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Sample records for matter dominated universe

  1. Asymmetric Dark Matter in the shear-dominated universe

    NASA Astrophysics Data System (ADS)

    Iminniyaz, Hoernisa

    2017-02-01

    We explore the relic abundance of asymmetric Dark Matter in shear-dominated universe in which it is assumed the universe is expanded anisotropically. The modified expansion rate leaves its imprint on the relic density of asymmetric Dark Matter particles if the asymmetric Dark Matter particles are decoupled in shear dominated era. We found the relic abundances for particle and anti-particle are increased. The particle and anti-particle abundances are almost in the same amount for the larger value of the shear factor xe which makes the indirect detection possible for asymmetric Dark Matter. We use the present day Dark Matter density from the observation to find the constraints on the parameter space in this model.

  2. Gravitational particle creation in a stiff matter dominated universe

    NASA Astrophysics Data System (ADS)

    Lankinen, Juho; Vilja, Iiro

    2017-08-01

    A scenario for gravitational particle creation in a stiff matter dominated flat Friedmann-Robertson-Walker universe is presented. The primary creation of scalar particles is calculated using quantum field theory in curved spacetime and it is found to be strongly dependent on the scalar mass and the expansion parameter of the universe. The particle creation is most effective for a very massive scalar field and large expansion parameter. We demonstrate the phenomenon by applying it to cosmological toy model scenario, where secondary particles are created by the scalar field decay.

  3. Bulk viscous matter-dominated Universes: asymptotic properties

    SciTech Connect

    Avelino, Arturo; García-Salcedo, Ricardo; Gonzalez, Tame; Nucamendi, Ulises; Quiros, Israel E-mail: rigarcias@ipn.mx E-mail: ulises@ifm.umich.mx

    2013-08-01

    By means of a combined use of the type Ia supernovae and H(z) data tests, together with the study of the asymptotic properties in the equivalent phase space — through the use of the dynamical systems tools — we demonstrate that the bulk viscous matter-dominated scenario is not a good model to explain the accepted cosmological paradigm, at least, under the parametrization of bulk viscosity considered in this paper. The main objection against such scenarios is the absence of conventional radiation and matter-dominated critical points in the phase space of the model. This entails that radiation and matter dominance are not generic solutions of the cosmological equations, so that these stages can be implemented only by means of unique and very specific initial conditions, i. e., of very unstable particular solutions. Such a behavior is in marked contradiction with the accepted cosmological paradigm which requires of an earlier stage dominated by relativistic species, followed by a period of conventional non-relativistic matter domination, during which the cosmic structure we see was formed. Also, we found that the bulk viscosity is positive just until very late times in the cosmic evolution, around z < 1. For earlier epochs it is negative, been in tension with the local second law of thermodynamics.

  4. Large scale structure in universes dominated by cold dark matter

    NASA Technical Reports Server (NTRS)

    Bond, J. Richard

    1986-01-01

    The theory of Gaussian random density field peaks is applied to a numerical study of the large-scale structure developing from adiabatic fluctuations in models of biased galaxy formation in universes with Omega = 1, h = 0.5 dominated by cold dark matter (CDM). The angular anisotropy of the cross-correlation function demonstrates that the far-field regions of cluster-scale peaks are asymmetric, as recent observations indicate. These regions will generate pancakes or filaments upon collapse. One-dimensional singularities in the large-scale bulk flow should arise in these CDM models, appearing as pancakes in position space. They are too rare to explain the CfA bubble walls, but pancakes that are just turning around now are sufficiently abundant and would appear to be thin walls normal to the line of sight in redshift space. Large scale streaming velocities are significantly smaller than recent observations indicate. To explain the reported 700 km/s coherent motions, mass must be significantly more clustered than galaxies with a biasing factor of less than 0.4 and a nonlinear redshift at cluster scales greater than one for both massive neutrino and cold models.

  5. Recent heavy-particle decay in a matter-dominated universe

    NASA Technical Reports Server (NTRS)

    Olive, K. A.; Seckel, D.; Vishniac, E.

    1985-01-01

    The cold matter scenario for galaxy formation solves the dark matter problem very nicely on small scales corresponding to galaxies and clusters of galaxies. It is, however, difficult to reconcile with a Universe with an Einstein-deSitter value of (UC OMEGA) = 1. Cold matter and (UC OMEGA) = 1 can be made compatible while retaining the feature that the Universe is matter dominated today. This is done by means of heavy (cold) particles whose decay subsequently leads to the unbinding of a large fraction of lighter clustered matter.

  6. Recent heavy-particle decay in a matter-dominated universe

    NASA Technical Reports Server (NTRS)

    Olive, K. A.; Seckel, D.; Vishniac, E.

    1985-01-01

    The cold matter scenario for galaxy formation solves the dark matter problem very nicely on small scales corresponding to galaxies and clusters of galaxies. It is, however, difficult to reconcile with a Universe with an Einstein-deSitter value of (UC OMEGA) = 1. Cold matter and (UC OMEGA) = 1 can be made compatible while retaining the feature that the Universe is matter dominated today. This is done by means of heavy (cold) particles whose decay subsequently leads to the unbinding of a large fraction of lighter clustered matter.

  7. The distribution of dark matter, galaxies, and the intergalactic medium in a cold dark matter dominated universe

    NASA Technical Reports Server (NTRS)

    Ryu, Dongsu; Vishniac, Ethan T.; Chiang, Wei-Hwan

    1988-01-01

    The evolution and distribution of galaxies and the intergalactic medium (IGM) have been studied, along with collisionless dark matter in a Universe dominated by cold dark matter. The Einstein-deSitter universe with omega sub 0 = 1 and h = 0.5 was considered (here h = H sub 0 bar 100/kms/Mpc and H sub 0 is the present value of the Hubble constant). It is assumed that initially dark matter composes 90 pct and baryonic matter composes 10 pct of total mass, and that the primordial baryonic matter is comprised of H and He, with the abundance of He equal to 10 pct of H by number. Galaxies are allowed to form out of the IGM, if the total density and baryonic density satisfy an overdensity criterion. Subsequently, the newly formed galaxies release 10 to the 60th ergs of energy into the IGM over a period of 10 to the 8th years. Calculations have been performed with 32 to the 3rd dark matter particles and 32 to the 3rd cells in a cube with comoving side length L = 9.6/h Mpc. Dark matter particles and galaxies have been followed with an N-body code, while the IGM has been followed with a fluid code.

  8. Cosmic background radiation anisotropies in universes dominated by nonbaryonic dark matter

    NASA Technical Reports Server (NTRS)

    Bond, J. R.; Efstathiou, G.

    1984-01-01

    Detailed calculations of the temperature fluctuations in the cosmic background radiation for universes dominated by massive collisionless relics of the big bang are presented. An initially adiabatic constant curvature perturbation spectrum is assumed. In models with cold dark matter, the simplest hypothesis - that galaxies follow the mass distribution leads to small-scale anisotropies which exceed current observational limits if omega is less than 0.2 h to the -4/3. Since low values of omega are indicated by dynamical studies of galaxy clustering, cold particle models in which light traces mass are probably incorrect. Reheating of the pregalactic medium is unlikely to modify this conclusion. In cold particle or neutrino-dominated universes with omega = 1, presented predictions for small-scale and quadrupole anisotropies are below current limits. In all cases, the small-scale fluctuations are predicted to be about 10 percent linearly polarized.

  9. Dilaton dominance in the early universe dilutes dark matter relic abundances

    SciTech Connect

    Lahanas, A. B.

    2011-05-15

    The role of the dilaton field and its coupling to matter may result in a dilution of dark matter (DM) relic densities. This is to be contrasted with quintessence scenarios in which relic densities are augmented, due to modification of the expansion rate, since the Universe is not radiation dominated at DM decoupling. The dilaton field, besides this, affects relic densities through its coupling to dust which tends to decrease relic abundances. Thus two separate mechanisms compete with each other resulting, in general, in a decrease of the relic density. This feature may be welcomed and can help the situation if direct dark matter experiments point towards small neutralino-nucleon cross sections, implying small neutralino annihilation rates and hence large relic densities, at least in the popular supersymmetric scenarios. In the presence of a diluting mechanism, both experimental constraints can be met. The role of the dilaton for this mechanism has been studied in the context of the noncritical string theory but in this work we follow a rather general approach assuming that the dilaton dominates only at early eras long before big bang nucleosynthesis.

  10. Galaxy and cluster formation in a universe dominated by cold dark matter

    SciTech Connect

    Primack, J.R.

    1984-07-01

    The dark matter (DM) that appears to be gravitationally dominant on all astronomical scales larger than the cores of galaxies can be classified, on the basis of its characteristic free-streaming damping mass M/sub D/, as hot (M/sub D/ approx. 10/sup 15/ M/sub mass/), warm (M/sub D/ approx. 10/sup 11/ M/sub mass/), or cold (M/sub D < 10/sup 8/ M/sub mass/). For the case of cold DM, the shape of the DM fluctuation spectrum is determined by (a) the primordial spectrum (on scales larger than the horizon), and (b) stagspansion, the stagnation of the growth of DM fluctuations that enter the horizon while the universe is still radiation-dominated. An attractive feature of the cold dark matter hypothesis is its considerable predictive power: the post-recombination fluctuation spectrum is calculable, and it in turn governs the formation of galaxies and clusters. Good agreement with the data is obtained for a Zeldovich spectrum of primordial fluctuations.

  11. The evolution of large-scale structure in a universe dominated by cold dark matter

    NASA Technical Reports Server (NTRS)

    Davis, M.; Efstathiou, G.; Frenk, C. S.; White, S. D. M.

    1985-01-01

    The results of numerical simulations of nonlinear gravitational clustering in universes dominated by weakly interacting, 'cold' dark matter are presented. The numerical methods used and the way in which initial conditions were generated are described, and the simulations performed are catalogued. The evolution of the fundamental statistical properties of the models is described and their comparability with observation is discussed. Graphical comparisons of these open models with the observed galaxy distribution in a large redshift survey are made. It is concluded that a model with a cosmological density parameter omega equal to one is quite unacceptable if galaxies trace the mass distribution, and that models with omega of roughly two, while better, still do not provide a fully acceptable match with observation. Finally, a situation in which galaxy formation is suppressed except in sufficiently dense regions is modelled which leads to models which can agree with observation quite well even for omega equal to one.

  12. Matter dominated universe and study of {sup 48}Ca double beta decay

    SciTech Connect

    Kishimoto, Tadafumi

    2010-08-12

    We have been studying double beta decay of {sup 48}Ca. Neutrino-less double beta decay (0{nu}{beta}{beta}) is currently known to be only experiment to verify whether lepton number is not conserved. The non-conservation is the key to create matter dominated universe by the so-called Leptogenesys. Our first stage experiment using the ELEGANT VI detector system gave the best lower limit of the half life of 0{nu}{beta}{beta} of {sup 48}Ca. We have been developing CANDLES detector system to sense much longer life-time region. We have developed techniques to reduce backgrounds further. The CADLES detector system was installed at Kamioka underground laboratory. Here I describe a schematic view of the system.

  13. Quantum cosmology on (k = -1)-Friedmann-Robertson-Walker Universe evolving from stiff matter era to the dust dominated one

    NASA Astrophysics Data System (ADS)

    Dariescu, Marina-Aura; Dariescu, Ciprian

    2017-01-01

    This work is devoted to the spatially open Friedmann-Robertson-Walker (FRW) Universe evolving from the stiff matter era to the dust dominated one. Within the quantum analysis based on the Wheeler-DeWitt equation, we derive the wave function of the (k = -1)-FRW Universe with combined matter sources. On the classical level, one has to deal with the Friedmann equation which leads on a dependence of the scale function on time generally expressed from functional relations involving elliptic integrals.

  14. Cold dark matter dominated, inflationary universe with Omega(0) less than 1 and n less than 1

    SciTech Connect

    Vittorio, N.; Matarrese, S.; Lucchin, F.

    1988-05-01

    The theoretical prejudice for a flat universe with an initially scale-invariant power spectrum has restricted the number of cosmological scenarios investigated for studying the formation of structure in the universe. A cold dark matter-dominated universe with a density parameter Omega(0) and a primordial spectral index n different from unity is considered, and its possible consistency with the inflationary model is discussed. It is shown that some of the difficulties of a flat cold dark matter scenario can be avoided by having Omega(0) less than 1 and n less than 1. For Omega(0) roughly 0.4 and n roughly 0.75 a good agreement is obtained with the large-scale drifts, the bounds on the cosmic microwave background smoothness, the Abell cluster abundance, and their correlation function. 85 references.

