book

    Science.gov (United States)

    Peebles, P. J. E.; Silk, Joseph

    1988-10-01

    A system of assigning odds to the basic elements of cosmological theories is proposed in order to evaluate the strengths and weaknesses of the theories. A figure of merit for the theories is obtained by counting and weighing the plausibility of each of the basic elements that is not substantially supported by observation or mature fundamental theory. The magnetized strong model is found to be the most probable. In order of decreasing probability, the ranking for the rest of the models is: (1) the magnetized string model with no exotic matter and the baryon adiabatic model; (2) the hot dark matter model and the model of cosmic string loops; (3) the canonical cold dark matter model, the cosmic string loops model with hot dark matter, and the baryonic isocurvature model; and (4) the cosmic string loops model with no exotic matter.

  4. P-MaNGA: Gradients in Recent Star Formation Histories as Diagnostics for Galaxy Growth and Death

    CERN Document Server

    Li, Cheng; Lin, Lin; Bershady, Matthew A; Bundy, Kevin; Tremonti, Christy A; Xiao, Ting; Yan, Renbin; Bizyaev, Dmitry; Blanton, Michael; Cales, Sabrina; Cherinka, Brian; Cheung, Edmond; Drory, Niv; Emsellem, Eric; Fu, Hai; Gelfand, Joseph; Law, David R; Lin, Lihwai; MacDonald, Nick; Maraston, Claudia; Masters, Karen L; Merrifield, Michael R; Pan, Kaike; Sanchez, S F; Schneider, Donald P; Thomas, Daniel; Wake, David; Wang, Lixin; Weijmans, Anne-Marie; Wilkinson, David; Yoachim, Peter; Zhang, Kai; Zheng, Tiantian

    2015-01-01

    We present an analysis of the data produced by the MaNGA prototype run (P-MaNGA), aiming to test how the radial gradients in recent star formation histories, as indicated by the 4000AA-break (D4000), Hdelta absorption (EW(Hd_A)) and Halpha emission (EW(Ha)) indices, can be useful for understanding disk growth and star formation cessation in local galaxies. We classify 12 galaxies observed on two P-MaNGA plates as either centrally quiescent (CQ) or centrally star-forming (CSF), according to whether D4000 measured in the central spaxel of each datacube exceeds 1.6. For each galaxy we generate both 2D maps and radial profiles of D4000, EW(Hd_A) and EW(Ha). We find that CSF galaxies generally show very weak or no radial variation in these diagnostics. In contrast, CQ galaxies present significant radial gradients, in the sense that D4000 decreases, while both EW(Hd_A) and EW(Ha) increase from the galactic center outward. The outer regions of the galaxies show greater scatter on diagrams relating the three paramete...

  5. SDSS IV MaNGA: Gradients in Recent Star Formation Histories as Diagnostics for Galaxy Growth and Death

    Science.gov (United States)

    Li, Cheng; MaNGA Team

    2016-01-01

    The spatially resolved spectroscopy from MaNGA allows the radial gradients of recent star formation histories (SFH), as indicated by the 4000Å break (D4000) and the equivalent width of both Hδ absorption line and Hα emission line, to be obtained with high accuracy for a large sample of galaxies in the nearby universe. Analyses of both a dozen galaxies observed by the MaNGA prototype run (P-MaNGA) and ~700 galaxies in the current MaNGA sample have shown that the SFH gradients are useful for understanding disk growth and star formation cessation in local galaxies. We find the SFH gradient of a galaxy to strongly depend on the evolution stage of its central region. Centrally star-forming galaxies generally show very weak or no radial variations. In contrast, centrally quiescent galaxies present significant radial gradients in the sense that Dn(4000) decreases, while both EW(HδA) and EW(Hα) increase from the galactic center outward. This effect is seen mainly for high-mass galaxies with stellar mass above a few ×1010 M⊙, and depends weakly on galaxy morphology type. These results are consistent with a picture in which the cessation of star formation propagates from the center of a galaxy outward as it moves to the red sequence. In this talk I will present these analyses and discuss their implications on galaxy evolution.

  6. Adiabatic fluctuations from cosmic strings in a contracting universe

    CERN Document Server

    Brandenberger, Robert H; Yamaguchi, Masahide

    2008-01-01

    We show that adiabatic, super-Hubble, and almost scale invariant density fluctuations are produced by cosmic strings in a contracting universe. An essential point is that isocurvature perturbations produced by topological defects such as cosmic strings on super-Hubble scales lead to a source term which seeds the growth of curvature fluctuations on these scales. Once the symmetry has been restored at high temperatures, the isocurvature seeds disappear, and the fluctuations evolve as adiabatic ones in the expanding phase. Thus, cosmic strings may be resurrected as a mechanism for generating the primordial density fluctuations observed today.

  7. A disintegrating cosmic string

    CERN Document Server

    Griffiths, J B

    2002-01-01

    We present a simple sandwich gravitational wave of the Robinson-Trautman family. This is interpreted as representing a shock wave with a spherical wavefront which propagates into a Minkowski background minus a wedge. (i.e. the background contains a cosmic string.) The deficit angle (the tension) of the string decreases through the gravitational wave, which then ceases. This leaves an expanding spherical region of Minkowski space behind it. The decay of the cosmic string over a finite interval of retarded time may be considered to generate the gravitational wave.

  8. Cosmic Sum Rules

    DEFF Research Database (Denmark)

    T. Frandsen, Mads; Masina, Isabella; Sannino, Francesco

    2011-01-01

    We introduce new sum rules allowing to determine universal properties of the unknown component of the cosmic rays and show how it can be used to predict the positron fraction at energies not yet explored by current experiments and to constrain specific models.......We introduce new sum rules allowing to determine universal properties of the unknown component of the cosmic rays and show how it can be used to predict the positron fraction at energies not yet explored by current experiments and to constrain specific models....

  9. Dynamic Cosmic Strings, 1

    CERN Document Server

    Sjodin, K R P; Vickers, J A

    2001-01-01

    The field equations for a time dependent cylindrical cosmic string coupled togravity are reformulated in terms of geometrical variables defined on a2+1-dimensional spacetime by using the method of Geroch decomposition. Unlikethe 4-dimensional spacetime the reduced case is asymptotically flat. Anumerical method for solving the field equations which involves conformallycompactifying the space and including null infinity as part of the grid isdescribed. It is shown that the code reproduces the results of a number ofvacuum solutions with one or two degrees of freedom. In the final section theinteraction between the cosmic string and a pulse of gravitational radiation isbriefly described. This will be fully analysed in the sequel.

  10. Fluorescent minerals - A potential source of UV protection and visible light for the growth of green algae and cyanobacteria in extreme cosmic environments

    Science.gov (United States)

    Omairi, Tareq; Wainwright, Milton

    2015-07-01

    We propose that green algae (Chlorella variabilis and Dunaliella tertiolecta) and cyanobacteria (Synechococcus elongatus and Nostoc commune) can grow inside fluorescent rock minerals which convert damaging UV light to visible light, thereby allowing these organisms to survive and thrive in UV-rich environments without (or with limited) visible light, which would otherwise be inimical to them. The four microorganisms were incubated inside fluorescent rocks composed of fluorite, calcite and pyrite. The resultant growth was then measured following exposure to UV radiation, with the use of optical density and measurement of chlorophyll concentration. Results show that the microorganisms were shielded from harmful UV in these semi-transparent rocks, while at the same time benefiting from the fact that the minerals converted UV to visible light; this have been shown by a statistically significant increase in their growth, which although lower than when the cells were incubated in sunlight, was significantly higher than in controls incubated in the dark.

  11. 9,400 years of cosmic radiation and solar activity from ice cores and tree rings

    National Research Council Canada - National Science Library

    Friedhelm Steinhilber; Jose A. Abreu; Jürg Beer; Irene Brunner; Marcus Christl; Hubertus Fischer; Ulla Heikkilä; Peter W. Kubik; Mathias Mann; Ken G. McCracken; Heinrich Miller; Hiroko Miyahara; Hans Oerter; Frank Wilhelms

    2012-01-01

    .... Cosmic-ray produced radionuclides, such as ¹⁰Be and ¹⁴C which are stored in polar ice cores and tree rings, offer the unique opportunity to reconstruct the history of cosmic radiation and solar activity over many millennia...

  12. The Cosmic Microwave Background

    OpenAIRE

    Silk, Joseph

    2002-01-01

    This set of lectures provides an overview of the basic theory and phenomenology of the cosmic microwave background. Topics include a brief historical review; the physics of temperature and polarization fluctuations; acoustic oscillations of the primordial plasma; the space of inflationary cosmological models; current and potential constraints on these models from the microwave background; and constraints on inflation.

  13. Simulating Cosmic Reionisation

    NARCIS (Netherlands)

    Pawlik, Andreas Heinz

    2009-01-01

    The first stars formed a few hundred million years after the Big Bang, when the Universe was only a small fraction of its present age. Their radiation transformed the previously cold and neutral hydrogen that filled intergalactic space into the hot and ionised cosmic plasma that is observed today. T

  14. Simulating Cosmic Reionisation

    NARCIS (Netherlands)

    Pawlik, Andreas Heinz

    2009-01-01

    The first stars formed a few hundred million years after the Big Bang, when the Universe was only a small fraction of its present age. Their radiation transformed the previously cold and neutral hydrogen that filled intergalactic space into the hot and ionised cosmic plasma that is observed today.

  15. Antarctic Cosmic Ray Astronomy

    Science.gov (United States)

    Duldig, Marc

    Cosmic ray observations related to Antarctica commenced in the austral summer of 1947-48 from sub-Antarctic Heard and Macquarie Islands and from the HMAS Wyatt Earp. Muon telescope observations from Mawson station Antarctica commenced in 1955. The International Geophysical Year was the impetus for the installation of a number of neutron monitors around Antarctica observing the lowest energy cosmic rays accessible by ground based instruments. In 1971 a new observatory was built at Mawson including the only underground muon telescope system at polar latitudes in either hemisphere. In the 1980s the South Pole Air Shower Experiment (SPASE) opened the highest energy cosmic ray window over Antarctica and this was followed by the in-ice neutrino experiment AMANDA. Over more than half a century cosmic ray astronomy has been undertaken from Antarctica and its surrounding regions and these observations have been critical to our growing understanding of nearby astrophysical structures. For example the Parker spiral magnetic field of the sun was confirmed through Mawson observations of a Solar flare induced Ground Level Enahncement in 1960 long before spacecraft were able to directly observe the interplanetary magnetic field. A summary of the Antarctic instrumental developments and the scientific advances that resulted will be presented.

  16. Hydrology and Cosmic radiation

    DEFF Research Database (Denmark)

    Andreasen, Mie

    and calibration. Yet, soil moisture measurements are traditionally provided on either point or kilometer scale from electromagnetic based sensors and satellite retrievals, respectively. Above the ground surface, the cosmic-ray neutron intensity (eV range) is inversely correlated to all hydrogen present...

  17. Cosmic rays and climate

    CERN Multimedia

    2009-01-01

    Inside the new chamber the CLOUD team will be able to recreate the conditions of any part of the atmosphere, from the polar stratosphere to the low level tropics (top). The new chamber safely in position in the East hall. Once carefully cleaned the chamber will be turned sideways onto its legs ready for the beam of 'cosmic rays' (bottom).

  18. Fluorescent minerals--A potential source of UV protection and visible light for the growth of green algae and cyanobacteria in extreme cosmic environments.

    Science.gov (United States)

    Omairi, Tareq; Wainwright, Milton

    2015-07-01

    We propose that green algae (Chlorella variabilis and Dunaliella tertiolecta) and cyanobacteria (Synechococcus elongatus and Nostoc commune) can grow inside fluorescent rock minerals which convert damaging UV light to visible light, thereby allowing these organisms to survive and thrive in UV-rich environments without (or with limited) visible light, which would otherwise be inimical to them. The four microorganisms were incubated inside fluorescent rocks composed of fluorite, calcite and pyrite. The resultant growth was then measured following exposure to UV radiation, with the use of optical density and measurement of chlorophyll concentration. Results show that the microorganisms were shielded from harmful UV in these semi-transparent rocks, while at the same time benefiting from the fact that the minerals converted UV to visible light; this have been shown by a statistically significant increase in their growth, which although lower than when the cells were incubated in sunlight, was significantly higher than in controls incubated in the dark. Copyright © 2015 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  19. Cosmic Rays at Earth

    Science.gov (United States)

    Grieder, P. K. F.

    In 1912 Victor Franz Hess made the revolutionary discovery that ionizing radiation is incident upon the Earth from outer space. He showed with ground-based and balloon-borne detectors that the intensity of the radiation did not change significantly between day and night. Consequently, the sun could not be regarded as the sources of this radiation and the question of its origin remained unanswered. Today, almost one hundred years later the question of the origin of the cosmic radiation still remains a mystery. Hess' discovery has given an enormous impetus to large areas of science, in particular to physics, and has played a major role in the formation of our current understanding of universal evolution. For example, the development of new fields of research such as elementary particle physics, modern astrophysics and cosmology are direct consequences of this discovery. Over the years the field of cosmic ray research has evolved in various directions: Firstly, the field of particle physics that was initiated by the discovery of many so-called elementary particles in the cosmic radiation. There is a strong trend from the accelerator physics community to reenter the field of cosmic ray physics, now under the name of astroparticle physics. Secondly, an important branch of cosmic ray physics that has rapidly evolved in conjunction with space exploration concerns the low energy portion of the cosmic ray spectrum. Thirdly, the branch of research that is concerned with the origin, acceleration and propagation of the cosmic radiation represents a great challenge for astrophysics, astronomy and cosmology. Presently very popular fields of research have rapidly evolved, such as high-energy gamma ray and neutrino astronomy. In addition, high-energy neutrino astronomy may soon initiate as a likely spin-off neutrino tomography of the Earth and thus open a unique new branch of geophysical research of the interior of the Earth. Finally, of considerable interest are the biological

  20. COBE battery overview: History, handling, and performance

    Science.gov (United States)

    Yi, Thomas; Tiller, Smith; Sullivan, David

    1991-01-01

    The following topics are presented in viewgraph format: Cosmic Background Explorer (COBE) mission background; battery background and specifications; cell history; battery mechanical/structural design; battery test data; and flowcharts of the various battery approval procedures.

  1. Paradigm transition in cosmic plasma physics

    Science.gov (United States)

    Alfven, H.

    1982-01-01

    New discoveries in cosmic plasma physics are described, and their applications to solar, interstellar, galactic, and cosmological problems are discussed. The new discoveries include the existence of double layers in magnetized plasmas and in the low magnetosphere, and energy transfer by electric current in the auroral circuit. It is argued that solar flares and the solar wind-magnetosphere interaction should not be interpreted in terms of magnetic merging theories, and that electric current needs to be explicitly taken account of in understanding these phenomena. The filamentary structure of cosmic plasmas may be caused by electric currents in space, and the pinch effect may have a central role to play in the evolutionary history of interstellar clouds, stars, and solar systems. Space may have a cellular structure, with the cell walls formed by thin electric current layers. Annihilation may be the source of energy for quasars and the Hubble expansion, and the big bang cosmology may well be wrong.

  2. Cosmic Neutrinos and Other Light Relics

    CERN Document Server

    Meyers, Joel

    2016-01-01

    Cosmological measurements of the radiation density in the early universe can be used as a sensitive probe of physics beyond the standard model. Observations of primordial light element abundances have long been used to place non-trivial constraints on models of new physics and to inform our understanding of the thermal history to the first few minutes of our present phase of expansion. Precision measurements of the angular power spectrum of the cosmic microwave background temperature and polarization will drastically improve our measurement of the cosmic radiation density over the next decade. These improved measurements will either uncover new physics or place much more stringent constraints on physics beyond the standard model, while pushing our understanding of the early universe to much earlier times.

  3. Early Stress History Alters Serum Insulin-Like Growth Factor-1 and Impairs Muscle Mitochondrial Function in Adult Male Rats.

    Science.gov (United States)

    Ghosh, S; Banerjee, K K; Vaidya, V A; Kolthur-Seetharam, U

    2016-09-01

    Early-life adversity is associated with an enhanced risk for adult psychopathology. Psychiatric disorders such as depression exhibit comorbidity for metabolic dysfunction, including obesity and diabetes. However, it is poorly understood whether, besides altering anxiety and depression-like behaviour, early stress also evokes dysregulation of metabolic pathways and enhances vulnerability for metabolic disorders. We used the rodent model of the early stress of maternal separation (ES) to examine the effects of early stress on serum metabolites, insulin-like growth factor (IGF)-1 signalling, and muscle mitochondrial content. Adult ES animals exhibited dyslipidaemia, decreased serum IGF1 levels, increased expression of liver IGF binding proteins, and a decline in the expression of specific metabolic genes in the liver and muscle, including Pck1, Lpl, Pdk4 and Hmox1. These changes occurred in the absence of alterations in body weight, food intake, glucose tolerance, insulin tolerance or insulin levels. ES animals also exhibited a decline in markers of muscle mitochondrial content, such as mitochondrial DNA levels and expression of TFAM (transcription factor A, mitochondrial). Furthermore, the expression of several genes involved in mitochondrial function, such as Ppargc1a, Nrf1, Tfam, Cat, Sesn3 and Ucp3, was reduced in skeletal muscle. Adult-onset chronic unpredictable stress resulted in overlapping and distinct consequences from ES, including increased circulating triglyceride levels, and a decline in the expression of specific metabolic genes in the liver and muscle, with no change in the expression of genes involved in muscle mitochondrial function. Taken together, our results indicate that a history of early adversity can evoke persistent changes in circulating IGF-1 and muscle mitochondrial function and content, which could serve to enhance predisposition for metabolic dysfunction in adulthood. © 2016 British Society for Neuroendocrinology.

  4. P-MaNGA: GRADIENTS IN RECENT STAR FORMATION HISTORIES AS DIAGNOSTICS FOR GALAXY GROWTH AND DEATH

    Energy Technology Data Exchange (ETDEWEB)

    Li, Cheng; Wang, Enci; Lin, Lin; Xiao, Ting [Partner Group of Max-Planck Institute for Astrophysics, Shanghai Astronomical Observatory, Nandan Road 80, Shanghai 200030 (China); Bershady, Matthew A.; Tremonti, Christy A. [Department of Astronomy, University of Wisconsin–Madison, Madison, WI 53706 (United States); Bundy, Kevin; Cheung, Edmond [Kavli Institute for the Physics and Mathematics of the universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, the University of Tokyo, Kashiwa 277-8583 (Japan); Yan, Renbin [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Bizyaev, Dmitry [Apache Point Observatory and New Mexico State University, P.O. Box 59, Sunspot, NM, 88349-0059 (United States); Blanton, Michael; Gelfand, Joseph [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Cales, Sabrina [Yale Center for Astronomy and Astrophysics, Physics Department, Yale University, P.O. Box 208120, New Haven, CT 06520-8120 (United States); Cherinka, Brian; Law, David R. [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Drory, Niv [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Emsellem, Eric [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Fu, Hai [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Lin, Lihwai [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 106, Taiwan (China); MacDonald, Nick, E-mail: leech@shao.ac.cn [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); and others

    2015-05-10

    We present an analysis of the data produced by the MaNGA prototype run (P-MaNGA), aiming to test how the radial gradients in recent star formation histories, as indicated by the 4000 Å break (D{sub n}(4000)), Hδ absorption (EW(Hδ{sub A})), and Hα emission (EW(Hα)) indices, can be useful for understanding disk growth and star formation cessation in local galaxies. We classify 12 galaxies observed on two P-MaNGA plates as either centrally quiescent (CQ) or centrally star-forming (CSF), according to whether D{sub n}(4000) measured in the central spaxel of each datacube exceeds 1.6. For each spaxel we generate both 2D maps and radial profiles of D{sub n}(4000), EW(Hδ{sub A}), and EW(Hα). We find that CSF galaxies generally show very weak or no radial variation in these diagnostics. In contrast, CQ galaxies present significant radial gradients, in the sense that D{sub n}(4000) decreases, while both EW(Hδ{sub A}) and EW(Hα) increase from the galactic center outward. The outer regions of the galaxies show greater scatter on diagrams relating the three parameters than their central parts. In particular, the clear separation between centrally measured quiescent and star-forming galaxies in these diagnostic planes is largely filled in by the outer parts of galaxies whose global colors place them in the green valley, supporting the idea that the green valley represents a transition between blue-cloud and red-sequence phases, at least in our small sample. These results are consistent with a picture in which the cessation of star formation propagates from the center of a galaxy outward as it moves to the red sequence.

  5. P-MaNGA: Gradients in Recent Star Formation Histories as Diagnostics for Galaxy Growth and Death

    Science.gov (United States)

    Li, Cheng; Wang, Enci; Lin, Lin; Bershady, Matthew A.; Bundy, Kevin; Tremonti, Christy A.; Xiao, Ting; Yan, Renbin; Bizyaev, Dmitry; Blanton, Michael; Cales, Sabrina; Cherinka, Brian; Cheung, Edmond; Drory, Niv; Emsellem, Eric; Fu, Hai; Gelfand, Joseph; Law, David R.; Lin, Lihwai; MacDonald, Nick; Maraston, Claudia; Masters, Karen L.; Merrifield, Michael R.; Pan, Kaike; Sánchez, S. F.; Schneider, Donald P.; Thomas, Daniel; Wake, David; Wang, Lixin; Weijmans, Anne-Marie; Wilkinson, David; Yoachim, Peter; Zhang, Kai; Zheng, Tiantian

    2015-05-01

    We present an analysis of the data produced by the MaNGA prototype run (P-MaNGA), aiming to test how the radial gradients in recent star formation histories, as indicated by the 4000 Å break (Dn(4000)), Hδ absorption (EW(HδA)), and Hα emission (EW(Hα)) indices, can be useful for understanding disk growth and star formation cessation in local galaxies. We classify 12 galaxies observed on two P-MaNGA plates as either centrally quiescent (CQ) or centrally star-forming (CSF), according to whether Dn(4000) measured in the central spaxel of each datacube exceeds 1.6. For each spaxel we generate both 2D maps and radial profiles of Dn(4000), EW(HδA), and EW(Hα). We find that CSF galaxies generally show very weak or no radial variation in these diagnostics. In contrast, CQ galaxies present significant radial gradients, in the sense that Dn(4000) decreases, while both EW(HδA) and EW(Hα) increase from the galactic center outward. The outer regions of the galaxies show greater scatter on diagrams relating the three parameters than their central parts. In particular, the clear separation between centrally measured quiescent and star-forming galaxies in these diagnostic planes is largely filled in by the outer parts of galaxies whose global colors place them in the green valley, supporting the idea that the green valley represents a transition between blue-cloud and red-sequence phases, at least in our small sample. These results are consistent with a picture in which the cessation of star formation propagates from the center of a galaxy outward as it moves to the red sequence.

  6. Using measurements of the cosmic bulk flow to constrain f(R) Gravity

    Science.gov (United States)

    Seiler, Jacob; Parkinson, David

    2016-10-01

    As an alternate explanation for the cosmic acceleration, f(R) theories of gravity can predict an almost identical expansion history to standard Λ cold dark matter (ΛCDM), yet make very different predictions for the growth of cosmological structures. Measurements of the cosmic bulk flow provide a method for determining the strength of gravity over the history of structure formation. We use the modified gravity N-body code ECOSMOG to simulate dark matter particles and make predictions for the bulk flow magnitude in both ΛCDM and f(R) gravity. With the peculiar velocities output by ECOSMOG, we determine the bulk flow at depths ranging from 20 to 50 h-1Mpc, following the redshift and sky distribution of the 2MASS Tully-Fisher survey (2MTF). At each depth, we find that the ΛCDM and fR0 = 10-5 simulations produce bulk flow measurements that are consistent with ΛCDM predictions and the 2MTF survey at a 1σ level. We also find that adopting an f(R) strength of fR0 = 10-3 predict a much larger value for the bulk flow, which disagree with ΛCDM predictions at all depths considered. We conclude that fR0 must be constrained to a level no greater than 10-4 to agree with bulk flow measurements.

  7. Using measurements of the cosmic bulk flow to constrain $f(R)$ Gravity

    CERN Document Server

    Seiler, Jacob

    2016-01-01

    As an alternative explanation for the cosmic acceleration, $f(R)$ theories of gravity can predict an almost identical expansion history to standard $\\Lambda$CDM, yet make very different predictions for the growth of cosmological structures. Measurements of the cosmic bulk flow provides a method for determining the strength of gravity over the history of structure formation. We use the modified gravity N-body code ECOSMOG to simulate dark matter particles and make predictions for the bulk flow magnitude in both $\\Lambda$CDM and $f(R)$ gravity. With the peculiar velocities output by ECOSMOG we determine the bulk flow at depths ranging from $20h^{-1}$Mpc to $50h^{-1}$Mpc, following the redshift and sky distribution of the 2MASS Tully-Fisher survey (2MTF). At each depth, we find that the $\\Lambda$CDM and $f_{R0} = 10^{-5}$ simulations produce bulk flow measurements that are consistent with $\\Lambda$CDM predictions and the 2MTF survey at a $1\\sigma$ level. We also find that adopting an $f(R)$ strength of $f_{R0} =...

  8. Cross correlations of the cosmic infrared background

    CERN Document Server

    Zhang, P

    2003-01-01

    Cosmic infrared background (CIB) is a sensitive measure of the structure formation of the universe, especially the star formation history. But this background is overwhelmed by foregrounds. The cross correlation of CIB with galaxies is able to eliminate such foregrounds, minimize and localize several backgrounds which could bias the study of the star formation history. The cross correlation study of CIB has three advantages. (1) Combining the galaxy photometric redshift information, it directly measures the structure formation history. (2) The sky area used for CIB analysis is no long limited to the relatively clean sky. The utilization of CIB full sky data minimizes the sample variance. (3) The CIB measurement is no longer limited to several narrow frequency windows. This allows the measurement of CIB based on integrated intensity, whose theoretical prediction is based on energy conservation, thus is fairly model independent and robust. The cross correlation can be measured with 10% accuracy (statistical and...

  9. Numerical investigation of thermal history and residual stress of grown multi-crystalline silicon at the various growth stages for PV applications

    Science.gov (United States)

    Srinivasan, M.; Ramasamy, P.

    2016-05-01

    The directional solidification is a very important technique for growing high quality multi-crystalline silicon at large scale for PV solar cells. Time dependent numerical modelling of the temperature distribution, residual stress in multi-crystalline silicon ingots grown by directional solidification has been investigated for five growth stage. The computation was carried in a 2D axis symmetric model by the finite volume method. The history of temperature distribution, stress generation, are tracked in our modelling continuously to consider the growth process from the beginning to the end of solidification process. This paper is aimed to achieve an advanced understanding of the thermal and mechanical behavior of grown crystal.

  10. Anencephalus, drinking water, geomagnetism and cosmic radiation.

    Science.gov (United States)

    Archer, V E

    1979-01-01

    The mortality rates from anencephalus from 1950-1969 in Canadian cities are shown to be strongly correlated with city growth rate and with horizontal geomagnetic flux, which is directly related to the intensity of cosmic radiation. They are also shown to have some association with the magnesium content of drinking water. Prior work with these data which showed associations with magnesium in drinking water, mean income, latitude and longitude was found to be inadequate because it dismissed the observed geographic associations as having little biological meaning, and because the important variables of geomagnetism and city growth rate were overlooked.

  11. Dual Phase Cosmic Rays

    CERN Document Server

    Shurtleff, Richard

    2008-01-01

    A calculation based on flat spacetime symmetries shows how there can be two quantum phases. For one, extreme phase change determines a conventional classical trajectory and four-momentum, i.e. mass times four-velocity. The other phase occurs in an effective particle state, with the effective energy and momentum being the rate of change of the phase with respect to time and distance. A cosmic ray proton moves along a classical trajectory, but exists in an effective particle state with an effective energy that depends on the local gravitational potential. Assumptions are made so that a cosmic ray proton in an ultra-high energy state detected near the Earth was in a much less energetic state in interstellar space. A 300 EeV proton incident on the Earth was a 2 PeV proton in interstellar space. The model predicts such protons are in states with even more energy near the Sun than when near the Earth.

  12. Cosmic structure formation

    Science.gov (United States)

    Bertschinger, Edumund

    1994-01-01

    This article reviews the prevailing paradigm for how galaxies and larger structures formed in the universe: gravitational instability. Basic observational facts are summarized to motivate the standard cosmological framework underlying most detailed investigations of structure formation. The observed univers approaches spatial uniformity on scales larger than about 10(exp 26) cm. On these scales gravitational dynamics is almost linear and therefore relatively easy to relate to observations of large-scale structure. On smaller scales cosmic structure is complicated not only by nonlinear gravitational clustering but also by nonlinear nongravitational gas dynamical processes. The complexity of these phenomena makes galaxy formation one of the grand challenge problems of the physical sciences. No fully satisfactory theory can presently account in detail for the observed cosmic structure. However, as this article summarizes, significant progress has been made during the last few years.

  13. Understanding the cosmic web

    CERN Document Server

    Cautun, Marius; Jones, Bernard J T; Frenk, Carlos S

    2015-01-01

    We investigate the characteristics and the time evolution of the cosmic web from redshift, z=2, to present time, within the framework of the NEXUS+ algorithm. This necessitates the introduction of new analysis tools optimally suited to describe the very intricate and hierarchical pattern that is the cosmic web. In particular, we characterize filaments (walls) in terms of their linear (surface) mass density. This is very good in capturing the evolution of these structures. At early times the cosmos is dominated by tenuous filaments and sheets, which, during subsequent evolution, merge together, such that the present day web is dominated by fewer, but much more massive, structures. We also show that voids are more naturally described in terms of their boundaries and not their centres. We illustrate this for void density profiles, which, when expressed as a function of the distance from void boundary, show a universal profile in good qualitative agreement with the theoretical shell-crossing framework of expandin...

  14. Cosmic rays and climate

    CERN Document Server

    CERN. Geneva

    2009-01-01

    The current understanding of climate change in the industrial age is that it is predominantly caused by anthropogenic greenhouse gases, with relatively small natural contributions due to solar irradiance and volcanoes. However, palaeoclimatic reconstructions show that the climate has frequently varied on 100-year time scales during the Holocene (last 10 kyr) by amounts comparable to the present warming - and yet the mechanism or mechanisms are not understood. Some of these reconstructions show clear associations with solar variability, which is recorded in the light radio-isotope archives that measure past variations of cosmic ray intensity. However, despite the increasing evidence of its importance, solar-climate variability is likely to remain controversial until a physical mechanism is established. Estimated changes of solar irradiance on these time scales appear to be too small to account for the climate observations. This raises the question of whether cosmic rays may directly affect the climate, provi...