  15. Correlation of QSO absorption lines in universes dominated by cold dark matter

    NASA Technical Reports Server (NTRS)

    Salmon, J.; Hogan, C.

    1986-01-01

    Theoretical predictions for the redshift correlations between QSO absorption-line systems are investigated in the context of 'cold dark matter' cosmological models. Particles in 'particle-mesh' N-body simulations are interpreted as absorbing clouds at epochs corresponding to mean redshifts, z, of 0.0, 1.25, and 3.0. The velocity correlation function for absorbing clouds is found by passing lines-of-sight through the systems and computing velocity differences for those particles which lie close to the lines. It depends strongly on z and Omega but only weakly, if at all, on the number density, diameter or mass of the clouds. Two interpretations are possible: (1) the heavy element absorption systems are associated with galaxies which are an unbiased sample of the mass distribution in an Omega(0) = 0.2 universe or (2) the Lyman-alpha absorbers are an unbiased sample of the mass in an Omega(0) = 1 universe and the heavy-element absorption systems, like galaxies, are more strongly clustered than the mass.

  16. Exploring a matter-dominated model with bulk viscosity to drive the accelerated expansion of the Universe

    NASA Astrophysics Data System (ADS)

    Avelino, Arturo; Nucamendi, Ulises

    2010-08-01

    We explore the viability of a bulk viscous matter-dominated Universe to explain the present accelerated expansion of the Universe. The model is composed by a pressureless fluid with bulk viscosity of the form ζ = ζ0+ζ1H where ζ0 and ζ1 are constants and H is the Hubble parameter. The pressureless fluid characterizes both the baryon and dark matter components. We study the behavior of the Universe according to this model analyzing the scale factor as well as some curvature scalars and the matter density. On the other hand, we compute the best estimated values of ζ0 and ζ1 using the type Ia Supernovae (SNe Ia) probe. We find that from all the possible scenarios for the Universe, the preferred one by the best estimated values of (ζ0,ζ1) is that of an expanding Universe beginning with a Big-Bang, followed by a decelerated expansion at early times, and with a smooth transition in recent times to an accelerated expansion epoch that is going to continue forever. The predicted age of the Universe is a little smaller than the mean value of the observational constraint coming from the oldest globular clusters but it is still inside of the confidence interval of this constraint. A drawback of the model is the violation of the local second law of thermodynamics in redshifts zgtrsim1. However, when we assume ζ1 = 0, the simple model ζ = ζ0 evaluated at the best estimated value for ζ0 satisfies the local second law of thermodynamics, the age of the Universe is in perfect agreement with the constraint of globular clusters, and it also has a Big-Bang, followed by a decelerated expansion with the smooth transition to an accelerated expansion epoch in late times, that is going to continue forever.

  17. Exploring a matter-dominated model with bulk viscosity to drive the accelerated expansion of the Universe

    SciTech Connect

    Avelino, Arturo; Nucamendi, Ulises E-mail: ulises@ifm.umich.mx

    2010-08-01

    We explore the viability of a bulk viscous matter-dominated Universe to explain the present accelerated expansion of the Universe. The model is composed by a pressureless fluid with bulk viscosity of the form ζ = ζ{sub 0}+ζ{sub 1}H where ζ{sub 0} and ζ{sub 1} are constants and H is the Hubble parameter. The pressureless fluid characterizes both the baryon and dark matter components. We study the behavior of the Universe according to this model analyzing the scale factor as well as some curvature scalars and the matter density. On the other hand, we compute the best estimated values of ζ{sub 0} and ζ{sub 1} using the type Ia Supernovae (SNe Ia) probe. We find that from all the possible scenarios for the Universe, the preferred one by the best estimated values of (ζ{sub 0},ζ{sub 1}) is that of an expanding Universe beginning with a Big-Bang, followed by a decelerated expansion at early times, and with a smooth transition in recent times to an accelerated expansion epoch that is going to continue forever. The predicted age of the Universe is a little smaller than the mean value of the observational constraint coming from the oldest globular clusters but it is still inside of the confidence interval of this constraint. A drawback of the model is the violation of the local second law of thermodynamics in redshifts z∼>1. However, when we assume ζ{sub 1} = 0, the simple model ζ = ζ{sub 0} evaluated at the best estimated value for ζ{sub 0} satisfies the local second law of thermodynamics, the age of the Universe is in perfect agreement with the constraint of globular clusters, and it also has a Big-Bang, followed by a decelerated expansion with the smooth transition to an accelerated expansion epoch in late times, that is going to continue forever.

  18. A model for the distribution of dark matter, galaxies, and the intergalactic medium in a cold dark matter-dominated universe

    NASA Technical Reports Server (NTRS)

    Ryu, Dongsu; Vishniac, Ethan T.; Chiang, Wei-Hwan

    1989-01-01

    The spatial distribution of the cold-dark-matter (CDM) and baryonic components of CDM-dominated cosmological models are characterized, summarizing the results of recent theoretical investigations. The evolution and distribution of matter in an Einstein-de Sitter universe on length scales small enough so that the Newtonian approximation is valid is followed chronologically, assuming (1) that the galaxies, CDM, and the intergalactic medium (IGM) are coupled by gravity, (2) that galaxies form by taking mass and momentum from the IGM, and (3) that the IGM responds to the energy input from the galaxies. The results of the numerical computations are presented in extensive graphs and discussed in detail.

  19. A model for the distribution of dark matter, galaxies, and the intergalactic medium in a cold dark matter-dominated universe

    NASA Technical Reports Server (NTRS)

    Ryu, Dongsu; Vishniac, Ethan T.; Chiang, Wei-Hwan

    1989-01-01

    The spatial distribution of the cold-dark-matter (CDM) and baryonic components of CDM-dominated cosmological models are characterized, summarizing the results of recent theoretical investigations. The evolution and distribution of matter in an Einstein-de Sitter universe on length scales small enough so that the Newtonian approximation is valid is followed chronologically, assuming (1) that the galaxies, CDM, and the intergalactic medium (IGM) are coupled by gravity, (2) that galaxies form by taking mass and momentum from the IGM, and (3) that the IGM responds to the energy input from the galaxies. The results of the numerical computations are presented in extensive graphs and discussed in detail.

  20. Survival of the structures in the universe dominated by unstable dark matter

    NASA Astrophysics Data System (ADS)

    Suto, Y.; Noguchi, M.

    1986-04-01

    Dynamical evolution of non-linear structures in the universe dominated by unstable particles is studied by the numerical integration of the Vlasov equation. Their dynamical behaviour is determined by two parameters; one is the ratio of energy densities of baryons and unstable particles β and the other is the ratio of the lifetime of unstable particles τX to the initial free-fall time-scale tff,i. Non-linear structures satisfying the survival condition - τX/tff,i > 1/(2β2) - remains as bound systems irrespective of the decay of unstable particles. As long as one considers the cosmologically restricted range of τX and β, galaxies satisfy the survival condition and their evolution is well understood in terms of adiabatic behaviour. On the other hand, clusters of galaxies may be disrupted in future due to decay of unstable particles. A possible restriction to the formation of structures and the consequence of this scenario to the observed angular size of galaxies are discussed quantitatively.

  1. Large N-body simulations of a universe dominated by cold dark matter

    NASA Technical Reports Server (NTRS)

    Park, Changbom

    1990-01-01

    It is shown that pure gravitational evolution from an initial random density field with the standard cold dark matter (CDM) power spectrum does occasionally lead to filaments, walls, and voids remarkably like those seen in observed samples. A problem with the flat CDM model is the degree of streaming of galaxies relative to their velocity dispersion. A biased open CDM model seems to be more compatible with the observational data though it requires a higher amplitude of microwave background fluctuations.

  2. Dark matter universe.

    PubMed

    Bahcall, Neta A

    2015-10-06

    Most of the mass in the universe is in the form of dark matter--a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations--from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is "cold" (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology--a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)--fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle.

  3. Dark matter universe

    NASA Astrophysics Data System (ADS)

    Bahcall, Neta A.

    2015-10-01

    Most of the mass in the universe is in the form of dark matter-a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations-from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is "cold" (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology-a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)-fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle.

  4. Dark matter universe

    PubMed Central

    Bahcall, Neta A.

    2015-01-01

    Most of the mass in the universe is in the form of dark matter—a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations—from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is “cold” (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology—a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)—fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle. PMID:26417091

  5. Fine-scale anisotropy of the cosmic microwave background in a universe dominated by cold dark matter

    NASA Technical Reports Server (NTRS)

    Vittorio, N.; Silk, J.

    1984-01-01

    The fine-scale anisotropy of the cosmic microwave background radiation has been studied in cosmological models with a scale-invariant primordial adiabatic density fluctuation spectrum dominated by cold, weakly interacting particles. Normalization of the present fluctuation spectrum to the observed galaxy distribution results in excessive temperature anisotropy when compared to a recent upper limit on 4.5 arcmin unless the density parameter exceeds 0.4. When this result is combined with the requirement that the universe be at least 13 billion years old, it is found that if the cosmological constant is zero, then the density parameter is between roughly 0.4 and 1 and the Hubble constant is between roughly 60 km/s/Mpc and 50 km/s/Mpc.

  6. Can a matter-dominated model with constant bulk viscosity drive the accelerated expansion of the universe?

    SciTech Connect

    Avelino, Arturo; Nucamendi, Ulises E-mail: ulises@ifm.umich.mx

    2009-04-15

    We test a cosmological model which the only component is a pressureless fluid with a constant bulk viscosity as an explanation for the present accelerated expansion of the universe. We classify all the possible scenarios for the universe predicted by the model according to their past, present and future evolution and we test its viability performing a Bayesian statistical analysis using the SCP ''Union'' data set (307 SNe Ia), imposing the second law of thermodynamics on the dimensionless constant bulk viscous coefficient {zeta}-tilde and comparing the predicted age of the universe by the model with the constraints coming from the oldest globular clusters. The best estimated values found for {zeta}-tilde and the Hubble constant H{sub 0} are: {zeta}-tilde = 1.922{+-}0.089 and H{sub 0} = 69.62{+-}0.59 (km/s)Mpc{sup -1} with a {chi}{sup 2}{sub min} = 314 ({chi}{sup 2}{sub d.o.f} = 1.031). The age of the universe is found to be 14.95{+-}0.42 Gyr. We see that the estimated value of H{sub 0} as well as of {chi}{sup 2}{sub d.o.f} are very similar to those obtained from {Lambda}CDM model using the same SNe Ia data set. The estimated age of the universe is in agreement with the constraints coming from the oldest globular clusters. Moreover, the estimated value of {zeta}-tilde is positive in agreement with the second law of thermodynamics (SLT). On the other hand, we perform different forms of marginalization over the parameter H{sub 0} in order to study the sensibility of the results to the way how H{sub 0} is marginalized. We found that it is almost negligible the dependence between the best estimated values of the free parameters of this model and the way how H{sub 0} is marginalized in the present work. Therefore, this simple model might be a viable candidate to explain the present acceleration in the expansion of the universe.

  7. Was the Universe actually radiation dominated prior to nucleosynthesis?

    NASA Astrophysics Data System (ADS)

    Giblin, John T.; Kane, Gordon; Nesbit, Eva; Watson, Scott; Zhao, Yue

    2017-08-01

    Maybe not. String theory approaches to both beyond the Standard Model and inflationary model building generically predict the existence of scalars (moduli) that are light compared to the scale of quantum gravity. These moduli become displaced from their low energy minima in the early Universe and lead to a prolonged matter-dominated epoch prior to big bang nucleosynthesis (BBN). In this paper, we examine whether nonperturbative effects such as parametric resonance or tachyonic instabilities can shorten, or even eliminate, the moduli condensate and matter-dominated epoch. Such effects depend crucially on the strength of the couplings, and we find that unless the moduli become strongly coupled, the matter-dominated epoch is unavoidable. In particular, we find that in string and M-theory compactifications where the lightest moduli are near the TeV scale, a matter-dominated epoch will persist until the time of big bang nucleosynthesis.

  8. New bound on low reheating temperature for dark matter in models with early matter domination

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Young; Takahashi, Tomo

    2017-08-01

    We investigate a new bound on the low reheating temperature in a scenario where the Universe experiences early matter domination before reheating after which the standard big bang cosmology begins. In many models of dark matter (DM), the small scale fluctuations of DM grow during the early matter-domination era and seed the formation of the ultracompact minihalos (UCMHs). Using the constraints on the number of UCMHs from gamma-ray observations, we find a lower bound on the reheating temperature between O (10 )-O (100 ) MeV for WIMP dark matter depending on the nature of DM. A similar bound could be obtained for non-WIMP dark matter by observing UCMHs gravitationally such as pulsar timing, microlensing and so on, in some future observations.