  15. Cosmic Tidal Reconstruction

    CERN Document Server

    Zhu, Hong-Ming; Yu, Yu; Er, Xinzhong; Chen, Xuelei

    2015-01-01

    The gravitational coupling of a long wavelength tidal field with small scale density fluctuations leads to anisotropic distortions of the locally measured small scale matter correlation function. Since the local correlation function is statistically isotropic in the absence of such tidal interactions, the tidal distortions can be used to reconstruct the long wavelength tidal field and large scale density field in analogy with the cosmic microwave background lensing reconstruction. In this paper we present in detail a formalism for the cosmic tidal reconstruction and test the reconstruction in numerical simulations. We find that the density field on large scales can be reconstructed with good accuracy and the cross correlation coefficient between the reconstructed density field and the original density field is greater than 0.9 on large scales ($k\\lesssim0.1h/\\mathrm{Mpc}$). This is useful in the 21cm intensity mapping survey, where the long wavelength radial modes are lost due to foreground subtraction proces...

  16. Stable charged cosmic strings.

    Science.gov (United States)

    Weigel, H; Quandt, M; Graham, N

    2011-03-11

    We study the quantum stabilization of a cosmic string by a heavy fermion doublet in a reduced version of the standard model. We show that charged strings, obtained by populating fermionic bound state levels, become stable if the electroweak bosons are coupled to a fermion that is less than twice as heavy as the top quark. This result suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model. Numerically we find the most favorable string profile to be a simple trough in the Higgs vacuum expectation value of radius ≈10(-18)  m. The vacuum remains stable in our model, because neutral strings are not energetically favored.

  17. Cosmic Plasma Wakefield Acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P

    2004-04-26

    Recently we proposed a new cosmic acceleration mechanism which was based on the wakefields excited by the Alfven shocks in a relativistically owing plasma. In this paper we include some omitted details, and show that there exists a threshold condition for transparency below which the accelerating particle is collision-free and suffers little energy loss in the plasma medium. The stochastic encounters of the random accelerating-decelerating phases results in a power-law energy spectrum: f({epsilon}) {proportional_to} 1/{epsilon}{sup 2}. As an example, we discuss the possible production of super-GZK ultra high energy cosmic rays (UHECR) in the atmosphere of gamma ray bursts. The estimated event rate in our model agrees with that from UHECR observations.

  18. Cosmic Strings and Quintessence

    Institute of Scientific and Technical Information of China (English)

    段一士; 任继荣; 杨捷

    2003-01-01

    Using torsion two-form we present a new Lorentz gauge invariant U (1) topological field theory in Riemann-Cartan space-time manifold U4. By virtue of the decomposition theory of U(1) gauge potential and the φ-mapping topological current theory, it is proven that the U(1) complex scalar field φ(x) can be looked upon as the order parameter field in our Universe, and a set of zero points of φ(x) create the cosmic strings as the space-time defects in the early Universe. In the standard cosmology, this complex scalar order parameter field possesses negative pressure, provides an accelerating expansion of Universe, and be able to explain the inflation in the early Universe. Therefore this complex scalar field is not only the order parameter field created the cosmic strings in the early universe, but also reasonably behaves as the quintessence, the dark energy.

  19. Modeling cosmic void statistics

    Science.gov (United States)

    Hamaus, Nico; Sutter, P. M.; Wandelt, Benjamin D.

    2016-10-01

    Understanding the internal structure and spatial distribution of cosmic voids is crucial when considering them as probes of cosmology. We present recent advances in modeling void density- and velocity-profiles in real space, as well as void two-point statistics in redshift space, by examining voids identified via the watershed transform in state-of-the-art ΛCDM n-body simulations and mock galaxy catalogs. The simple and universal characteristics that emerge from these statistics indicate the self-similarity of large-scale structure and suggest cosmic voids to be among the most pristine objects to consider for future studies on the nature of dark energy, dark matter and modified gravity.

  20. A cosmic watershed : the WVF void detection technique

    NARCIS (Netherlands)

    Platen, Erwin; van de Weygaert, Rien; Jones, Bernard J. T.

    2007-01-01

    On megaparsec scales the Universe is permeated by an intricate filigree of clusters, filaments, sheets and voids, the cosmic web. For the understanding of its dynamical and hierarchical history it is crucial to identify objectively its complex morphological components. One of the most characteristic

  1. Bayesian analysis of the dynamic cosmic web in the SDSS galaxy survey

    Science.gov (United States)

    Leclercq, Florent; Jasche, Jens; Wandelt, Benjamin

    2015-06-01

    Recent application of the Bayesian algorithm \\textsc{borg} to the Sloan Digital Sky Survey (SDSS) main sample galaxies resulted in the physical inference of the formation history of the observed large-scale structure from its origin to the present epoch. In this work, we use these inferences as inputs for a detailed probabilistic cosmic web-type analysis. To do so, we generate a large set of data-constrained realizations of the large-scale structure using a fast, fully non-linear gravitational model. We then perform a dynamic classification of the cosmic web into four distinct components (voids, sheets, filaments, and clusters) on the basis of the tidal field. Our inference framework automatically and self-consistently propagates typical observational uncertainties to web-type classification. As a result, this study produces accurate cosmographic classification of large-scale structure elements in the SDSS volume. By also providing the history of these structure maps, the approach allows an analysis of the origin and growth of the early traces of the cosmic web present in the initial density field and of the evolution of global quantities such as the volume and mass filling fractions of different structures. For the problem of web-type classification, the results described in this work constitute the first connection between theory and observations at non-linear scales including a physical model of structure formation and the demonstrated capability of uncertainty quantification. A connection between cosmology and information theory using real data also naturally emerges from our probabilistic approach. Our results constitute quantitative chrono-cosmography of the complex web-like patterns underlying the observed galaxy distribution.

  2. Carl Sagan's Cosmic Connection

    Science.gov (United States)

    Sagan, Carl; Agel, Jerome

    2000-08-01

    Foreword Freeman Dyson; Personal reflections Ann Druyan; Preface; Part I. Cosmic Perspective: 1. A transitional animal; 2. The Unicorn of Cetus; 3. A message from earth; 4. A message to earth; 5. Experiments in utopias; 6. Chauvinism; 7. Space exploration as a human enterprise I. The scientific interest; 8. Space exploration as a human enterprise II. The public interest; 9. Space exploration as a human enterprise III. The historical interest; Part II. The Solar System: 10. On teaching the first grade; 11. 'The ancient and legendary Gods of old'; 12. The Venus detective story; 13. Venus is hell; 14. Science and 'intelligence'; 15. The moons of Barsoom; 16. The mountains of Mars I. Observations from earth; 17. The mountains of Mars II. Observations from space; 18. The canals of Mars; 19. The lost pictures of Mars; 20. The Ice Age and the cauldron; 21. Beginnings and ends of the Earth; 22. Terraforming the plants; 23. The exploration and utlization of the solar system; Part III. Beyond the Solar System: 24. Some of my best friends are dolphins; 25. 'Hello, central casting? Send me twenty extraterrestrials'; 26. The cosmic connection; 27. Extraterrestrial life: an idea whose time has come; 28. Has the Earth been visited?; 29. A search strategy for detecting extraterrestrial intelligence; 30. If we succeed 31. Cables, drums, and seashells; 32. The night freight to the stars; 33. Astroengineering; 34. Twenty questions: a classification of cosmic civilisations; 35. Galactic cultural exchanges; 36. A passage to elsewhere; 37. Starfolk I. A Fable; 38. Starfolk II. A future; 39. Starfolk III. The cosmic Cheshire cats; Epilog David Morrison; Index.

  3. Cosmic Rays in Thunderstorms

    Science.gov (United States)

    Buitink, Stijn; Scholten, Olaf; van den Berg, Ad; Ebert, Ute

    2013-04-01

    Cosmic Rays in Thunderstorms Cosmic rays are protons and heavier nuclei that constantly bombard the Earth's atmosphere with energies spanning a vast range from 109 to 1021 eV. At typical altitudes up to 10-20 km they initiate large particle cascades, called extensive air showers, that contain millions to billions of secondary particles depending on their initial energy. These particles include electrons, positrons, hadrons and muons, and are concentrated in a compact particle front that propagates at relativistic speed. In addition, the shower leaves behind a trail of lower energy electrons from ionization of air molecules. Under thunderstorm conditions these electrons contribute to the electrical and ionization processes in the cloud. When the local electric field is strong enough the secondary electrons can create relativistic electron run-away avalanches [1] or even non-relativistic avalanches. Cosmic rays could even trigger lightning inception. Conversely, strong electric fields also influence the development of the air shower [2]. Extensive air showers emit a short (tens of nanoseconds) radio pulse due to deflection of the shower particles in the Earth's magnetic field [3]. Antenna arrays, such as AERA, LOFAR and LOPES detect these pulses in a frequency window of roughly 10-100 MHz. These systems are also sensitive to the radiation from discharges associated to thunderstorms, and provide a means to study the interaction of cosmic ray air showers and the electrical processes in thunderstorms [4]. In this presentation we discuss the involved radiation mechanisms and present analyses of thunderstorm data from air shower arrays [1] A. Gurevich et al., Phys. Lett. A 165, 463 (1992) [2] S. Buitink et al., Astropart. Phys. 33, 1 (2010) [3] H. Falcke et al., Nature 435, 313 (2005) [4] S. Buitink et al., Astron. & Astrophys. 467, 385 (2007)

  4. Cosmic microwave background theory.

    Science.gov (United States)

    Bond, J R

    1998-01-06

    A long-standing goal of theorists has been to constrain cosmological parameters that define the structure formation theory from cosmic microwave background (CMB) anisotropy experiments and large-scale structure (LSS) observations. The status and future promise of this enterprise is described. Current band-powers in -space are consistent with a DeltaT flat in frequency and broadly follow inflation-based expectations. That the levels are approximately (10(-5))2 provides strong support for the gravitational instability theory, while the Far Infrared Absolute Spectrophotometer (FIRAS) constraints on energy injection rule out cosmic explosions as a dominant source of LSS. Band-powers at 100 suggest that the universe could not have re-ionized too early. To get the LSS of Cosmic Background Explorer (COBE)-normalized fluctuations right provides encouraging support that the initial fluctuation spectrum was not far off the scale invariant form that inflation models prefer: e.g., for tilted Lambda cold dark matter sequences of fixed 13-Gyr age (with the Hubble constant H0 marginalized), ns = 1.17 +/- 0.3 for Differential Microwave Radiometer (DMR) only; 1.15 +/- 0.08 for DMR plus the SK95 experiment; 1.00 +/- 0.04 for DMR plus all smaller angle experiments; 1.00 +/- 0.05 when LSS constraints are included as well. The CMB alone currently gives weak constraints on Lambda and moderate constraints on Omegatot, but theoretical forecasts of future long duration balloon and satellite experiments are shown which predict percent-level accuracy among a large fraction of the 10+ parameters characterizing the cosmic structure formation theory, at least if it is an inflation variant.

  5. Frontiers in Cosmic Rays

    CERN Document Server

    Anchordoqui, Luis A; Ringwald, Andreas; Anchordoqui, Luis A.; Dermer, Charles D.; Ringwald, Andreas

    2004-01-01

    This rapporteur review covers selected results presented in the Parallel Session HEA2 (High Energy Astrophysics 2) of the 10th Marcel Grossmann Meeting on General Relativity, held in Rio de Janeiro, Brazil, July 2003. The subtopics are: ultra high energy cosmic ray anisotropies, the possible connection of these energetic particles with powerful gamma ray bursts, and new exciting scenarios with a strong neutrino-nucleon interaction in the atmosphere.

  6. Cosmic ray modulation

    Science.gov (United States)

    Agarwal Mishra, Rekha; Mishra, Rajesh Kumar

    2016-07-01

    Propagation of cosmic rays to and inside the heliosphere, encounter an outward moving solar wind with cyclic magnetic field fluctuation and turbulence, causing convection and diffusion in the heliosphere. Cosmic ray counts from the ground ground-based neutron monitors at different cut of rigidity show intensity changes, which are anti-correlated with sunspot numbers. They also lose energy as they propagate towards the Earth and experience various types of modulations due to different solar activity indices. In this work, we study the first three harmonics of cosmic ray intensity on geo-magnetically quiet days over the period 1965-2014 for Beijing, Moscow and Tokyo neutron monitoring stations located at different cut off rigidity. The amplitude of first harmonic remains high for low cutoff rigidity as compared to high cutoff rigidity on quiet days. The diurnal amplitude significantly decreases during solar activity minimum years. The diurnal time of maximum significantly shifts to an earlier time as compared to the corotational direction having different cutoff rigidities. The time of maximum for first harmonic significantly shifts towards later hours and for second harmonic it shifts towards earlier hours at low cutoff rigidity station as compared to the high cut off rigidity station on quiet days. The amplitude of second/third harmonics shows a good positive correlation with solar wind velocity, while the others (i.e. amplitude and phase) have no significant correlation on quiet days. The amplitude and direction of the anisotropy on quiet days does not show any significant dependence on high-speed solar wind streams for these neutron monitoring stations of different cutoff rigidity threshold. Keywords: cosmic ray, cut off rigidity, quiet days, harmonics, amplitude, phase.

  7. A Cosmic Microwave Background feature consistent with a cosmic texture

    OpenAIRE

    Cruz, M.; Turok, N.; Vielva, P.; Martinez-Gonzalez, E.; Hobson, M.

    2007-01-01

    The Cosmic Microwave Background provides our most ancient image of the Universe and our best tool for studying its early evolution. Theories of high energy physics predict the formation of various types of topological defects in the very early universe, including cosmic texture which would generate hot and cold spots in the Cosmic Microwave Background. We show through a Bayesian statistical analysis that the most prominent, 5 degree radius cold spot observed in all-sky images, which is otherw...

  8. Regional variability in secondary remodeling within long bone cortices of catarrhine primates: the influence of bone growth history.

    Science.gov (United States)

    McFarlin, Shannon C; Terranova, Carl J; Zihlman, Adrienne L; Enlow, Donald H; Bromage, Timothy G

    2008-09-01

    Secondary intracortical remodeling of bone varies considerably among and within vertebrate skeletons. Although prior research has shed important light on its biomechanical significance, factors accounting for this variability remain poorly understood. We examined regional patterning of secondary osteonal bone in an ontogenetic series of wild-collected primates, at the midshaft femur and humerus of Chlorocebus (Cercopithecus) aethiops (n = 32) and Hylobates lar (n = 28), and the midshaft femur of Pan troglodytes (n = 12). Our major objectives were: 1) to determine whether secondary osteonal bone exhibits significant regional patterning across inner, mid-cortical and outer circumferential cortical rings within cross-sections; and if so, 2) to consider the manner in which this regional patterning may reflect the influence of relative tissue age and other circumstances of bone growth. Using same field-of-view images of 100-microm-thick cross-sections acquired in brightfield and circularly polarized light microscopy, we quantified the percent area of secondary osteonal bone (%HAV) for whole cross-sections and across the three circumferential rings within cross-sections. We expected bone areas with inner and middle rings to exhibit higher %HAV than the outer cortical ring within cross-sections, the latter comprising tissues of more recent depositional history. Observations of primary bone microstructural development provided an additional context in which to evaluate regional patterning of intracortical remodeling. Results demonstrated significant regional variability in %HAV within all skeletal sites. As predicted,%HAV was usually lowest in the outer cortical ring within cross-sections. However, regional patterning across inner vs. mid-cortical rings showed a more variable pattern across taxa, age classes, and skeletal sites examined. Observations of primary bone microstructure revealed that the distribution of endosteally deposited bone had an important influence on

  9. The natural history of the growth of the hand: I. Hand area as a percentage of body surface area.

    Science.gov (United States)

    Amirsheybani, H R; Crecelius, G M; Timothy, N H; Pfeiffer, M; Saggers, G C; Manders, E K

    2001-03-01

    The use of a patient's own hand as a tool to estimate the area of burn injury is well documented. The area of the palmar surface of one hand has been estimated to be 1 percent of the body surface area. The area of the palmar surface of the hand was measured to test the accuracy of this estimate and then compared with the body surface area as calculated by formulas in common use. This study also sought to determine the natural history of the growth of the hand to permit development of a readily available, bedside means of estimating hand area and body surface area. Bilateral hand tracings were obtained from 800 volunteers ranging in age from 2 to 89 years. The area of each tracing was determined using an integrating planimeter. The height and weight of each individual were measured, and his/her body surface area was calculated. The palmar hand's percentage of body surface area was determined by calculating the quotient for hand area divided by body surface area. Additionally, the width of the hand was measured from the ulnar aspect at the palmar digital crease of the small finger to the point where the thumb rested against the base of the index finger. The length of the hand was measured from the middle of the interstylon to the tip of the middle finger. These two figures were multiplied together to obtain a product which approximated the area of the hand. Based on the most commonly used DuBois formula for calculating body surface area, the area of palmar surface of the hand corresponds to 0.78 +/- 0.08 percent of the body surface area in adults. The percentage varies somewhat with age and reaches a maximum of 0.87 +/- 0.06 percent in young children. Multiplying the length of the hand by its width overestimates the area of the hand as determined by planimetry by only 2 percent. A patient's own hand may be used as a complementary, readily available template for estimation of burn area or other areas of disease or injury. In adults, the area of tracing of the outline

  10. Canny Algorithm, Cosmic Strings and the Cosmic Microwave Background

    Science.gov (United States)

    Danos, Rebecca J.; Brandenberger, Robert H.

    We describe a new code to search for signatures of cosmic strings in cosmic microwave anisotropy maps. The code implements the Canny algorithm, an edge detection algorithm designed to search for the lines of large gradients in maps. Such a gradient signature which is coherent in position-space is produced by cosmic strings via the Kaiser-Stebbins effect. We test the power of our new code to set limits on the tension of the cosmic strings by analyzing simulated data, with and without cosmic strings. We compare maps with a pure Gaussian scale-invariant power spectrum with maps which have a contribution of a distribution of cosmic strings obeying a scaling solution. The maps have angular scale and angular resolution comparable to what current and future ground-based small-scale cosmic microwave anisotropy experiments will achieve. We present tests of the codes, indicate the limits on the string tension which could be set with the current code, and describe various ways to refine the analysis. Our results indicate that when applied to the data of ongoing cosmic microwave experiments such as the South Pole Telescope project, the sensitivity of our method to the presence of cosmic strings will be more than an order of magnitude better than the limits from existing analyses.

  11. Parameter splitting in dark energy: is dark energy the same in the background and in the cosmic structures?

    Science.gov (United States)

    Bernal, J. L.; Verde, L.; Cuesta, A. J.

    2017-03-01

    We perform an empirical consistency test of General Relativity/dark energy by disentangling expansion history and growth of structure constraints. We replace each late-universe parameter that describes the behavior of dark energy with two meta-parameters: one describing geometrical information in cosmological probes, and the other controlling the growth of structure. If the underlying model is correct, that is under the null hypothesis, the two meta-parameters coincide. We present a global analysis using state-of-the-art cosmological data sets which points in the direction that cosmic structures prefer a weaker growth than that inferred by background probes. This result could signify inconsistencies of the model, the necessity of extensions to it or the presence of systematic errors in the data. We examine all these possibilities. The fact that the result is mostly driven by a specific sub-set of galaxy clusters abundance data, points to the need of a better understanding of this probe

  12. The Horizon-AGN simulation: evolution of galaxy properties over cosmic time

    CERN Document Server

    Kaviraj, S; Kimm, T; Devriendt, J E G; Dubois, Y; Pichon, C; Slyz, A; Chisari, E; Peirani, S

    2016-01-01

    We compare the predictions of Horizon-AGN, a hydro-dynamical cosmological simulation that uses an adaptive mesh refinement code, to observational data in the redshift range 0growth of galaxies over cosmic time: luminosity and stellar-mass functions, the star formation main sequence, rest-frame UV-optical-near infrared colours and the cosmic star-formation history. We show that Horizon-AGN, which is not tuned to reproduce the local Universe, produces good overall agreement with these quantities, from the present day to the epoch when the Universe was 5% of its current age. By comparison to Horizon-noAGN, a twin simulation without AGN feedback, we quantify how feedback from black holes is likely to help shape galaxy stellar-mass growth in the redshift range 0

  13. The glacial cycles and cosmic rays

    CERN Document Server

    Kirkby, Jasper; Müller, R A

    2004-01-01

    The cause of the glacial cycles remains a mystery. The origin is widely accepted to be astronomical since paleoclimatic archives contain strong spectral components that match the frequencies of Earth's orbital modulation. Milankovitch insolation theory contains similar frequencies and has become established as the standard model of the glacial cycles. However, high precision paleoclimatic data have revealed serious discrepancies with the Milankovitch model that fundamentally challenge its validity and re-open the question of what causes the glacial cycles. We propose here that the ice ages are initially driven not by insolation cycles but by cosmic ray changes, probably through their effect on clouds. This conclusion is based on a wide range of evidence, including results presented here on speleothem growth in caves in Austria and Oman, and on a record of cosmic ray flux over the past 220 kyr obtained from the 10Be composition of deep-ocean sediments.

  14. Cosmic Origin and Theology of the Revelation

    Science.gov (United States)

    Guijarro, José Francisco

    2007-04-01

    All along cultural history man has asked himself about the origin of man, the origin of life ante the origin of the cosmos. Regarding the question about the origin of the cosmos, any theological research must settle before any other goal the question of its language: what we understand as scientific, mythical or theological language. The biblical texts on Creation are analyzed in their historical, cultural and theological context. It is concluded that the fundamental religious meanings of the biblical texts are not in opposition to scientific interpretation of cosmic origin.

  15. Cosmic ray driven Galactic winds

    Science.gov (United States)

    Recchia, S.; Blasi, P.; Morlino, G.

    2016-11-01

    The escape of cosmic rays from the Galaxy leads to a gradient in the cosmic ray pressure that acts as a force on the background plasma, in the direction opposite to the gravitational pull. If this force is large enough to win against gravity, a wind can be launched that removes gas from the Galaxy, thereby regulating several physical processes, including star formation. The dynamics of these cosmic ray driven winds is intrinsically non-linear in that the spectrum of cosmic rays determines the characteristics of the wind (velocity, pressure, magnetic field) and in turn the wind dynamics affects the cosmic ray spectrum. Moreover, the gradient of the cosmic ray distribution function causes excitation of Alfvén waves, that in turn determines the scattering properties of cosmic rays, namely their diffusive transport. These effects all feed into each other so that what we see at the Earth is the result of these non-linear effects. Here, we investigate the launch and evolution of such winds, and we determine the implications for the spectrum of cosmic rays by solving together the hydrodynamical equations for the wind and the transport equation for cosmic rays under the action of self-generated diffusion and advection with the wind and the self-excited Alfvén waves.

  16. Cosmic ray: Studying the origin

    Energy Technology Data Exchange (ETDEWEB)

    Szabelski, J. [Cosmic Ray Laboratory, Soltan Institute for Nuclear Studies, Lodz (Poland)

    1997-12-31

    Investigations of the origin of cosmic rays are presented. Different methods are discussed: studies of cosmic gamma rays of energy from 30 MeV to about 10{sup 15} eV (since photons point to their places of origin), studies of the mass composition of cosmic rays (because it reflects source morphology), and studies of cosmic rays with energy above 1O{sup 19} eV (for these are the highest energies observed in nature). (author) 101 refs, 19 figs, 7 tabs

  17. Cosmic rays and molecular clouds

    OpenAIRE

    2012-01-01

    This paper deals with the cosmic-ray penetration into molecular clouds and with the related gamma--ray emission. High energy cosmic rays interact with the dense gas and produce neutral pions which in turn decay into two gamma rays. This makes molecular clouds potential sources of gamma rays, especially if they are located in the vicinity of a powerful accelerator that injects cosmic rays in the interstellar medium. The amplitude and duration in time of the cosmic--ray overdensity around a giv...

  18. Early Life-History Consequences of Growth-Hormone Transgenesis in Rainbow Trout Reared in Stream Ecosystem Mesocosms

    OpenAIRE

    2015-01-01

    There is persistent commercial interest in the use of growth modified fishes for shortening production cycles and increasing overall food production, but there is concern over the potential impact that transgenic fishes might have if ever released into nature. To explore the ecological consequences of transgenic fish, we performed two experiments in which the early growth and survival of growth-hormone transgenic rainbow trout (Oncorhynchus mykiss) were assessed in naturalized stream mesocosm...

  19. The Evolution of the Rest-frame V-band Luminosity Function from z=4: A Constant Faint-end Slope over the Last 12 Gyr of Cosmic History

    CERN Document Server

    Marchesini, Danilo; Brammer, Gabriel B; Whitaker, Katherine E

    2012-01-01

    We present the rest-frame V-band luminosity function (LF) of galaxies at 0.4cosmic variance; and (2) simultaneously constrain the bright and faint ends with unprecedented accuracy over the targeted redshift range, probing the LF down to 0.1 L* at z~3.9. We find that (1) the faint end is fairly flat and with a constant slope from z=4, with alpha= -1.27 +/- 0.05; (2) the characteristic magnitude has dimmed by 1.3 mag from z~3.7 to z=0.1; (3) the characteristic density has increased by a factor of ~8 from z~3.7 to z=0.1, with 50% of this increase from z~4 to z~1.8; and (4) the luminosity density peaks at z...

  20. Inner gorges incision history: A proxy for deglaciation? Insights from Cosmic Ray Exposure dating (10Be and 36Cl) of river-polished surfaces (Tinée River, SW Alps, France)

    Science.gov (United States)

    Rolland, Y.; Petit, C.; Saillard, M.; Braucher, R.; Bourlès, D.; Darnault, R.; Cassol, D.

    2017-01-01

    10Be and 36Cl Cosmic Ray Exposure (CRE) dating performed on river polished surfaces of river gorges in a mountain-to-sea river system in the French SW Alps highlights transient erosional events involving incision rates >10 mm a-1. These events took place during the last two major deglaciation phases following (1) the Last Glacial Maximum (LGM) at 16-14 ka, (2) the Younger Dryas at 8-11 ka, and during the warm and humid Holocene climatic optimum at 4-5 ka. These periods of high incision rates (3- > 30 mma-1) alternated with periods of low incision rates (<1 mm a-1), which probably correspond to a long-term equilibrium between incision and relative uplift. The Alpine river staircase shape profiles evidence local and transient responses that are ascribed to cumulate disequilibrium after the long-time-spanned glaciations. After each glaciation, rivers rush down to get closer to their equilibrium profile. Incision is amplified both by the sediment discharge due to the erosion of moraines and by landslides triggered by the glacier retreat.

  1. The Emergence of Cosmic Education. Spotlight: Cosmic Education.

    Science.gov (United States)

    Trudeau, Sr. Christina Marie

    2002-01-01

    Discusses the influence of Hindu, Moslem, and Buddhist metaphysics on Maria Montessori's own pedagogical philosophy of Cosmic Education, which she regarded as the core of all learning experiences, after her visit to India. Considers the relationship between Montessori's ideas of child development and Cosmic Education, and the effect of Indian…

  2. Atmospheric ionization and cosmic rays: studies and measurements before 1912

    CERN Document Server

    De Angelis, Alessandro

    2012-01-01

    The discovery of cosmic rays, a milestone in science, was based on the work by scientists in Europe and the New World and took place during a period characterised by nationalism and lack of communication. Many scientists that took part in this research a century ago were intrigued by the penetrating radiation and tried to understand the origin of it. Several important contributions to the discovery of the origin of cosmic rays have been forgotten; historical, political and personal facts might have contributed to their substantial disappearance from the history of science.

  3. Ultrahigh Energy Cosmic Rays and Black Hole Mergers

    CERN Document Server

    Kotera, Kumiko

    2016-01-01

    The recent detection of the gravitational wave source GW150914 by the LIGO collaboration motivates a speculative source for the origin of ultrahigh energy cosmic rays as a possible byproduct of the immense energies achieved in black hole mergers, provided that the black holes have spin as seems inevitable and there are relic magnetic fields and disk debris remaining from the formation of the black holes or from their accretion history. We argue that given the modest efficiency $< 0.01$ required per event per unit of gravitational wave energy release, merging black holes potentially provide an environment for accelerating cosmic rays to ultrahigh energies.

  4. Wormhole cosmic censorship

    Science.gov (United States)

    Matos, Tonatiuh; Ureña-López, L. Arturo; Miranda, Galaxia

    2016-05-01

    We analyze the properties of a Kerr-like wormhole supported by phantom matter, which is an exact solution of the Einstein-phantom field equations. It is shown that the solution has a naked ring singularity which is unreachable to null geodesics falling freely from the outside. Similarly to Roger Penrose's cosmic censorship, that states that all naked singularities in the Universe must be protected by event horizons, here we conjecture from our results that a naked singularity can also be fully protected by the intrinsic properties of a wormhole's throat.

  5. Cosmic baldness and stability

    Energy Technology Data Exchange (ETDEWEB)

    Panchapakesan, N.; Lohiya, D.

    1985-04-01

    The stability of the de Sitter metric and the relevance of the initial state of a domain which approaches a de Sitter universe asymptotically are investigated analytically, adapting the one-dimensional wave equation with effective potential derived by Khanal and Panchapakesan (1981), for the perturbations of the de Sitter-Schwarzschild metric, to the de Sitter case. It is demonstrated that initial nonspherical perturbations do not increase exponentially with time but rather decay, the frozen modes exponentially and the backscattered perturbations of finite angular momentum l as t to the -(2l - l). It is concluded that the cosmic horizon is stable and has no hair. 14 references.

  6. Wormhole cosmic strings

    CERN Document Server

    Clément, G

    1995-01-01

    We construct regular multi-wormhole solutions to a gravitating \\sigma model in three space-time dimensions, and extend these solutions to cylindrical traversable wormholes in four and five dimensions. We then discuss the possibility of identifying wormhole mouths in pairs to give rise to Wheeler wormholes. Such an identification is consistent with the original field equations only in the absence of the \\sigma-model source, but with possible naked cosmic string sources. The resulting Wheeler wormhole space-times are flat outside the sources and may be asymptotically Minkowskian.

  7. Pulsars: Cosmic Permanent 'Neutromagnets'?

    CERN Document Server

    Hansson, Johan

    2011-01-01

    We argue that pulsars may be spin-polarized neutron stars, i.e. cosmic permanent magnets. This would simply explain several observational facts about pulsars, including the 'beacon effect' itself i.e. the static/stable misalignment of rotational and magnetic axes, the extreme temporal stability of the pulses and the existence of an upper limit for the magnetic field strength - coinciding with the one observed in "magnetars". Although our model admittedly is speculative, this latter fact seems to us unlikely to be pure coincidence.

  8. Garden of cosmic speculation

    CERN Document Server

    Jencks, Charles

    2005-01-01

    This book tells the story of one of the most important gardens in Europe, created by the architectural critic and designer Charles Jencks and his late wife, the landscape architect and author Maggie Keswick. The Garden of Cosmic Speculation is a landscape that celebrates the new sciences of complexity and chaos theory and consists of a series of metaphors exploring the origins, the destiny and the substance of the Universe. The book is illustrated with year-round photography, bringing the garden's many dimensions vividly to life.

  9. The formation history of elliptical galaxies

    CERN Document Server

    De Lucia, G; White, S D M; Croton, D; Kauffmann, G; Lucia, Gabriella De; Springel, Volker; White, Simon D. M.; Croton, Darren; Kauffmann, Guinevere

    2006-01-01

    We take advantage of the largest high-resolution simulation of cosmic structure growth ever carried out -- the Millennium Simulation of the concordance LambdaCDM cosmogony -- to study how the star formation histories, ages and metallicities of elliptical galaxies depend on environment and on stellar mass. We concentrate on a galaxy formation model which is tuned to fit the joint luminosity/colour/morphology/clustering distribution of low redshift galaxies. Massive ellipticals in this model have higher metal abundances, older luminosity-weighted ages, shorter star formation timescales, but lower assembly redshifts than less massive systems. Within clusters the typical masses, ages and metal abundances of ellipticals are predicted to decrease, on average, with increasing distance from the cluster centre. We also quantify the effective number of progenitors of ellipticals as a function of present stellar mass, finding typical numbers below 2 for M* < 10^{11} Msun, rising to about 5 for the most massive system...

  10. Cosmic Ray ^3He Measurements

    OpenAIRE

    Mewaldt, R. A.

    1985-01-01

    Cosmic ray ^3He/^4He observations, including a new measurement at ~65 MeV/nucleon from ISEE-3, are compared with interstellar propagation and solar modulation models in an effort to understand the origin of cosmic ray He nuclei.

  11. Self--gravitating cosmic rings

    OpenAIRE

    Clément, Gérard

    1998-01-01

    The classical Einstein--Maxwell field equations admit static horizonless wormhole solutions with only a circular cosmic string singularity. We show how to extend these static solutions to exact rotating asymptotically flat solutions. For a suitable range of parameter values, these solutions describe charged or neutral rotating closed cosmic strings, with a perimeter of the order of their Schwarzschild radius.

  12. The Natural Science Underlying Big History

    Directory of Open Access Journals (Sweden)

    Eric J. Chaisson

    2014-01-01

    Full Text Available Nature’s many varied complex systems—including galaxies, stars, planets, life, and society—are islands of order within the increasingly disordered Universe. All organized systems are subject to physical, biological, or cultural evolution, which together comprise the grander interdisciplinary subject of cosmic evolution. A wealth of observational data supports the hypothesis that increasingly complex systems evolve unceasingly, uncaringly, and unpredictably from big bang to humankind. These are global history greatly extended, big history with a scientific basis, and natural history broadly portrayed across ∼14 billion years of time. Human beings and our cultural inventions are not special, unique, or apart from Nature; rather, we are an integral part of a universal evolutionary process connecting all such complex systems throughout space and time. Such evolution writ large has significant potential to unify the natural sciences into a holistic understanding of who we are and whence we came. No new science (beyond frontier, nonequilibrium thermodynamics is needed to describe cosmic evolution’s major milestones at a deep and empirical level. Quantitative models and experimental tests imply that a remarkable simplicity underlies the emergence and growth of complexity for a wide spectrum of known and diverse systems. Energy is a principal facilitator of the rising complexity of ordered systems within the expanding Universe; energy flows are as central to life and society as they are to stars and galaxies. In particular, energy rate density—contrasting with information content or entropy production—is an objective metric suitable to gauge relative degrees of complexity among a hierarchy of widely assorted systems observed throughout the material Universe. Operationally, those systems capable of utilizing optimum amounts of energy tend to survive, and those that cannot are nonrandomly eliminated.

  13. The natural science underlying big history.

    Science.gov (United States)

    Chaisson, Eric J

    2014-01-01

    Nature's many varied complex systems-including galaxies, stars, planets, life, and society-are islands of order within the increasingly disordered Universe. All organized systems are subject to physical, biological, or cultural evolution, which together comprise the grander interdisciplinary subject of cosmic evolution. A wealth of observational data supports the hypothesis that increasingly complex systems evolve unceasingly, uncaringly, and unpredictably from big bang to humankind. These are global history greatly extended, big history with a scientific basis, and natural history broadly portrayed across ∼14 billion years of time. Human beings and our cultural inventions are not special, unique, or apart from Nature; rather, we are an integral part of a universal evolutionary process connecting all such complex systems throughout space and time. Such evolution writ large has significant potential to unify the natural sciences into a holistic understanding of who we are and whence we came. No new science (beyond frontier, nonequilibrium thermodynamics) is needed to describe cosmic evolution's major milestones at a deep and empirical level. Quantitative models and experimental tests imply that a remarkable simplicity underlies the emergence and growth of complexity for a wide spectrum of known and diverse systems. Energy is a principal facilitator of the rising complexity of ordered systems within the expanding Universe; energy flows are as central to life and society as they are to stars and galaxies. In particular, energy rate density-contrasting with information content or entropy production-is an objective metric suitable to gauge relative degrees of complexity among a hierarchy of widely assorted systems observed throughout the material Universe. Operationally, those systems capable of utilizing optimum amounts of energy tend to survive, and those that cannot are nonrandomly eliminated.

  14. George's cosmic treasure hunt

    CERN Document Server

    Hawking, Lucy; Parsons, Gary

    2009-01-01

    George and Annie explore the galaxy in this cosmic adventure from Stephen Hawking and Lucy Hawking, complete with essays from Professor Hawking about the latest in space travel. George is heartbroken when he learns that his friend Annie and her father are moving to the US. Eric has a new job working for the space program, looking for signs of life in the Universe. Eric leaves George with a gift—a book called The User’s Guide to the Universe. But Annie and Eric haven’t been gone for very long when Annie believes that she is being contacted by aliens, who have a terrible warning for her. George joins her in the US to help her with her quest—and before he knows it, he, Annie, Cosmos, and Annie’s annoying cousin Emmett have been swept up in a cosmic treasure hunt, spanning the whole galaxy and beyond. Lucy Hawking's own experiences in zero-gravity flight and interviews with astronauts at Cape Kennedy and the Johnson Space Center lend the book a sense of realism and excitement that is sure to fire up ima...

  15. Evolution Of Cosmic Strings

    CERN Document Server

    Vanchurin, V

    2005-01-01

    We investigate the evolution of finite loops and infinite strings as a part of a complete cosmic string network. We give dynamical arguments showing that the structures on infinite strings should obey a scaling law. We perform a simulation of the network which uses functional forms for the string position and thus is exact to the limits of computer arithmetic. The effective box size of our simulation is at least two orders of magnitude larger than what was previously reached. Our results confirm that the wiggles on the strings obey a scaling law described by universal power spectrum. The average distance between long strings also scales accurately with the time. Production functions of string loops do not show scaling. With low intercommutation probability p the true scaling régime is not reached until very late cosmic times, which makes it difficult to simulate such evolutions. Via the expansion of the box technique, we were able to reach scaling with a wide range of p. The physical correlation ...

  16. Genuine cosmic hair

    Science.gov (United States)

    Kastor, David; Ray, Sourya; Traschen, Jennie

    2017-02-01

    We show that asymptotically future de Sitter (AFdS) spacetimes carry ‘genuine’ cosmic hair; information that is analogous to the mass and angular momentum of asymptotically flat spacetimes and that characterizes how an AFdS spacetime approaches its asymptotic form. We define new ‘cosmological tension’ charges associated with future asymptotic spatial translation symmetries, which are analytic continuations of the ADM mass and tensions of asymptotically planar AdS spacetimes, and which measure the leading anisotropic corrections to the isotropic, exponential de Sitter expansion rate. A cosmological Smarr relation, holding for AFdS spacetimes having exact spatial translation symmetry, is derived. This formula relates cosmological tension, which is evaluated at future infinity, to properties of the cosmology at early times, together with a ‘cosmological volume’ contribution that is analogous to the thermodynamic volume of AdS black holes. Smarr relations for different spatial directions imply that the difference in expansion rates between two directions at late times is related in a simple way to their difference at early times. Hence information about the very early universe can be inferred from cosmic hair, which is potentially observable in a late time de Sitter phase. Cosmological tension charges and related quantities are evaluated for Kasner–de Sitter spacetimes, which serve as our primary examples.

  17. L3 + Cosmics Experiment

    CERN Multimedia

    2002-01-01

    %RE4 %title\\\\ \\\\The L3+C experiment takes advantage of the unique properties of the L3 muon spectrometer to get an accurate measurement of cosmic ray muons 30 m underground. A new muon trigger, readout and DAQ system have been installed, as well as a scintillator array covering the upper surfaces of the L3 magnet for timing purposes. The acceptance amounts to 200 $m^2 sr$. The data are collected independently in parallel with L3 running. In spring 2000 a scintillator array will be installed on the roof of the SX hall in order to estimate the primary energy of air showers associated with events observed in L3+C.\\\\ \\\\The cosmic ray muon momentum spectrum, the zenith angular dependence and the charge ratio are measured with high accuracy between 20 and 2000 GeV/c. The results will provide new information about the primary composition, the shower development in the atmosphere, and the inclusive pion and kaon (production-) cross sections (specifically the "$\\pi$/K ratio") at high energies. These data will also hel...

  18. COSMIC monthly progress report

    Science.gov (United States)

    1994-01-01

    Activities of the Computer Software Management and Information Center (COSMIC) are summarized for the month of May 1994. Tables showing the current inventory of programs available from COSMIC are presented and program processing and evaluation activities are summarized. Nine articles were prepared for publication in the NASA Tech Brief Journal. These articles (included in this report) describe the following software items: (1) WFI - Windowing System for Test and Simulation; (2) HZETRN - A Free Space Radiation Transport and Shielding Program; (3) COMGEN-BEM - Composite Model Generation-Boundary Element Method; (4) IDDS - Interactive Data Display System; (5) CET93/PC - Chemical Equilibrium with Transport Properties, 1993; (6) SDVIC - Sub-pixel Digital Video Image Correlation; (7) TRASYS - Thermal Radiation Analyzer System (HP9000 Series 700/800 Version without NASADIG); (8) NASADIG - NASA Device Independent Graphics Library, Version 6.0 (VAX VMS Version); and (9) NASADIG - NASA Device Independent Graphics Library, Version 6.0 (UNIX Version). Activities in the areas of marketing, customer service, benefits identification, maintenance and support, and dissemination are also described along with a budget summary.

  19. From a Narrative of Suffering towards a Narrative of Growth: Norwegian History Textbooks in the Inter-War Period

    Science.gov (United States)

    Hovland, Brit Marie

    2013-01-01

    The article discusses changes and revisions of the Norwegian official Grand Narrative, as portrayed in primary school history textbooks. The selected corpus of textbooks of 1885-1940 shows narrative and historiographical changes supporting a hypothesis of a development from a "Narrative of Suffering" towards a "Narrative of…

  20. Cosmic rays and global warming

    Energy Technology Data Exchange (ETDEWEB)

    Erlykin, A.D. [P.N. Lebedev Physical Institute, Moscow (Russian Federation); Sloan, T. [Lancaster University (United Kingdom); Wolfendale, A.W. [Durham University (United Kingdom)

    2010-07-01

    The possible effects of cosmic rays on clouds could contribute to global warming. The argument is that the observed increased solar activity during the last century caused a decrease in the ionization due to cosmic rays since the lower energy cosmic particles are deflected by the magnetic field created by the increasing solar wind. This would lead to a decrease in cloud cover allowing more heating of the earth by the sun. Meteorological data combined to solar activity observations and simulations show that any effect of solar activity on clouds and the climate is likely to be through irradiance rather than cosmic rays. Since solar irradiance transfers 8 orders of magnitude more energy to the atmosphere than cosmic rays it is more plausible that this can produce a real effect. The total contribution of variable solar activity to global warming is shown to be less than 14% of the total temperature rise. (A.C.)

  1. IMPACT OF HATCH-DATE ON EARLY LIFE GROWTH AND SURVIVAL OF MUELLER’S PEARLSIDE (MAUROLICUS MUELLERI) LARVAE, AND LIFE-HISTORY CONSEQUENCES

    KAUST Repository

    Folkvord, Arild

    2015-08-11

    Growth and survival of Maurolicus muelleri larvae in Herdlefjorden, Norway were investigated by daily otolith increment analysis. While high egg densities were generally observed throughout the spawning season, three cohorts each with a narrow window of hatching dates were identified. The first of these cohorts was characterized by low growth and poor morphometric condition and disappeared from the fjord during autumn. High resolution drift modeling indicated that Herdlefjorden had a net export of larvae and negligible import in the period cohort 1 disappeared. Yet, the advective loss rate of larvae was not considered high enough to explain the near complete disappearance of the first cohort. An otolith based growth chronology indicated that growth conditions in Herdlefjorden improved noticeably around mid-September, and remained favorable the following month. The analysis of daily otolith increments could thus be used to document within-season variability in larval growth and survival. The low and variable survival due to short term fluctuations in environmental conditions indicate that multiple batch spawning is an adequately evolved life history strategy for marine planktivorous fish such as M. muelleri.

  2. Modelli di crescita limitata dalla bilancia dei pagamenti: storia e panoramica (Balance of payments constrained growth models: history and overview

    Directory of Open Access Journals (Sweden)

    Anthony P. Thirlwall

    2012-01-01

    Full Text Available Thirlwall’s 1979 balance of payments constrained growth model predicts that a country’s long run growth of GDP can be approximated by the ratio of the growth of real exports to the income elasticity of demand for imports assuming negligible effects from real exchange rate movements. The paper surveys developments of the model since then, allowing for capital flows, interest payments on debt, terms of trade movements, and disaggregation of the model by commodities and trading partners. Various tests of the model are discussed, and an extensive list of papers that have examined the model is presented.  JEL Codes: F32; F40; F43Keywords: Balance of payments; growth; Thirlwall’s Law; dynamic Harrod multiplier

  3. Comparison of Growth Parameters in Five Year-Old Children with and Without History of Low Birth Weight

    Directory of Open Access Journals (Sweden)

    A Dehghanpoor

    2012-01-01

    Full Text Available Introduction: Nowadays Low birth weight(LBW or birth weight<2500g is one of the most serious problems among children around the world. The purpose of this study was to evaluate and compare the growth parameters(weight, height, head circumference and BMI of LBW children at the age of five years with normal birth weight (NBW: birth weight: 2500- 4000 g children. Methods: In a cross-sectional analytic study, growth parameters of five year-old children referred to Azadshahr health care center in Yazd, Iran, from December 2008 to June 2009 were evaluated. NBW and LBW children were selected as control and case groups, respectively. Results: Means of all growth parameters were significantly lower in LBW group. Frequency of severe failure to thrive and short stature was significantly higher in LBW group. Frequency of underweight was higher in LBW group and frequency of obesity was higher in NBW one. Frequency of underweight was higher in LBW girls. Conclusion: Considering that growth in LBW children is slower than NBW children in the first five years of life, it is necessary to emphasize the importance of growth assessment of LBW children for early and timely diagnosis, work-up and management of growth retardation and prevention of subsequent problems.

  4. Effect of petroleum-derived substances on life history traits of black bean aphid (Aphis fabae Scop.) and on the growth and chemical composition of broad bean

    OpenAIRE

    Rusin, Milena; GOSPODAREK, Janina; Nadgórska-Socha, Aleksandra; Barczyk, Gabriela

    2017-01-01

    The aim of the study was to determine the effects of various petroleum-derived substances, namely petrol, diesel fuel and spent engine oil, on life history traits and population dynamics of the black bean aphid Aphis fabae Scop. and on growth and chemical composition of its host plant Vicia faba L. Each substance was tested separately, using two concentrations (9 g kg−1 and 18 g kg−1). The experiment was conducted in four replications (four pots with five plants in each pot per treatment). Pl...

  5. Cosmic radiation algorithm utilizing flight time tables

    Energy Technology Data Exchange (ETDEWEB)

    Katja Kojo, M.Sc.; Mika Helminen, M.Sc.; Anssi Auvinen, M.D.Ph.D. [STUK - Radiation and Nuclear Safety Authority, Helsinki (Finland); Katja Kojo, M.Sc.; Anssi Auvinen, M.D.Ph.D. [Tampere Univ., School of Public Health (Finland); Gerhard Leuthold, D.Sc. [GSF - Research Center, Institute of Radiation Protection, Neuherberg (Germany)

    2006-07-01

    Cosmic radiation is considerably higher on cruising altitudes used in aviation than at ground level. Exposure to cosmic radiation may increase cancer risk among pilots and cabin crew. The International Commission on Radiation Protection (ICRP) has recommended that air crew should be classified as radiation workers. Quantification of cosmic radiation doses is necessary for assessment of potential health effects of such occupational exposure. For Finnair cabin crew (cabin attendants and stewards), flight history is not available for years prior to 1991 and therefore, other sources of information on number and type of flights have to be used. The lack of systematically recorded information is a problem for dose estimation for many other flight companies personnel as well. Several cosmic radiation dose estimations for cabin crew have been performed using different methods (e.g. 2-5), but they have suffered from various shortcomings. Retrospective exposure estimation is not possible with personal portable dosimeters. Methods that employ survey data for occupational dose assessment are prone to non-differential measurement error i.e. the cabin attendants do not remember correctly the number of past flights. Assessment procedures that utilize surrogate measurement methods i.e. the duration of employment, lack precision. The aim of the present study was to develop an assessment method for individual occupational exposure to cosmic radiation based on flight time tables. Our method provides an assessment method that does not require survey data or systematic recording of flight history, and it is rather quick, inexpensive, and possible to carry out in all other flight companies whose past time tables for the past periods exist. Dose assessment methods that employ survey data are prone to random error i.e. the cabin attendants do not remember correctly the number or types of routes that they have flown during the past. Our method avoids this since survey data are not needed

  6. Current discontinuities on superconducting cosmic strings

    Energy Technology Data Exchange (ETDEWEB)

    Troyan, E., E-mail: et@iaaru.astronautiko.org; Vlasov, Yu. V. [Moscow Institute of Physics and Technology (Russian Federation)

    2011-07-15

    The propagation of current perturbations on superconducting cosmic strings is considered. The conditions for the existence of discontinuities similar to shock waves have been found. The formulas relating the string parameters and the discontinuity propagation speed are derived. The current growth law in a shock wave is deduced. The propagation speeds of shock waves with arbitrary amplitudes are calculated. The reason why there are no shock waves in the case of time-like currents (in the 'electric' regime) is explained; this is attributable to the shock wave instability with respect to perturbations of the string world sheet.

  7. THE EVOLUTION OF THE REST-FRAME V-BAND LUMINOSITY FUNCTION FROM z = 4: A CONSTANT FAINT-END SLOPE OVER THE LAST 12 Gyr OF COSMIC HISTORY

    Energy Technology Data Exchange (ETDEWEB)

    Marchesini, Danilo [Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Stefanon, Mauro [Observatori Astronomic Universitat de Valencia, C/Catedratico Agustin Escardino Benlloch, 7, 46980, Valencia (Spain); Brammer, Gabriel B. [European Southern Observatory (ESO), Santiago (Chile); Whitaker, Katherine E. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States)

    2012-04-01

    We present the rest-frame V-band luminosity function (LF) of galaxies at 0.4 {<=} z < 4.0, measured from a near-infrared selected sample constructed from the NMBS, the FIRES, the FIREWORKS, and the ultra-deep NICMOS and WFC3 observations in the HDFN, HUDF, and GOODS-CDFS, all having high-quality optical-to-mid-infrared data. This unique sample combines data from surveys with a large range of depths and areas in a self-consistent way, allowing us to (1) minimize the uncertainties due to cosmic variance; and (2) simultaneously constrain the bright and faint ends with unprecedented accuracy over the targeted redshift range, probing the LF down to 0.1L* at z {approx} 3.9. We find that (1) the faint end is fairly flat and with a constant slope from z = 4, with {alpha} = -1.27 {+-} 0.05; (2) the characteristic magnitude has dimmed by 1.3 mag from z {approx} 3.7 to z = 0.1; (3) the characteristic density has increased by a factor of {approx}8 from z {approx} 3.7 to z = 0.1, with 50% of this increase from z {approx} 4 to z {approx} 1.8; and (4) the luminosity density peaks at z Almost-Equal-To 1-1.5, increasing by a factor of {approx}4 from z = 4.0 to z Almost-Equal-To 1-1.5, and subsequently decreasing by a factor of {approx}1.5 by z = 0.1. We find no evidence for a steepening of the faint-end slope with redshift out to z = 4, in contrast with previous observational claims and theoretical predictions. The constant faint-end slope suggests that the efficiency of stellar feedback may evolve with redshift. Alternative interpretations are discussed, such as different masses of the halos hosting faint galaxies at low and high redshifts and/or environmental effects.

  8. WATER AND THE HISTORY OF MAN

    Science.gov (United States)

    The importance of water is presented from a myriad of aspects including its creation in cosmic history; its importance in the texts of ancient history; references within various religious writings; and significance with respect to modern science, art, music, transportation, archi...

  9. Experimental Summary: Very High Energy Cosmic Rays and their Interactions

    Science.gov (United States)

    Kampert, Karl-Heinz

    2013-06-01

    The XVII International Symposium on Very High Energy Cosmic Ray Interactions, held in August of 2012 in Berlin, was the first one in the history of the Symposium,where a plethora of high precision LHC data with relevance for cosmic ray physics was presented. This report aims at giving a brief summary of those measurements andit discusses their relevance for observations of high energy cosmic rays. Enormous progress has been made also in air shower observations and in direct measurements of cosmic rays, exhibiting many more structure in the cosmic ray energy spectrum than just a simple power law with a knee and an ankle. At the highest energy, the flux suppression may not be dominated by the GZK-effect but by the limiting energy of a nearby source or source population. New projects and application of new technologies promise further advances also in the near future. We shall discuss the experimental and theoretical progress in the field and its prospects for coming years.

  10. Experimental Summary: Very High Energy Cosmic Rays and their Interactions

    Directory of Open Access Journals (Sweden)

    Kampert Karl-Heinz

    2013-06-01

    Full Text Available The XVII International Symposium on Very High Energy Cosmic Ray Interactions, held in August of 2012 in Berlin, was the first one in the history of the Symposium,where a plethora of high precision LHC data with relevance for cosmic ray physics was presented. This report aims at giving a brief summary of those measurements andit discusses their relevance for observations of high energy cosmic rays. Enormous progress has been made also in air shower observations and in direct measurements of cosmic rays, exhibiting many more structure in the cosmic ray energy spectrum than just a simple power law with a knee and an ankle. At the highest energy, the flux suppression may not be dominated by the GZK-effect but by the limiting energy of a nearby source or source population. New projects and application of new technologies promise further advances also in the near future. We shall discuss the experimental and theoretical progress in the field and its prospects for coming years.

  11. Cosmic ray driven Galactic winds

    CERN Document Server

    Recchia, S; Morlino, G

    2016-01-01

    The escape of cosmic rays from the Galaxy leads to a gradient in the cosmic ray pressure that acts as a force on the background plasma, in the direction opposite to the gravitational pull. If this force is large enough to win against gravity, a wind can be launched that removes gas from the Galaxy, thereby regulating several physical processes, including star formation. The dynamics of these cosmic ray driven winds is intrinsically non-linear in that the spectrum of cosmic rays determines the characteristics of the wind (velocity, pressure, magnetic field) and in turn the wind dynamics affects the cosmic ray spectrum. Moreover, the gradient of the cosmic ray distribution function causes excitation of Alfven waves, that in turn determine the scattering properties of cosmic rays, namely their diffusive transport. These effects all feed into each other so that what we see at the Earth is the result of these non-linear effects. Here we investigate the launch and evolution of such winds, and we determine the impli...

  12. Cosmic magnetic fields

    CERN Document Server

    Kronberg, Philipp P

    2016-01-01

    Magnetic fields are important in the Universe and their effects contain the key to many astrophysical phenomena that are otherwise impossible to understand. This book presents an up-to-date overview of this fast-growing topic and its interconnections to plasma processes, astroparticle physics, high energy astrophysics, and cosmic evolution. The phenomenology and impact of magnetic fields are described in diverse astrophysical contexts within the Universe, from galaxies to the filaments and voids of the intergalactic medium, and out to the largest redshifts. The presentation of mathematical formulae is accessible and is designed to add insight into the broad range of topics discussed. Written for graduate students and researchers in astrophysics and related disciplines, this volume will inspire readers to devise new ways of thinking about magnetic fields in space on galaxy scales and beyond.

  13. Microphysics of cosmic plasmas

    CERN Document Server

    Bykov, Andrei; Cargill, Peter; Dendy, Richard; Wit, Thierry; Raymond, John

    2014-01-01

    This title presents a review of the detailed aspects of the physical processes that underlie the observed properties, structures and dynamics of cosmic plasmas. An assessment of the status of understanding of microscale processes in all astrophysical collisionless plasmas is provided. The topics discussed include  turbulence in astrophysical and solar system plasmas as a phenomenological description of their dynamic properties on all scales; observational, theoretical and modelling aspects of collisionless magnetic reconnection; the formation and dynamics of shock waves; and a review and assessment of microprocesses, such as the hierarchy of plasma instabilities, non-local and non-diffusive transport processes and ionisation and radiation processes.  In addition, some of the lessons that have been learned from the extensive existing knowledge of laboratory plasmas as applied to astrophysical problems are also covered.   This volume is aimed at graduate students and researchers active in the areas of cosmi...

  14. Cosmic Ray Antimatter

    CERN Document Server

    CERN. Geneva

    2017-01-01

    Over the last decade, space-born experiments have delivered new measurements of high energy cosmic-ray (CR) antiprotons and positrons, opening new frontiers in energy reach and precision. While being a promising discovery tool for new physics or exotic astrophysical phenomena, an irreducible background of antimatter comes from CR collisions with interstellar matter in the Galaxy. Understanding this irreducible source or constraining it from first principles is an interesting challenge: a game of hide-and-seek where the objective is to identify the laws of basic particle physics among the forest of astrophysical uncertainties. I describe an attempt to obtain such understanding, combining information from a zoo of CR species including massive nuclei and relativistic radioisotopes. I show that: (i) CR antiprotons most likely come from CR-gas collisions; (ii) positron data is consistent with, and suggestive of the same astrophysical production mechanism responsible for antiprotons and dominated by proton-proton c...

  15. The Cosmic Microwave Background

    Directory of Open Access Journals (Sweden)

    Jones Aled

    1998-01-01

    Full Text Available We present a brief review of current theory and observations of the cosmic microwave background (CMB. New predictions for cosmological defect theories and an overview of the inflationary theory are discussed. Recent results from various observations of the anisotropies of the microwave background are described and a summary of the proposed experiments is presented. A new analysis technique based on Bayesian statistics that can be used to reconstruct the underlying sky fluctuations is summarised. Current CMB data is used to set some preliminary constraints on the values of fundamental cosmological parameters $Omega$ and $H_circ$ using the maximum likelihood technique. In addition, secondary anisotropies due to the Sunyaev-Zel'dovich effect are described.

  16. Acceleration of cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Berezhko, E [Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy, 31 Lenin Ave., 677980 Yakutsk (Russian Federation)], E-mail: berezhko@ikfia.ysn.ru

    2008-07-15

    Cosmic ray (CR) origin problem is briefly discussed. It is argued that CRs with energies up to 10{sup 17} eV are produced in galactic supernova remnants, whereas ultra high energy CRs are extragalactic. CR composition strongly changes within the transition from galactic to extragalactic CR component, therefore precise measurements of CR composition at energies 10{sup 17} - 10{sup 19} eV are needed for the reliable determination of this transition. The possible sources of extragalactic CRs are briefly discussed. It is argued that CR acceleration at the shock created by the expanding cocoons around active galactic nuclei has to be considered as a prime candidate for the sources of extragalactic CRs.

  17. Cosmic string loop shapes

    CERN Document Server

    Blanco-Pillado, Jose J; Shlaer, Benjamin

    2015-01-01

    We analyze the shapes of cosmic string loops found in large-scale simulations of an expanding-universe string network. The simulation does not include gravitational back reaction, but we model that process by smoothing the loop using Lorentzian convolution. We find that loops at formation consist of generally straight segments separated by kinks. We do not see cusps or any cusp-like structure at the scale of the entire loop, although we do see very small regions of string that move with large Lorentz boosts. However, smoothing of the string almost always introduces two cusps on each loop. The smoothing process does not lead to any significant fragmentation of loops that were in non-self-intersecting trajectories before smoothing.

  18. Simulating Cosmic Structure Formation

    CERN Document Server

    Weinberg, D H; Hernquist, L E; Weinberg, David H.; Katz, Neal; Hernquist, Lars

    1997-01-01

    We describe cosmological simulation techniques and their application to studies of cosmic structure formation, with particular attention to recent hydrodynamic simulations of structure in the high redshift universe. Collisionless N-body simulations with Gaussian initial conditions produce a pattern of sheets, filaments, tunnels, and voids that resembles the observed large scale galaxy distribution. Simulations that incorporate gas dynamics and dissipation form dense clumps of cold gas with sizes and masses similar to the luminous parts of galaxies. Models based on inflation and cold dark matter predict a healthy population of high redshift galaxies, including systems with star formation rates of 20 M_{\\sun}/year at z=6. At z~3, most of the baryons in these models reside in the low density intergalactic medium, which produces fluctuating Lyman-alpha absorption in the spectra of background quasars. The physical description of this ``Lyman-alpha forest'' is particularly simple if the absorption spectrum is viewe...

  19. Cosmic Light EDU kit

    Science.gov (United States)

    Doran, Rosa

    2015-08-01

    In 2015 we celebrate the International Year of Light, a great opportunity to promote awareness about the importance of light coming from the Cosmos and what messages it is bringing to mankind. In parallel a unique moment to attract the attention of stakeholders on the dangers of light pollution and its impact in our lives and our pursuit of more knowledge. In this presentation I want to present one of the conrnerstones of IYL2015, a partnership between the Galileo Teacher Training Program, Universe Awareness and Globe at Night, the Cosmic Light EDU kit. The aim of this project is to assemble a core set of tools and resources representing our basic knowledge pilars about the Universe and simple means to preserve our night sky.

  20. Cosmic ray synergies

    CERN Multimedia

    Laëtitia Pedroso

    2010-01-01

    In laboratories, cosmic rays have been the subject of scientific research for many years. A more recent development is their appearance in schools, as educational tools. A recent workshop at CERN, organised by ASPERA in collaboration with EPPOG and EPPCN, had the goal of bringing together ideas and initiatives with a view to setting up a future common project.   Presentation at the workshop on 15 October. In research, as in education, you can sometimes get things done more rapidly and easily by joining forces. For roughly the past decade, physicists have been taking their particle detectors to secondary schools. “The challenge now is to bring all of these existing projects together in a network,” says Arnaud Marsollier, in charge of communication for the ASPERA network and organiser of the workshop. The workshop held on Friday, 15 October was attended by representatives of major European educational projects and members of the European Particle Physics Communication Network...

  1. Genuine Cosmic Hair

    CERN Document Server

    Kastor, David; Traschen, Jennie

    2016-01-01

    We show that asymptotically future deSitter (AFdS) spacetimes carry 'genuine' cosmic hair; information that is analogous to the mass and angular momentum of asymptotically flat spacetimes and that characterizes how an AFdS spacetime approaches its asymptotic form. We define new 'cosmological tension' charges associated with future asymptotic spatial translation symmetries, which are analytic continuations of the ADM mass and tensions of asymptotically planar AdS spacetimes, and which measure the leading anisotropic corrections to the isotropic, exponential deSitter expansion rate. A cosmological Smarr relation, holding for AFdS spacetimes having exact spatial translation symmetry, is derived. This formula relates cosmological tension, which is evaluated at future infinity, to properties of the cosmology at early times, together with a 'cosmological volume' contribution that is analogous to the thermodynamic volume of AdS black holes. Smarr relations for different spatial directions imply that the difference i...