  9. Dark Matter in the Universe

    NASA Astrophysics Data System (ADS)

    Freese, Katherine

    2017-06-01

    “What is the Universe made of?” This question is the longest outstanding problem in all of modern physics, and it is one of the most important research topics in cosmology and particle physics today. The ordinary atoms that make up the known universe, from our bodies and the air we breathe to the planets and stars, constitute only 5% of all matter and energy in the cosmos. The remaining 95% is made up of a recipe of 25% dark matter and 70% dark energy, both nonluminous components whose nature remains a mystery. I’ll begin by discussing the evidence that dark matter is the predominant mass in galaxies, and then turn to the hunt to understand its nature. Leading candidates are fundamental particles including WIMPs (weakly interacting massive particles), axions, and sterile neutrinos. There are three approaches in the experimental searches for WIMPs: at the Large Hadron Collider at CERN in Geneva; in underground laboratory experiments; and with astrophysical searches for dark matter annihilation products. If WIMPs do constitute the dark matter, they would have been the power source for the first stars to form in the Universe; these Dark Stars may be detectable with the upcoming James Webb Space Telescope. At the end of the talk I'll turn to dark energy and its effect on the future of the Universe.

  10. Dark matter in the Universe

    SciTech Connect

    Turner, M.S. Chicago Univ., IL . Enrico Fermi Inst.)

    1991-03-01

    What is the quantity and composition of material in the universe This is one of the most fundamental questions we can ask about the universe, and its answer bears on a number of important issues including the formation of structure in the universe, and the ultimate fate and the earliest history of the universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand: most of the material in the universe does not give off detectable radiation, i.e., is dark;'' the dark matter associated with bright galaxies contributes somewhere between 10% and 30% of the critical density (by comparison luminous matter contributes less than 1%); baryonic matter contributes between 1.1% and 12% of critical. The case for the spatially-flat, Einstein-de Sitter model is supported by three compelling theoretical arguments -- structure formation, the temporal Copernican principle, and inflation -- and by some observational data. If {Omega} is indeed unity--or even just significantly greater than 0.1--then there is a strong case for a universe comprised of nonbaryonic matter. There are three well motivated particle dark-matter candidates: an axion of mass 10{sup {minus}6} eV to 10{sup {minus}4} eV; a neutralino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either being planned or are underway. 71 refs., 6 figs.

  11. Dark matter in the universe

    SciTech Connect

    Turner, M.S. Chicago Univ., IL . Enrico Fermi Inst.)

    1990-11-01

    What is the quantity and composition of material in the Universe This is one of the most fundamental questions we can ask about the Universe, and its answer bears on a number of important issues including the formation of structure in the Universe, and the ultimate fate and the earliest history of the Universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand: Most of the material in the Universe does not give off detectable radiation, i.e., is dark;'' the dark matter associated with bright galaxies contributes somewhere between 10% and 30% of the critical density (by comparison luminous matter contributes less than 1%); baryonic matter contributes between 1.1% and 12% of critical. The case for the spatially-flat, Einstein-de Sitter model is supported by three compelling theoretical arguments--structure formation, the temporal Copernican principle, and inflation--and by some observational data. If {Omega} is indeed unity--or even just significantly greater than 0.1--then there is a strong case for a Universe comprised of nonbaryonic matter. There are three well motivated particle dark-matter candidates: an axion of mass 10{sup {minus}6} eV to 10{sup {minus}4} eV; a neutralino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either being planned or are underway. 63 refs.

  12. Damping of gravitational waves in matter and Λ - dominated era

    NASA Astrophysics Data System (ADS)

    Khodagholizadeh, Jafar; Abbassi, Amir H.; Asgari, Ali A.

    2017-10-01

    The goal of this paper is studying the integro-differential equation of gravitational waves (GWs) in matter-dominated era while the presence of free streaming neutrinos is taken into account via stress tensor with high accuracy. Our focus is on GWs that enter the horizon in the matter dominated era and transmitted to the Λ - dominated era. The results show that the squared amplitude is reduced by ∼ 3% (61%) in the matter dominated era and this reduction is less after transition for the flat (closed) background. Finally, we compared with the radiation-dominated era for both flat and closed background as well. A stable global topological effect has been inferred from comparison of results for two cases.

  13. Noncommutative accelerated multidimensional universe dominated by quintessence

    NASA Astrophysics Data System (ADS)

    El-Nabulsi, Ahmad Rami

    2010-04-01

    Noncommutative Geometry recently attracted growing interest of cosmologists, mainly after the greatest success of unifying the forces of nature into a single gravitational spectral action in a purely algebraic way, rather than as being an entirely new formalism. In the present work, we discuss a multidimensional Friedmann-Robertson-Walker flat universe in which the perfect fluid has a Gaussian profile in time and depends on a fundamental minimal length sqrt{θ} like ρ= ρ(0)exp (- t 2/4 θ) for some positive constant ρ(0). This special form is motivated by a more recent noncommutative inflationary cosmological model, which was found to be able to drive the universe through a bounce without the need of any scalar field. Furthermore, we conjecture that the generalized equation of state has the special form p= ω a m ρ- ρ,( ω, m)∈ℝ where a( t) is the scale factor. It was found that the expansion of the multidimensional universe accelerates in time and is dominated for very large time by quintessence. Many additional consequences are revealed and discussed in some detail.

  14. Dark matter in the universe

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.

    1991-01-01

    What is the quantity and composition of material in the Universe? This is one of the most fundamental questions we can ask about the Universe, and its answer bears on a number of important issues including the formation of structure in the Universe, and the ultimate fate and the earliest history of the Universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand. Most of the radiation in the Universe does not give off detectable radiation; it is dark. The dark matter associated with bright galaxies contributes somewhere between 10 and 30 percent of the critical density; baryonic matter contributes between 1.1 and 12 percent of the critical. The case for the spatially flat, Einstein-de Sitter model is supported by three compelling theoretical arguments - structure formation, the temporal Copernican principle, and inflation - and by some observational data. If Omega is indeed unity, or even just significantly greater than 0.1, then there is a strong case for a Universe comprised of nonbaryonic matter. There are three well motivated particle dark matter candidates: an axion of mass 10 (exp -6) eV to 10 (exp -4) eV; a neutrino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either planned or are underway.

  15. Voids in a neutrino-dominated universe

    NASA Technical Reports Server (NTRS)

    Zeng, Ning; White, Simon D. M.

    1991-01-01

    In a neutrino-dominated universe, galaxies are expected to form only in large-scale sheets and filaments. Most of space should be filled by low-density regions devoid of galaxies. In this paper, N-body simulations are used to estimate the size distribution for these regions for quantitative comparison with the observed voids in recent red-shift surveys. The theoretical distribution depends very weakly on the mode or epoch of galaxy formation. With very conservative assumptions, at best marginal consistency is found even for cosmological parameters as extreme as Omega(v) = 1 and H(0) = 100 km/s per/Mpc. Any significant reduction in either H(0) or Omega(v) leads to predicted void sizes much larger than those observed. This difficulty arises because the observed voids are rarely completely empty.

  16. Are Quasar Jets Matter Or Poynting Flux Dominated?

    SciTech Connect

    Sikora, Marek; Madejski, Greg M.; Lasota, Jean-Pierre; Begelman, Mitchell C.; /JILA, Boulder

    2005-10-03

    If quasar jets are accelerated by magnetic fields but terminate as matter dominated, where and how does the transition occur between the Poynting-dominated and matter-dominated regimes? To address this question, we study constraints which are imposed on the jet structure by observations at different spatial scales. We demonstrate that observational data are consistent with a scenario where the acceleration of a jet occurs within 10{sup 3-4}R{sub g}. In this picture, the non-thermal flares--important defining attributes of the blazar phenomenon--are produced by strong shocks formed in the region where the jet inertia becomes dominated by matter. Such shocks may be formed due to collisions between the portions of a jet accelerated to different velocities, and the acceleration differentiation is very likely to be related to global MHD instabilities.

  17. Magnetised Strings in Λ-Dominated Anisotropic Universe

    NASA Astrophysics Data System (ADS)

    Goswami, G. K.; Yadav, Anil Kumar; Dewangan, R. N.

    2016-11-01

    In this paper, we have searched the existence of Λ-dominated anisotropic universe filled with magnetized strings. The observed acceleration of universe has been explained by introducing a positive cosmological constant Λ in the Einstein's field equation which is mathematically equivalent to dark energy with equation of state (EOS) parameter set equal to -1. The present values of the matter and the dark energy parameters (Ω m )0 & (ΩΛ)0 are estimated for high red shift (.3 ≤ z ≤ 1.4) SN Ia supernova data's of observed apparent magnitude along with their possible error taken from Union 2.1 compilation. It is found that the best fit value for (Ω m )0 & (ΩΛ)0 are 0.2920 & 0.7076 respectively which are in good agreement with recent astrophysical observations in the latest surveys like WMAP and Plank. Various physical parameters such as the matter and dark energy densities, the present age of the universe and the present value of deceleration parameter have been obtained on the basis of the values of (Ω m )0 & (ΩΛ)0.Also, we have estimated that the acceleration would have begun in the past at z = 0.6845 i. e. 6.2341 Gyrs before from now.

  18. Dark matter in a bouncing universe

    SciTech Connect

    Cheung, Yeuk-Kwan E.; Kang, Jin U; Li, Changhong E-mail: jin.u.kang2@gmail.com

    2014-11-01

    We investigate a new scenario of dark matter production in a bouncing universe, in which dark matter was produced completely out of equilibrium in the contracting as well as expanding phase. We explore possibilities of using dark matter as a probe of the bouncing universe, focusing on the relationship between a critical temperature of the bouncing universe and the present relic abundance of dark matter.

  19. Our Lopsided Universe: The Matter with Anti-Matter

    SciTech Connect

    Sekula, Steve

    2004-06-29

    Half of our universe appears to be missing, and scientists at SLAC and all over the world are trying to understand why. Don't miss this talk in which Steve Sekula will explain the core issues surrounding matter and anti-matter.

  20. Terrestrial dominance of organic matter in north temperate lakes

    NASA Astrophysics Data System (ADS)

    Wilkinson, G.; Pace, M. L.; Cole, J. J.

    2012-12-01

    Aquatic ecosystems are hotspots of decomposition and a source of carbon dioxide to the atmosphere that is globally significant. Carbon exported from land (allochthonous) also supplements the carbon fixed by photosynthesis in aquatic ecosystems (autochthonous), contributing to the organic matter (OM) that supports aquatic consumers. Although the presence of terrestrial compounds in aquatic OM is well known, the contribution of terrestrial versus aquatic sources to the composition of OM has been quantified for only a handful of systems. Here we use stable isotopes of hydrogen and carbon to demonstrate that the terrestrial contribution to particulate organic matter (POM) is as large or larger (mean=54.6% terrestrial) than the algal contribution in 39 lakes of the northern highlands region of Wisconsin and Michigan. Further, the largest carbon pool, dissolved organic matter (DOM), is strongly dominated by allochthonous material (mean for the same set of lakes approximately 100% terrestrial). Among lakes, increases in terrestrial contribution to POM are significantly correlated with more acidic pH. Extrapolating this relationship using a survey of pH in 1692 lakes in the region reveals that, with the exception of eutrophic lakes, most of the OM in lakes is of terrestrial origin. These results are consistent with the growing evidence that terrestrial OM may support many lake food webs, and that lakes are significant conduits for returning degraded terrestrial carbon to the atmosphere.

  1. Terrestrial dominance of organic matter in north temperate lakes

    NASA Astrophysics Data System (ADS)

    Wilkinson, Grace M.; Pace, Michael L.; Cole, Jonathan J.

    2013-01-01

    Aquatic ecosystems are hotspots of decomposition and sources of carbon dioxide to the atmosphere that are globally significant. Carbon exported from land (allochthonous) also supplements the carbon fixed by photosynthesis in aquatic ecosystems (autochthonous), contributing to the organic matter (OM) that supports aquatic consumers. Although the presence of terrestrial compounds in aquatic OM is well known, the contribution of terrestrial versus aquatic sources to the composition of OM has been quantified for only a handful of systems. Here we use stable isotopes of hydrogen and carbon to demonstrate that the terrestrial contribution (ΦTerr) to particulate organic matter (POM) is as large or larger (mean = 54.6% terrestrial) than the algal contribution in 39 lakes of the northern highlands region of Wisconsin and Michigan. Further, the largest carbon pool, dissolved organic matter (DOM), is strongly dominated by allochthonous material (mean for the same set of lakes approximately 100% terrestrial). Among lakes, increases in terrestrial contribution to POM are significantly correlated with more acidic pH. Extrapolating this relationship using a survey of pH in 1692 lakes in the region reveals that, with the exception of eutrophic lakes, most of the OM in lakes is of terrestrial origin. These results are consistent with the growing evidence that lakes are significant conduits for returning degraded terrestrial carbon to the atmosphere.

  2. Dark Energy Coupled with Relativistic Dark Matter in Accelerating Universe

    NASA Astrophysics Data System (ADS)

    Zhang, Yang

    2003-10-01

    Recent observations favour an accelerating Universe dominated by the dark energy. We take the effective Yang-Mills condensate as the dark energy and couple it to a relativistic matter which is created by the decaying condensate. The dynamic evolution has asymptotic behaviour with finite constant energy densities, and the fractional densities OmegaLambda~0.7 for dark energy and Omegam~0.3 for relativistic matter are achieved at proper values of the decay rate. The resulting expansion of the Universe is in the de Sitter acceleration.

  3. Why Does the USA Dominate University League Tables?

    ERIC Educational Resources Information Center

    Li, Mei; Shankar, Sriram; Tang, Kam Ki

    2011-01-01

    According to the Academic Ranking of World Universities, the world's top 500 universities are located in only 38 countries, with the USA alone having 157 of them. This article investigates the socioeconomic determinants of the wide performance gap between countries, and whether the USA's dominance is largely due to its economic power. A large…

  4. Why Does the USA Dominate University League Tables?

    ERIC Educational Resources Information Center

    Li, Mei; Shankar, Sriram; Tang, Kam Ki

    2011-01-01

    According to the Academic Ranking of World Universities, the world's top 500 universities are located in only 38 countries, with the USA alone having 157 of them. This article investigates the socioeconomic determinants of the wide performance gap between countries, and whether the USA's dominance is largely due to its economic power. A large…

  5. 39 CFR 3020.111 - Limitations applicable to market dominant mail matter.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Limitations applicable to market dominant mail... Size and Weight Limitations for Mail Matter § 3020.111 Limitations applicable to market dominant mail... market dominant mail matter by filing notice with the Commission 45 days prior to the effective date of...

  6. 39 CFR 3020.111 - Limitations applicable to market dominant mail matter.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 39 Postal Service 1 2013-07-01 2013-07-01 false Limitations applicable to market dominant mail... Size and Weight Limitations for Mail Matter § 3020.111 Limitations applicable to market dominant mail... market dominant mail matter by filing notice with the Commission 45 days prior to the effective date...

  7. 39 CFR 3020.111 - Limitations applicable to market dominant mail matter.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 39 Postal Service 1 2012-07-01 2012-07-01 false Limitations applicable to market dominant mail... Size and Weight Limitations for Mail Matter § 3020.111 Limitations applicable to market dominant mail... market dominant mail matter by filing notice with the Commission 45 days prior to the effective date...

  8. 39 CFR 3020.111 - Limitations applicable to market dominant mail matter.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 39 Postal Service 1 2011-07-01 2011-07-01 false Limitations applicable to market dominant mail... Size and Weight Limitations for Mail Matter § 3020.111 Limitations applicable to market dominant mail... market dominant mail matter by filing notice with the Commission 45 days prior to the effective date...

  9. 39 CFR 3020.111 - Limitations applicable to market dominant mail matter.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 39 Postal Service 1 2014-07-01 2014-07-01 false Limitations applicable to market dominant mail... Size and Weight Limitations for Mail Matter § 3020.111 Limitations applicable to market dominant mail... market dominant mail matter by filing notice with the Commission 45 days prior to the effective date...

  10. Light and dark matter in the universe

    SciTech Connect

    2010-01-01

    This simulation follows the growth of density perturbations in both gas and dark matter components in a volume 1 billion light years on a side beginning shortly after the Big Bang and evolved to half the present age of the universe. It calculates the gravitational clumping of intergalactic gas and dark matter modeled using a computational grid of 64 billion cells and 64 billion dark matter particles. The simulation uses a computational grid of 4096^3 cells and took over 4,000,000 CPU hours to complete. Read more: http://www.anl.gov/Media_Center/News/2010/news100104.html

  11. Missing dark matter in the local universe

    NASA Astrophysics Data System (ADS)

    Karachentsev, I. D.

    2012-04-01

    A sample of 11 thousand galaxies with radial velocities V LG < 3500 km/s is used to study the features of the local distribution of luminous (stellar) and dark matter within a sphere of radius of around 50 Mpc around us. The average density of matter in this volume, Ω m,loc = 0.08 ± 0.02, turns out to be much lower than the global cosmic density Ω m,glob = 0.28 ± 0.03. We discuss three possible explanations of this paradox: 1) galaxy groups and clusters are surrounded by extended dark halos, the major part of the mass of which is located outside their virial radii; 2) the considered local volume of the Universe is not representative, being situated inside a giant void; and 3) the bulk of matter in the Universe is not related to clusters and groups, but is rather distributed between them in the form of massive dark clumps. Some arguments in favor of the latter assumption are presented. Besides the two well-known inconsistencies of modern cosmological models with the observational data: the problem of missing satellites of normal galaxies and the problem of missing baryons, there arises another one—the issue of missing dark matter.

  12. Acceleration of Dominant Supermassive Black Hole Singularities Serving as the Catalyst of Dark Energy in the Formation of Universes

    NASA Astrophysics Data System (ADS)

    Wilson, John

    2013-04-01

    Cosmological process analysis is used to develop the singularity acceleration hypothesis which is based on nine universe formation axioms. Singularity acceleration universe formation is a cyclic process analogous to a branching universe having the following seven phases reoccurring in each daughter universe: 1. A phase transition big bang that forms a new universe 2. Expansion of the new universe and its structure 3. Dispersion of its mass and increasing entropy 4. Isolation of its galaxy clusters and supercluster complexes beyond event horizons 5. Many separate consolidations of all forms of matter, forces, and energy within these supercluster complexes into dominant supermassive black hole gravitational singularities 6. The resulting acceleration of singularities warping space to the speed of light 7. The independent separation of each of these singularities from the universe causing a big bang phase transition and producing all forms of matter, forces, and energy in a new universe.

  13. G4beamline Particle Tracking in Matter Dominated Beam Lines

    SciTech Connect

    T.J. Roberts, K.B. Beard, S. Ahmed, D. Huang, D.M. Kaplan

    2011-03-01

    The G4beamline program is a useful and steadily improving tool to quickly and easily model beam lines and experimental equipment without user programming. It has both graphical and command-line user interfaces. Unlike most accelerator physics codes, it easily handles a wide range of materials and fields, being particularly well suited for the study of muon and neutrino facilities. As it is based on the Geant4 toolkit, G4beamline includes most of what is known about the interactions of particles with matter. We are continuing the development of G4beamline to facilitate its use by a larger set of beam line and accelerator developers. A major new feature is the calculation of space-charge effects. G4beamline is open source and freely available at http://g4beamline.muonsinc.com

  14. Singular F(R) cosmology unifying early- and late-time acceleration with matter and radiation domination era

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-06-01

    We present some cosmological models which unify the late- and early-time acceleration eras with the radiation and the matter domination era, and we realize the cosmological models by using the theoretical framework of F(R) gravity. Particularly, the first model unifies the late- and early-time acceleration with the matter domination era, and the second model unifies all the evolution eras of our Universe. The two models are described in the same way at early and late times, and only the intermediate stages of the evolution have some differences. Each cosmological model contains two Type IV singularities which are chosen to occur one at the end of the inflationary era and one at the end of the matter domination era. The cosmological models at early times are approximately identical to the R 2 inflation model, so these describe a slow-roll inflationary era which ends when the slow-roll parameters become of order one. The inflationary era is followed by the radiation era and after that the matter domination era follows, which lasts until the second Type IV singularity, and then the late-time acceleration era follows. The models have two appealing features: firstly they produce a nearly scale invariant power spectrum of primordial curvature perturbations and a scalar-to-tensor ratio which are compatible with the most recent observational data and secondly, it seems that the deceleration-acceleration transition is crucially affected by the presence of the second Type IV singularity which occurs at the end of the matter domination era. As we demonstrate, the Hubble horizon at early times shrinks, as expected for an initially accelerating Universe, then during the matter domination era, it expands and finally after the Type IV singularity, the Hubble horizon starts to shrink again, during the late-time acceleration era. Intriguingly enough, the deceleration-acceleration transition, occurs after the second Type IV singularity. In addition, we investigate which F(R) gravity

  15. Nuclear matter in the early universe

    SciTech Connect

    Barros, Celso de Camargo; Cunha, Ivan Eugênio da

    2015-12-17

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

  16. Redshift remapping and cosmic acceleration in dark-matter-dominated cosmological models

    NASA Astrophysics Data System (ADS)

    Wojtak, Radosław; Prada, Francisco

    2017-10-01

    The standard relation between the cosmological redshift and cosmic scalefactor underlies cosmological inference from virtually all kinds of cosmological observations, leading to the emergence of the Λ cold-dark-matter (ΛCDM) cosmological model. This relation is not a fundamental theory and thus observational determination of this function (redshift remapping) should be regarded as an insightful alternative to holding its standard form in analyses of cosmological data. Here we present non-parametric reconstructions of redshift remapping in dark-matter-dominated models and constraints on cosmological parameters from a joint analysis of all primary cosmological probes including the local measurement of the Hubble constant, Type Ia supernovae, baryon acoustic oscillations (BAO), Planck observations of the cosmic microwave background (CMB) radiation (temperature power spectrum) and cosmic chronometers. The reconstructed redshift remapping points to an additional boost of redshift operating in late epoch of cosmic evolution, but affecting both low-redshift observations and the CMB. The model predicts a significant difference between the actual Hubble constant, h = 0.48 ± 0.02, and its local determination, hobs = 0.73 ± 0.02. The ratio of these two values coincides closely with the maximum expansion rate inside voids formed in the corresponding open cosmological model with Ωm = 0.87 ± 0.03, whereas the actual value of the Hubble constant implies the age of the Universe that is compatible with the Planck ΛCDM cosmology. The model with redshift remapping provides excellent fits to all data and eliminates recently reported tensions between the PlanckΛCDM cosmology, the local determination of the Hubble constant and the BAO measurements from the Ly α forest of high-redshift quasars.

  17. SUSY dark matter and non-universal gaugino masses

    SciTech Connect

    Birkedal-Hansen, Andreas

    2002-04-15

    In this talk the authors investigate the dark matter prospects for supersymmetric models with non-universal gaugino masses. They motivate the use of non-universal gaugino masses from several directions, including problems, with the current favorite scenario, the cMSSM. They then display new corridors of parameter space that allow an acceptable dark matter relic density once gaugino mass universality is relaxed. They finish with a specific string-derived model that allows this universality relaxation and then use the dark matter constraint to make specific statements about the hidden sector of the model.

  18. About matter and dark-energy domination eras in Rn gravity or lack thereof

    NASA Astrophysics Data System (ADS)

    Jaime, Luisa G.; Patiño, Leonardo; Salgado, Marcelo

    2013-01-01

    We provide further numerical evidence which shows that Rn models in f(R) metric gravity produce a late time acceleration in the Universe or a matter domination era (usually a transient one) but not both. Our results confirm the findings of Amendola et al. [Phys. Rev. Lett. 98, 131302 (2007); PRLTAO0031-9007Phys. Rev. D 75, 083504 (2007); PRVDAQ1550-7998Int. J. Mod. Phys. D 16, 1555 (2007)IMPDEO0218-2718], but using a different approach that avoids the mapping to scalar-tensor theories of gravity, and therefore, spares us from any discussion or debate about frames (Einstein vs Jordan) which are endemic in this subject. This class of models has been used extensively in the literature as an alternative to dark energy, but should be considered ruled out for being inconsistent with the observations. Finally, we discuss a caveat in the analysis by Faraoni [Phys. Rev. D 83, 124044 (2011)PRVDAQ1550-7998], which was used to further constrain these models by using a chameleon mechanism.