  2. THE COSMIC ORIGINS SPECTROGRAPH

    Energy Technology Data Exchange (ETDEWEB)

    Green, James C.; Michael Shull, J.; Snow, Theodore P.; Stocke, John [Department of Astrophysical and Planetary Sciences, University of Colorado, 391-UCB, Boulder, CO 80309 (United States); Froning, Cynthia S.; Osterman, Steve; Beland, Stephane; Burgh, Eric B.; Danforth, Charles; France, Kevin [Center for Astrophysics and Space Astronomy, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Ebbets, Dennis [Ball Aerospace and Technologies Corp., 1600 Commerce Street, Boulder, CO 80301 (United States); Heap, Sara H. [NASA Goddard Space Flight Center, Code 681, Greenbelt, MD 20771 (United States); Leitherer, Claus; Sembach, Kenneth [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Linsky, Jeffrey L. [JILA, University of Colorado and NIST, Boulder, CO 80309-0440 (United States); Savage, Blair D. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Siegmund, Oswald H. W. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Spencer, John; Alan Stern, S. [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Welsh, Barry [Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720 (United States); and others

    2012-01-01

    The Cosmic Origins Spectrograph (COS) is a moderate-resolution spectrograph with unprecedented sensitivity that was installed into the Hubble Space Telescope (HST) in 2009 May, during HST Servicing Mission 4 (STS-125). We present the design philosophy and summarize the key characteristics of the instrument that will be of interest to potential observers. For faint targets, with flux F{sub {lambda}} Almost-Equal-To 1.0 Multiplication-Sign 10{sup -14} erg cm{sup -2} s{sup -1} A{sup -1}, COS can achieve comparable signal to noise (when compared to Space Telescope Imaging Spectrograph echelle modes) in 1%-2% of the observing time. This has led to a significant increase in the total data volume and data quality available to the community. For example, in the first 20 months of science operation (2009 September-2011 June) the cumulative redshift pathlength of extragalactic sight lines sampled by COS is nine times than sampled at moderate resolution in 19 previous years of Hubble observations. COS programs have observed 214 distinct lines of sight suitable for study of the intergalactic medium as of 2011 June. COS has measured, for the first time with high reliability, broad Ly{alpha} absorbers and Ne VIII in the intergalactic medium, and observed the He II reionization epoch along multiple sightlines. COS has detected the first CO emission and absorption in the UV spectra of low-mass circumstellar disks at the epoch of giant planet formation, and detected multiple ionization states of metals in extra-solar planetary atmospheres. In the coming years, COS will continue its census of intergalactic gas, probe galactic and cosmic structure, and explore physics in our solar system and Galaxy.

  3. The Cosmic Origins Spectrograph

    Science.gov (United States)

    Green, James C.; Froning, Cynthia S.; Osterman, Steve; Ebbets, Dennis; Heap, Sara H.; Leitherer, Claus; Linsky, Jeffrey L.; Savage, Blair D.; Sembach, Kenneth; Shull, J. Michael; Siegmund, Oswald H. W.; Snow, Theodore P.; Spencer, John; Stern, S. Alan; Stocke, John; Welsh, Barry; Beland, Stephane; Burgh, Eric B.; Danforth, Charles; France, Kevin; Keeney, Brian; McPhate, Jason; Penton, Steven V; Andrews, John; Morse, Jon

    2010-01-01

    The Cosmic Origins Spectrograph (COS) is a moderate-resolution spectrograph with unprecedented sensitivity that was installed into the Hubble Space Telescope (HST) in May 2009, during HST Servicing Mission 4 (STS-125). We present the design philosophy and summarize the key characteristics of the instrument that will be of interest to potential observers. For faint targets, with flux F(sub lambda) approximates 1.0 X 10(exp -14) ergs/s/cm2/Angstrom, COS can achieve comparable signal to noise (when compared to STIS echelle modes) in 1-2% of the observing time. This has led to a significant increase in the total data volume and data quality available to the community. For example, in the first 20 months of science operation (September 2009 - June 2011) the cumulative redshift pathlength of extragalactic sight lines sampled by COS is 9 times that sampled at moderate resolution in 19 previous years of Hubble observations. COS programs have observed 214 distinct lines of sight suitable for study of the intergalactic medium as of June 2011. COS has measured, for the first time with high reliability, broad Lya absorbers and Ne VIII in the intergalactic medium, and observed the HeII reionization epoch along multiple sightlines. COS has detected the first CO emission and absorption in the UV spectra of low-mass circumstellar disks at the epoch of giant planet formation, and detected multiple ionization states of metals in extra-solar planetary atmospheres. In the coming years, COS will continue its census of intergalactic gas, probe galactic and cosmic structure, and explore physics in our solar system and Galaxy.

  4. Test particle trajectories near cosmic strings

    Indian Academy of Sciences (India)

    Farook Rahaman; Subenoy Chakraborty; K Maity

    2002-01-01

    We present a detailed analysis of the motion of test particle in the gravitational field of cosmic strings in different situations using the Hamilton–Jacobi (H–J) formalism. We have discussed the trajectories near static cosmic string, cosmic string in Brans–Dicke theory and cosmic string in dilaton gravity.

  5. A cosmic microwave background feature consistent with a cosmic texture.

    Science.gov (United States)

    Cruz, M; Turok, N; Vielva, P; Martínez-González, E; Hobson, M

    2007-12-07

    The Cosmic Microwave Background provides our most ancient image of the universe and our best tool for studying its early evolution. Theories of high-energy physics predict the formation of various types of topological defects in the very early universe, including cosmic texture, which would generate hot and cold spots in the Cosmic Microwave Background. We show through a Bayesian statistical analysis that the most prominent 5 degrees -radius cold spot observed in all-sky images, which is otherwise hard to explain, is compatible with having being caused by a texture. From this model, we constrain the fundamental symmetry-breaking energy scale to be (0) approximately 8.7 x 10(15) gigaelectron volts. If confirmed, this detection of a cosmic defect will probe physics at energies exceeding any conceivable terrestrial experiment.

  6. Spherical Orbifolds for Cosmic Topology

    CERN Document Server

    Kramer, Peter

    2012-01-01

    Harmonic analysis is a tool to infer cosmic topology from the measured astrophysical cosmic microwave background CMB radiation. For overall positive curvature, Platonic spherical manifolds are candidates for this analysis. We combine the specific point symmetry of the Platonic manifolds with their deck transformations. This analysis in topology leads from manifolds to orbifolds. We discuss the deck transformations of the orbifolds and give basis functions for the harmonic analysis as linear combinations of Wigner polynomials on the 3-sphere. They provide new tools for detecting cosmic topology from the CMB radiation.

  7. Cosmic rays, clouds, and climate

    DEFF Research Database (Denmark)

    Marsh, N.; Svensmark, Henrik

    2000-01-01

    cloud radiative properties. Thus, a moderate influence on atmospheric aerosol distributions from cosmic ray ionisation would have a strong influence on the Earth's radiation budget. Historical evidence over the past 1000 years indicates that changes in climate have occurred in accord with variability...... in the Earth's radiation budget through trapping outgoing radiation and reflecting incoming radiation. If a physical link between these two features can be established, it would provide a mechanism linking solar activity and Earth's climate. Recent satellite observations have further revealed a correlation...... in cosmic ray intensities. Such changes are in agreement with the sign of cloud radiative forcing associated with cosmic ray variability as estimated from satellite observations....

  8. Planck intermediate results: XLVII. Planck constraints on reionization history

    DEFF Research Database (Denmark)

    Adam, R.; Aghanim, N.; Ashdown, M.

    2016-01-01

    We investigate constraints on cosmic reionization extracted from the Planck cosmic microwave background (CMB) data. We combine the Planck CMB anisotropy data in temperature with the low-multipole polarization data to fit ΛCDM models with various parameterizations of the reionization history. We o...

  9. Predictors of future growth of sporadic vestibular schwannomas obtained by history and radiologic assessment of the tumor.

    NARCIS (Netherlands)

    Artz, J.C.; Timmer, F.C.A.; Mulder, J.J.S.; Cremers, C.W.R.J.; Graamans, K.

    2009-01-01

    Management of a sporadic vestibular schwannoma (VS) is still a subject of controversy, mainly due to distinct and unpredictable growth patterns. To embark on an appropriate therapy it is necessary to dispose of a reliable prediction about tumor progression. This study aims to design a risk profile

  10. Predictors of future growth of sporadic vestibular schwannomas obtained by history and radiologic assessment of the tumor.

    NARCIS (Netherlands)

    Artz, J.C.; Timmer, F.C.A.; Mulder, J.J.S.; Cremers, C.W.R.J.; Graamans, K.

    2009-01-01

    Management of a sporadic vestibular schwannoma (VS) is still a subject of controversy, mainly due to distinct and unpredictable growth patterns. To embark on an appropriate therapy it is necessary to dispose of a reliable prediction about tumor progression. This study aims to design a risk profile w

  11. Industrious Selection: Explaining Five Revolutions and Two Divergences in Eurasian Economic History within a Unified Growth Framework

    OpenAIRE

    Ho, Chi Pui

    2016-01-01

    We develop a unified growth theory with Industrious Selection to explain the Five Revolutions in the development process (Agricultural Revolution, Structural Transformation, Industrial Revolution, Industrious Revolution, Demographic Revolution) and the Two Divergences in Eurasia (Little Divergence, Great Divergence) in AD0-AD2000. Industrious Selection refers to industrious (hardworking and cooperative) individuals gradually dominating the population composition through labor-leisure optimiza...

  12. Maximizing growth rate at low temperatures: RNA:DNA allocation strategies and life history traits of Arctic and temperate Daphnia

    NARCIS (Netherlands)

    Van Geest, G.J.; Sachse, R.; Brehm, Michaela; Van Donk, E.; Hessen, D.O.

    2010-01-01

    Many short-lived or univoltine organisms at high latitudes and altitudes face the challenge to complete their life-cycle within a brief growing season. This means that they need to maintain a high growth rate at low temperatures, and one way of doing this is to allocate limiting resources like phosp

  13. Preheating of the Universe by cosmic rays from primordial supernovae at the beginning of cosmic reionization

    CERN Document Server

    Sazonov, Sergey

    2015-01-01

    The 21-cm signal from the cosmic reionization epoch can shed light on the history of heating of the primordial intergalactic medium (IGM) at z~30-10. It has been suggested that X-rays from the first accreting black holes could significantly heat the Universe at these early epochs. Here we propose another IGM heating mechanism associated with the first stars. As known from previous work, the remnants of powerful supernovae (SNe) ending the lives of massive Population III stars could readily expand out of their host dark matter minihalos into the surrounding IGM, aided by the preceeding photoevaporation of the halo's gas by the UV radiation from the progenitor star. We argue that during the evolution of such a remnant a significant fraction of the SN kinetic energy can be put into low-energy (E<30 MeV) cosmic rays that will eventually escape into the IGM. These subrelativistic cosmic rays could propagate through the Universe and heat the IGM by ~10-100 K by z~15, before more powerful reionization/heating mec...

  14. Cosmic Christ in a Quantum Universe.

    Science.gov (United States)

    Kohli, Mary Ann

    This study examines the figure of the second American Adam--the cosmic Christ archetype--in terms of a possible shift in the focus of Western consciousness. As science moves closer to religion and as Newtonian dualism gives way to a more holistic theory (in which observer, observed, and process of observation are all intricately interlinked), the cosmic Christ emerges as a symbol in contemporary American fiction of a potentially unified awareness which could reconnect post-Christian man to God, to the world, and to the self. Such a rebirth of unity would be contingent upon the death of a consciousness reliant upon the rational, linear, masculine, left-brained thinking associated with the old Newtonian paradigm. The resurrected consciousness would consolidate Eastern and Western religion by acknowledging the God within man through the Western symbology of the Christ prototype. It would also balance the intuitional with the rational, the cyclical with the linear, the feminine with the masculine, and the right brain with the left. In other words, the repressed elements of the collective Western psyche would be allowed to come to awareness and be integrated into the mind at large. This integrating process is implicit in the cosmic Christ imagery. The novels which are considered are all concerned with the role of consciousness in the postmodern world and the part that science and religion play in determining the nature of that role. In such varied works as Thomas Pynchon's Gravity's Rainbow, John Updike's Roger's Version, Saul Bellow's Herzog, Joan Didion's A Book of Common Prayer, and William Vollmann's The Ice-Shirt, a cosmic Christ figure invariably appears. The success of this figure, however, is ambiguous and uncertain. At best, the transition of consciousness that is achieved is individual rather than communal. Nevertheless, as chaos theory has demonstrated, small changes can bring about major effects. Consequently, both the science of today and the rapid growth

  15. Using the life history model to set the stage(s) of growth and senescence in bioarchaeology and paleodemography.

    Science.gov (United States)

    Roksandic, Mirjana; Armstrong, Stephanie D

    2011-07-01

    Paleodemography, the study of demographic parameters of past human populations, relies on assumptions including biological uniformitarianism, stationary populations, and the ability to determine point age estimates from skeletal material. These assumptions have been widely criticized in the literature and various solutions have been proposed. The majority of these solutions rely on statistical modeling, and have not seen widespread application. Most bioarchaeologists recognize that our ability to assess chronological age is inherently limited, and have instead resorted to large, qualitative, age categories. However, there has been little attempt in the literature to systematize and define the stages of development and ageing used in bioarchaeology. We propose that stages should be based in the human life history pattern, and their skeletal markers should have easily defined and clear endpoints. In addition to a standard five-stage developmental model based on the human life history pattern, current among human biologists, we suggest divisions within the adult stage that recognize the specific nature of skeletal samples. We therefore propose the following eight stages recognizable in human skeletal development and senescence: infancy, early childhood, late childhood, adolescence, young adulthood, full adulthood, mature adulthood, and senile adulthood. Striving toward a better prediction of chronological ages will remain important and could eventually help us understand to what extent past societies differed in the timing of these life stages. Furthermore, paleodemographers should try to develop methods that rely on the type of age information accessible from the skeletal material, which uses life stages, rather than point age estimates.

  16. Dark matter and cosmic structure

    OpenAIRE

    2012-01-01

    We review the current standard model for the evolution of cosmic structure, tracing its development over the last forty years and focusing specifically on the role played by numerical simulations and on aspects related to the nature of dark matter.

  17. Effect of petroleum-derived substances on life history traits of black bean aphid (Aphis fabae Scop.) and on the growth and chemical composition of broad bean.

    Science.gov (United States)

    Rusin, Milena; Gospodarek, Janina; Nadgórska-Socha, Aleksandra; Barczyk, Gabriela

    2017-04-01

    The aim of the study was to determine the effects of various petroleum-derived substances, namely petrol, diesel fuel and spent engine oil, on life history traits and population dynamics of the black bean aphid Aphis fabae Scop. and on growth and chemical composition of its host plant Vicia faba L. Each substance was tested separately, using two concentrations (9 g kg(-1) and 18 g kg(-1)). The experiment was conducted in four replications (four pots with five plants in each pot per treatment). Plants were cultivated in both control and contaminated soils. After six weeks from soil contamination and five weeks from sowing the seeds, observations of the effect of petroleum-derived substances on traits of three successive generations of aphids were conducted. Aphids were inoculated separately on leaves using cylindrical cages hermetically closed on both sides. Contamination of aphid occurred through its host plant. Results showed that all tested substances adversely affected A. fabae life history traits and population dynamics: extension of the prereproductive period, reduction of fecundity and life span, reduction of the population intrinsic growth rate. In broad bean, leaf, roots, and shoot growth was also impaired in most conditions, whereas nutrient and heavy metal content varied according to substances, their concentration, as well as plant part analysed. Results indicate that soil contamination with petroleum-derived substances entails far-reaching changes not only in organisms directly exposed to these pollutants (plants), but also indirectly in herbivores (aphids) and consequently provides information about potential negative effects on further links of the food chain, i.e., for predators and parasitoids.

  18. A relationship between galactic cosmic radiation and tree rings.

    Science.gov (United States)

    Dengel, Sigrid; Aeby, Dominik; Grace, John

    2009-11-01

    Here, we investigated the interannual variation in the growth rings formed by Sitka spruce (Picea sitchensis) trees in northern Britain (55 degrees N, 3 degrees W) over the period 1961-2005 in an attempt to disentangle the influence of atmospheric variables acting at different times of year. Annual growth rings, measured along the north radius of freshly cut (frozen) tree discs and climatological data recorded at an adjacent site were used in the study. Correlations were based on Pearson product-moment correlation coefficients between the annual growth anomaly and these climatic and atmospheric factors. Rather weak correlations between these variables and growth were found. However, there was a consistent and statistically significant relationship between growth of the trees and the flux density of galactic cosmic radiation. Moreover, there was an underlying periodicity in growth, with four minima since 1961, resembling the period cycle of galactic cosmic radiation. * We discuss the hypotheses that might explain this correlation: the tendency of galactic cosmic radiation to produce cloud condensation nuclei, which in turn increases the diffuse component of solar radiation, and thus increases the photosynthesis of the forest canopy.

  19. The Cosmic Baryon Cycle and Galaxy Mass Assembly in the FIRE Simulations

    CERN Document Server

    Anglés-Alcázar, Daniel; Kereš, Dušan; Hopkins, Philip F; Quataert, Eliot; Murray, Norman

    2016-01-01

    We use cosmological simulations from the FIRE (Feedback In Realistic Environments) project to study the baryon cycle and galaxy mass assembly for central galaxies in the halo mass range $M_{\\rm halo} \\sim 10^{10} - 10^{13} M_{\\odot}$. By tracing cosmic inflows, galactic outflows, gas recycling, and merger histories, we quantify the contribution of physically distinct sources of material to galaxy growth. We show that in situ star formation fueled by fresh accretion dominates the early growth of galaxies of all masses, while the re-accretion of gas previously ejected in galactic winds often dominates the gas supply for a large portion of every galaxy's evolution. Externally processed material contributes increasingly to the growth of central galaxies at lower redshifts. This includes stars formed ex situ and gas delivered by mergers, as well as smooth intergalactic transfer of gas from other galaxies, an important but previously under-appreciated growth mode. By $z=0$, wind transfer, i.e. the exchange of gas b...

  20. Cosmic-ray exposure ages of chondrules

    Science.gov (United States)

    Roth, Antoine S. G.; Metzler, Knut; Baumgartner, Lukas P.; Leya, Ingo

    2016-07-01

    If chondrules were exposed to cosmic rays prior to meteorite compaction, they should retain an excess of cosmogenic noble gases. Beyersdorf-Kuis et al. (2015) showed that such excesses can be detected provided that the chemical composition of each individual chondrule is precisely known. However, their study was limited to a few samples as they had to be irradiated in a nuclear reactor for instrumental neutron activation analysis. We developed a novel analytical protocol that combines the measurements of He and Ne isotopic concentrations with a fast method to correct for differences in chemical composition using micro X-ray computed tomography. Our main idea is to combine noble gas, nuclear track, and petrography data for numerous chondrules to understand the precompaction exposure history of the chondrite parent bodies. Here, we report our results for a total of 77 chondrules and four matrix samples from NWA 8276 (L3.00), NWA 8007 (L3.2), and Bjurböle (L/LL4). All chondrules from the same meteorite have within uncertainty identical 21Ne exposure ages, and all chondrules from Bjurböle have within uncertainty identical 3He exposure ages. However, most chondrules from NWA 8276 and a few from NWA 8007 show small but resolvable differences in 3He exposure age that we attribute to matrix contamination and/or gas loss. The finding that none of the chondrules has noble gas excesses is consistent with the uniform track density found for each meteorite. We conclude that the studied chondrules did not experience a precompaction exposure longer than a few Ma assuming present-day flux of galactic cosmic rays. A majority of chondrules from L and LL chondrites thus rapidly accreted and/or was efficiently shielded from cosmic rays in the solar nebula.

  1. X-ray Multiple Diffraction Topographic Imaging Technique For Growth History Study of Habit Modifying Impurity Doped Crystals

    Institute of Scientific and Technical Information of China (English)

    LAI X.; MA C.; K. J. Robert; M. C. Miller

    2004-01-01

    A novel crystal characterization instrument has been built up in which a combination of X-ray multiple diffraction and X-ray topography is applied to enabling the cross-correlation between micro-crystallographic symmetry and its spatial dependence in relation to lattice defects. This facility is used to examine, in a selfconsistent manner, growth sector-dependant changes to both the crystallographic structure and the lattice defects associated with the action of habit-modifying additives in a number of representative crystal growth systems. In addition, the new instrument can be used to probe micro-crystallographic aspects (such as distortion to crystal symmetry) and relate these in a spatially resolved manner to the crystal defect structure in crystals doped with known habit modifiers.

  2. Cosmic Strings as the Source of Small-Scale Microwave Background Anisotropy

    CERN Document Server

    Pogosian, Levon; Wasserman, Ira; Wyman, Mark

    2008-01-01

    Cosmic string networks generate cosmological perturbations actively throughout the history of the universe. Thus, the string sourced anisotropy of the cosmic microwave background is not affected by Silk damping as much as the anisotropy seeded by inflation. The spectrum of perturbations generated by strings does not match the observed CMB spectrum on large angular scales (l2000) will dominate over that created by the primary inflationary perturbations. This range of angular scales in the CMB is presently being measured by a number of experiments; their results will test this prediction of cosmic string networks soon.

  3. Yangbajain Cosmic Ray Observatory -- The world's largest experimental base on high elevation

    Institute of Scientific and Technical Information of China (English)

    Tan Youheng

    2004-01-01

    @@ Cosmic rays are flows of highenergy particles coming from the deep of the universe as material samples voluntarily making their way to the Earth from an extra-terrestrial origin. They are involved with some key, unsolved and long-standing puzzles on the cosmic history, evolution of celestial bodies,spatial environment etc. On the Earth's surface, the observation of the primary cosmic rays is to detect the groups of secondary particles resulting from the interaction between them and the atomic nuclei of the atmosphere - the extensive air shower (EAS).

  4. Cosmic-ray-produced neon and helium in the summit lavas of Maui

    Science.gov (United States)

    Marti, K.; Craig, H.

    1987-01-01

    The identification of cosmic-ray-produced Ne-21c in addition to He-3c, components attributed to cosmic ray-induced spallation reactions, are reported in gases extracted by fusion of olivines and clinopyroxenes after vacuum-crushing. The observed (He-3/Ne-21)c ratios and the ratio of Ne-21c in olivine to that in clinopyroxene are consistent with an in situ origin of He-3c and Ne-21c by cosmic-ray spallation reactions. These components could be important for interpreting helium isotopic data in terrestrial reservoirs. Geophysical applications could include determinations of erosion rates and exposure histories of terrestrial rocks.

  5. PLASMA EFFECTS ON EXTRAGALACTIC ULTRAHIGH-ENERGY COSMIC-RAY HADRON BEAMS IN COSMIC VOIDS. II. KINETIC INSTABILITY OF PARALLEL ELECTROSTATIC WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Krakau, S.; Schlickeiser, R., E-mail: steffen.krakau@rub.de, E-mail: rsch@tp4.rub.de [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)

    2016-02-20

    The linear instability of an ultrarelativistic hadron beam in the unmagnetized intergalactic medium (IGM) is investigated with respect to the excitation of parallel electrostatic and electromagnetic fluctuations. This analysis is important for the propagation of extragalactic ultrarelativistic cosmic rays from their distant sources to Earth. As opposed to the previous paper, we calculate the minimum instability growth time for Lorentz-distributed cosmic rays which traverse the hot IGM. The growth times are orders of magnitude higher than the cosmic-ray propagation time in the IGM. Since the backreaction of the generated plasma fluctuations (plateauing) lasts longer than the propagation time, the cosmic-ray hadron beam can propagate to the Earth without losing a significant amount of energy to electrostatic turbulence.

  6. Gravitational energy as dark energy: Cosmic structure and apparent acceleration

    CERN Document Server

    Wiltshire, David L

    2011-01-01

    Below scales of about 100/h Mpc our universe displays a complex inhomogeneous structure dominated by voids, with clusters of galaxies in sheets and filaments. The coincidence that cosmic expansion appears to start accelerating at the epoch when such structures form has prompted a number of researchers to question whether dark energy is a signature of a failure of the standard cosmology to properly account, on average, for the distribution of matter we observe. Here I discuss the timescape scenario, in which cosmic acceleration is understood as an apparent effect, due to gravitational energy gradients that grow when spatial curvature gradients become significant with the nonlinear growth of cosmic structure. I discuss conceptual issues related to the averaging problem, and their impact on the calibration of local geometry to the solutions of the volume-average evolution equations corrected by backreaction, and the question of nonbaryonic dark matter in the timescape framework. I further discuss recent work on ...

  7. Inhomogeneous recombinations during cosmic reionization

    OpenAIRE

    Sobacchi, Emanuele; Mesinger, Andrei

    2014-01-01

    By depleting the ionizing photon budget available to expand cosmic HII regions, recombining systems (or Lyman limit systems) can have a large impact during (and following) cosmic reionization. Unfortunately, directly resolving such structures in large-scale reionization simulations is computationally impractical. Instead, here we implement a sub-grid prescription for tracking inhomogeneous recombinations in the intergalactic medium. Building on previous work parameterizing photo-heating feedb...

  8. Cosmic rays from thermal sources

    CERN Document Server

    Wlodarczyk, Z

    2007-01-01

    The energy spectrum of cosmic rays (CR) exhibits very characteristic power-like behavior with the "knee" structure. We consider a generalized statistical model for the production process of cosmic rays which accounts for such behavior in a natural way either by assuming the existence of temperature fluctuations in the source of CR, or by assuming specific temperature distribution of the CR sources. Both possibilities yield the so called Tsallis statistics and lead to the power-like distribution.

  9. Cosmic rays and Earth's climate

    DEFF Research Database (Denmark)

    Svensmark, Henrik

    2000-01-01

    During the last solar cycle the Earth's cloud cover underwent a modulation in phase with the cosmic ray flux. Assuming that there is a causal relationship between the two, it is expected and found that the Earth's temperature follows more closely decade variations in cosmic ray flux than other...... solar activity parameters. If the relationship is real the state of the Heliosphere affects the Earth's climate....

  10. Calculation of cosmic ray induced single event upsets: Program CRUP (Cosmic Ray Upset Program)

    Science.gov (United States)

    Shapiro, P.

    1983-09-01

    This report documents PROGRAM CRUP, COSMIC RAY UPSET PROGRAM. The computer program calculates cosmic ray induced single-event error rates in microelectronic circuits exposed to several representative cosmic-ray environments.

  11. Cosmic Rays and Particle Physics

    Science.gov (United States)

    Gaisser, Thomas K.; Engel, Ralph; Resconi, Elisa

    2016-06-01

    Preface to the first edition; Preface to the second edition; 1. Cosmic rays; 2. Cosmic ray data; 3. Particle physics; 4. Hadronic interactions and accelerator data; 5. Cascade equations; 6. Atmospheric muons and neutrinos; 7. Neutrino masses and oscillations; 8. Muons and neutrinos underground; 9. Cosmic rays in the Galaxy; 10. Extragalactic propagation of cosmic rays; 11. Astrophysical - rays and neutrinos; 12. Acceleration; 13. Supernovae in the Milky Way; 14. Astrophysical accelerators and beam dumps; 15. Electromagnetic cascades; 16. Extensive air showers; 17. Very high energy cosmic rays; 18. Neutrino astronomy; A.1. Units, constants and definitions; A.2. References to flux measurements; A.3. Particle flux, density, and interaction cross section; A.4. Fundamentals of scattering theory; A.5. Regge amplitude; A.6. Glauber model of nuclear cross sections; A.7. Earth's atmosphere; A.8. Longitudinal development of air showers; A.9. Secondary positrons and electrons; A.10. Liouville's theorem and cosmic ray propagation; A.11. Cosmology and distances measures; A.12. The Hillas splitting algorithm; References; Index.

  12. Cosmic Microwave Background Mapping

    Science.gov (United States)

    Verkhodanov, O. V.; Doroshkevich, A. G.

    2012-03-01

    The last decade of research in cosmology was connected with the ambitious experiments including space and ground base observations. Among the most impressive results of these investigations are the measurements of the cosmic microwave background (CMB) radiation like WMAP* and Planck. Exactly from the CMB studies, we have started the epoch of the precision cosmology when generally the values of cosmological parameters have been known and present research is devoted to improvement of the precision. These achievements are connected with both the creation of the new facilities in millimeter and submillimeter astronomy (e.g., satellites, receivers, antennas, computers) and development of the methods for the CMB data analysis. Actually, the process of data analysis contains several technical stages including 1. Registration of time-ordered data (TOD) 2. Pixelization of the CMB data - map preparation 3. Component separation 4. Map statistics analysis 5. Map - spherical harmonics transformation 6. C(l)-spectrum calculation and spectrum statistics analysis 7. Cosmological parameters estimation Starting from the cosmic background explorer (COBE) experiment using the so-called Quadrilateralized Sky Cube Projection (see [1-3]), the problem of the whole sky CMB pixelization has attracted great interest and many such schemes were developed. Let us note however that accurate pixelization of the CMB data on the sphere is very important but not the final step of analysis. Usually, the next step implies the determination of the coefficients of the spherical harmonic decomposition of the CMB signal for both anisotropy and polarization. This means that some of the pixelization schemes provide a very accurate map but are inconvenient for further decomposition. This also means that the choice of suitable pixelization schemes depends upon the general goals of the investigation. In this review, we consider several of the most popular sky map pixelization schemes and link them with the

  13. Global simulations of galactic winds including cosmic ray streaming

    CERN Document Server

    Ruszkowski, Mateusz; Zweibel, Ellen

    2016-01-01

    Galactic outflows play an important role in galactic evolution. Despite their importance, a detailed understanding of the physical mechanisms responsible for the driving of these winds is lacking. In an effort to gain more insight into the nature of these flows, we perform global three-dimensional magneto-hydrodynamical simulations of an isolated Milky Way-size starburst galaxy. We focus on the dynamical role of cosmic rays injected by supernovae, and specifically on the impact of the streaming and anisotropic diffusion of cosmic rays along the magnetic fields. We find that these microphysical effects can have a significant effect on the wind launching and mass loading factors depending on the details of the plasma physics. Due to the cosmic ray streaming instability, cosmic rays propagating in the interstellar medium scatter on self-excited Alfven waves and couple to the gas. When the wave growth due to the streaming instability is inhibited by some damping process, such as the turbulent damping, the cosmic ...