  19. University Press Meeting Dominated by Donor Proposal and Digital Publishing

    ERIC Educational Resources Information Center

    Howard, Jennifer

    2007-01-01

    A surprise request for proposals from the Andrew W. Mellon Foundation and a forthcoming report on university publishing in the digital age were among topics discussed at the annual meeting of the Association of American University Presses. The offer from the Mellon Foundation concerns support for collaborative, monograph-centered projects in…

  20. University Press Meeting Dominated by Donor Proposal and Digital Publishing

    ERIC Educational Resources Information Center

    Howard, Jennifer

    2007-01-01

    A surprise request for proposals from the Andrew W. Mellon Foundation and a forthcoming report on university publishing in the digital age were among topics discussed at the annual meeting of the Association of American University Presses. The offer from the Mellon Foundation concerns support for collaborative, monograph-centered projects in…

  1. Towards understanding thermal history of the Universe through direct and indirect detection of dark matter

    NASA Astrophysics Data System (ADS)

    Roszkowski, Leszek; Trojanowski, Sebastian; Turzyński, Krzysztof

    2017-10-01

    We examine the question to what extent prospective detection of dark matter by direct and indirect- detection experiments could shed light on what fraction of dark matter was generated thermally via the freeze-out process in the early Universe. By simulating putative signals that could be seen in the near future and using them to reconstruct WIMP dark matter properties, we show that, in a model- independent approach this could only be achieved in a thin sliver of the parameter space. However, with additional theoretical input the hypothesis about the thermal freeze-out as the dominant mechanism for generating dark matter can potentially be verified. We illustrate this with two examples: an effective field theory of dark matter with a vector messenger and a higgsino or wino dark matter within the MSSM.

  2. Study of dark matter physics in non-universal gaugino mass scenario

    NASA Astrophysics Data System (ADS)

    Kawamura, Junichiro; Omura, Yuji

    2017-08-01

    We study dark matter physics in the Minimal Supersymmetric Standard Model with non-universal gaugino masses at the unification scale. In this scenario, the specific ratio of wino and gluino masses realizes the electro-weak scale naturally and achieves 125 GeV Higgs boson mass. Then, relatively light higgsino is predicted and the lightest neutral particle, that is dominantly given by the neutral component of higgsino, is a good dark matter candidate. The direct detection of the dark matter is sensitive to not only a higgsino mass but also gaugino masses significantly. The upcoming XENON1T experiment excludes the parameter region where bino or gluino is lighter than about 2.5 TeV if the higgsino and the gaugino mass parameters have same signs. We see that the direct detection of dark matter gives stronger bound than the direct search at the LHC experiment when higgsino gives sizable contribution to the dark matter abundance.

  3. Dark Energy Coupled with Dark Matter in the Accelerating Universe

    NASA Astrophysics Data System (ADS)

    Zhang, Yang

    2004-06-01

    To model the observed Universe containing both dark energy and dark matter, we study the effective Yang Mills condensate model of dark energy and add a non-relativistic matter component as the dark matter, which is generated out of the decaying dark energy at a constant rate Gamma, a parameter of our model. For the Universe driven by these two components, the dynamic evolution still has asymptotic behaviour: the expansion of the Universe is accelerating with an asymptotically constant rate H, and the densities of both components approach to finite constant values. Moreover, OmegaLambdasimeq0.7 for dark energy and Omegamsimeq0.3 for dark matter are achieved if the decay rate Gamma is chosen such that Gamma/H~1.

  4. Evolution of linear wave dark matter perturbations in the radiation-dominated era

    NASA Astrophysics Data System (ADS)

    Zhang, Ui-Han; Chiueh, Tzihong

    2017-07-01

    Linear perturbations of the wave dark matter, or ψ dark matter (ψ DM ), of particle mass ˜10-22 eV in the radiation-dominant era are analyzed, and the matter power spectrum at the photon-matter equality is obtained. We identify four phases of evolution for ψ DM perturbations, where the dynamics can be vastly different from the counterparts of cold dark matter (CDM). While in late stages, after mass oscillation, long-wave ψ DM perturbations are almost identical to CDM perturbations, some subtle differences remain. The differences are even greater with intermediate-to-short waves that bear no resemblance to those of CDM throughout the whole evolutionary history. The dissimilarity is due to quantum mechanical effects which lead to severe mode suppression. We also discuss the axion model with a cosine field potential. The power spectrum of axion models is generally almost identical to that of ψ DM , but in the extreme case, when the initial axion angle is near the field potential top, this axion model predicts a power excess over a range of wave numbers and a higher spectral cutoff than ψ DM , as if ψ DM had a higher particle mass.

  5. Cosmological Model with Dark Matter in a Dissipative Universe

    NASA Astrophysics Data System (ADS)

    Timoshkin, A. V.

    2016-12-01

    A cosmological model is considered, in which two ideal fluids interact: dark energy and dark matter, in a homogeneous and isotropic flat Friedmann-Lemaître-Robertson-Walker Universe with scattering. Scattering in this Universe is investigated in two ways: in terms of bulk viscosity and with the help of the entropic model. The interaction between dark energy and dark matter is described in terms of parameters of the equation of state for dark energy, which take account of dissipative properties of the Universe. In the example of the model of the Universe with a singularity known as the Little Rip, application of a formalism describing dissipative properties is demonstrated. An analytical representation of this model in terms of thermodynamic parameters of the equation of state for dark energy, taking dissipation into account, is obtained. In the expression for the coefficient of bulk viscosity, corrections are taken into account which are due to the interaction between dark energy and dark matter.

  6. Comment on String-Dominated Universe(SDU)

    SciTech Connect

    Turner, M.S.

    1984-09-01

    Theoretical prejudice favors the flat(k=0) cosmology, and the inflationary Universe scenario implements this prejudice in a natural way. For the k=0 model ..cap omega.. (defined as rho total/rho critical; rho total = rho NR + rho vac + rho R + rho S) = 1. However, observational data suggests: ..cap omega../sub OBS/ approx. = 0.2' +- 0.1', where +- 0.1 indicates the range of values reported. This discrepancy is known as the ..cap omega..-problem. A number of solutions have been suggested: ..cap omega../sub OBS/ is determined by assuming that light (i.e., galaxies) traces mass - perhaps this assumption is not valid; ..cap omega../sub OBS/ is not sensitive to a smoothly-distributed component of mass density - perhaps most of the mass density resides in a smooth component. Candidates for the smooth component include: relativistic particles (rho/sub R/), a relic cosmological term (rho/sub vac/), and in a recent letter Vilenkin has suggested fast-moving strings (rho/sub S/).

  7. Ten Reasons Service Science Matters to Universities

    ERIC Educational Resources Information Center

    Spohrer, Jim; Fodell, Dianne; Murphy, Wendy

    2012-01-01

    Higher education is being reshaped little by little every day. Slowly but surely, from the smallest community colleges to the teaching institutions to the most prestigious research universities, a new set of key performance indicators (KPIs) is transforming what excellence means in higher education. For developed and emerging market nations…

  8. University Ideological Conflict: Does It Matter?

    ERIC Educational Resources Information Center

    Browder, Lesley H., Jr.

    1997-01-01

    If American society is caught between a waning traditional Judeo-Christian moral sense and an emerging postmodern secular moral sense, what are the implications for codes of professional ethics? Answers might be found by examining the university's mission, the Western rationalistic tradition, the postmodern transformation view, ideological…

  9. Ten Reasons Service Science Matters to Universities

    ERIC Educational Resources Information Center

    Spohrer, Jim; Fodell, Dianne; Murphy, Wendy

    2012-01-01

    Higher education is being reshaped little by little every day. Slowly but surely, from the smallest community colleges to the teaching institutions to the most prestigious research universities, a new set of key performance indicators (KPIs) is transforming what excellence means in higher education. For developed and emerging market nations…

  10. Widespread grey matter pathology dominates the longitudinal cerebral MRI and clinical landscape of amyotrophic lateral sclerosis.

    PubMed

    Menke, Ricarda A L; Körner, Sonja; Filippini, Nicola; Douaud, Gwenaëlle; Knight, Steven; Talbot, Kevin; Turner, Martin R

    2014-09-01

    . Although a consistent core white matter pathology was found cross-sectionally, grey matter pathology was dominant longitudinally, and included progression in clinically silent areas such as the basal ganglia, believed to reflect their wider cortical connectivity. Such changes were significant across a range of apparently sporadic patients rather than being a genotype-specific effect. It is also suggested that the upper motor neuron lesion in amyotrophic lateral sclerosis may be relatively constant during the established symptomatic period. These findings have implications for the development of effective diagnostic versus therapeutic monitoring magnetic resonance imaging biomarkers. Amyotrophic lateral sclerosis may be characterized initially by a predominantly white matter tract pathological signature, evolving as a widespread cortical network degeneration.

  11. Widespread grey matter pathology dominates the longitudinal cerebral MRI and clinical landscape of amyotrophic lateral sclerosis

    PubMed Central

    Menke, Ricarda A. L.; Körner, Sonja; Filippini, Nicola; Douaud, Gwenaëlle; Knight, Steven; Talbot, Kevin

    2014-01-01

    disability. Although a consistent core white matter pathology was found cross-sectionally, grey matter pathology was dominant longitudinally, and included progression in clinically silent areas such as the basal ganglia, believed to reflect their wider cortical connectivity. Such changes were significant across a range of apparently sporadic patients rather than being a genotype-specific effect. It is also suggested that the upper motor neuron lesion in amyotrophic lateral sclerosis may be relatively constant during the established symptomatic period. These findings have implications for the development of effective diagnostic versus therapeutic monitoring magnetic resonance imaging biomarkers. Amyotrophic lateral sclerosis may be characterized initially by a predominantly white matter tract pathological signature, evolving as a widespread cortical network degeneration. PMID:24951638

  12. Statistics of the cosmic Mach number from numerical simulations of a cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Suto, Yasushi; Cen, Renyue; Ostriker, Jeremiah P.

    1992-01-01

    Results are presented of an analysis of the cosmic Mach number, M, the ratio of the streaming velocity, v, to the random velocity dispersion, sigma, of galaxies in a given patch of the universe, which was performed on the basis of hydrodynamical simulations of the cold dark matter scenario. Galaxy formation is modeled by application of detailed physical processes rather than by the ad hoc assumption of 'bias' between dark matter and galaxy fluctuations. The correlation between M and sigma is found to be very weak for both components. No evidence is found for a physical 'velocity bias' in the quantities which appear in the definition of M. Standard cold-dark-matter-dominated universes are in conflict, at a statistically significant level, with the available observation, in that they predict a Mach number considerably lower than is observed.

  13. Statistics of the cosmic Mach number from numerical simulations of a cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Suto, Yasushi; Cen, Renyue; Ostriker, Jeremiah P.

    1992-01-01

    Results are presented of an analysis of the cosmic Mach number, M, the ratio of the streaming velocity, v, to the random velocity dispersion, sigma, of galaxies in a given patch of the universe, which was performed on the basis of hydrodynamical simulations of the cold dark matter scenario. Galaxy formation is modeled by application of detailed physical processes rather than by the ad hoc assumption of 'bias' between dark matter and galaxy fluctuations. The correlation between M and sigma is found to be very weak for both components. No evidence is found for a physical 'velocity bias' in the quantities which appear in the definition of M. Standard cold-dark-matter-dominated universes are in conflict, at a statistically significant level, with the available observation, in that they predict a Mach number considerably lower than is observed.

  14. Primordial black holes from inflaton and spectator field perturbations in a matter-dominated era

    NASA Astrophysics Data System (ADS)

    Carr, Bernard; Tenkanen, Tommi; Vaskonen, Ville

    2017-09-01

    We study production of primordial black holes (PBHs) during an early matter-dominated phase. As a source of perturbations, we consider either an inflaton field with a running spectral index or a spectator field that has a blue spectrum and thus provides a significant contribution to PBH production at small scales. First, we identify the region of the parameter space where a significant fraction of the observed dark matter can be produced, taking into account all current PBH constraints. Then, we present constraints on the amplitude and spectral index of the spectator field as a function of the reheating temperature. We also derive constraints on the running of the inflaton spectral index, d n /d ln k ≲0.001 , which are comparable to those from the Planck satellite for a scenario where the spectator field is absent.

  15. Particulate organic matter predicts bacterial productivity in a river dominated estuary

    NASA Astrophysics Data System (ADS)

    Crump, B. C.