  14. Illustrated cosmic monopole

    CERN Document Server

    Seagrave, Wyken

    2015-01-01

    Truly bizarre, utterly unique I've never read a novel quite like this before. The author takes you on an exciting adventure full of unforgettable and vivid imagery. Solidly written with each character's personality shining through. If you find physics fascinating you will not be disappointed by the author's keen intellect and clear understanding of this most challenging (for me anyway) scientific subject. This is not a novel I will forget anytime soon, I would highly recommend it. Andrewly Very imaginative tale Anybody interested in a very imaginative and engrossing sci fi story needs to check this one out. I have been reading sci fi for decades and this story has elements that surprise me which is very unusual considering the number of novels and stories I have over the years. ric freeman Summary of the story The cosmic monopole has been wandering the Universe since it was created in the Big Bang. Its existence is fundamental to the way the Universe works. It is finally trapped by the powerful magnetic f...

  15. Cosmic string loop microlensing

    Science.gov (United States)

    Bloomfield, Jolyon K.; Chernoff, David F.

    2014-06-01

    Cosmic superstring loops within the galaxy microlens background point sources lying close to the observer-string line of sight. For suitable alignments, multiple paths coexist and the (achromatic) flux enhancement is a factor of two. We explore this unique type of lensing by numerically solving for geodesics that extend from source to observer as they pass near an oscillating string. We characterize the duration of the flux doubling and the scale of the image splitting. We probe and confirm the existence of a variety of fundamental effects predicted from previous analyses of the static infinite straight string: the deficit angle, the Kaiser-Stebbins effect, and the scale of the impact parameter required to produce microlensing. Our quantitative results for dynamical loops vary by O(1) factors with respect to estimates based on infinite straight strings for a given impact parameter. A number of new features are identified in the computed microlensing solutions. Our results suggest that optical microlensing can offer a new and potentially powerful methodology for searches for superstring loop relics of the inflationary era.

  16. Cosmic ray driven outflows

    CERN Document Server

    Hanasz, Michal; Naab, Thorsten; Gawryszczak, Artur; Kowalik, Kacper; Wóltański, Dominik

    2013-01-01

    We present simulations of the magnetized interstellar medium (ISM) in models of massive star forming (40 Msun / yr) disk galaxies with high gas surface densities (~100 Msun / pc^2) similar to observed star forming high-redshift disks. We assume that type II supernovae deposit 10 per cent of their energy into the ISM as cosmic rays and neglect the additional deposition of thermal energy or momentum. With a typical Galactic diffusion coefficient for CRs (3e28 cm^2 / s) we demonstrate that this process alone can trigger the local formation of a strong low density galactic wind maintaining vertically open field lines. Driven by the additional pressure gradient of the relativistic fluid the wind speed can exceed 1000 km/s, much higher than the escape velocity of the galaxy. The global mass loading, i.e. the ratio of the gas mass leaving the galactic disk in a wind to the star formation rate becomes of order unity once the system has settled into an equilibrium. We conclude that relativistic particles accelerated i...

  17. Cosmic Ray Helium Hardening

    CERN Document Server

    Ohira, Yutaka

    2010-01-01

    Recent observations by CREAM, ATIC-2 and PAMELA experiments suggest that (1) the spectrum of cosmic ray (CR) helium is harder than that of CR proton below the knee $10^15 eV$ and (2) all CR spectra become hard at $\\gtrsim 10^{11} eV/n$. We propose a new picture that higher energy CRs are generated in more helium-rich region to explain the hardening (1) without introducing different sources for CR helium. The helium to proton ratio at $\\sim 100$ TeV exceeds the Big Bang abundance $Y=0.25$ by several times, and the different spectrum is not reproduced within the diffusive shock acceleration theory. We argue that CRs are produced in the chemically enriched region, such as a superbubble, and the outward-decreasing abundance naturally leads to the hard spectrum of CR helium when escaping from the supernova remnant (SNR) shock. We provide a simple analytical spectrum that also fits well the hardening (2) because of the decreasing Mach number in the hot superbubble with $\\sim 10^6$ K. Our model predicts hard and con...

  18. The Cosmic Origins Spectrograph

    CERN Document Server

    Green, James C; Osterman, Steve; Ebbets, Dennis; Heap, Sara H; Linsky, Claus Leitherer Jeffrey L; Savage, Blair D; Sembach, Kenneth; Shull, J Michael; Siegmund, Oswald H W; Snow, Theodore P; Spencer, John; Stern, S Alan; Stocke, John; Welsh, Barry; Beland, Stephane; Burgh, Eric B; Danforth, Charles; France, Kevin; Keeney, Brian; McPhate, Jason; Penton, Steven V; Andrews, John; Brownsberger, Kenneth; Morse, Jon; Wilkinson, Erik

    2011-01-01

    The Cosmic Origins Spectrograph (COS) is a moderate-resolution spectrograph with unprecedented sensitivity that was installed into the Hubble Space Telescope (HST) in May 2009, during HST Servicing Mission 4 (STS-125). We present the design philosophy and summarize the key characteristics of the instrument that will be of interest to potential observers. For faint targets, with flux F_lambda ~ 1.0E10-14 ergs/s/cm2/Angstrom, COS can achieve comparable signal to noise (when compared to STIS echelle modes) in 1-2% of the observing time. This has led to a significant increase in the total data volume and data quality available to the community. For example, in the first 20 months of science operation (September 2009 - June 2011) the cumulative redshift pathlength of extragalactic sight lines sampled by COS is 9 times that sampled at moderate resolution in 19 previous years of Hubble observations. COS programs have observed 214 distinct lines of sight suitable for study of the intergalactic medium as of June 2011....

  19. Cosmic rays and terrestrial life: A brief review

    Science.gov (United States)

    Atri, Dimitra; Melott, Adrian L.

    2014-01-01

    “The investigation into the possible effects of cosmic rays on living organisms will also offer great interest.” - Victor F. Hess, Nobel Lecture, December 12, 1936 High-energy radiation bursts are commonplace in our Universe. From nearby solar flares to distant gamma ray bursts, a variety of physical processes accelerate charged particles to a wide range of energies, which subsequently reach the Earth. Such particles contribute to a number of physical processes occurring in the Earth system. A large fraction of the energy of charged particles gets deposited in the atmosphere, ionizing it, causing changes in its chemistry and affecting the global electric circuit. Remaining secondary particles contribute to the background dose of cosmic rays on the surface and parts of the subsurface region. Life has evolved over the past ∼3 billion years in presence of this background radiation, which itself has varied considerably during the period [1-3]. As demonstrated by the Miller-Urey experiment, lightning plays a very important role in the formation of complex organic molecules, which are the building blocks of more complex structures forming life. There is growing evidence of increase in the lightning rate with increasing flux of charged particles. Is there a connection between enhanced rate of cosmic rays and the origin of life? Cosmic ray secondaries are also known to damage DNA and cause mutations, leading to cancer and other diseases. It is now possible to compute radiation doses from secondary particles, in particular muons and neutrons. Have the variations in cosmic ray flux affected the evolution of life on earth? We describe the mechanisms of cosmic rays affecting terrestrial life and review the potential implications of the variation of high-energy astrophysical radiation on the history of life on earth.

  20. Introducing the Illustris project: the evolution of galaxy populations across cosmic time

    Science.gov (United States)

    Genel, Shy; Vogelsberger, Mark; Springel, Volker; Sijacki, Debora; Nelson, Dylan; Snyder, Greg; Rodriguez-Gomez, Vicente; Torrey, Paul; Hernquist, Lars

    2014-11-01

    We present an overview of galaxy evolution across cosmic time in the Illustris simulation. Illustris is an N-body/hydrodynamical simulation that evolves 2 × 18203 resolution elements in a (106.5 Mpc)3 box from cosmological initial conditions down to z = 0 using the AREPO moving-mesh code. The simulation uses a state-of-the-art set of physical models for galaxy formation that was tuned to reproduce the z = 0 stellar mass function and the history of the cosmic star formation rate density. We find that Illustris successfully reproduces a plethora of observations of galaxy populations at various redshifts, for which no tuning was performed, and provide predictions for future observations. In particular, we discuss (a) the buildup of galactic mass, showing stellar mass functions and the relations between stellar mass and halo mass from z = 7 to 0, (b) galaxy number density profiles around massive central galaxies out to z = 4, (c) the gas and total baryon content of both galaxies and their haloes for different redshifts, and as a function of mass and radius, and (d) the evolution of galaxy specific star formation rates up to z = 8. In addition, we (i) present a qualitative analysis of galaxy morphologies from z = 5 to 0, for the stellar as well as the gaseous components, and their appearance in Hubble Space Telescope mock observations, (ii) follow galaxies selected at z = 2 to their z = 0 descendants, and quantify their growth and merger histories, and (iii) track massive z = 0 galaxies to high redshift and study their joint evolution in star formation activity and compactness. We conclude with a discussion of several disagreements with observations, and lay out possible directions for future research.

  1. Ice Processes and Growth History on Arctic and Sub-Arctic Lakes Using ERS-1 SAR Data

    Science.gov (United States)

    Morris, K.; Jeffries, M. O.; Weeks, W. F.

    1995-01-01

    A survey of ice growth and decay processes on a selection of shallow and deep sub-Arctic and Arctic lakes was conducted using radiometrically calibrated ERS-1 SAR images. Time series of radar backscatter data were compiled for selected sites on the lakes during the period ot ice cover (September to June) for the years 1991-1992 and 1992-1993. A variety of lake-ice processes could be observed, and significant changes in backscatter occurred from the time of initial ice formation in autumn until the onset of the spring thaw. Backscatter also varied according to the location and depth of the lakes. The spatial and temporal changes in backscatter were most constant and predictable at the shallow lakes on the North Slope of Alaska. As a consequence, they represent the most promising sites for long-term monitoring and the detection of changes related to global warming and its effects on the polar regions.

  2. Serum concentrations of fibroblast growth factors 19 and 21 in women with gestational diabetes mellitus: association with insulin resistance, adiponectin, and polycystic ovary syndrome history.

    Science.gov (United States)

    Wang, Dongyu; Zhu, Wenjing; Li, Jieming; An, Chongyou; Wang, Zilian

    2013-01-01

    Fibroblast growth factor 19 (FGF19) and FGF21 are considered to be novel adipokines that improve glucose tolerance and insulin sensitivity. In the current study, we investigated serum FGF19 and FGF21 levels in patients with gestational diabetes mellitus (GDM) and explored their relationships with anthropometric and endocrine parameters. Serum FGF19 and FGF21 levels were determined by enzyme-linked immunosorbent assay (ELISA) in patients with GDM (n = 30) and healthy pregnant controls (n = 60) matched for maternal and gestational age. Serum FGF19 and FGF21 levels were correlated with anthropometric, metabolic, and endocrine parameters. Circulating levels of FGF19 were significantly reduced in patients with GDM relative to healthy pregnant subjects, whereas FGF21 levels were increased in GDM patients. Serum FGF19 levels independently and inversely correlated with insulin resistance (increased homeostasis model assessment of insulin resistance, HOMA-IR) and were positively related to serum adiponectin in both groups. In contrast, serum FGF21 levels independently and positively correlated with insulin resistance and serum triglycerides and were inversely related to serum adiponectin. In addition, in the combined population of both groups, those women with preconception polycystic ovary syndrome (PCOS) history had the lowest levels of FGF19, which were significantly lower than those in GDM patients without PCOS history and those in controls without PCOS history. Circulating FGF19 levels are reduced in GDM patients, in contrast with FGF21 levels. Both serum FGF19 and FGF21 levels are strongly related to insulin resistance and serum levels of adiponectin. Considering the different situation between FGF19 and FGF21, we suggest that reduced serum FGF19 levels could be involved in the pathophysiology of GDM, while increased serum FGF21 levels could be in a compensatory response to this disease.

  3. Serum concentrations of fibroblast growth factors 19 and 21 in women with gestational diabetes mellitus: association with insulin resistance, adiponectin, and polycystic ovary syndrome history.

    Directory of Open Access Journals (Sweden)

    Dongyu Wang

    Full Text Available BACKGROUND: Fibroblast growth factor 19 (FGF19 and FGF21 are considered to be novel adipokines that improve glucose tolerance and insulin sensitivity. In the current study, we investigated serum FGF19 and FGF21 levels in patients with gestational diabetes mellitus (GDM and explored their relationships with anthropometric and endocrine parameters. METHOD: Serum FGF19 and FGF21 levels were determined by enzyme-linked immunosorbent assay (ELISA in patients with GDM (n = 30 and healthy pregnant controls (n = 60 matched for maternal and gestational age. Serum FGF19 and FGF21 levels were correlated with anthropometric, metabolic, and endocrine parameters. RESULTS: Circulating levels of FGF19 were significantly reduced in patients with GDM relative to healthy pregnant subjects, whereas FGF21 levels were increased in GDM patients. Serum FGF19 levels independently and inversely correlated with insulin resistance (increased homeostasis model assessment of insulin resistance, HOMA-IR and were positively related to serum adiponectin in both groups. In contrast, serum FGF21 levels independently and positively correlated with insulin resistance and serum triglycerides and were inversely related to serum adiponectin. In addition, in the combined population of both groups, those women with preconception polycystic ovary syndrome (PCOS history had the lowest levels of FGF19, which were significantly lower than those in GDM patients without PCOS history and those in controls without PCOS history. CONCLUSIONS: Circulating FGF19 levels are reduced in GDM patients, in contrast with FGF21 levels. Both serum FGF19 and FGF21 levels are strongly related to insulin resistance and serum levels of adiponectin. Considering the different situation between FGF19 and FGF21, we suggest that reduced serum FGF19 levels could be involved in the pathophysiology of GDM, while increased serum FGF21 levels could be in a compensatory response to this disease.

  4. Cosmic web imager

    Science.gov (United States)

    Rahman, Shahinur; Martin, Chris; McLean, Ryan; Matuszewski, Matt; Chang, Daphne

    2006-06-01

    We are developing the Cosmic Web Imager (CWI) to detect and map emission from the intergalactic medium (IGM). CWI will observe the strong, redshift UV resonance lines of Lyα 1216, CIV 1550, and OVI 1033 over 3600-9000 Å to trace IGM at 1 view of 60 × 40 arcsec2 for observing extended emission over a large region. The spectrograph using Volume-Phase Holographic gratings have high peak diffraction efficiency and are tunable for covering a large bandpass with a single grating. A low read noise CCD combined with source/background shiftand-nod allowing control of systematics and Poisson-imited sky subtraction to observe the low surface brightness universe. With a resolution of R=10,000 CWI is sensitive to limiting surface brightness ranging from 25 - 27.5 mag/arcsec2 (10 min - 8 hours integration). Recent high resolution simulations predict Lyα Fluorescence from IGM at 100 - 1000 LU1. CWI with sensitivity of ~200 LU improves the current observational effort by an order of magnitude and enables us to explore wide range of overdensity (δ ~ 30 - 104) testing the standard model of structure formation in the universe. CWI also serves as the counter part to the balloon borne integral-field spectrograph Faint Intergalactic medium Redshifted Emission Balloon (FIREBALL) currently being built and planned to be launched in Summer 2007. FIREBALL will observe Lyα Fluorescence from IGM at z = 0.7. CWI combined with FIREBALL will enable us to observe the evolution of IGM and the low surface brightness universe.

  5. Cosmic logic: a computational model

    Science.gov (United States)

    Vanchurin, Vitaly

    2016-02-01

    We initiate a formal study of logical inferences in context of the measure problem in cosmology or what we call cosmic logic. We describe a simple computational model of cosmic logic suitable for analysis of, for example, discretized cosmological systems. The construction is based on a particular model of computation, developed by Alan Turing, with cosmic observers (CO), cosmic measures (CM) and cosmic symmetries (CS) described by Turing machines. CO machines always start with a blank tape and CM machines take CO's Turing number (also known as description number or Gödel number) as input and output the corresponding probability. Similarly, CS machines take CO's Turing number as input, but output either one if the CO machines are in the same equivalence class or zero otherwise. We argue that CS machines are more fundamental than CM machines and, thus, should be used as building blocks in constructing CM machines. We prove the non-computability of a CS machine which discriminates between two classes of CO machines: mortal that halts in finite time and immortal that runs forever. In context of eternal inflation this result implies that it is impossible to construct CM machines to compute probabilities on the set of all CO machines using cut-off prescriptions. The cut-off measures can still be used if the set is reduced to include only machines which halt after a finite and predetermined number of steps.

  6. Cosmic Microwave Background Data Analysis

    Science.gov (United States)

    Paykari, Paniez; Starck, Jean-Luc Starck

    2012-03-01

    About 400,000 years after the Big Bang the temperature of the Universe fell to about a few thousand degrees. As a result, the previously free electrons and protons combined and the Universe became neutral. This released a radiation which we now observe as the cosmic microwave background (CMB). The tiny fluctuations* in the temperature and polarization of the CMB carry a wealth of cosmological information. These so-called temperature anisotropies were predicted as the imprints of the initial density perturbations which gave rise to the present large-scale structures such as galaxies and clusters of galaxies. This relation between the present-day Universe and its initial conditions has made the CMB radiation one of the most preferred tools to understand the history of the Universe. The CMB radiation was discovered by radio astronomers Arno Penzias and Robert Wilson in 1965 [72] and earned them the 1978 Nobel Prize. This discovery was in support of the Big Bang theory and ruled out the only other available theory at that time - the steady-state theory. The crucial observations of the CMB radiation were made by the Far-Infrared Absolute Spectrophotometer (FIRAS) instrument on the Cosmic Background Explorer (COBE) satellite [86]- orbited in 1989-1996. COBE made the most accurate measurements of the CMB frequency spectrum and confirmed it as being a black-body to within experimental limits. This made the CMB spectrum the most precisely measured black-body spectrum in nature. The CMB has a thermal black-body spectrum at a temperature of 2.725 K: the spectrum peaks in the microwave range frequency of 160.2 GHz, corresponding to a 1.9mmwavelength. The results of COBE inspired a series of ground- and balloon-based experiments, which measured CMB anisotropies on smaller scales over the next decade. During the 1990s, the first acoustic peak of the CMB power spectrum (see Figure 5.1) was measured with increasing sensitivity and by 2000 the BOOMERanG experiment [26] reported

  7. HD/H2 as a probe of the roles of gas, dust, light, metallicity and cosmic rays in promoting the growth of molecular hydrogen in the diffuse interstellar medium

    CERN Document Server

    Liszt, H S

    2014-01-01

    We modelled recent observations of UV absorption of HD and \\HH\\ in the Milky Way and toward damped/sub-damped Lyman alpha systems at z=0.18 and z $>$ 1.7. N(HD)/N(\\HH) ratios reflect the separate self-shieldings of HD and \\HH\\ and the coupling introduced by deuteration chemistry. Locally, observations are explained by diffuse molecular gas with $ 16 \\pccc \\la$ n(H) $\\la 128 \\pccc $ if the cosmic-ray ionization rate per H-nucleus \\zetaH $= 2\\times 10^{-16}\\ps$ as inferred from \\H3\\p\\ and OH\\p. The dominant influence on N(HD)/N(\\HH) is the cosmic-ray ionization rate with a much weaker downward dependence on n(H) at Solar metallicity, but dust-extinction can drive N(HD) higher as with N(\\HH). At z $>$ 1.7, N(HD) is comparable to the Galaxy but with 10x smaller N(\\HH) and somewhat smaller N(\\HH)/N(H I). Comparison of our Galaxy and the Magellanic Clouds shows that smaller \\HH/H is expected at sub-Solar metallicity and we show by modelling that HD/\\HH\\ increases with density at low metallicity, opposite to the Mil...

  8. Clusters and the Cosmic Web

    CERN Document Server

    Van de Weygaert, R

    2006-01-01

    We discuss the intimate relationship between the filamentary features and the rare dense compact cluster nodes in this network, via the large scale tidal field going along with them, following the cosmic web theory developed Bond et al. The Megaparsec scale tidal shear pattern is responsible for the contraction of matter into filaments, and its link with the cluster locations can be understood through the implied quadrupolar mass distribution in which the clusters are to be found at the sites of the overdense patches. We present a new technique for tracing the cosmic web, identifying planar walls, elongated filaments and cluster nodes in the galaxy distribution. This will allow the practical exploitation of the concept of the cosmic web towards identifying and tracing the locations of the gaseous WHIM. These methods, the Delaunay Tessellation Field Estimator (DTFE) and the Morphology Multiscale Filter (MMF) find their basis in computational geometry and visualization.

  9. Cosmic rays and particle physics

    CERN Document Server

    Gaisser, Thomas K; Resconi, Elisa

    2016-01-01

    Fully updated for the second edition, this book introduces the growing and dynamic field of particle astrophysics. It provides an overview of high-energy nuclei, photons and neutrinos, including their origins, their propagation in the cosmos, their detection on Earth and their relation to each other. Coverage is expanded to include new content on high energy physics, the propagation of protons and nuclei in cosmic background radiation, neutrino astronomy, high-energy and ultra-high-energy cosmic rays, sources and acceleration mechanisms, and atmospheric muons and neutrinos. Readers are able to master the fundamentals of particle astrophysics within the context of the most recent developments in the field. This book will benefit graduate students and established researchers alike, equipping them with the knowledge and tools needed to design and interpret their own experiments and, ultimately, to address a number of questions concerning the nature and origins of cosmic particles that have arisen in recent resea...

  10. Cosmic Ray Origins: An Introduction

    Science.gov (United States)

    Blandford, Roger; Simeon, Paul; Yuan, Yajie

    2014-11-01

    Physicists have pondered the origin of cosmic rays for over a hundred years. However the last few years have seen an upsurge in the observation, progress in the theory and a genuine increase in the importance attached to the topic due to its intimate connection to the indirect detection of evidence for dark matter. The intent of this talk is to set the stage for the meeting by reviewing some of the basic features of the entire cosmic ray spectrum from GeV to ZeV energy and some of the models that have been developed. The connection will also be made to recent developments in understanding general astrophysical particle acceleration in pulsar wind nebulae, relativistic jets and gamma ray bursts. The prospects for future discoveries, which may elucidate the origin of cosmic rays, are bright.

  11. Cosmic Ray Origins: An Introduction

    Energy Technology Data Exchange (ETDEWEB)

    Blandford, Roger; Simeon, Paul; Yuan, Yajie

    2014-11-15

    Physicists have pondered the origin of cosmic rays for over a hundred years. However the last few years have seen an upsurge in the observation, progress in the theory and a genuine increase in the importance attached to the topic due to its intimate connection to the indirect detection of evidence for dark matter. The intent of this talk is to set the stage for the meeting by reviewing some of the basic features of the entire cosmic ray spectrum from GeV to ZeV energy and some of the models that have been developed. The connection will also be made to recent developments in understanding general astrophysical particle acceleration in pulsar wind nebulae, relativistic jets and gamma ray bursts. The prospects for future discoveries, which may elucidate the origin of cosmic rays, are bright.

  12. Cosmic Ray Origins: An Introduction

    CERN Document Server

    Blandford, Roger; Yuan, Yajie

    2014-01-01

    Physicists have pondered the origin of cosmic rays for over a hundred years. However the last few years have seen an upsurge in the observation, progress in the theory and a genuine increase in the importance attached to the topic due to its intimate connection to the indirect detection of evidence for dark matter. The intent of this talk is to set the stage for the meeting by reviewing some of the basic features of the entire cosmic ray spectrum from GeV to ZeV energy and some of the models that have been developed. The connection will also be made to recent developments in understanding general astrophysical particle acceleration in pulsar wind nebulae, relativistic jets and gamma ray bursts. The prospects for future discoveries, which may elucidate the origin of cosmic rays, are bright.

  13. Cosmic Ray Energetics and Mass

    CERN Document Server

    Baylon cardiel, J L; Wallace, K C; Anderson, T B; Copley, M

    The cosmic-ray energetics and mass (CREAM) investigation is designed to measure cosmic-ray composition to the supernova energy scale of 10$^{15}$ eV in a series of ultra long duration balloon (ULDB) flights. The first flight is planned to be launched from Antarctica in December 2004. The goal is to observe cosmic-ray spectral features and/or abundance changes that might signify a limit to supernova acceleration. The particle ($\\{Z}$) measurements will be made with a timing-based charge detector and a pixelated silicon charge detector to minimize the effect of backscatter from the calorimeter. The particle energy measurements will be made with a transition radiation detector (TRD) for $\\{Z}$ > 3 and a sampling tungsten/scintillator calorimeter for $\\{Z}$ $\\geq$1 particles, allowing inflight cross calibration of the two detectors. The status of the payload construction and flight preparation are reported in this paper.

  14. Cosmic Rays: What Gamma Rays Can Say

    OpenAIRE

    2014-01-01

    We will review the main channels of gamma ray emission due to the acceleration and propagation of cosmic rays, discussing the cases of both galactic and extra-galactic cosmic rays and their connection with gamma rays observations.

  15. Rates of molecular evolution vary in vertebrates for insulin-like growth factor-1 (IGF-1), a pleiotropic locus that regulates life history traits.

    Science.gov (United States)

    Sparkman, Amanda M; Schwartz, Tonia S; Madden, Jill A; Boyken, Scott E; Ford, Neil B; Serb, Jeanne M; Bronikowski, Anne M

    2012-08-01

    Insulin-like growth factor-1 (IGF-1) is a member of the vertebrate insulin/insulin-like growth factor/relaxin gene family necessary for growth, reproduction, and survival at both the cellular and organismal level. Its sequence, protein structure, and function have been characterized in mammals, birds, and fish; however, a notable gap in our current knowledge of the function of IGF-1 and its molecular evolution is information in ectothermic reptiles. To address this disparity, we sequenced the coding region of IGF-1 in 11 reptile species-one crocodilian, three turtles, three lizards, and four snakes. Complete sequencing of the full mRNA transcript of a snake revealed the Ea-isoform, the predominant isoform of IGF-1 also reported in other vertebrate groups. A gene tree of the IGF-1 protein-coding region that incorporated sequences from diverse vertebrate groups showed similarity to the species phylogeny, with the exception of the placement of Testudines as sister group to Aves, due to their high nucleotide sequence similarity. In contrast, long-branch lengths indicate more rapid divergence in IGF-1 among lizards and snakes. Additionally, lepidosaurs (i.e., lizards and snakes) had higher rates of non-synonymous:synonymous substitutions (dN/dS) relative to archosaurs (i.e., birds and crocodilians) and turtles. Tests for positive selection on specific codons within branches and evaluation of the changes in the amino acid properties, suggested positive selection in lepidosaurs on the C domain of IGF-1, which is involved in binding affinity to the IGF-1 receptor. Predicted structural changes suggest that major alterations in protein structure and function may have occurred in reptiles. These data propose new insights into the molecular co-evolution of IGF-1 and its receptors, and ultimately the evolution of IGF-1's role in regulating life-history traits across vertebrates.

  16. The Cosmic Shoreline

    Science.gov (United States)

    Zahnle, Kevin J.; Catling, D. C.

    2013-01-01

    in 2004 when there were just two transiting exoplanets to consider. The trend was well-defined by late 2007. Figure 1 shows how matters stood in Dec 2012 with approx.240 exoplanets. The figure shows that the boundary between planets with and without active volatiles - the cosmic shoreline, as it were - is both well-defined and follows a power law.

  17. Neutralino Clumps and Cosmic Rays

    CERN Document Server

    Salati, P

    2007-01-01

    The halo of the Miky Way might contain numerous and dense substructures inside which the putative weakly interacting massive particles (suggested as the main constituent of the astronomical dark matter) would produce a stronger annihilation signal than in the smooth regions. The closer the nearest clump, the larger the positron and antiproton cosmic ray fluxes at the Earth. But the actual distribution of these substructures is not known. The predictions on the antimatter yields at the Earth are therefore affected by a kind of cosmic variance whose analysis is the subject of this contribution. The statistical tools to achieve that goal are presented and Monte Carlo simulations are compared to analytic results.

  18. Cosmic Strings with Small Tension

    CERN Document Server

    Halyo, Edi

    2009-01-01

    We describe cosmic F--term strings with exponentially small tension which are D3 branes wrapped on deformed $A_3$ singularities. We show that brane instanton effects which can be calculated after a geometric transition give rise to an exponentially small volume for the node on which the D3 branes wrap leading to a string with small tension. We generalize our description to the case of non--Abelian cosmic strings and argue that these strings are stable against monopole--anti monopole pair creation.

  19. Aligned interactions in cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Kempa, J., E-mail: kempa@pw.plock.pl [Warsaw University of Technology Branch Plock (Poland)

    2015-12-15

    The first clean Centauro was found in cosmic rays years many ago at Mt Chacaltaya experiment. Since that time, many people have tried to find this type of interaction, both in cosmic rays and at accelerators. But no one has found a clean cases of this type of interaction.It happened finally in the last exposure of emulsion at Mt Chacaltaya where the second clean Centauro has been found. The experimental data for both the Centauros and STRANA will be presented and discussed in this paper. We also present our comments to the intriguing question of the existence of a type of nuclear interactions at high energy with alignment.

  20. Closing CMS to hunt cosmic rays

    CERN Multimedia

    Claudia Marcelloni

    2006-01-01

    Every second the Earth is bombarded by billions of cosmic rays and occasionally one of these cosmic particles will collide with the Earth's atmosphere generating a shower of particles known as an 'air shower'. This is similiar to the collisions and subsequent particle showers observed in accelerators such as the LHC. Here the CMS detector is closed so that systems can be tested using muon cosmic rays in the 'Cosmic Challenge'.

  1. Cosmic-Ray Detectors With Interdigitated Electrodes

    Science.gov (United States)

    Cunningham, Thomas J.; Mazed, Mohammed; Holtzman, Melinda J.; Fossum, Eric R.

    1995-01-01

    Detectors measure both positions of incidence and energies of incident charged particles. Stack of detector wafers intercept cosmic ray. Measure positions of incidence to determine cosmic-ray trajectory and charge generated within them (proportional to cosmic-ray energy dissipated within them). Interdigital electrode pattern repeated over many rows and columns on tops of detector wafers in stack. Electrode pattern defines pixels within which points of incidence of incident cosmic rays located.

  2. Voids and the Cosmic Web: cosmic depression & spatial complexity

    NARCIS (Netherlands)

    van de Weygaert, Rien; Shandarin, S.; Saar, E.; Einasto, J.