    2015-12-01

    Estuaries act as coastal filters for organic and inorganic fluvial materials in which microbial, biogeochemical, and ecological processes combine to transform organic matter and nutrients prior to export to the coastal ocean. The function of this estuarine 'bioreactor' is linked to the residence times of those materials and to rates of microbial heterotrophic activity. Our ability to forecast the impact of global change on estuarine bioreactor function requires an understanding of the basic controls on microbial community activity and diversity. In the Columbia River estuary, the microbial community undergoes a dramatic seasonal shift in species composition during which a spring bacterioplankton community, dominated by Flavobacteriaceae and Oceanospirillales, is replaced by a summer community, dominated by Rhodobacteraceae and several common marine taxa. This annual shift occurs in July, following the spring freshet, when river flow and river chlorophyll concentration decrease and when estuarine water residence time increases. Analysis of a large dataset from 17 research cruises (1990-2014) showed that the composition of particulate organic matter in the estuary changes after the freshet with decreasing organic carbon and nitrogen content, and increasing contribution of marine and autochthonous estuarine organic matter (based on PO13C and pigment ratios). Bacterial production rates (measured as leucine or thymidine incorporation rates) in the estuary respond to this change, and correlate strongly with labile particulate nitrogen concentration and temperature during individual sampling campaigns, and with the concentration of chlorophyll in the Columbia River across all seasons. Regression models suggest that the concentration of labile particulate nitrogen and the rate of bacterial production can be predicted from sensor measurements of turbidity, salinity, and temperature in the estuary and chlorophyll in the river. These results suggest that the quality of

  16. Action approach to cosmological perturbations: the second-order metric in matter dominance

    SciTech Connect

    Boubekeur, Lotfi; Creminelli, Paolo; Vernizzi, Filippo; Norena, Jorge

    2008-08-15

    We study nonlinear cosmological perturbations during post-inflationary evolution, using the equivalence between a perfect barotropic fluid and a derivatively coupled scalar field with Lagrangian [-({partial_derivative}{phi}){sup 2}]{sup (1+w)/2w}. Since this Lagrangian is just a special case of k-inflation, this approach is analogous to the one employed in the study of non-Gaussianities from inflation. We use this method to derive the second-order metric during matter dominance in the comoving gauge directly as a function of the primordial inflationary perturbation {zeta}. Going to Poisson gauge, we recover the metric previously derived in the literature.

  17. Split universal extra dimension and dark matter

    SciTech Connect

    Park, Seong Chan; Shu Jing

    2009-05-01

    Motivated by the recent observation of the high energy electron and positron excesses in cosmic ray by PAMELA and ATIC/PPB-BETS, we suggest an anomaly-free scenario for the universal extra dimension that localizes the standard model quarks and splits the spectrum of Kaluza-Klein (KK) quarks from KK leptons. When the SM quarks are 'well localized' at the boundaries, the most stringent bound of the model (1/R>510 GeV) comes from the resonance search for the Tevatron dijet channels. Even at the early stage of LHC, one can discover the second KK gluon for masses up to 4 TeV.

  18. Induced matter brane gravity and Einstein static universe

    SciTech Connect

    Heydarzade, Y.; Darabi, F. E-mail: f.darabi@azaruniv.edu

    2015-04-01

    We investigate stability of the Einstein static universe against the scalar, vector and tensor perturbations in the context of induced matter brane gravity. It is shown that in the framework of this model, the Einstein static universe has a positive spatial curvature. In contrast to the classical general relativity, it is found that a stable Einstein static universe against the scalar perturbations does exist provided that the variation of time dependent geometrical equation of state parameter is proportional to the minus of the variation of the scale factor, δ ω{sub g}(t) = −Cδ a(t). We obtain neutral stability against the vector perturbations, and the stability against the tensor perturbations is guaranteed due to the positivity of the spatial curvature of the Einstein static universe in induced matter brane gravity.

  19. The Matter-Antimatter Asymmetry of the Universe

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    I will give here an overview of the present observational and theoretical situation regarding the question of the matter-antimatter asymmetry of the universe and the related question of the existence of antimatter on a cosmological scale. I will also give a simple discussion of the role of CP (charge conjugation parity) violation in this subject.

  20. CP Violation and the Matter Anti-Matter Asymmetry of the Universe

    NASA Astrophysics Data System (ADS)

    Cahn, Robert

    2012-02-01

    There is no scientific question more fundamental than ``Why are we here?'' or as we physicists might phrase it ``Why is there more matter than anti-matter?'' Because, as Andrei Sakharov first showed, CP violation is necessary to any explanation of the matter anti-matter asymmetry, CP violation is the focus of much of the international experimental program in particle physics. CP conservation was what could be salvaged after parity was overthrown in 1956, but it survived only until 1964 when K mesons were found not to respect it. While parity violation was a large effect in weak interactions, CP violation seemed small and confined to the kaons. When the Standard Model of particle physics emerged in early 1970's, Kobayashi and Maskawa observed that if there were three families of quarks, CP violation would arise quite naturally. The Standard Model suggested that CP violation could be large in decays of B mesons. Nonetheless, no matter what parameters are used in the Standard Model, CP violation among quarks cannot be large enough to explain the matter anti-matter asymmetry. Major experiments in the U.S. and Japan were undertaken to explore CP violation in B mesons to search for signs of CP violation outside the Standard Model, which might explain the dominance of matter over anti-matter. Neither experiment found such a discrepancy, but new programs will continue this search with much higher statistics. While the three families of leptons are in many ways analogous to the three families of quarks, the neutrinos have a unique character. As neutral particles, it is possible that they are their own antiparticles. If this is so, there may be additional, very heavy, neutrinos beyond those we know already. If they violate CP they may be the source of the matter anti-matter asymmetry. But do neutrinos experience CP violation? Experiments around the world are just now setting out to answer this question.

  1. Large-scale structure and matter in the Universe.

    PubMed

    Peacock, J A

    2003-11-15

    This paper summarizes the physical mechanisms that encode the type and quantity of cosmological matter in the properties of large-scale structure, and reviews the application of such tests to current datasets. The key lengths of the horizon size at matter-radiation equality and at last scattering determine the total matter density and its ratio to the relativistic density; acoustic oscillations can diagnose whether the matter is collisionless, and small-scale structure or its absence can limit the mass of any dark-matter relic particle. The most stringent constraints come from combining data on present-day galaxy clustering with data on CMB anisotropies. Such an analysis breaks the degeneracies inherent in either dataset alone, and proves that the Universe is very close to flat. The matter content is accurately consistent with pure cold dark matter, with ca. 25% of the critical density, and fluctuations that are scalar only, adiabatic and scale invariant. It is demonstrated that these conclusions cannot be evaded by adjusting either the equation of state of the vacuum, or the total relativistic density.

  2. Dynamics of the NGC 4636 globular cluster system. An extremely dark matter dominated galaxy?

    NASA Astrophysics Data System (ADS)

    Schuberth, Y.; Richtler, T.; Dirsch, B.; Hilker, M.; Larsen, S. S.; Kissler-Patig, M.; Mebold, U.

    2006-11-01

    Context: .We present the first dynamical study of the globular cluster system of NGC 4636. It is the southernmost giant elliptical galaxy of the Virgo cluster and is claimed to be extremely dark matter dominated, according to X-ray observations. Aims: .Globular clusters are used as dynamical tracers to investigate, by stellar dynamical means, the dark matter content of this galaxy. Methods: .Several hundred medium resolution spectra were acquired at the VLT with FORS 2/MXU. We obtained velocities for 174 globular clusters in the radial range 0.90 arcmin < R < 15.5 arcmin, or 0.5-9~Re in units of effective radius. Assuming a distance of 15 Mpc, the clusters are found at projected galactocentric distances in the range 4 to 70 kpc, the overwhelming majority within 30 kpc. The measured line-of-sight velocity dispersions are compared to Jeans-models. Results: .We find some indication of a rotation of the red (metal-rich) clusters about the minor axis. Out to a radius of 30 kpc, we find a roughly constant projected velocity dispersion for the blue clusters of σ ≈ 200~km s-1. The red clusters are found to have a distinctly different behavior: at a radius of about 3', the velocity dispersion drops by ~50~km s-1 to about 170~km s-1, which then remains constant out to a radius of 7'. The cause might be the steepening of the number density profile at ~3' observed for the red clusters. Using only the blue clusters as dynamical tracers, we perform Jeans-analyses for different assumptions of the orbital anisotropy. Enforcing the model dark halos to be of the NFW type, we determine their structural parameters. Depending on the anisotropy and the adopted M/L-values, we find that the dark matter fraction within one effective radius can vary between 20% and 50%, with most a probable range between 20% and 30%. The ambiguity of the velocity dispersion in the outermost bin is a main source of uncertainty. A comparison with cosmological N-body simulations reveals no striking

  3. Growth response of dominant and co-dominant loblolly pines to organic matter removal, soil compaction, and competition control

    Treesearch

    Robert Eaton; William Smith; Kim Ludovici

    2010-01-01

    The Long Term Soil Productivity (LTSP) experiment is a U.S. Forest Service led effort to test the effects that organic matter removal, soil compaction, and competition control have forest soil productivity, as measured by tree growth. A replicated experiment was installed on the Croatan National Forest, NC, in winter 1991 and loblolly pine (Pinus taeda...

  4. SECOND-ORDER SOLUTIONS OF COSMOLOGICAL PERTURBATION IN THE MATTER-DOMINATED ERA

    SciTech Connect

    Hwang, Jai-chan; Noh, Hyerim; Gong, Jinn-Ouk

    2012-06-10

    We present the growing mode solutions of cosmological perturbations to the second order in the matter-dominated era. We also present several gauge-invariant combinations of perturbation variables to the second order in the most general fluid context. Based on these solutions, we study the Newtonian correspondence of relativistic perturbations to the second order. In addition to the previously known exact relativistic/Newtonian correspondence of density and velocity perturbations to the second order in the comoving gauge, here we show that in the sub-horizon limit we have the correspondences for density, velocity, and potential perturbations in the zero-shear gauge and in the uniform-expansion gauge to the second order. Density perturbation in the uniform-curvature gauge also shows the correspondence to the second order in the sub-horizon scale. We also identify the relativistic gravitational potential that shows exact correspondence to the Newtonian one to the second order.

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

    NASA Astrophysics Data System (ADS)

    Tawfik, A.; Magdy, H.

    2012-05-01

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

  6. Universality of slip avalanches in flowing granular matter.

    PubMed

    Denisov, D V; Lörincz, K A; Uhl, J T; Dahmen, K A; Schall, P

    2016-02-17

    The search for scale-bridging relations in the deformation of amorphous materials presents a current challenge with tremendous applications in material science, engineering and geology. While generic features in the flow and microscopic dynamics support the idea of a universal scaling theory of deformation, direct microscopic evidence remains poor. Here, we provide the first measurement of internal scaling relations in the deformation of granular matter. By combining macroscopic force fluctuation measurements with internal strain imaging, we demonstrate the existence of robust scaling relations from particle-scale to macroscopic flow. We identify consistent power-law relations truncated by systematic pressure-dependent cutoff, in agreement with recent mean-field theory of slip avalanches in elasto-plastic materials, revealing the existence of a mechanical critical point. These results experimentally establish scale-bridging relations in the flow of matter, paving the way to a new universal theory of deformation.

  7. Universality of slip avalanches in flowing granular matter

    NASA Astrophysics Data System (ADS)

    Denisov, D. V.; Lörincz, K. A.; Uhl, J. T.; Dahmen, K. A.; Schall, P.

    2016-02-01

    The search for scale-bridging relations in the deformation of amorphous materials presents a current challenge with tremendous applications in material science, engineering and geology. While generic features in the flow and microscopic dynamics support the idea of a universal scaling theory of deformation, direct microscopic evidence remains poor. Here, we provide the first measurement of internal scaling relations in the deformation of granular matter. By combining macroscopic force fluctuation measurements with internal strain imaging, we demonstrate the existence of robust scaling relations from particle-scale to macroscopic flow. We identify consistent power-law relations truncated by systematic pressure-dependent cutoff, in agreement with recent mean-field theory of slip avalanches in elasto-plastic materials, revealing the existence of a mechanical critical point. These results experimentally establish scale-bridging relations in the flow of matter, paving the way to a new universal theory of deformation.

  8. Universality of slip avalanches in flowing granular matter

    PubMed Central

    Denisov, D. V.; Lörincz, K. A.; Uhl, J. T.; Dahmen, K. A.; Schall, P.

    2016-01-01

    The search for scale-bridging relations in the deformation of amorphous materials presents a current challenge with tremendous applications in material science, engineering and geology. While generic features in the flow and microscopic dynamics support the idea of a universal scaling theory of deformation, direct microscopic evidence remains poor. Here, we provide the first measurement of internal scaling relations in the deformation of granular matter. By combining macroscopic force fluctuation measurements with internal strain imaging, we demonstrate the existence of robust scaling relations from particle-scale to macroscopic flow. We identify consistent power-law relations truncated by systematic pressure-dependent cutoff, in agreement with recent mean-field theory of slip avalanches in elasto-plastic materials, revealing the existence of a mechanical critical point. These results experimentally establish scale-bridging relations in the flow of matter, paving the way to a new universal theory of deformation. PMID:26883071

  9. [Dark matter and dark energy of the universe].