    2016-01-01

    Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do theyrepresent a key constituent of the Cosmic Web, they also are one of the cleanest probesand measures of global cosmological parameters. The shape and evolution of voids are highly sensitive tothe natu

  3. Chandra Discovers Cosmic Cannonball

    Science.gov (United States)

    2007-11-01

    One of the fastest moving stars ever seen has been discovered with NASA's Chandra X-ray Observatory. This cosmic cannonball is challenging theories to explain its blistering speed. Astronomers used Chandra to observe a neutron star, known as RX J0822-4300, over a period of about five years. During that span, three Chandra observations clearly show the neutron star moving away from the center of the Puppis A supernova remnant. This remnant is the stellar debris field created during the same explosion in which the neutron star was created about 3700 years ago. Chandra X-ray Image of RX J0822-4300 in Puppis A Chandra X-ray Image of RX J0822-4300 in Puppis A By combining how far it has moved across the sky with its distance from Earth, astronomers determined the neutron star is moving at over 3 million miles per hour. At this rate, RX J0822-4300 is destined to escape from the Milky Way after millions of years, even though it has only traveled about 20 light years so far. "This star is moving at 3 million miles an hour, but it's so far away that the apparent motion we see in five years is less than the height of the numerals in the date on a penny, seen from the length of a football field," said Frank Winkler of Middlebury College in Vermont. "It's remarkable, and a real testament to the power of Chandra, that such a tiny motion can be measured." Labeled Image of RX J0822-4300 in Puppis A Labeled Image of RX J0822-4300 in Puppis A "Just after it was born, this neutron star got a one-way ticket out of the Galaxy," said co-author Robert Petre of NASA's Goddard Space Flight Center in Greenbelt, Md. "Astronomers have seen other stars being flung out of the Milky Way, but few as fast as this." So-called hypervelocity stars have been previously discovered shooting out of the Milky Way with speeds around one million miles per hour. One key difference between RX J0822-4300 and these other reported galactic escapees is the source of their speed. The hypervelocity stars are

  4. Cosmic Ray elimination using the Wavelet Transform

    Science.gov (United States)

    Orozco-Aguilera, M. T.; Cruz, J.; Altamirano, L.; Serrano, A.

    2009-11-01

    In this work, we present a method for the automatic cosmic ray elimination in a single CCD exposure using the Wavelet Transform. The proposed method can eliminate cosmic rays of any shape or size. With this method we can eliminate over 95% of cosmic rays in a spectral image.

  5. COSMIC RAY ELIMINATION USING THE WAVELET TRANSFORM

    Directory of Open Access Journals (Sweden)

    M. T. Orozco-Aguilera

    2009-01-01

    Full Text Available In this work, we present a method for the automatic cosmic ray elimination in a single CCD exposure using the Wavelet Transform. The proposed method can eliminate cosmic rays of any shape or size. With this method we can eliminate over 95% of cosmic rays in a spectral image.

  6. Cosmic Flows and the Structure of the Local Universe

    Science.gov (United States)

    Steinmetz, Matthias

    2016-03-01

    The Local Volume is the area of the cosmos we can analyze in most detail with respect to the properties of its galaxy population, their abundance, their inner structure, their distribution, and their formation. Indeed, many challenges of the cosmological concordance model such as the substructure crisis or the surprising occurrence of vast planes of satellite galaxies are intimately linked to observations of the local galaxy population. However, owing to the peculiar environment of our Milky Way system and its cosmic neighborhood, the Local Volume may also be severely biased. Cosmography, i.e. the reconstruction of the local cosmic web from cosmic flows, and constrained simulations of structure formation as a tool to produce simulated local group analogues provide a powerful method to analyze and quantify these biases. Possible applications include the analysis of the local distribution of dwarf galaxies around luminous galaxies and the characterization of the mass accretion history of these objects. Thanks to the extension of galaxy velocity data out to distances in excess of 200Mpc, we are now capable to reconstruct the 3D matter distribution out to these distances, thus constraining the formation history of object such as the Virgo Cluster.

  7. Diagnostic potential of cosmic-neutrino absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Barenboim, Gabriela; /Valencia U.; Mena Requejo, Olga; Quigg, Chris; /Fermilab

    2004-12-01

    Annihilation of extremely energetic cosmic neutrinos on the relic-neutrino background can give rise to absorption lines at energies corresponding to formation of the electroweak gauge boson Z{sup 0}. The positions of the absorption dips are set by the masses of the relic neutrinos. Suitably intense sources of extremely energetic (10{sup 21} - 10{sup 25}-eV) cosmic neutrinos might therefore enable the determination of the absolute neutrino masses and the flavor composition of the mass eigenstates. Several factors--other than neutrino mass and composition--distort the absorption lines, however. We analyze the influence of the time-evolution of the relic-neutrino density and the consequences of neutrino decay. We consider the sensitivity of the lineshape to the age and character of extremely energetic neutrino sources, and to the thermal history of the Universe, reflected in the expansion rate. We take into account Fermi motion arising from the thermal distribution of the relic-neutrino gas. We also note the implications of Dirac vs. Majorana relics, and briefly consider unconventional neutrino histories. We ask what kinds of external information would enhance the potential of cosmic-neutrino absorption spectroscopy, and estimate the sensitivity required to make the technique a reality.

  8. Cosmic structure, averaging and dark energy

    CERN Document Server

    Wiltshire, David L

    2013-01-01

    These lecture notes review the theoretical problems associated with coarse-graining the observed inhomogeneous structure of the universe at late epochs, of describing average cosmic evolution in the presence of growing inhomogeneity, and of relating average quantities to physical observables. In particular, a detailed discussion of the timescape scenario is presented. In this scenario, dark energy is realized as a misidentification of gravitational energy gradients which result from gradients in the kinetic energy of expansion of space, in the presence of density and spatial curvature gradients that grow large with the growth of structure. The phenomenology and observational tests of the timescape model are discussed in detail, with updated constraints from Planck satellite data. In addition, recent results on the variation of the Hubble expansion on < 100/h Mpc scales are discussed. The spherically averaged Hubble law is significantly more uniform in the rest frame of the Local Group of galaxies than in t...

  9. Model-independent tests of cosmic gravity.

    Science.gov (United States)

    Linder, Eric V

    2011-12-28

    Gravitation governs the expansion and fate of the universe, and the growth of large-scale structure within it, but has not been tested in detail on these cosmic scales. The observed acceleration of the expansion may provide signs of gravitational laws beyond general relativity (GR). Since the form of any such extension is not clear, from either theory or data, we adopt a model-independent approach to parametrizing deviations to the Einstein framework. We explore the phase space dynamics of two key post-GR functions and derive a classification scheme, and an absolute criterion on accuracy necessary for distinguishing classes of gravity models. Future surveys will be able to constrain the post-GR functions' amplitudes and forms to the required precision, and hence reveal new aspects of gravitation.

  10. Planetary Habitability over Cosmic-Time Based on Cosmic-Ray Levels

    Science.gov (United States)

    Mason, Paul A.; Biermann, Peter L.

    2016-01-01

    Extreme cosmic-ray (CR) fluxes have a negative effect on life when flux densities are high enough to cause excessive biological, especially DNA, damage. The CR history of a planet plays an important role in its potential surface habitation. Both global and local CR conditions determine the ability of life to survive for astrobiologically relevant time periods. We highlight two CR life-limiting factors: 1) General galactic activity, starburst and AGN, was up by about a factor of 30 at redshift 1 - 2, per comoving frame, averaged over all galaxies. And 2) AGN activity is highly intermittent, so extreme brief but powerful bursts (Her A for example) can be detrimental at great distances. This means that during such brief bursts of AGN activity the extragalactic CRs might even overpower the local galactic CRs. But as shown by the starburst galaxy M82, the local CRs in a starburst can also be quite high. Moreover, in our cosmic neighborhood we have several super-massive black holes. These are in M31, M32, M81, NGC5128 (Cen A), and in our own Galaxy, all within about 4 Mpc today. Within about 20 Mpc today there are many more super-massive black holes. Cen A is of course the most famous one now, since it may be a major source of the ultra-high-energy CRs (UHECRs). Folding in what redshift means in terms of cosmic time, this implies that there may have been little chance for life to survive much earlier than Earth's starting epoch. We speculate, on whether the very slow start oflife on Earth is connected to the decay of disturbing CR activity.

  11. Forming Stars From the Cosmic Web

    Science.gov (United States)

    Kohler, Susanna

    2015-09-01

    Scientists have recently identified a connection between metal-poor regions in a set of dwarf galaxies and bursts of star-formation activity within them. These observations provide long-awaited evidence supporting predictions of how stars formed in the early universe and in dwarf galaxies today. Metal-Poor Clues: The primary driver of star formation over cosmic history is thought to be the accretion onto galaxies of cold gas streaming from the cosmic web. The best way to confirm this model would be to observe a cloud of cosmic gas flowing into an otherwise-quiescent galaxy and launching a wave of star formation. But because cold gas doesnt emit much radiation, its difficult to detect directly.Now, a team of scientists have found a clever way around this problem: they searched galaxies for a correlation between areas of active star formation and metal-poor regions. Why? Because metal-poor regions could be a smoking gun indicating a recently accreted cloud of cold gas from the cosmic web. Impacting Clouds: Distribution of metallicity along the major axis of one of the target galaxies. The red bar in the top image shows the position of the spectrograph slit along the galaxy, with the arrow showing the direction of growing distance in the plot below. The plot shows the metallicity variation (red symbols) and star-formation rate (blue line) along the galaxys major axis. The metallicity drop coincides with the brightest knot of the galaxy. [Snchez Almeida et al. 2015]The authors of this study, led by Jorge Snchez Almeida (Instituto de Astrofisica de Canarias and University of La Laguna, Spain), used the Great Canary Telescope to obtain high-quality spectra of ten dwarf galaxies with especially low average metallicities. They aligned the spectrograph slit along the major axes of the galaxies in order to measure abundances as a function of position within each galaxy.The team found that, in nine out of the ten cases, the galaxies displayed sharp drops (by factors of 310

  12. The Cosmic Ray Electron Excess

    Science.gov (United States)

    Chang, J.; Adams, J. H.; Ahn, H. S.; Bashindzhagyan, G. L.; Christl, M.; Ganel, O.; Guzik, T. G.; Isbert, J.; Kim, K. C.; Kuznetsov, E. N.; Panasyuk, M. I.; Panov, A. D.; Schmidt, W. K. H.; Seo, E. S.; Sokolskaya, N. V.; Watts, J. W.; Wefel, J. P.; Wu, J.; Zatsepin, V. I.

    2008-01-01

    This slide presentation reviews the possible sources for the apparent excess of Cosmic Ray Electrons. The presentation reviews the Advanced Thin Ionization Calorimeter (ATIC) instrument, the various parts, how cosmic ray electrons are measured, and shows graphs that review the results of the ATIC instrument measurement. A review of Cosmic Ray Electrons models is explored, along with the source candidates. Scenarios for the excess are reviewed: Supernova remnants (SNR) Pulsar Wind nebulae, or Microquasars. Each of these has some problem that mitigates the argument. The last possibility discussed is Dark Matter. The Anti-Matter Exploration and Light-nuclei Astrophysics (PAMELA) mission is to search for evidence of annihilations of dark matter particles, to search for anti-nuclei, to test cosmic-ray propagation models, and to measure electron and positron spectra. There are slides explaining the results of Pamela and how to compare these with those of the ATIC experiment. Dark matter annihilation is then reviewed, which represent two types of dark matter: Neutralinos, and kaluza-Kline (KK) particles, which are next explained. The future astrophysical measurements, those from GLAST LAT, the Alpha Magnetic Spectrometer (AMS), and HEPCAT are reviewed, in light of assisting in finding an explanation for the observed excess. Also the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) could help by revealing if there are extra dimensions.

  13. Evolution of the cosmic web

    NARCIS (Netherlands)

    Cautun, Marius; van de Weygaert, Rien; Jones, Bernard J. T.; Frenk, Carlos S.

    2014-01-01

    The cosmic web is the largest scale manifestation of the anisotropic gravitational collapse of matter. It represents the transitional stage between linear and non-linear structures and contains easily accessible information about the early phases of structure formation processes. Here we investigate

  14. Cosmic Censorship for Gowdy Spacetimes.

    Science.gov (United States)

    Ringström, Hans

    2010-01-01

    Due to the complexity of Einstein's equations, it is often natural to study a question of interest in the framework of a restricted class of solutions. One way to impose a restriction is to consider solutions satisfying a given symmetry condition. There are many possible choices, but the present article is concerned with one particular choice, which we shall refer to as Gowdy symmetry. We begin by explaining the origin and meaning of this symmetry type, which has been used as a simplifying assumption in various contexts, some of which we shall mention. Nevertheless, the subject of interest here is strong cosmic censorship. Consequently, after having described what the Gowdy class of spacetimes is, we describe, as seen from the perspective of a mathematician, what is meant by strong cosmic censorship. The existing results on cosmic censorship are based on a detailed analysis of the asymptotic behavior of solutions. This analysis is in part motivated by conjectures, such as the BKL conjecture, which we shall therefore briefly describe. However, the emphasis of the article is on the mathematical analysis of the asymptotics, due to its central importance in the proof and in the hope that it might be of relevance more generally. The article ends with a description of the results that have been obtained concerning strong cosmic censorship in the class of Gowdy spacetimes.

  15. Global diffusion of cosmic rays

    CERN Document Server

    Snodin, A P; Sarson, G R; Bushby, P J; Rodrigues, L F S

    2015-01-01

    The propagation of charged particles, including cosmic rays, in a partially ordered magnetic field is characterized by a diffusion tensor whose components depend on the particle's Larmor radius $R_L$ and the degree of order in the magnetic field. This prescription relies explicitly on the assumption of a scale separation between random and mean magnetic fields, which usually applies in laboratory plasmas, but not in most astrophysical environments such as the interstellar medium (ISM). Direct estimates of the cosmic-ray diffusion tensor from test particle simulations have explored the range of particle energies corresponding to $10^{-2} \\lesssim R_L/l_c \\lesssim 10^{3}$, where $l_c$ is the magnetic correlation length. Modern simulations of the ISM have numerical resolution of order 1 pc, so the Larmor radius of the cosmic ray particles that dominate in their energy density is at least $10^{6}$ times smaller than the numerically resolved scales of the random magnetic field. Large-scale simulations of cosmic ra...

  16. Cosmic Logic: a Computational Model

    CERN Document Server

    Vanchurin, Vitaly

    2015-01-01

    We describe a simple computational model of cosmic logic suitable for analysis of, for example, discretized cosmological systems. The construction is based on a particular model of computation, developed by Alan Turing, with cosmic observers (CO), cosmic measures (CM) and cosmic symmetries (CS) described by Turing machines. CO machines always start with a blank tape and CM machines take CO's Turing number (also known as description number or G{\\" o}del number) as input and output the corresponding probability. Similarly, CS machines take CO's Turing number as input, but output either one if the CO machines are in the same equivalence class or zero otherwise. We argue that CS machines are more fundamental than CM machines and, thus, should be used as building blocks in constructing CM machines. We prove the non-computability of a CS machine which discriminates between two classes of CO machines: mortal that halts in finite time and immortal that runs forever. In context of eternal inflation this result implies...

  17. Decoherence, Entanglement and Cosmic Evolution

    CERN Document Server

    Capozziello, Salvatore

    2013-01-01

    The possible imprint of quantum decoherence, in the framework of cosmology, is here investigated. Particular attention is paid to the observational fact that entanglement could lead to the interaction of different eras of cosmic evolution. The role played by decoherence provides the existence of "quantum entanglement" between cosmological eras giving, as observational results, dynamical constraints on the corresponding cosmological models.

  18. Cosmic Rays and Radiative Instabilities

    CERN Document Server

    Hartquist, T W; Falle, S A E G; Pittard, J M; Van Loo, S

    2011-01-01

    In the absence of magnetic fields and cosmic rays, radiative cooling laws with a range of dependences on temperature affect the stability of interstellar gas. For about four and a half decades, astrophysicists have recognised the importance of the thermal instablity for the formation of clouds in the interstellar medium. Even in the past several years, many papers have concerned the role of the thermal instability in the production of molecular clouds. About three and a half decades ago, astrophysicists investigating radiative shocks noticed that for many cooling laws such shocks are unstable. Attempts to address the effects of cosmic rays on the stablity of radiative media that are initially uniform or that have just passed through shocks have been made. The simplest approach to such studies involves the assumption that the cosmic rays behave as a fluid. Work based on such an approach is described. Cosmic rays have no effect on the stability of initially uniform, static media with respect to isobaric perturb...

  19. The L3+Cosmics experiment

    CERN Document Server

    Le Coultre, Pierre

    2003-01-01

    Thanks to the unique properties of the L3+C detector, muon research topics relevant to various current problems in cosmic ray and particle astrophysics can be studied. A short overview of the physics topics is presented as well as a description of the detector. (19 refs).

  20. Cosmology, Relativity and Cosmic Rays

    Science.gov (United States)

    López, Rebeca; Martínez, Humberto; Zepeda, Arnulfo

    2009-04-01

    This is a short review of the evolution of ideas and concepts about the Universe. It is based on the introductory talk given on the 25 of July 2008 within the Third School on Cosmic Rays and Astrophysics held in Arequipa, Peru.

  1. Fireballs from Superconducting Cosmic Strings

    CERN Document Server

    Gruzinov, Andrei

    2016-01-01

    Thermalized fireballs should be created by cusp events on superconducting cosmic strings. This simple notion allows to reliably estimate particle emission from the cusps in a given background magnetic field. With plausible assumptions about intergalactic magnetic fields, the cusp events can produce observable fluxes of high-energy photons and neutrinos with unique signatures.

  2. Fireballs from superconducting cosmic strings

    Science.gov (United States)

    Gruzinov, Andrei; Vilenkin, Alexander

    2017-01-01

    Thermalized fireballs should be created by cusp events on superconducting cosmic strings. This simple notion allows to reliably estimate particle emission from the cusps in a given background magnetic field. With plausible assumptions about intergalactic magnetic fields, the cusp events can produce observable fluxes of high-energy photons and neutrinos with unique signatures.

  3. Surprising results from cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Wilk, G. [Soltan Institute for Nuclear Studies, Warsaw (Poland); Wlodarczyk, Z. [Institute for Physics, Pedagogical University, Kielce (Poland)

    1996-10-01

    A number of seemingly exotic phenomena seen in the highest cosmic-ray experiments are briefly discussed. We argue that they indicate existence of non-statistical fluctuations and strong correlations in the fragmentation region of multiparticle production processes unaccessible to the present accelerators. (author) 12 refs, 3 figs

  4. Cosmic rays, aerosol formation and cloud-condensation nuclei: sensitivities to model uncertainties

    Directory of Open Access Journals (Sweden)

    E. J. Snow-Kropla

    2011-01-01

    Full Text Available The flux of cosmic rays to the atmosphere has been observed to correlate with cloud and aerosol properties. One proposed mechanism for these correlations is the "ion-aerosol clear-air" mechanism where the cosmic rays modulate atmospheric ion concentrations, ion-induced nucleation of aerosols and cloud condensation nuclei (CCN concentrations. We use a global chemical transport model with online aerosol microphysics to explore the dependence of CCN concentrations on the cosmic-ray flux. Expanding upon previous work, we test the sensitivity of the cosmic-ray/CCN connection to several uncertain parameters in the model including primary emissions, Secondary Organic Aerosol (SOA condensation and charge-enhanced condensational growth. The sensitivity of CCN to cosmic rays increases when simulations are run with decreased primary emissions, but show location-dependent behavior from increased amounts of secondary organic aerosol and charge-enhanced growth. For all test cases, the change in the concentration of particles larger than 80 nm between solar minimum (high cosmic ray flux and solar maximum (low cosmic ray flux simulations is less than 0.2%. The change in the total number of particles larger than 10 nm was larger, but always less than 1%. The simulated change in the column-integrated Ångström exponent was negligible for all test cases. Additionally, we test the predicted aerosol sensitivity to week-long Forbush decreases of cosmic rays and find that the maximum change in aerosol properties for these cases is similar to steady-state aerosol differences between the solar maximum and solar minimum. These results provide evidence that the effect of cosmic rays on CCN and clouds through the ion-aerosol clear-sky mechanism is limited by dampening from aerosol processes.

  5. Cosmic rays, aerosol formation and cloud-condensation nuclei: sensitivities to model uncertainties

    Directory of Open Access Journals (Sweden)

    E. J. Snow-Kropla

    2011-04-01

    Full Text Available The flux of cosmic rays to the atmosphere has been reported to correlate with cloud and aerosol properties. One proposed mechanism for these correlations is the "ion-aerosol clear-air" mechanism where the cosmic rays modulate atmospheric ion concentrations, ion-induced nucleation of aerosols and cloud condensation nuclei (CCN concentrations. We use a global chemical transport model with online aerosol microphysics to explore the dependence of CCN concentrations on the cosmic-ray flux. Expanding upon previous work, we test the sensitivity of the cosmic-ray/CCN connection to several uncertain parameters in the model including primary emissions, Secondary Organic Aerosol (SOA condensation and charge-enhanced condensational growth. The sensitivity of CCN to cosmic rays increases when simulations are run with decreased primary emissions, but show location-dependent behavior from increased amounts of secondary organic aerosol and charge-enhanced growth. For all test cases, the change in the concentration of particles larger than 80 nm between solar minimum (high cosmic ray flux and solar maximum (low cosmic ray flux simulations is less than 0.2 %. The change in the total number of particles larger than 10 nm was larger, but always less than 1 %. The simulated change in the column-integrated Ångström exponent was negligible for all test cases. Additionally, we test the predicted aerosol sensitivity to week-long Forbush decreases of cosmic rays and find that the maximum change in aerosol properties for these cases is similar to steady-state aerosol differences between the solar maximum and solar minimum. These results provide evidence that the effect of cosmic rays on CCN and clouds through the ion-aerosol clear-sky mechanism is limited by dampening from aerosol processes.

  6. Monazite Growth from the Eocene to the Miocene: New Interpretations of the Metamorphic History of Greater Himalayan Rocks in the Eastern Himalaya

    Science.gov (United States)

    Gordon, S. M.; Kauffman, R.; Gonzales-Clayton, B.; Long, S. P.; Kylander-Clark, A. R.

    2015-12-01

    Across the Himalaya, mid- to lower-crustal Greater-Himalayan (GH) rocks have been exhumed during active continent-continent collision. In the eastern Himalaya within Bhutan, GH rocks are divided into an upper and lower level by an intra-GH shear zone, the Kakthang thrust (KT). To decipher the metamorphic, melt-crystallization and exhumation history of the GH rocks exposed above and below the KT, monazite from metapelites and migmatites was dated and trace elements were analyzed by laser-ablation, split-stream ICPMS. The trace elements from the monazite were used to track when the rocks were at near-peak conditions (based on the depletion of HREE and the likely presence of garnet during monazite growth) versus likely undergoing initial exhumation and garnet breakdown (based on an increase in HREE). Samples were collected from two N-S transects that cross the KT in central and eastern Bhutan. The eastern transect reveals a progressive younging of near-peak metamorphism within the GH, with dates of ca. 23-20 Ma for the structurally-highest sample versus ca. 18-16 Ma in the structurally-lowest sample. The youngest dates from all structural levels of the eastern Bhutan metapelites are 13-15 Ma; the same analyses yield higher HREE abundances, suggesting garnet breakdown during their (re)crystallization. The migmatites yield ca. 14-16 Ma melt-crystallization ages, consistent with the GH having undergone cooling and initial exhumation to cause garnet breakdown by ca. 15 Ma. In comparison, the central Bhutan transect reveals older near-peak metamorphic ages, with garnet-stable monazite populations at ca. 48­-46 Ma within the KT zone, ca. 38-30 Ma for rocks in the middle of the upper-GH, and ca. 25-22 Ma for the structurally-highest sample. Youngest monazites from the central Bhutan transect that yield growth or recrystallization at garnet-unstable conditions range from ca. 17-26 Ma. These results suggest earlier metamorphism and exhumation of GH rocks in central Bhutan

  7. Galactic cosmic ray propagation models using Picard

    CERN Document Server

    Kissmann, Ralf; Strong, Andrew W

    2015-01-01

    We present results obtained from our newly developed Galactic cosmic-ray transport code PICARD, that solves the cosmic-ray transport equation. This code allows for the computation of cosmic-ray spectra and the resulting gamma-ray emission. Relying on contemporary numerical solvers allows for efficient computation of models with deca-parsec resolution. PICARD can handle locally anisotropic spatial diffusion acknowledging a full diffusion tensor. We used this framework to investigate the transition from axisymmetric to spiral-arm cosmic-ray source distributions. Wherever possible we compare model predictions with constraining observables in cosmic-ray astrophysics.

  8. Bayesian large-scale structure inference and cosmic web analysis

    CERN Document Server

    Leclercq, Florent

    2015-01-01

    Surveys of the cosmic large-scale structure carry opportunities for building and testing cosmological theories about the origin and evolution of the Universe. This endeavor requires appropriate data assimilation tools, for establishing the contact between survey catalogs and models of structure formation. In this thesis, we present an innovative statistical approach for the ab initio simultaneous analysis of the formation history and morphology of the cosmic web: the BORG algorithm infers the primordial density fluctuations and produces physical reconstructions of the dark matter distribution that underlies observed galaxies, by assimilating the survey data into a cosmological structure formation model. The method, based on Bayesian probability theory, provides accurate means of uncertainty quantification. We demonstrate the application of BORG to the Sloan Digital Sky Survey data and describe the primordial and late-time large-scale structure in the observed volume. We show how the approach has led to the fi...

  9. Connecting inflation with late cosmic acceleration by particle production

    CERN Document Server

    Nunes, Rafael C

    2016-01-01

    A continuous process of creation of particles is investigated as a possible connection between the inflationary stage with late cosmic acceleration. In this model, the inflationary era occurs due to a continuous and fast process of creation of relativistic particles, and the recent accelerating phase is driven by the non-relativistic matter creation from the gravitational field acting on the quantum vacuum, which finally results in an effective equation of state less than $-1$. Thus, explaining recent results in favor of a phantom dynamics without the need of any modifications in the gravity theory has been proposed. Finally, we confront the model with recent observational data of type Ia Supernova, history of the Hubble parameter, baryon acoustic oscillations, and the cosmic microwave background.

  10. Fundamental constants and cosmic vacuum: the micro and macro connection

    CERN Document Server

    Fritzsch, Harald

    2015-01-01

    The idea that the vacuum energy density $\\rho_{\\Lambda}$ could be time dependent is a most reasonable one in the expanding Universe; in fact, much more reasonable than just a rigid cosmological constant for the entire cosmic history. Being $\\rho_{\\Lambda}=\\rho_{\\Lambda}(t)$ dynamical, it offers a possibility to tackle the cosmological constant problem in its various facets. Furthermore, for a long time (most prominently since Dirac's first proposal on a time variable gravitational coupling) the possibility that the fundamental "constants" of Nature are slowly drifting with the cosmic expansion has been continuously investigated. In the last two decades, and specially in recent times, mounting experimental evidence attests that this could be the case. In this paper, we consider the possibility that these two groups of facts might be intimately connected, namely that the observed acceleration of the Universe and the possible time variation of the fundamental constants are two manifestations of the same underlyi...

  11. Cosmological structure formation shocks and cosmic rays in hydrodynamical simulations

    CERN Document Server

    Pfrommer, C; Ensslin, T A; Jubelgas, M; Pfrommer, Christoph; Springel, Volker; Ensslin, Torsten A.; Jubelgas, Martin

    2006-01-01

    Cosmological shock waves during structure formation not only play a decisive role for the thermalization of gas in virializing structures but also for the acceleration of relativistic cosmic rays (CRs) through diffusive shock acceleration. We discuss a novel numerical treatment of the physics of cosmic rays in combination with a formalism for identifying and measuring the shock strength on-the-fly during a smoothed particle hydrodynamics simulation. In our methodology, the non-thermal CR population is treated self-consistently in order to assess its dynamical impact on the thermal gas as well as other implications on cosmological observables. Using this formalism, we study the history of the thermalization process in high-resolution hydrodynamic simulations of the Lambda cold dark matter model. Collapsed cosmological structures are surrounded by shocks with high Mach numbers up to 1000, but they play only a minor role in the energy balance of thermalization. However, this finding has important consequences fo...

  12. Cosmic rays and hadronic interactions

    Directory of Open Access Journals (Sweden)

    Lipari Paolo

    2015-01-01

    Full Text Available The study of cosmic rays, and more in general of the “high energy universe” is at the moment a vibrant field that, thanks to the observations by several innovative detectors for relativistic charged particles, gamma–rays, and neutrinos continue to generate surprising and exciting results. The progress in the field is rapid but many fundamental problems remain open. There is an intimate relation between the study of the high energy universe and the study of the properties of hadronic interactions. High energy cosmic rays can only be studied detecting the showers they generate in the atmosphere, and for the interpretation of the data one needs an accurate modeling of the collisions between hadrons. Also the study of cosmic rays inside their sources and in the Galaxy requires a precise description of hadronic interactions. A program of experimental studies at the LHC and at lower energy, designed to address the most pressing problems, could significantly reduce the existing uncertainties and is very desirable. Such an experimental program would also have a strong intrinsic scientific interest, allowing the broadening and deepening of our understanding of Quantum Chromo Dynamics in the non–perturbative regime, the least understood sector of the Standard Model of particle physics. It should also be noted that the cosmic ray spectrum extends to particles with energy E ∼ 1020 eV, or a nucleon–nucleon c.m. energy √s ≃ 430 TeV, 30 times higher than the current LHC energy. Cosmic ray experiments therefore offer the possibility to perform studies on the properties of hadronic interactions that are impossible at accelerators.

  13. Direct Determination of Expansion History Using Redshift Distortions

    CERN Document Server

    Song, Yong-Seon

    2012-01-01

    We investigate direct determination of expansion history using redshift distortions without plugging into detailed cosmological parameters. The observed spectra in redshift space include a mixture of information: fluctuations of density-density and velocity-velocity spectra, and distance measures of perpendicular and parallel components to the line of sight. Unfortunately it is hard to measure all the components simultaneously without any specific prior assumption. Common prior assumptions include a linear/quasi-linear model of redshift distortions or a model for the shape of the power spectra, which eventually breaks down on small scales at later epochs where nonlinear structure formation disturbs coherent growth. The degeneracy breaking between the effect of cosmic distances and redshift distortions for example depends on the prior we assume. As an alternative approach is to utilize the cosmological principle inscribed in the heart of the Friedmann-Lema\\^itre-Robertson-Walker (hereafter FLRW) universe, that...

  14. The Cosmic Star-Formation History The UV finds most

    CERN Document Server

    Adelberger, K L

    2001-01-01

    This is a summary of arguments in favor of observing high-redshift star formation in the UV as presented at the Ringberg meeting in September 2000. The most rapidly star-forming galaxies are very dusty, easier to detect at 850um than in the UV, but less rapidly star-forming galaxies are less obscured by dust and as a result the comparatively faint galaxies that hosted most high-redshift star formation are easiest to detect in the UV. The correlation of star-formation rate and dust obscuration implies that extremely luminous dusty galaxies are usually as bright in the UV as the less luminous dust-free galaxies, and that any UV survey at a given redshift 0

  15. X-Ray Probes of Cosmic Star Formation History

    Science.gov (United States)

    Ghosh, Pranab; White, Nicholas E.

    2001-01-01

    We discuss the imprints left by a cosmological evolution of the star formation rate (SFR) on the evolution of X-ray luminosities Lx of normal galaxies, using the scheme earlier proposed by us, wherein the evolution of LX of a galaxy is driven by the evolution of its X-ray binary population. As indicated in our earlier work, the profile of Lx with redshift can both serve as a diagnostic probe of the SFR profile and constrain evolutionary models for X-ray binaries. We report here the first calculation of the expected evolution of X-ray luminosities of galaxies, updating our work by using a suite of more recently developed SFR profiles that span the currently plausible range. The first Chandra deep imaging results on Lx evolution are beginning to probe the SFR profile of bright spiral galaxies; the early results are consistent with predictions based on current SFR models. Using these new SFR profiles, the resolution of the "birthrate problem" of low-mass X-ray binaries and recycled, millisecond pulsars in terms of an evolving global SFR is more complete. We discuss the possible impact of the variations in the SFR profile of individual galaxies and galaxy types.