    PubMed

    Aguilar Peris, José

    2005-01-01

    At the turn of the 20th Century, the Universe was thought to consist of our solar system, the Sun, planets, satellites and comets, floating under the Milky Way. The astronomers were ignorant of the existence of galaxies, clusters, quasars and black holes. Over the last ten years the Cosmology has made remarkable progress in our understanding of the composition of the Universe: 23 per cent is in an unknown form called dark matter; 73 per cent in another form called dark energy; 3 per cent is made of free hydrogen and helium atoms; 0.5 per cent makes up all the light we see in the night including the stars, clusters and superclusters; 0.3 per cent is in free neutrino particles; and finally, 0.03 per cent is in the heavier nuclei of which the Sun, the Earth and ourselves are made. In this work we study specially the dark matter and the dark energy. The first one appears to be attached to galaxies, and astronomers agree that it is cold, meaning that the particles that make up that matter are not moving fast. Very recently astronomers discovered that a tremendous amount of the so-cahled dark energy exists and that it is pushing and accelerating the expansion of the Universe. Should this expansion continue for another 14,000 million years, the sky will darken with only a handful of galaxies remaining visible.

  10. Large-scale structure formation and cosmic microwave anisotropy in a cold plus hot dark matter universe

    NASA Technical Reports Server (NTRS)

    Schaefer, Robert K.; Shafi, Qaisar; Stecker, Floyd W.

    1989-01-01

    Several particle physics models suggest the simultaneous existence of both cold and hot forms of dark matter particles. Assuming a Harrison-Zel'dovich spectrum of primordial density fluctuations and Omega = 1, the formation of structure in a universe dominated by a combination of cold dark matter and massive neutrinos is explored. It is found that the presence of the hot dark matter component can cause enough power on large scales to explain some recent observations, while there is still sufficient power on small scales to allow galactic structure formation. Spatial anisotropies in the microwave background radiation are computed and found to be compatible with observational limits.

  11. Large-scale structure formation and cosmic microwave anisotropy in a cold plus hot dark matter universe

    NASA Technical Reports Server (NTRS)

    Schaefer, Robert K.; Shafi, Qaisar; Stecker, Floyd W.

    1989-01-01

    Several particle physics models suggest the simultaneous existence of both cold and hot forms of dark matter particles. Assuming a Harrison-Zel'dovich spectrum of primordial density fluctuations and Omega = 1, the formation of structure in a universe dominated by a combination of cold dark matter and massive neutrinos is explored. It is found that the presence of the hot dark matter component can cause enough power on large scales to explain some recent observations, while there is still sufficient power on small scales to allow galactic structure formation. Spatial anisotropies in the microwave background radiation are computed and found to be compatible with observational limits.

  12. Dark energy and dark matter perturbations in singular universes

    SciTech Connect

    Denkiewicz, Tomasz

    2015-03-01

    We discuss the evolution of density perturbations of dark matter and dark energy in cosmological models which admit future singularities in a finite time. Up to now geometrical tests of the evolution of the universe do not differentiate between singular universes and ΛCDM scenario. We solve perturbation equations using the gauge invariant formalism. The analysis shows that the detailed reconstruction of the evolution of perturbations within singular cosmologies, in the dark sector, can exhibit important differences between the singular universes models and the ΛCDM cosmology. This is encouraging for further examination and gives hope for discriminating between those models with future galaxy weak lensing experiments like the Dark Energy Survey (DES) and Euclid or CMB observations like PRISM and CoRE.

  13. Sensitivity and specificity of Ankara University Cerebral Dominance Inventory in comparison with the Wada test.

    PubMed

    Yılmaz, Nesrin Helvacı; Bingol, Ayse Petek

    2014-03-01

    We aimed to examine the sensitivity and specificity of the Ankara University Cerebral Dominance Inventory (AUCDI) in determining left cerebral dominance compared with the Wada test. The AUCDI and Wada test were applied to 49 patients referred to Ankara University for epilepsy surgery. Hand, foot and 'total' preference scores were specified according to the results of the inventory. Thirty-eight of the patients had left cerebral dominance and 11 had atypical cerebral dominance for language. 86 % of the patients were right-handed and 43 % were right-footed. When compared with the results of the Wada test, the sensitivity of the AUCDI for each 'total preference', and hand and foot preference was 90, 95 and 50 % and specificity was 46, 46 and 82 %, respectively. The percentage of right-footed patients was low when compared with the other studies. This difference might result from the method used for assessing foot preference by the actual demonstration of the task rather than just asking about the performance. The AUCDI was found to be sensitive in terms of 'total preference' and hand preference, and specific in terms of foot preference for determining the left hemisphere dominance in patients preferring the right side. It was a cheap and noninvasive alternative to the Wada test, appropriate for clinical bedside evaluation.

  14. The others: universals and cultural specificities in the perception of status and dominance from nonverbal behavior.

    PubMed

    Bente, Gary; Leuschner, Haug; Al Issa, Ahmad; Blascovich, James J

    2010-09-01

    The current study analyzes trans-cultural universalities and specificities in the recognition of status roles, dominance perception and social evaluation based on nonverbal cues. Using a novel methodology, which allowed to mask clues to ethnicity and cultural background of the agents, we compared impression of Germans, Americans and Arabs observing computer-animated interactions from the three countries. Only in the German stimulus sample the status roles (employee vs. supervisor) could be recognized above chance level. However we found significant correlations in dominance perception across all countries. Significant correlations were only found for evaluation between German observers and observers from the other two countries. Perceived dominance uniformly predicted the assignment of status-roles in all cultures. Microanalysis of movement behavior further revealed predictive value of specific nonverbal cues for dominance ratings. Results support the hypothesis of universalities in the processing of dominance cues and point to cultural specificities in evaluative responses to nonverbal behavior. Copyright © 2010 Elsevier Inc. All rights reserved.

  15. Galaxies and gas in a cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Katz, Neal; Hernquist, Lars; Weinberg, David H.

    1992-01-01

    We use a combined gravity/hydrodynamics code to simulate the formation of structure in a random 22 Mpc cube of a cold dark matter universe. Adiabatic compression and shocks heat much of the gas to temperatures of 10 exp 6 - 10 exp 7 K, but a fraction of the gas cools radiatively to about 10 exp 4 K and condenses into discrete, highly overdense lumps. We identify these lumps with galaxies. The high-mass end of their baryonic mass function fits the form of the observed galaxy luminosity function. They retain independent identities after their dark halos merge, so gravitational clustering produces groups of galaxies embedded in relatively smooth envelopes of hot gas and dark matter. The galaxy correlation function is approximately an r exp -2.1 power law from separations of 35 kpc to 7 Mpc. Galaxy fluctuations are biased relative to dark matter fluctuations by a factor b about 1.5. We find no significant 'velocity bias' between galaxies and dark matter particles. However, virial analysis of the simulation's richest group leads to an estimated Omega of about 0.3, even though the simulation adopts Omega = 1.

  16. Galaxies and gas in a cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Katz, Neal; Hernquist, Lars; Weinberg, David H.

    1992-01-01

    We use a combined gravity/hydrodynamics code to simulate the formation of structure in a random 22 Mpc cube of a cold dark matter universe. Adiabatic compression and shocks heat much of the gas to temperatures of 10 exp 6 - 10 exp 7 K, but a fraction of the gas cools radiatively to about 10 exp 4 K and condenses into discrete, highly overdense lumps. We identify these lumps with galaxies. The high-mass end of their baryonic mass function fits the form of the observed galaxy luminosity function. They retain independent identities after their dark halos merge, so gravitational clustering produces groups of galaxies embedded in relatively smooth envelopes of hot gas and dark matter. The galaxy correlation function is approximately an r exp -2.1 power law from separations of 35 kpc to 7 Mpc. Galaxy fluctuations are biased relative to dark matter fluctuations by a factor b about 1.5. We find no significant 'velocity bias' between galaxies and dark matter particles. However, virial analysis of the simulation's richest group leads to an estimated Omega of about 0.3, even though the simulation adopts Omega = 1.

  17. Universal parametrization of thermal photon rates in hadronic matter

    NASA Astrophysics Data System (ADS)

    Heffernan, Matthew; Hohler, Paul; Rapp, Ralf

    2015-02-01

    Electromagnetic (EM) radiation off strongly interacting matter created in high-energy heavy-ion collisions (HICs) encodes information on the high-temperature phases of nuclear matter. Microscopic calculations of thermal EM emission rates are usually rather involved and not readily accessible to broad applications in models of the fireball evolution which are required to compare with experimental data. An accurate and universal parametrization of the microscopic calculations is thus key to honing the theory behind the EM spectra. Here we provide such a parametrization for photon emission rates from hadronic matter, including the contributions from in-medium ρ mesons (which incorporate effects from baryons and antibaryons), as well as bremsstrahlung from π π scattering. Individual parametrizations for each contribution are numerically determined through nested fitting functions for photon energies from 0.2 to 5 GeV in chemically equilibrated matter of temperatures 100-180 MeV and baryon chemical potentials 0-400 MeV. Special care is taken to extent the parametrizations to chemical off-equilibrium as encountered in HICs after chemical freeze-out. This provides a functional description of thermal photon rates within a 20% variation of the microscopically calculated values.

  18. Evolution of the principal mode of density perturbations in a neutrino-dominated universe

    NASA Astrophysics Data System (ADS)

    Khlebnikov, V. I.

    1982-05-01

    The paper examines the physical features of the evolution of the growing mode of density perturbations in homogeneous isotropic cosmological models. The evolution of density perturbations in the long-wave limit in a neutrino-dominated Friedman universe is determined in the ultrarelativistic asymptotic case and in the general case. It is shown that all natural modes of long-wave scalar perturbations in a relativistic neutrino-dominated universe contain corresponding quadrupole components of the perturbed neutrino-distribution function. With neutrino separation from the Pascal fluid, quadrupole distributions of various modes mutually compensate one another; however, further on there occurs a disharmony of quadrupole moments owing to the difference in the laws of evolution of the natural modes of perturbations.

  19. Constraints on the very early universe from thermal WIMP dark matter

    SciTech Connect

    Drees, Manuel; Kakizaki, Mitsuru; Iminniyaz, Hoernisa

    2007-11-15

    We investigate the relic density n{sub {chi}} of nonrelativistic long-lived or stable particles {chi} in nonstandard cosmological scenarios. We calculate the relic abundance starting from arbitrary initial temperatures of the radiation-dominated epoch, and derive the lower bound on the initial temperature T{sub 0}{>=}m{sub {chi}}/23, assuming that thermally produced {chi} particles account for the dark matter energy density in the Universe; this bound holds for all {chi} annihilation cross sections. We also investigate cosmological scenarios with modified expansion rate. Even in this case an approximate formula similar to the standard one is capable of predicting the final relic abundance correctly. Choosing the {chi} annihilation cross section such that the observed cold dark matter abundance is reproduced in standard cosmology, we constrain possible modifications of the expansion rate at T{approx}m{sub {chi}}/20, well before big bang nucleosynthesis.

  20. Carbon star radial velocities and dark matter in the universe

    NASA Technical Reports Server (NTRS)

    Jura, M.

    1986-01-01

    Optical radial velocities of carbon stars in the Milky Way are compared to center-of-mass velocities derived from CO radio emission produced in their circumstellar envelopes. It seems that there is an intrinsic velocity dispersion in the optically measured radial velocities. If the carbon stars in the dwarf spheroidals behave in a fashion similar to those in the Milky Way, then the use of their optical radial velocities to infer the mass-to-light ratio of dwarf spheroidal galaxies and the nature of the dark matter in the universe is suspect. Measurement of the radial velocities of K giants may possibly avoid these uncertainties associated with atmospheric motions.

  1. Dark matter and the baryon asymmetry of the universe.

    PubMed

    Farrar, Glennys R; Zaharijas, Gabrijela

    2006-02-03

    We present a mechanism to generate the baryon asymmetry of the Universe which preserves the net baryon number created in the big bang. If dark matter particles carry baryon number Bx, and sigmaxannih

  2. Second order gravitational effects on CMB temperature anisotropy in {lambda} dominated flat universes

    SciTech Connect

    Tomita, Kenji; Inoue, Kaiki Taro

    2008-05-15

    We study second order gravitational effects of local inhomogeneities on the cosmic microwave background radiation in flat universes with matter and a cosmological constant {lambda}. We find that the general relativistic correction to the Newtonian approximation is negligible at second order provided that the size of the inhomogeneous region is sufficiently smaller than the horizon scale. For a spherically symmetric top-hat type quasilinear perturbation, the first order temperature fluctuation corresponding to the linear integrated Sachs-Wolfe effect is enhanced (suppressed) by the second order one for a compensated void (lump). As a function of redshift of the local inhomogeneity, the second order temperature fluctuations due to evolution of the gravitational potential have a peak before the matter-{lambda} equality epoch for a fixed comoving size and a density contrast. The second order gravitational effects from local quasilinear inhomogeneities at a redshift z{approx}1 may significantly affect the cosmic microwave background.