  16. Floristic patterns and disturbance history in karri ( Eucalyptus diversicolor: Myrtaceae) forest, south-western Australia: 2. Origin, growth form and fire response

    Science.gov (United States)

    Wardell-Johnson, Grant W.; Williams, M. R.; Mellican, A. E.; Annells, A.

    2007-03-01

    We examined the influence of disturbance history on the floristic composition of a single community type in karri forest, south-western Australia. Cover-abundance of 224 plant species and six disturbance and site-based environmental variables were recorded in 91, 20 m × 20 m quadrats. Numerical taxonomic and correlation approaches were used to relate these and 10 plant species-group variables based on origin, growth form and fire response. Ordination revealed no discernable pattern of sites based on floristic composition. However, all 10 species-group variables were significantly correlated with the ordination axes. Species richness within these groups varied with category and with respect to many of the disturbance and site variables. We encountered low diversity of vascular plants at the community level and limited diversity of growth forms. Thus most species were herbs (62.1%) or shrubs (30.3%), and there were no epiphytes and few species of trees or climbers. Although many introduced species were recorded (18.3% of all taxa), virtually all (83%) were herbs that demonstrated little persistence in the community, and there was limited evidence of transformer species. Time-since-fire (and other disturbance) influenced species richness more than the number of recent past fires because of a high proportion of ephemerals associated with the immediate post-fire period. Long-lived shrubs with soil stored seed dominate numerically, and in understorey biomass in comparison with neighboring vegetation types because of their greater flexibility of response following irregular, but intense disturbance events. However, interactions between nutrient status, regeneration mechanisms and community composition may be worthy of further investigation.

  17. Life History, Immune Function, and Intestinal Helminths: Trade-Offs Among Immunoglobulin E, C-Reactive Protein, and Growth in an Amazonian Population

    Science.gov (United States)

    BLACKWELL, AARON D.; SNODGRASS, J. JOSH; MADIMENOS, FELICIA C.; SUGIYAMA, LAWRENCE S.

    2010-01-01

    Objectives Infection with helminths is associated with shifts in host immunity, including increased production of immunoglobulin E (IgE) and reduced inflammation. Given limited energy budgets, these shifts may involve changes in energy allocation toward competing demands. Here we test for potential trade-offs between growth, IgE, and the inflammatory marker C-reactive protein (CRP). Methods Dried blood spots and anthropometrics were collected from 162 Shuar forager-horticulturalists from a village in southeastern Ecuador. Enzyme-linked immunosorbent assays (ELISAs) were used to measure IgE and CRP. Relationships among IgE, CRP, and anthropometrics were examined in three groups: children aged 2–7 years (n = 63), children aged 8–15 (n = 61), and adults over age 18 (n = 37). Results Geometric mean IgE was 1,196 IU ml−1 while geometric mean CRP was 1.33 mg l−1. In children, IgE and CRP were negatively correlated (r = −0.21, P = 0.02, df = 122). Controlling for fat stores and age, IgE was associated with lower stature in children (t = −2.04, P = 0.04, df = 109), and adults (t = −3.29, P < 0.01, df = 33). In children there was a significant interaction between age and CRP, such that in younger children CRP was associated with shorter stature, but in older children was associated with greater stature (t = 2.15, P = 0.04, df = 109). Conclusions These results suggest that infection with helminths may have hidden costs associated with immunological changes, and that these costs may ultimately affect growth and other life history parameters. PMID:20865759

  18. MARS A Cosmic Stepping Stone Uncovering Humanity’s Cosmic Context

    CERN Document Server

    Nolan, Kevin

    2008-01-01

    The questions of our origin and cosmic abundance of life are among the most compelling facing humanity. We have determined much about the nature and origin of the Universe and our place in it, but with virtually all evidence of our origin long since gone from our world and an unimaginably vast Universe still to explore, defining answers are difficult to obtain. For all of the difficulties facing us however, the planet Mars may act as a ‘cosmic stepping stone’ in uncovering some of the answers. Although different today, the origin and early history of both Earth and Mars may have been similar enough to consider an origin to life on both. But because Mars’ planetary processes collapsed over three billion years ago – just as life was beginning to flourish on Earth – a significant and unique record of activity from that era perhaps relevant to the origin of life still resides there today. In recognition of this, both the US and Europe are currently engaged in one of the most ambitious programs of explor...

  19. A Cosmic Battery Reconsidered

    CERN Document Server

    Bisnovatyi-Kogan, G S; Belinsky, V A

    2002-01-01

    We revisit the problem of magnetic field generation in accretion flows onto black holes owing to the excess radiation force on electrons. This excess force may arise from the Poynting-Robertson effect. Instead of a recent claim of the generation of dynamically important magnetic fields, we establish the validity of earlier results from 1977 which show only small magnetic fields are generated. The radiative force causes the magnetic field to initially grow linearly with time. However, this linear growth holds for only a {\\it restricted} time interval which is of the order of the accretion time of the matter. The large magnetic fields recently found result from the fact that the linear growth is unrestricted. A model of the Poynting-Robertson magnetic field generation close to the horizon of a Schwarzschild black hole is solved exactly using General Relativity, and the field is also found to be dynamically insignificant. These weak magnetic fields may however be important as seed fields for dynamos.

  20. Cosmic Ballet or Devil's Mask?

    Science.gov (United States)

    2004-04-01

    . The warped appearance of the dust lane in NGC 6771 might also be interpreted as more evidence of interactions. Moreover, NGC 6769 and NGC 6770 are receding from us at a similar velocity of about 3800 km/s - a redshift just over 0.01 - while that of NGC 6771 is slightly larger, 4200 km/s. A stellar baby-boom As dramatic and destructive as this may seem, such an event is also an enrichment, a true baby-star boom. As the Phoenix reborn from its ashes, a cosmic catastrophe like this one normally results in the formation of many new stars. This is obvious from the blueish nature of the spiral arms in NGC 6769 and NGC 6770 and the presence of many sites of star forming regions. Similarly, the spiral arms of the well-known Whirlpool galaxy (Messier 51) may have been produced by a close encounter with a second galaxy that is now located at the end of one of the spiral arms; the same may be true for the beautiful southern galaxy NGC 1232 depicted in another VLT photo (PR Photo 37d/98). Nearer to us, a stream of hydrogen gas, similar to the one seen in ESO PR Photo 12/04, connects our Galaxy with the LMC, a relict of dramatic events in the history of our home Galaxy. And the stormy time is not yet over: now the Andromeda Galaxy, another of the Milky Way neighbours in the Local Group of Galaxies, is approaching us. Still at a distance of over 2 million light-years, calculations predict that it will collide with our galaxy in about 6,000 million years! More stunning images obtained with the Very Large Telescope can be found on the Top 20 page.

  1. Life history, immune function, and intestinal helminths: Trade-offs among immunoglobulin E, C-reactive protein, and growth in an Amazonian population.

    Science.gov (United States)

    Blackwell, Aaron D; Snodgrass, J Josh; Madimenos, Felicia C; Sugiyama, Lawrence S

    2010-01-01

    Infection with helminths is associated with shifts in host immunity, including increased production of immunoglobulin E (IgE) and reduced inflammation. Given limited energy budgets, these shifts may involve changes in energy allocation toward competing demands. Here we test for potential trade-offs between growth, IgE, and the inflammatory marker C-reactive protein (CRP). Dried blood spots and anthropometrics were collected from 162 Shuar forager-horticulturalists from a village in southeastern Ecuador. Enzyme-linked immunosorbent assays (ELISAs) were used to measure IgE and CRP. Relationships among IgE, CRP, and anthropometrics were examined in three groups: children aged 2-7 years (n = 63), children aged 8-15 (n = 61), and adults over age 18 (n = 37). Geometric mean IgE was 1,196 IU ml⁻¹ while geometric mean CRP was 1.33 mg l⁻¹. In children, IgE and CRP were negatively correlated (r = -0.21, P = 0.02, df = 122). Controlling for fat stores and age, IgE was associated with lower stature in children (t = -2.04, P = 0.04, df = 109), and adults (t = -3.29, P history parameters. © 2010 Wiley-Liss, Inc.

  2. Cosmic vacuum energy decay and creation of cosmic matter

    CERN Document Server

    Fahr, H J

    2016-01-01

    In the more recent literature on cosmological evolutions of the universe the cosmic vacuum energy has become a non-renouncable ingredient. The cosmological constant $\\Lambda$, first invented by Einstein, but later also rejected by him, presently experiences an astonishing revival. Interestingly enough it acts, like a constant vacuum energy density would also do. Namely, it has an accelerating action on cosmic dynamics without which, as it appears, presently obtained cosmological data cannot be conciliated with theory. As we are going to show in this review, however, the concept of a constant vacuum energy density is unsatisfactory for very basic reasons, since it would claim for a physical reality that acts upon spacetime and matter dynamics without itself being acted upon by spacetime or matter.

  3. Voids and the Cosmic Web: cosmic depressions & spatial complexity

    CERN Document Server

    van de Weygaert, Rien

    2016-01-01

    Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do they represent a key constituent of the Cosmic Web, they also are one of the cleanest probes and measures of global cosmological parameters. The shape and evolution of voids are highly sensitive to the nature of dark energy, while their substructure and galaxy population provides a direct key to the nature of dark matter. Also, the pristine environment of void interiors is an important testing ground for our understanding of environmental influences on galaxy formation and evolution. In this paper, we review the key aspects of the structure and dynamics of voids, with a particular focus on the hierarchical evolution of the void population. We demonstrate how the rich structural pattern of the Cosmic Web is related to the complex evolution and buildup of voids.

  4. Dynamic Cosmic Strings Numerical evolution of excited Cosmic Strings

    CERN Document Server

    Sperhake, U; Vickers, J A

    2001-01-01

    An implicit, fully characteristic, numerical scheme for solving the field equations of a cosmic string coupled to gravity is described. The inclusion of null infinity as part of the numerical grid allows us to apply suitable boundary conditions on the metric and matter fields to suppress unphysical divergent solutions. The code is tested by comparing the results with exact solutions, checking that static cosmic string initial data remain constant when evolved and undertaking a time dependent convergence analysis of the code. It is shown that the code is accurate, stable and exhibits clear second order convergence. The code is used to analyse the interaction between a Weber--Wheeler pulse of gravitational radiation with the string. The interaction causes the string to oscillate at frequencies inversely proportional to the masses of the scalar and vector fields of the string. After the pulse has largely radiated away the string continues to ring but the oscillations slowly decay and eventually the variables ret...

  5. Voids and the Cosmic Web: cosmic depression & spatial complexity

    Science.gov (United States)

    van de Weygaert, Rien

    2016-10-01

    Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do theyrepresent a key constituent of the Cosmic Web, they also are one of the cleanest probesand measures of global cosmological parameters. The shape and evolution of voids are highly sensitive tothe nature of dark energy, while their substructure and galaxy population provides a direct key to thenature of dark matter. Also, the pristine environment of void interiors is an important testing groundfor our understanding of environmental influences on galaxy formation and evolution. In this paper, we reviewthe key aspects of the structure and dynamics ofvoids, with a particular focus on the hierarchical evolution of the void population. We demonstratehow the rich structural pattern of the Cosmic Web is related to the complex evolution and buildupof voids.

  6. Atmospheric histories and growth trends of C4F10, C5F12, C6F14, C7F16 and C8F18

    Directory of Open Access Journals (Sweden)

    R. F. Weiss

    2012-02-01

    Full Text Available The first atmospheric observations and trends are presented for the high molecular weight perfluorocarbons (PFCs: decafluorobutane (C4F10, dodecafluoropentane (C5F12, tetradecafluorohexane (C6F14, hexadecafluoroheptane (C7F16 and octadecafluorooctane (C8F18. Their atmospheric histories are based on measurements of 38 Northern Hemisphere and 46 Southern Hemisphere archived air samples collected between 1973 to 2011 using the Advanced Global Atmospheric Gases Experiment (AGAGE "Medusa" preconcentration gas chromatography-mass spectrometry systems. A new calibration scale was prepared for each PFC, with estimated accuracies of 6.8% for C4F10, 7.8% for C5F12, 4.0% for C6F14, 6.6% for C7F16 and 7.9% for C8F18. Based on our observations the 2011 globally averaged dry air mole fractions of these heavy PFCs are: 0.18 parts-per-trillion (ppt, i.e., parts per 1012 for C4F10, 0.12 ppt for C5F12, 0.28 ppt for C6F14, 0.12 ppt for C7F16 and 0.09 ppt for C8F18. These atmospheric mole fractions combine to contribute to a global average radiative forcing of 0.35 mW m−2, which is 3.6% of the total PFC radiative forcing. The globally averaged mean atmospheric growth rates of these PFCs during 1973–2011 are 4.58 parts per quadrillion (ppq, i.e., parts per 1015 per year (yr for C4F10, 3.29 ppq yr−1 for C5F12, 7.50 ppq yr−1 for C6F14, 3.19 ppq yr−1 for C7F16 and 2.51 ppq yr−1 for C8F18. The growth rates of the heavy perfluorocarbons were largest in the early 1990s for C4F10 and C5F12 and in the mid-to-late 1990s for C6F14, C7F16 and C8F18. The more recent slow down in the growth rates of the high molecular weight PFCs suggests that emissions are declining as compared to the 1980s and 1990s. Nevertheless continued monitoring of these potent, extremely long-lived greenhouse gases is necessary to verify that global PFC emissions continue to decline.

  7. Atmospheric histories and growth trends of C4F10, C5F12, C6F14, C7F16 and C8F18

    Directory of Open Access Journals (Sweden)

    R. F. Weiss

    2012-05-01

    Full Text Available Atmospheric observations and trends are presented for the high molecular weight perfluorocarbons (PFCs: decafluorobutane (C4F10, dodecafluoropentane (C5F12, tetradecafluorohexane (C6F14, hexadecafluoroheptane (C7F16 and octadecafluorooctane (C8F18. Their atmospheric histories are based on measurements of 36 Northern Hemisphere and 46 Southern Hemisphere archived air samples collected between 1973 to 2011 using the Advanced Global Atmospheric Gases Experiment (AGAGE "Medusa" preconcentration gas chromatography-mass spectrometry systems. A new calibration scale was prepared for each PFC, with estimated accuracies of 6.8% for C4F10, 7.8% for C5F12, 4.0% for C6F14, 6.6% for C7F16 and 7.9% for C8F18. Based on our observations the 2011 globally averaged dry air mole fractions of these heavy PFCs are: 0.17 parts-per-trillion (ppt, i.e., parts per 1012 for C4F10, 0.12 ppt for C5F12, 0.27 ppt for C6F14, 0.12 ppt for C7F16 and 0.09 ppt for C8F18. These atmospheric mole fractions combine to contribute to a global average radiative forcing of 0.35 mW m−2, which is 6% of the total anthropogenic PFC radiative forcing (Montzka and Reimann, 2011; Oram et al., 2012. The growth rates of the heavy perfluorocarbons were largest in the late 1990s peaking at 6.2 parts per quadrillion (ppq, i.e., parts per 1015 per year (yr for C4F10, at 5.0 ppq yr−1 for C5F12 and 16.6 ppq yr−1 for C6F14 and in the early 1990s for C7F16 at 4.7 ppq yr−1 and in the mid 1990s for C8F18 at 4.8 ppq yr−1. The 2011 globally averaged mean atmospheric growth rates of these PFCs are subsequently lower at 2.2 ppq yr−1 for C4F10, 1.4 ppq yr−1 for C5F12, 5.0 ppq yr−1 for C6F14, 3.4 ppq yr−1 for C7F16 and 0.9 ppq yr−1 for C8F18. The more recent slowdown in the growth rates suggests that emissions are declining as compared to the 1980s and 1990s.

  8. Syn-Rift Stratigraphic Architecture Reveals the Growth History of a Sub-basinal Fault Population in the Outer Moray Firth, North Sea

    Science.gov (United States)

    Kane, K.; Gupta, S.; Trudgill, B.; Johnson, H.

    2003-12-01

    Processes of normal fault propagation and linkage are recorded in the stratigraphic record by syn-rift sedimentary deposits that fill the generated accommodation volume. Using 3D seismic stratigraphic analysis, supported by well log and core interpretation, we investigate how the growth of an intrabasinal fault population led to the progressive development of an extensional sub-basin in the Moray Firth rift arm of the North Sea. The North Halibut Graben sub-basin has an E-W to WNW-ESE orientation and formed through the interaction of two main structural trends during late Jurassic rifting. E-W trending structural barriers bound the sub-basin to the north (Tartan and Petronella Ridges) and south (Halibut Horst Spur) whilst major NE-SW trending structures occur at the eastern margin. Spatial and temporal changes in syn-rift stratigraphic architecture reflect the history of faulting within the North Halibut Graben sub-basin. Fault parallel seismic profiles and intra-syn rift isochron maps demonstrate how faults initially developed as separate segments and subsequently linked to form longer strands through progressive growth and propagation. They also provide clear evidence that a major change in the structural framework occurred during rifting, supporting earlier studies advocating sequential rather than synchronous normal fault activity. The syn-rift sequence can be divided into at least two phases based on shifts in sedimentary packages and reorganistation of sequence thicknesses. Isochron maps illustrate that from late Oxfordian times (syn-rift phase I), early syn-rift sedimentation was controlled solely by NE-SW trending faults at the eastern margin of the basin. Strain was initially accommodated across several distributed, highly segmented faults but, with progressive linkage, stress became localised on one or two major through-going fault strands whilst shorter surrounding segments were switched off. From early-mid Volgian times we observe a progressive switch

  9. The Early Growth of the First Black Holes

    Science.gov (United States)

    Johnson, Jarrett L.; Haardt, Francesco

    2016-03-01

    With detections of quasars powered by increasingly massive black holes at increasingly early times in cosmic history over the past decade, there has been correspondingly rapid progress made on the theory of early black hole formation and growth. Here, we review the emerging picture of how the first massive black holes formed from the primordial gas and then grew to supermassive scales. We discuss the initial conditions for the formation of the progenitors of these seed black holes, the factors dictating the initial masses with which they form, and their initial stages of growth via accretion, which may occur at super-Eddington rates. Finally, we briefly discuss how these results connect to large-scale simulations of the growth of supermassive black holes in the first billion years after the Big Bang.

  10. The Early Growth of the First Black Holes

    CERN Document Server

    Johnson, Jarrett L

    2016-01-01

    With detections of quasars powered by increasingly massive black holes (BHs) at increasingly early times in cosmic history over the past decade, there has been correspondingly rapid progress made on the theory of early BH formation and growth. Here we review the emerging picture of how the first massive BHs formed from the primordial gas and then grew to supermassive scales. We discuss the initial conditions for the formation of the progenitors of these seed BHs, the factors dictating the initial masses with which they form, and their initial stages of growth via accretion, which may occur at super-Eddington rates. Finally, we briefly discuss how these results connect to large-scale simulations of the growth of supermassive BHs over the course of the first billion years following the Big Bang.

  11. Evolution of the cosmic web

    CERN Document Server

    Cautun, Marius; Jones, Bernard J T; Frenk, Carlos S

    2014-01-01

    The cosmic web is the largest scale manifestation of the anisotropic gravitational collapse of matter. It represents the transitional stage between linear and non-linear structures and contains easily accessible information about the early phases of structure formation processes. Here we investigate the characteristics and the time evolution of morphological components since. Our analysis involves the application of the NEXUS Multiscale Morphology Filter (MMF) technique, predominantly its NEXUS+ version, to high resolution and large volume cosmological simulations. We quantify the cosmic web components in terms of their mass and volume content, their density distribution and halo populations. We employ new analysis techniques to determine the spatial extent of filaments and sheets, like their total length and local width. This analysis identifies cluster and filaments as the most prominent components of the web. In contrast, while voids and sheets take most of the volume, they correspond to underdense environ...

  12. Nexus of the Cosmic Web

    CERN Document Server

    Cautun, Marius; Jones, Bernard J T; Frenk, Carlos S; Hellwing, Wojcieh A

    2012-01-01

    One of the important unknowns of current cosmology concerns the effects of the large scale distribution of matter on the formation and evolution of dark matter haloes and galaxies. One main difficulty in answering this question lies in the absence of a robust and natural way of identifying the large scale environments and their characteristics. This work summarizes the NEXUS+ formalism which extends and improves our multiscale scale-space MMF method. The new algorithm is very successful in tracing the Cosmic Web components, mainly due to its novel filtering of the density in logarithmic space. The method, due to its multiscale and hierarchical character, has the advantage of detecting all the cosmic structures, either prominent or tenuous, without preference for a certain size or shape. The resulting filamentary and wall networks can easily be characterized by their direction, thickness, mass density and density profile. These additional environmental properties allows to us to investigate not only the effect...

  13. Aerosols Produced by Cosmic Rays

    DEFF Research Database (Denmark)

    Enghoff, Martin Andreas Bødker

    , it will be possible to develop the experiment to cover additional processes involved in the route to cloud droplet formation. The experiment will be conducted at the Danish National Space Center where a clean room facility has been provided. It comprises a 7 m3 reaction chamber across which an electric field......Satellite observations have shown that the Earth’s cloud cover is strongly correlated with the galactic cosmic ray flux. While this correlation is indicative of a possible physical connection, there is currently no confirmation that a physical mechanism exists. We are therefore setting up...... mechanism linking cosmic rays to clouds and climate is currently speculative, there have been various suggestions of the role atmospheric ions may play; these involve any one of a number of processes from the nucleation of aerosols up to the collection processes of cloud droplets. We have chosen to start...

  14. The Imperatives of Cosmic Biology

    CERN Document Server

    Gibson, Carl H

    2010-01-01

    The transformation of organic molecules into the simplest self-replicating living system,a microorganism, is accomplished from a unique event or rare events that occurred early in the Universe. The subsequent dispersal on cosmic scales and evolution of life is guaranteed, being determined by well-understood processes of physics and biology. Entire galaxies and clusters of galaxies can be considered as connected biospheres, with lateral gene transfers, as initially theorized by Joseph (2000), providing for genetic mixing and Darwinian evolution on a cosmic scale. Big bang cosmology modified by modern fluid mechanics suggests the beginning and wide intergalactic dispersal of life occurred immediately after the end of the plasma epoch when the gas of protogalaxies in clusters fragmented into clumps of planets. Stars are born from binary mergers of such planets within such clumps. When stars devour their surrounding planets to excess they explode, distributing necessary fertilizing chemicals created only in stars...

  15. Cosmic Strings on the Lattice

    CERN Document Server

    Bukenov, A K; Polikarpov, M I; Polley, L; Wiese, U J

    1992-01-01

    We develop a formalism for the quantization of topologically stable excitations in the 4-dimensional abelian lattice gauge theory. The excitations are global and local (Abrikosov-Nielsen-Olesen) strings and monopoles. The operators of creation and annihilation of string states are constructed; the string Green functions are represented as a path integral over random surfaces. Topological excitations play an important role in the early universe. In the broken symmetry phase of the $U(1)$ spin model, closed global cosmic strings arise, while in the Higgs phase of the noncompact gauge-Higgs model, local cosmic strings are present. The compact gauge-Higgs model also involves monopoles. Then the strings can break if their ends are capped by monopoles. The topology of the Euclidean string world sheets are studied by numerical simulations.

  16. Cosmic Revelation: Making Astroparticles Visible

    Science.gov (United States)

    Roth, T. O.; Haungs, A.; Schieler, H.; Weindl, A.

    2010-06-01

    Cosmic Revelation is a prime example of a successful art and science project connecting art and astroparticle physics. One of the main reasons for its success might be that the collaboration between the KArlsruhe Shower Core and Array DEtector (KASCADE) experiment and Tim Otto Roth is both a minimalist light art project and a scientific experiment. In a field of 16 flashing mirror sculptures connected to the KASCADE detector field at KIT (Karlsruhe Institute of Technology, Germany) the impact of high energy cosmic rays on Earth can be experienced directly. In just one year the project has developed from the initial concept to its first presentation in a public space in autumn 2008. We explain how the project developed, and also highlight the practical and conceptual conditions for its realisation.

  17. Emergent Spacetime and Cosmic Inflation

    CERN Document Server

    Yang, Hyun Seok

    2015-01-01

    We propose a background-independent formulation of cosmic inflation. The inflation in this picture corresponds to a dynamical process to generate space and time while the conventional inflation is simply an (exponential) expansion of a preexisting spacetime owing to the vacuum energy carried by an inflaton field. We observe that the cosmic inflation is triggered by the condensate of Planck energy into vacuum responsible for the generation of spacetime and must be a single event according to the exclusion principle of noncommutative spacetime caused by the Planck energy condensate in vacuum. The emergent spacetime picture admits a background-independent formulation so that the inflation can be described by a conformal Hamiltonian system characterized by an exponential phase space expansion without introducing any inflaton field as well as an ad hoc inflation potential. This implies that the emergent spacetime may incapacitate all the rationales to introduce the multiverse hypothesis.

  18. X-ray spectroscopy of clusters of galaxies and of the cosmic web

    NARCIS (Netherlands)

    Werner, N.

    2008-01-01

    I present the results on the study of the chemical evolution of the intra-cluster medium (ICM) and on the evolution of clusters of galaxies in the context of the cosmic web. Clusters of galaxies are excellent laboratories to study the chemical enrichment history of the Universe. This thesis presents

  19. Dust Versus Cosmic Acceleration

    CERN Document Server

    Aguirre, A N

    1999-01-01

    Two groups have recently discovered a statistically significant deviation in the fluxes of high-redshift type Ia supernovae from the predictions of a Friedmann model with zero cosmological constant. This letter argues that bright, dusty, starburst galaxies would preferentially eject a dust component with a shallower opacity curve (hence less reddening) and a higher opacity/mass than the observed galactic dust which is left behind. Such dust could cause the falloff in flux at high-z without violating constraints on reddening or metallicity. The specific model presented is of needle-like dust, which is expected from the theory of crystal growth and has been detected in samples of interstellar dust. Carbon needles with conservative properties can supply the necessary opacity, and would very likely be ejected from galaxies as required. The model is not subject to the arguments given in the literature against grey dust, but may be constrained by future data from supernova searches done at higher redshift, in clust...

  20. Cosmic Visions Dark Energy: Technology

    Energy Technology Data Exchange (ETDEWEB)

    Dodelson, Scott [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Heitmann, Katrin [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Hirata, Chris [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Honscheid, Klaus [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Roodman, Aaron [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Seljak, Uroš [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Slosar, Anže [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Trodden, Mark [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2016-04-26

    A strong instrumentation and detector R&D program has enabled the current generation of cosmic frontier surveys. A small investment in R&D will continue to pay dividends and enable new probes to investigate the accelerated expansion of the universe. Instrumentation and detector R&D provide critical training opportunities for future generations of experimentalists, skills that are important across the entire Department of Energy High Energy Physics program.

  1. Electromagnetic field and cosmic censorship

    CERN Document Server

    Düztaş, Koray

    2013-01-01

    We construct a gedanken experiment in which an extremal Kerr black hole interacts with a test electromagnetic field. Using Teukolsky's solutions for electromagnetic perturbations in Kerr spacetime, and the conservation laws imposed by the energy momentum tensor of the electromagnetic field and the Killing vectors of the spacetime, we prove that this interaction cannot convert the black hole into a naked singularity, thus cosmic censorship conjecture is not violated in this case.

  2. Cosmic crystallography in a circle

    CERN Document Server

    Teixeira, A F F

    2000-01-01

    In a circle (an $S^1$) with circumference 1 assume $m$ objects distributed pseudo-randomly. In the universal covering $R^1$ assume the objects replicated accordingly, and take an interval $L>1$. In this interval, make the normalized histogram of the pair separations which are not an integer. The theoretical (expected) such histogram is obtained in this report, as well as its difference to a similar histogram for non-replicated objects. The whole study is of interest for the cosmic crystallography.

  3. Racetrack Inflation and Cosmic Strings

    CERN Document Server

    Brax, Philippe; Davis, Anne-Christine; Davis, Stephen C; Jeannerot, Rachel; Postma, Marieke

    2008-01-01

    We consider the coupling of racetrack inflation to matter fields as realised in the D3/D7 brane system. In particular, we investigate the possibility of cosmic string formation in this system. We find that string formation before or at the onset of racetrack inflation is possible, but they are then inflated away. Furthermore, string formation at the end of inflation is prevented by the presence of the moduli sector. As a consequence, no strings survive racetrack inflation.

  4. Charged Cosmic Rays and Neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Kachelrieß, M.

    2013-04-15

    High-energy neutrino astronomy has grown up, with IceCube as one of its main experiments having sufficient sensitivity to test “vanilla” models of astrophysical neutrinos. I review predictions of neutrino fluxes as well as the status of cosmic ray physics. I comment also briefly on an improvement of the Fermi-LAT limit for cosmogenic neutrinos and on the two neutrino events presented by IceCube first at “Neutrino 2012”.

  5. Cosmic microwave background theory

    Science.gov (United States)

    Bond, J. Richard

    1998-01-01

    A long-standing goal of theorists has been to constrain cosmological parameters that define the structure formation theory from cosmic microwave background (CMB) anisotropy experiments and large-scale structure (LSS) observations. The status and future promise of this enterprise is described. Current band-powers in ℓ-space are consistent with a ΔT flat in frequency and broadly follow inflation-based expectations. That the levels are ∼(10−5)2 provides strong support for the gravitational instability theory, while the Far Infrared Absolute Spectrophotometer (FIRAS) constraints on energy injection rule out cosmic explosions as a dominant source of LSS. Band-powers at ℓ ≳ 100 suggest that the universe could not have re-ionized too early. To get the LSS of Cosmic Background Explorer (COBE)-normalized fluctuations right provides encouraging support that the initial fluctuation spectrum was not far off the scale invariant form that inflation models prefer: e.g., for tilted Λ cold dark matter sequences of fixed 13-Gyr age (with the Hubble constant H0 marginalized), ns = 1.17 ± 0.3 for Differential Microwave Radiometer (DMR) only; 1.15 ± 0.08 for DMR plus the SK95 experiment; 1.00 ± 0.04 for DMR plus all smaller angle experiments; 1.00 ± 0.05 when LSS constraints are included as well. The CMB alone currently gives weak constraints on Λ and moderate constraints on Ωtot, but theoretical forecasts of future long duration balloon and satellite experiments are shown which predict percent-level accuracy among a large fraction of the 10+ parameters characterizing the cosmic structure formation theory, at least if it is an inflation variant. PMID:9419321

  6. Cosmic ray physics goes to school

    CERN Multimedia

    2002-01-01

    With the help of a CERN physicist, German Schools bring the Largest Cosmic Ray Detector in Europe one step closer to reality   Eric Berthier and Robert Porret (CERN, ST/HM), Frej Torp and Christian Antfolk from the Polytechnics Arcada in Finland, and Karsten Eggert, physicist at CERN who initiated this project, during the installation of cosmic ray detectors in the Pays de Gex, at point 4. Niina Patrikainen and Frej Torp, Finnish students from Rovaniemi and Arcada Polytechnics, installing cosmic ray counters at the Fachhochschule in Duesseldorf. The science of cosmic ray detection is growing, literally. Cosmic rays, energetic particles from space, strike our planet all the time. They collide with the air molecules in our upper atmosphere and initiate large showers of elementary particles (mainly electrons, photons, hadrons and muons) which rain down upon the earth. The shower size and the particle density in the showers reflect the initial energy of the cosmic ray particle, a detail which makes d...

  7. Cosmic ray penetration in diffuse clouds

    CERN Document Server

    Morlino, G

    2015-01-01

    Cosmic rays are a fundamental source of ionization for molecular and diffuse clouds, influencing their chemical, thermal, and dynamical evolution. The amount of cosmic rays inside a cloud also determines the $\\gamma$-ray flux produced by hadronic collisions between cosmic rays and cloud material. We study the spectrum of cosmic rays inside and outside of a diffuse cloud, by solving the stationary transport equation for cosmic rays including diffusion, advection and energy losses due to ionization of neutral hydrogen atoms. We found that the cosmic ray spectrum inside a diffuse cloud differs from the one in the interstellar medium for energies smaller than $E_{br}\\approx 100$ MeV, irrespective of the model details. Below $E_{br}$, the spectrum is harder (softer) than that in the interstellar medium if the latter is a power law $\\propto p^{-s}$ with $s$ larger (smaller) than $\\sim0.42$.

  8. Effect of temperature on life history and population growth parameters of Planococcus citri (Homoptera, Pseudococcidae on coleus [Solenostemon scutellarioides (L. Codd.

    Directory of Open Access Journals (Sweden)

    Goldasteh Shila

    2009-01-01

    Full Text Available The development, life history, reproduction, and population growth parameters of Planococcus citri Risso on coleus [Solenostemon scutellarioides (L. Codd.] were studied at various temperatures ranging from 10 to 37ºC, 70±10% RH, and photoperiod length of 16: 8 h (L: D. Females and males successfully developed into adults at from 15 to 32ºC and 18 to 32ºC, respectively. All first instars died at 10, 12, and 37ºC. Lower temperatures (10, 12, and 15ºC caused higher egg mortality than did higher temperatures (32, 35, and 37ºC. At all temperatures (except 15ºC, the highest percentage of nymphal mortality was observed in the first instar. The sex ratio was female-biased between 15 and 30ºC, but there was a slightly higher number of males at 32ºC. The highest adult longevities of females and males were obtained at 18 and 25°C, respectively. The pre-oviposition, oviposition, and post-oviposition periods were significantly different at various temperatures. The highest fecundity was observed at 23ºC. The shortest and longest oviposition periods occurred at 32 and 18ºC, respectively. Maximum values of the intrinsic rate of natural increase (rm, net reproduction rate (R0, and finite rate of increase (λ and the shortest mean generation time (T and doubling time (DT were obtained at 25ºC. Our findings showed citrus mealybug performances to be highly affected by temperature.

  9. Maternal History and Uterine Artery Doppler in the Assessment of Risk for Development of Early- and Late-Onset Preeclampsia and Intrauterine Growth Restriction

    Directory of Open Access Journals (Sweden)

    Elisa Llurba

    2009-01-01

    Full Text Available Objective. To examine the value of one-step uterine artery Doppler at 20 weeks of gestation in the prediction pre-eclampsia (PE and/or intrauterine growth restriction (IUGR. Methods. A prospective multicentre study that included all women with singleton pregnancies at 19–22 weeks of gestation (w. The mean pulsatility index (mPI of both uterine arteries was calculated. Receiver-operating characteristics curves (ROC were drawn to compare uterine artery Doppler and maternal risk factors for the prediction of early-onset PE and/or IUGR (before 32 w and late-onset PE and/or IUGR. Results. 6,586 women were included in the study. Complete outcome data was recorded for 6,035 of these women (91.6%. PE developed in 75 (1.2% and IUGR in 69 (1.1% cases. Uterine Doppler mPI was 0.99 and the 90th centile was 1.40. For 10% false-positive rate, uterine Doppler mPI identified 70.6% of pregnancies that subsequently developed early-onset PE and 73.3% of pregnancies that developed early-onset IUGR. The test had a lower detection rate for the late-onset forms of the disease (23.5% for PE and 30% for IUGR. Maternal history has a low sensitivity in the detection of early-onset cases, although it is better at detecting late-onset PE. Conclusion. Uterine artery Doppler and maternal risk factors seem to select two different populations - early and late-onset PE which might suggest a different pathogenesis.

  10. Measuring the universe cosmic dimensions from Aristarchus to Halley

    CERN Document Server

    Van Helden, Albert

    2010-01-01

    Measuring the Universe is the first history of the evolution of cosmic dimensions, from the work of Eratosthenes and Aristarchus in the third century B.C. to the efforts of Edmond Halley (1656-1742). ""Van Helden's authoritative treatment is concise and informative; he refers to numerous sources of information, draws on the discoveries of modern scholarship, and presents the first book-length treatment of this exceedingly important branch of science.""-Edward Harrison, American Journal of Physics ""Van Helden writes well, with a flair for clear explanation. I

  11. Cosmic Connections:. from Cosmic Rays to Gamma Rays, Cosmic Backgrounds and Magnetic Fields

    Science.gov (United States)

    Kusenko, Alexander

    2013-12-01

    Combined data from gamma-ray telescopes and cosmic-ray detectors have produced some new surprising insights regarding intergalactic and galactic magnetic fields, as well as extragalactic background light. We review some recent advances, including a theory explaining the hard spectra of distant blazars and the measurements of intergalactic magnetic fields based on the spectra of distant sources. Furthermore, we discuss the possible contribution of transient galactic sources, such as past gamma-ray bursts and hypernova explosions in the Milky Way, to the observed ux of ultrahigh-energy cosmicrays nuclei. The need for a holistic treatment of gamma rays, cosmic rays, and magnetic fields serves as a unifying theme for these seemingly unrelated phenomena.

  12. The cosmic baryon cycle and galaxy mass assembly in the FIRE simulations

    Science.gov (United States)

    Anglés-Alcázar, Daniel; Faucher-Giguère, Claude-André; Kereš, Dušan; Hopkins, Philip F.; Quataert, Eliot; Murray, Norman

    2017-10-01

    We use cosmological simulations from the FIRE (Feedback In Realistic Environments) project to study the baryon cycle and galaxy mass assembly for central galaxies in the halo mass range Mhalo ˜ 1010-1013 M⊙. By tracing cosmic inflows, galactic outflows, gas recycling and merger histories, we quantify the contribution of physically distinct sources of material to galaxy growth. We show that in situ star formation fuelled by fresh accretion dominates the early growth of galaxies of all masses, while the re-accretion of gas previously ejected in galactic winds often dominates the gas supply for a large portion of every galaxy's evolution. Externally processed material contributes increasingly to the growth of central galaxies at lower redshifts. This includes stars formed ex situ and gas delivered by mergers, as well as smooth intergalactic transfer of gas from other galaxies, an important but previously underappreciated growth mode. By z = 0, wind transfer, i.e. the exchange of gas between galaxies via winds, can dominate gas accretion on to ˜L* galaxies over fresh accretion and standard wind recycling. Galaxies of all masses re-accrete ≳50 per cent of the gas ejected in winds and recurrent recycling is common. The total mass deposited in the intergalactic medium per unit stellar mass formed increases in lower mass galaxies. Re-accretion of wind ejecta occurs over a broad range of time-scales, with median recycling times (˜100-350 Myr) shorter than previously found. Wind recycling typically occurs at the scale radius of the halo, independent of halo mass and redshift, suggesting a characteristic recycling zone around galaxies that scales with the size of the inner halo and the galaxy's stellar component.

  13. Astronomers Unveiling Life's Cosmic Origins

    Science.gov (United States)

    2009-02-01

    Processes that laid the foundation for life on Earth -- star and planet formation and the production of complex organic molecules in interstellar space -- are yielding their secrets to astronomers armed with powerful new research tools, and even better tools soon will be available. Astronomers described three important developments at a symposium on the "Cosmic Cradle of Life" at the annual meeting of the American Association for the Advancement of Science in Chicago, IL. Chemistry Cycle The Cosmic Chemistry Cycle CREDIT: Bill Saxton, NRAO/AUI/NSF Full Size Image Files Chemical Cycle Graphic (above image, JPEG, 129K) Graphic With Text Blocks (JPEG, 165K) High-Res TIFF (44.2M) High-Res TIFF With Text Blocks (44.2M) In one development, a team of astrochemists released a major new resource for seeking complex interstellar molecules that are the precursors to life. The chemical data released by Anthony Remijan of the National Radio Astronomy Observatory (NRAO) and his university colleagues is part of the Prebiotic Interstellar Molecule Survey, or PRIMOS, a project studying a star-forming region near the center of our Milky Way Galaxy. PRIMOS is an effort of the National Science Foundation's Center for Chemistry of the Universe, started at the University of Virginia (UVa) in October 2008, and led by UVa Professor Brooks H. Pate. The data, produced by the NSF's Robert C. Byrd Green Bank Telescope (GBT) in West Virginia, came from more than 45 individual observations totalling more than nine GigaBytes of data and over 1.4 million individual frequency channels. Scientists can search the GBT data for specific radio frequencies, called spectral lines -- telltale "fingerprints" -- naturally emitted by molecules in interstellar space. "We've identified more than 720 spectral lines in this collection, and about 240 of those are from unknown molecules," Remijan said. He added, "We're making available to all scientists the best collection of data below 50 GHz ever produced for

  14. 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.

  15. Cosmic Censorship: the Role of Quantum Physics

    OpenAIRE

    Hod, Shahar

    1999-01-01

    The cosmic censorship hypothesis introduced by Penrose thirty years ago is still one of the most important open questions in {\\it classical} general relativity. The main goal of this paper is to put forward the idea that cosmic censorship is intrinsically a {\\it quantum} phenomena. We construct a gedanken experiment which seems to violate the cosmic censorship principle within the purely {\\it classical} framework of general relativity. We prove, however, that {\\it quantum} physics restores th...

  16. On the Properties of Cosmic String Loops

    Science.gov (United States)

    Casper, Paul Henry

    1996-01-01

    When coupled with the prevailing ideas of cosmology, the standard model of particle physics implies that the early universe underwent a sequence of phase transitions. Such phase transitions can lead to topological defects such as magnetic monopoles, domain walls and cosmic strings. The formation and subsequent evolution of a network of cosmic strings may have played a key role in the development of the early universe. One of the most crucial elements in the evolution of the cosmic string network is the formation and decay of closed loops of cosmic string. After formation, the loops lose their energy by emitting gravitational radiation. This provides the primary energy loss mechanism for the cosmic string network. In addition, the cosmic string loops may display a number of observable features through which the cosmic string model may be constrained. In this dissertation a number of the key properties of cosmic string loops are investigated. A general method for determining the rates at which cosmic string loops radiate both energy and linear momentum is developed and implemented. Exact solutions for the radiation rates of a several new classes of loops are derived and used to test the validity of using the piecewise linear method on smooth loop trajectories. A large set of representative loop trajectories is produced using the method of loop fragmentation. These trajectories are analyzed to provide useful information on the properties of realistic cosmic string loops. The fraction of cosmic string loops which would collapse to form black holes is determined and used to place a new observational limit on the mass per unit length of cosmic strings.

  17. ACORDE - A Cosmic Ray Detector for ALICE

    CERN Document Server

    INSPIRE-00247175; Pagliarone, C.

    2006-01-01

    ACORDE, the ALICE COsmic Ray DEtector is one of the ALICE detectors, presently under construction. It consists of an array of plastic scintillator counters placed on the three upper faces of the ALICE magnet. This array will act as Level 0 cosmic ray trigger and, together with other ALICE sub-detectors, will provide precise information on cosmic rays with primary energies around $10^{15-17}$ eV. In this paper we will describe the ACORDE detector, trigger design and electronics.

  18. Interacting holographic generalized cosmic Chaplygin gas model

    Science.gov (United States)

    Naji, Jalil

    2014-03-01

    In this paper we consider a correspondence between the holographic dark energy density and interacting generalized cosmic Chaplygin gas energy density in flat FRW universe. Then, we reconstruct the potential of the scalar field which describe the generalized cosmic Chaplygin cosmology. In the special case we obtain time-dependent energy density and study cosmological parameters. We find stability condition of this model which is depend on cosmic parameter.

  19. Solar History An Introduction

    CERN Document Server

    Vita-Finzi, Claudio

    2013-01-01

    Beyond the four centuries of sunspot observation and the five decades during which artificial satellites have monitored the Sun – that is to say for 99.99999% of the Sun’s existence – our knowledge of solar history depends largely on analogy with kindred main sequence stars, on the outcome of various kinds of modelling, and on indirect measures of solar activity. They include the analysis of lunar rocks and meteorites for evidence of solar flares and other components of the solar cosmic-ray (SCR) flux, and the measurement of cosmogenic isotopes in wood, stratified ice and marine sediments to evaluate changes in the galactic cosmic-ray (GCR) flux and thus infer changes in the sheltering magnetic fields of the solar wind. In addition, shifts in the global atmospheric circulation which appear to result from cyclic fluctuations in solar irradiance have left their mark in river sediments and in the isotopic composition of cave deposits. In this volume the results these sources have already produced have bee...

  20. Dark Matter detection via lepton cosmic rays

    CERN Document Server

    Lineros, Roberto A

    2010-01-01

    Recent observations of lepton cosmic rays, coming from the PAMELA and FERMI experiments, have pushed our understanding of the interstellar medium and cosmic rays sources to unprecedented levels. The imprint of dark matter on lepton cosmic rays is the most exciting explanation of both PAMELA's positron excess and FERMI's total flux of electrons. Alternatively, supernovae are astrophysical objects with the same potential to explain these observations. In this work, we present an updated study of the astrophysical sources of lepton cosmic rays and the possible trace of a dark matter signal on the positron excess and total flux of electrons.

  1. Cosmic Ray Acceleration in Supernova Remnants

    CERN Document Server

    Blasi, Pasquale

    2010-01-01

    We review the main observational and theoretical facts about acceleration of Galactic cosmic rays in supernova remnants, discussing the arguments in favor and against a connection between cosmic rays and supernova remnants, the so-called supernova remnant paradigm for the origin of Galactic cosmic rays. Recent developments in the modeling of the mechanism of diffusive shock acceleration are discussed, with emphasis on the role of 1) magnetic field amplification, 2) acceleration of nuclei heavier than hydrogen, 3) presence of neutrals in the circumstellar environment. The status of the supernova-cosmic ray connection in the time of Fermi-LAT and Cherenkov telescopes is also discussed.

  2. High Energy Cosmic Electrons: Messengers from Nearby Cosmic Ray Sources or Dark Matter?

    Science.gov (United States)

    Moiseev, Alexander

    2011-01-01

    This slide presentation reviews the recent discoveries by the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-Ray Telescope in reference to high energy cosmic electrons, and whether their source is cosmic rays or dark matter. Specific interest is devoted to Cosmic Ray electrons anisotropy,

  3. Electrodynamics of a Cosmic Dark Fluid

    Directory of Open Access Journals (Sweden)

    Alexander B. Balakin

    2016-06-01

    Full Text Available Cosmic Dark Fluid is considered as a non-stationary medium, in which electromagnetic waves propagate, and magneto-electric field structures emerge and evolve. A medium-type representation of the Dark Fluid allows us to involve in its analysis the concepts and mathematical formalism elaborated in the framework of classical covariant electrodynamics of continua, and to distinguish dark analogs of well-known medium-effects, such as optical activity, pyro-electricity, piezo-magnetism, electro- and magneto-striction and dynamo-optical activity. The Dark Fluid is assumed to be formed by a duet of a Dark Matter (a pseudoscalar axionic constituent and Dark Energy (a scalar element; respectively, we distinguish electrodynamic effects induced by these two constituents of the Dark Fluid. The review contains discussions of 10 models, which describe electrodynamic effects induced by Dark Matter and/or Dark Energy. The models are accompanied by examples of exact solutions to the master equations, correspondingly extended; applications are considered for cosmology and space-times with spherical and pp-wave symmetries. In these applications we focused the attention on three main electromagnetic phenomena induced by the Dark Fluid: first, emergence of Longitudinal Magneto-Electric Clusters; second, generation of anomalous electromagnetic responses; third, formation of Dark Epochs in the Universe history.

  4. The cosmic MeV neutrino background as a laboratory for black hole formation

    Directory of Open Access Journals (Sweden)

    Hasan Yüksel

    2015-12-01

    Full Text Available Calculations of the cosmic rate of core collapses, and the associated neutrino flux, commonly assume that a fixed fraction of massive stars collapse to black holes. We argue that recent results suggest that this fraction instead increases with redshift. With relatively more stars vanishing as “unnovae” in the distant universe, the detectability of the cosmic MeV neutrino background is improved due to their hotter neutrino spectrum, and expectations for supernova surveys are reduced. We conclude that neutrino detectors, after the flux from normal SNe is isolated via either improved modeling or the next Galactic SN, can probe the conditions and history of black hole formation.

  5. About cosmic gamma ray lines

    Science.gov (United States)

    Diehl, Roland

    2017-06-01

    Gamma ray lines from cosmic sources convey the action of nuclear reactions in cosmic sites and their impacts on astrophysical objects. Gamma rays at characteristic energies result from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. The gamma-ray line from the annihilation of positrons at 511 keV falls into the same energy window, although of different origin. We present here the concepts of cosmic gamma ray spectrometry and the corresponding instruments and missions, followed by a discussion of recent results and the challenges and open issues for the future. Among the lessons learned are the diffuse radioactive afterglow of massive-star nucleosynthesis in 26Al and 60Fe gamma rays, which is now being exploited towards the cycle of matter driven by massive stars and their supernovae; large interstellar cavities and superbubbles have been recognised to be of key importance here. Also, constraints on the complex processes making stars explode as either thermonuclear or core-collapse supernovae are being illuminated by gamma-ray lines, in this case from shortlived radioactivities from 56Ni and 44Ti decays. In particular, the three-dimensionality and asphericities that have recently been recognised as important are enlightened in different ways through such gamma-ray line spectroscopy. Finally, the distribution of positron annihilation gamma ray emission with its puzzling bulge-dominated intensity disctribution is measured through spatially-resolved spectra, which indicate that annihilation conditions may differ in different parts of our Galaxy. But it is now understood that a variety of sources may feed positrons into the interstellar medium, and their characteristics largely get lost during slowing down and propagation of positrons before annihilation; a recent microquasar flare was caught as an opportunity to see positrons annihilate at a source.

  6. Cosmic Shear Bias and Calibration in Cosmic Shear Studies

    CERN Document Server

    Taylor, A N

    2016-01-01

    With the advent of large-scale weak lensing surveys there is a need to understand how realistic, scale-dependent systematics bias cosmic shear and dark energy measurements, and how they can be removed. Here we describe how spatial variations in the amplitude and orientation of realistic image distortions convolve with the measured shear field, mixing the even-parity convergence and odd-parity modes, and bias the shear power spectrum. Many of these biases can be removed by calibration to external data, the survey itself, or by modelling in simulations. The uncertainty in the calibration must be marginalised over and we calculate how this propagates into parameter estimation, degrading the dark energy Figure-of-Merit. We find that noise-like biases affect dark energy measurements the most, while spikes in the bias power have the least impact, reflecting their correlation with the effect of cosmological parameters. We argue that in order to remove systematic biases in cosmic shear surveys and maintain statistica...

  7. Parameter splitting in dark energy: is dark energy the same in the background and in the cosmic structures?

    CERN Document Server

    Bernal, José Luis; Cuesta, Antonio J

    2015-01-01

    We perform an empirical consistency test of General Relativity/dark energy by disentangling expansion history and growth of structure constraints. We replace each late-universe parameter that describes the behavior of dark energy with two meta-parameters: one describing geometrical information in cosmological probes, and the other controlling the growth of structure. If the underlying model (a standard wCDM cosmology with General Relativity) is correct, that is under the null hypothesis, the two meta-parameters coincide. If they do not, it could indicate a failure of the model or systematics in the data. We present a global analysis using state-of-the-art cosmological data sets which points in the direction that cosmic structures prefer a weaker growth than that inferred by background probes. This result could signify inconsistencies of the model, the necessity of extensions to it or the presence of systematic errors in the data. We examine all these possibilities. The fact that the result is mostly driven by...

  8. Cosmic rays, clouds, and climate

    DEFF Research Database (Denmark)

    Marsh, N.; Svensmark, Henrik

    2000-01-01

    in the Earth's radiation budget through trapping outgoing radiation and reflecting incoming radiation. If a physical link between these two features can be established, it would provide a mechanism linking solar activity and Earth's climate. Recent satellite observations have further revealed a correlation...... between cosmic ray flux and low cloud top temperature. The temperature of a cloud depends on the radiation properties determined by its droplet distribution. Low clouds are warm (> 273 K) and therefore consist of liquid water droplets. At typical atmospheric supersaturations (similar to1%) a liquid cloud...

  9. International Conference on Cosmic Rays

    CERN Multimedia

    W.O. LOCK

    1964-01-01

    Towards the end of last year the 8th International conference on cosmic rays, held under the auspices of the International Union of Pure and Applied Physics (I.U.P.A.P.) and the Department of Atomic Energy of the Government of India, was held at Jaipur, India. Among the participants was W.O. Lock, head of CERN's Emulsion Group, who gave an invited talk on recent work in the field of what is normally known as high-energy physics — though in the context of this conference such energies seem quite low. In this article, Dr. Lock gives a general review of the conference and of the subjects discussed.

  10. Cosmic polarimetry in magnetoactive plasmas

    CERN Document Server

    Giovannini, Massimo

    2009-01-01

    Polarimetry of the Cosmic Microwave Background (CMB) represents one of the possible diagnostics aimed at testing large-scale magnetism at the epoch of the photon decoupling. The propagation of electromagnetic disturbances in a magnetized plasma leads naturally to a B-mode polarization whose angular power spectrum is hereby computed both analytically and numerically. Combined analyses of all the publicly available data on the B-mode polarization are presented, for the first time, in the light of the magnetized $\\Lambda$CDM scenario. Novel constraints on pre-equality magnetism are also derived in view of the current and expected sensitivities to the B-mode polarization.

  11. The Cosmic Background Explorer Satellite

    Science.gov (United States)

    Mather, J.; Kelsall, T.

    1980-01-01

    The Cosmic Background Explorer (COBE) satellite, planned for launch in 1985, will measure the diffuse infrared and microwave radiation of the universe over the entire wavelength range from a few microns to 1.3 cm. It will include three instruments: a set of microwave isotropy radiometers at 23, 31, 53, and 90 GHz, an interferometer spectrometer from 1 to 100/cm, and a filter photometer from 1 to 300 microns. The COBE satellite is designed to reach the sensitivity limits set by foreground sources such as the interstellar and interplanetary dust, starlight, and galactic synchrotron radiation, so that a diffuse residual radiation may be interpreted unambiguously as extragalactic

  12. Ground level cosmic ray observations

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, S.A. [Tata Institute of Fundamental Research, Bombay (International Commission on Radiation Units and Measurements); Grimani, C.; Brunetti, M.T.; Codino, A. [Perugia Univ. (Italy)]|[INFN, Perugia (Italy); Papini, P.; Massimo Brancaccio, F.; Piccardi, S. [Florence Univ. (Italy)]|[INFN, Florence (Italy); Basini, G.; Bongiorno, F. [INFN, Laboratori Nazionali di Frascati, Rome (Italy); Golden, R.L. [New Mexico State Univ., Las Cruces, NM (United States). Particle Astrophysics Lab.; Hof, M. [Siegen Univ. (Germany). Fachbereich Physik

    1995-09-01

    Cosmic rays at ground level have been collected using the NMSU/Wizard - MASS2 instrument. The 17-hr observation run was made on September 9. 1991 in Fort Sumner, New Mexico, Usa. Fort Sumner is located at 1270 meters a.s.l., corresponding to an atmospheric depth of about 887 g/cm{sup 2}. The geomagnetic cutoff is 4.5 GV/c. The charge ratio of positive and negative muons and the proton to muon ratio have been determined. These observations will also be compared with data collected at a higher latitude using the same basic apparatus.

  13. The cosmic production of Helium

    CERN Document Server

    Jiménez, R; MacDonald, J; Gibson, B K; Jimenez, Raul; Flynn, Chris; Donald, James Mac; Gibson, Brad K.

    2003-01-01

    We estimate the cosmic production rate of helium relative to metals ($\\Delta Y/\\Delta Z$) using K dwarf stars in the Hipparcos catalog with accurate spectroscopic metallicities. The best fitting value is $\\Delta Y/\\Delta Z=2.1 \\pm 0.4$ at the 68% confidence level. Our derived value agrees with determinations from HII regions and with theoretical predictions from stellar yields with standard assumptions for the initial mass function. The amount of helium in stars determines how long they live and therefore how fast they will enrich the insterstellar medium with fresh material.

  14. The Cosmic Ray Lepton Puzzle

    CERN Document Server

    Brun, Pierre; Cirelli, Marco; Moulin, Emmanuel; Glicenstein, Jean-Francois; Iocco, Fabio; Pieri, Lidia

    2010-01-01

    Recent measurements of cosmic ray electrons and positrons by PAMELA, ATIC, Fermi and HESS have revealed interesting excesses and features in the GeV-TeV range. Many possible explanations have been suggested, invoking one or more nearby primary sources such as pulsars and supernova remnants, or dark matter. Based on the output of the TANGO in PARIS --Testing Astroparticle with the New GeV/TeV Observations in Positrons And electRons : Identifying the Sources-- workshop held in Paris in May 2009, we review here the latest experimental results and we discuss some virtues and drawbacks of the many theoretical interpretations proposed so far.

  15. Thermal and Shock Histories of Gas in Galaxy Clusters

    Science.gov (United States)

    Benjamin, Sarah; Nagai, D.; Wetzel, A. R.

    2014-01-01

    Galaxy clusters are the most recently formed cosmological objects in the universe, making them ideal for studying the interplay between cosmology and baryonic physics in structure formation. Understanding their formation and growth requires not only an understanding of the baryonic physics, but also the detailed dynamics of how gas accretes from cosmic filaments onto a cluster throughout its lifetime. One of the outstanding questions concerning galaxy clusters currently is the baryon deficit in their interior as well as non-equilibrium phenomena (such as turbulence and gas clumping) in the virialization regions. Recent X-ray and microwave observations have revealed detailed thermodynamic structure of the cluster hot gas from the core to their virial radii, making comparisons of gas accretion in simulations to observations a strong cosmological probe. In this work, we focus on quantifying gas accretion in non-radiative cosmological simulations of galaxy clusters, where the only significant changes in entropy will be due to shock heating. In order to track each gas element, we implemented a tracer particle module in the Adaptive Refinement Tree cosmological simulation code. By following the thermal histories of each tracer particle, we measure the Mach number of every shock the particle experienced and identify periods of significant shock-heating. Combining this with measurements of how the temperature distribution of regions of the halo change over time, we then investigate whether gas had significantly different histories based on whether they accrete straight from the cosmic background or by first accreting onto a subhalo, the change in accretion due to the mass of the final main halo, and the disruptive effect mergers have on the smooth accretion process. We discuss implications of our results for understanding recent deep Chandra X-ray observations of Abell 133 which revealed several unexpected structural features connected to its gas accretion, including a

  16. Cosmic chronometers in the Rh = ct Universe

    Science.gov (United States)

    Melia, Fulvio; Maier, Robert S.

    2013-07-01

    The use of luminous red galaxies as cosmic chronometers provides us with an indispensable method of measuring the universal expansion rate H(z) in a model-independent way. Unlike many probes of the cosmological history, this approach does not rely on integrated quantities, such as the luminosity distance, and therefore does not require the pre-assumption of any particular model, which may bias subsequent interpretations of the data. We employ three statistical tools - the Akaike, Kullback and Bayes Information Criteria (AIC, KIC and BIC) - to compare the Λ cold dark matter (ΛCDM) model and the Rh = ct Universe with the currently available measurements of H(z), and show that the Rh = ct Universe is favoured by these model selection criteria. The parameters in each model are individually optimized by maximum likelihood estimation. The Rh = ct Universe fits the data with a reduced χ2dof=0.745 for a Hubble constant H0 = 63.2 ± 1.6 km s-1 Mpc-1, and H0 is the sole parameter in this model. By comparison, the optimal ΛCDM model, which has three free parameters (including H0 = 68.9 ± 3.3 km s-1 Mpc-1, Ωm = 0.32, and a dark-energy equation of state pde = -ρde), fits the H(z) data with a reduced χ2dof = 0.777. With these χ2dof values, the AIC yields a likelihood of ≈82 per cent that the distance-redshift relation of the Rh = ct Universe is closer to the correct cosmology, than is the case for ΛCDM. If the alternative BIC criterion is used, the respective Bayesian posterior probabilities are 91.2 per cent (Rh = ct) versus 8.8 per cent (ΛCDM). Using the concordance ΛCDM parameter values, rather than those obtained by fitting ΛCDM to the cosmic chronometer data, would further disfavour ΛCDM.

  17. The Spine of the Cosmic Web

    NARCIS (Netherlands)

    Aragón-Calvo, Miguel A.; Platen, Erwin; van de Weijgaert, Rien; Szalay, Alexander S.

    2010-01-01

    We present the SpineWeb framework for the topological analysis of the Cosmic Web and the identification of its walls, filaments, and cluster nodes. Based on the watershed segmentation of the cosmic density field, the SpineWeb method invokes the local adjacency properties of the boundaries between th

  18. NEXUS: tracing the cosmic web connection

    NARCIS (Netherlands)

    Cautun, Marius; van de Weygaert, Rien; Jones, Bernard J. T.

    2013-01-01

    We introduce the NEXUS algorithm for the identification of cosmic web environments: clusters, filaments, walls and voids. This is a multiscale and automatic morphological analysis tool that identifies all the cosmic structures in a scale free way, without preference for a certain size or shape. We d

  19. The Temperature of the Cosmic Microwave Background

    CERN Document Server

    Fixsen, D J

    2009-01-01

    The FIRAS data are independently recalibrated using the WMAP data to obtain a CMB temperature of 2.7260 +/- 0.0013. Measurements of the temperature of the cosmic microwave background are reviewed. The determination from the measurements from the literature is cosmic microwave background temperature of 2.72548 +/- 0.00057 K.

  20. Cosmic-ray acceleration in supernova remnants

    NARCIS (Netherlands)

    Helder, E.A.

    2010-01-01

    Supernovae are among the most energetic events in the Universe. During the event, they expel their material with enormous speeds into the surroundings. In addition, supernovae are thought to transfer a sizable fraction of their energy into just a few particles: cosmic rays. These cosmic rays acquire