  3. Quantum-Electrodynamic Processes in a Radiation-Dominated Robertson-Walker Universe

    NASA Astrophysics Data System (ADS)

    Buchbinder, I. L.; Tsaregorodtsev, L. I.

    Quantum electrodynamics in an expanding Robertson-Walker universe with the line element ds2=dt2 - a2(t)(dx2+dy2+dz2) (radiation-dominated universe) is considered. The differential probability of bremsstrahlung of an electron in the external gravitational field and the differential probability of an electron-positron pair and photon creation from the vacuum are calculated by using the perturbative S-matrix formalism. The behavior of these probabilities in different kinematic regions is investigated. The total probabilities are shown to be finite. In conclusion, the total probability of a pair and photon creation from vacuum We is compared with the total probability of pair production due to an expansion of the universe W0. The comparison shows that We=1.9·10-2W0 at about the Compton time of an electron.

  4. Energy density of standing sound waves at the radiation-dominated phase of the universe expansion (hydrodynamic derivation)

    NASA Astrophysics Data System (ADS)

    Inogamov, N. A.; Sunyaev, R. A.

    2015-12-01

    In the early Universe up to hydrogen recombination in the Universe, the radiation pressure was much greater than the pressure of baryons and electrons. Moreover, the energy density of cosmic microwave background (CMB) photons was greater than or close to the energy density contained in the rest mass of baryonic matter, i.e., the primordial plasma was a radiated-dominated one and the adiabatic index was close to 4/3. The small density perturbations from which the observed galaxies have grown grew as long as the characteristic perturbation scales exceeded the horizon of the Universe сt at that time. On smaller scales, the density perturbations were standing sound waves. Radiative viscosity and heat conduction must have led to the damping of sound waves on very small scales. After the discovery of the cosmic microwave background, J. Silk calculated the scales of this damping, which is now called Silk damping, knowing the CMBtemperature and assuming the density of baryons and electrons. Observations with the South Pole Telescope, the Atacama Cosmology Telescope, and the Planck satellite have revealed the predicted damping of acoustic peaks in the CMB power spectrum and confirmed one important prediction of the theory. In 1970, R.A. Sunyaev and Ya.B. Zeldovich showed that such energy release in the early Universe should lead to characteristic deviations of the CMB spectrum from the Planck one. The development of the technology of cryogenic detectors of submillimeter and millimeter wavelength radiation has made it possible to measure the CMB spectral distortions at 10-8 of its total intensity (PIXIE). This has sharply increased the interest of theoretical cosmologists in the problem of energy release when smallscale sound waves are damped. We have derived a relativistic formula for the energy of a standing sound wave in a photon-baryon-electron plasma from simple hydrodynamic and thermodynamic relations. This formula is applicable for an arbitrary relation between the

  5. Ecogeomorphology of Spartina patens-dominated tidal marshes: Soil organic matter accumulation, marsh elevation dynamics, and disturbance

    USGS Publications Warehouse

    Cahoon, D.R.; Ford, M.A.; Hensel, P.F.; Fagherazzi, Sergio; Marani, Marco; Blum, Linda K.

    2004-01-01

    Marsh soil development and vertical accretion in Spartina patens (Aiton) Muhl.-dominated tidal marshes is largely dependent on soil organic matter accumulation from root-rhizome production and litter deposition. Yet there are few quantitative data sets on belowground production and the relationship between soil organic matter accumulation and soil elevation dynamics for this marsh type. Spartina patens marshes are subject to numerous stressors, including sea-level rise, water level manipulations (i.e., flooding and draining) by impoundments, and prescribed burning. These stressors could influence long-term marsh sustainability by their effect on root production, soil organic matter accumulation, and soil elevation dynamics. In this review, we summarize current knowledge on the interactions among vegetative production, soil organic matter accumulation and marsh elevation dynamics, or the ecogeomorphology, of Spartina patens-dominated tidal marshes. Additional studies are needed of belowground production/decomposition and soil elevation change (measured simultaneously) to better understand the links among soil organic matter accumulation, soil elevation change, and disturbance in this marsh type. From a management perspective, we need to better understand the impacts of disturbance stressors, both lethal and sub-lethal, and the interactive effect of multiple stressors on soil elevation dynamics in order to develop better management practices to safeguard marsh sustainability as sea level rises.

  6. Large-scale structure from cosmic-string loops in a baryon-dominated universe

    NASA Technical Reports Server (NTRS)

    Melott, Adrian L.; Scherrer, Robert J.

    1988-01-01

    The results are presented of a numerical simulation of the formation of large-scale structure in a universe with Omega(0) = 0.2 and h = 0.5 dominated by baryons in which cosmic strings provide the initial density perturbations. The numerical model yields a power spectrum. Nonlinear evolution confirms that the model can account for 700 km/s bulk flows and a strong cluster-cluster correlation, but does rather poorly on smaller scales. There is no visual 'filamentary' structure, and the two-point correlation has too steep a logarithmic slope. The value of G mu = 4 x 10 to the -6th is significantly lower than previous estimates for the value of G mu in baryon-dominated cosmic string models.

  7. Dark Matter in the Universe and in the Galaxy

    NASA Technical Reports Server (NTRS)

    Kamionkowski, Marc

    1999-01-01

    During the past four years, Prof. Kamionkowski and collaborators have made progress in research on the nature and distribution of dark-matter in the Universe and in the Galaxy, and on related topics in astrophysics and cosmology. We have made progress on research on the cosmic microwave background, large-scale structure, issues related to particle dark matter, and the gamma-ray-burst enigma. A significant fraction of the research supported by this ATP has been on the cosmic microwave background (CMB). Prof. Kamionkowski and collaborators showed how the polarization of the CMB could be used to detect long-wavelength gravitational waves, such as those produced by inflation. With Kosowsky, Prof. Kamionkowski calculated the amplitude of a stochastic gravitational-wave background that could be detected for a satellite experiment of a given sensitivity and angular resolution. They showed that polarization should improve the sensitivity oa MAP to these gravity waves, and that the Planck Surveyor should do even better. Prof. Kamionkowski, Caldwell, and a student calculated and illustrated the CMB temperature/polarization pattern produced by a single plane-wave gravitational wave. They calculated the amplitude of such a wave that would be detectable with MAP and Planck, and compared that with the sensitivity of traditional gravitational-wave detectors like LIGO and LISA. With Lue and Wang, the PI showed how parity violation from new high-energy physics could conceivably give rise to an observable signature in the CMB polarization. With Loeb, Prof. Kamionkowski showed how measurement of the polarization of CMB photons scattered by hot gas in a cluster could be used to determine the quadrupole moment of the CMB incident on that cluster. Prof. Kamionkowski and Jaffe calculated the amplitude of secondary anisotropies produced by scattering of CMB photons from reionized regions. Research has also been carried out on probing the large-scale distribution of mass in the Universe

  8. The universe dominated by oscillating scalar with non-minimal derivative coupling to gravity

    SciTech Connect

    Jinno, Ryusuke; Mukaida, Kyohei; Nakayama, Kazunori E-mail: mukaida@hep-th.phys.s.u-tokyo.ac.jp

    2014-01-01

    We study the expansion law of the universe dominated by the oscillating scalar field with non-minimal derivative coupling to gravity as G{sup μν}∂{sub μ}φ∂{sub ν}φ. In this system the Hubble parameter oscillates with a frequency of the effective mass of the scalar field, which formerly caused a difficulty in analyzing how the universe expands. We find an analytical solution for power law potentials and interpret the solution in an intuitive way by using a new invariant of the system. As a result, we find marginally accelerated expansion for the quadratic potential and no accelerated expansion for the potential with higher power.

  9. Too many Asians in universities? The effect of social dominance orientation on support for admissions limits.

    PubMed

    Gutierrez, Angelica

    2017-09-05

    This paper tests the hypothesis that support for limits on the admission of Asian students into universities is motivated by people's social motivation - namely the desire to maintain the status hierarchy. Study 1 found that, among participants who evaluated a proposed limit to the number of Asian applicants admitted to universities, social dominance orientation (SDO) was positively related to policy support. Conversely, among participants who evaluated a proposed limit on White admits, SDO was negatively related to policy support. Study 2 found that the perceived threat of the group getting admitted at high rates explained differential support of policies that seek to limit group-specific admissions. In all, these findings suggest that attitudes toward changes in campus demographics may be rooted in a desire to maintain the status hierarchy.

  10. Declining diversity in abandoned grasslands of the carpathian mountains: do dominant species matter?

    PubMed

    Csergő, Anna Mária; Demeter, László; Turkington, Roy

    2013-01-01

    Traditional haymaking has created exceptionally high levels of plant species diversity in semi-natural grasslands of the Carpathian Mountains (Romania), the maintenance of which is jeopardized by recent abandonment and subsequent vegetation succession. We tested the hypothesis that the different life history strategies of dominant grasses cause different patterns of diversity loss after abandonment of traditional haymaking in two types of meadow. Although diversity loss rate was not significantly different, the mechanism of loss depended on the life history of dominant species. In meadows co-dominated by competitive stress-tolerant ruderals, diversity loss occurred following the suppression of dominant grasses by tall forbs, whereas in meadows dominated by a stress-tolerant competitor, diversity loss resulted from increased abundance and biomass of the dominant grass. We conclude that management for species conservation in abandoned grasslands should manipulate the functional turnover in communities where the dominant species is a weaker competitor, and abundance and biomass of dominant species in communities where the dominant species is the stronger competitor.

  11. Gravitational lensing in a cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Narayan, Ramesh; White, Simon D. M.

    1988-01-01

    Gravitational lensing due to mass condensations in a biased cold dark matter (CDM) universe is investigated using the Press-Schechter (1974) theory with density fluctuation amplitudes taken from previous N-body work. Under the critical assumption that CDM haloes have small core radii, a distribution of image angular separations for high-z lensed quasars with a peak at about 1 arcsec and a half-width of a factor of about 10. Allowing for selection effects at small angular separations, this is in good agreement with the observed separations. The estimated frequency of lensing is somewhat lower than that observed, but the discrepancy can be removed by invoking amplification bias and by making a small upward adjustment to the density fluctuation amplitudes assumed in the CDM model.

  12. Gravitational lensing in a cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Narayan, Ramesh; White, Simon D. M.

    1988-01-01

    Gravitational lensing due to mass condensations in a biased cold dark matter (CDM) universe is investigated using the Press-Schechter (1974) theory with density fluctuation amplitudes taken from previous N-body work. Under the critical assumption that CDM haloes have small core radii, a distribution of image angular separations for high-z lensed quasars with a peak at about 1 arcsec and a half-width of a factor of about 10. Allowing for selection effects at small angular separations, this is in good agreement with the observed separations. The estimated frequency of lensing is somewhat lower than that observed, but the discrepancy can be removed by invoking amplification bias and by making a small upward adjustment to the density fluctuation amplitudes assumed in the CDM model.

  13. Matrix protected organic matter in a river dominated margin: A possible mechanism to sequester terrestrial organic matter?

    NASA Astrophysics Data System (ADS)

    Mead, Ralph N.; Goñi, Miguel A.

    2008-06-01

    The provenance of organic matter in surface sediments from the northern Gulf of Mexico was investigated by analyzing the compositions of lipid biomarkers ( n-alkanes, fatty acids, sterols) liberated after a series of chemical treatments designed to remove different organo-mineral matrix associations (i.e. freely extractable, base-hydrolyzable, unhydrolyzable). Bulk analyses of the organic matter (carbon content, carbon:nitrogen ratios, stable and radiocarbon isotopic analyses) were also performed on the intact sediments and their non-hydrolyzable, demineralized residue. We found recognizable lipids from distinct sources, including terrestrial vascular plants, bacteria and marine algae and zooplankton, within each of the isolated fractions. Based on the lipid signatures and bulk compositions, the organic matter within the unhydrolyzable fractions appeared to be the most diagenetically altered, was the oldest in age, and had the highest abundance of terrigenous lipids. In contrast, the base-hydrolyzable fraction was the most diagentically unaltered, had the youngest ages and was most enriched in N and marine lipids. Our results indicate that fresh, autochthonous organic matter is the most important contributor to base-hydrolyzable lipids, whereas highly altered allochthonous sources appear to be predominant source of unhydrolyzable lipids in the surface sediments from the Atchafalaya River shelf. Overall, the lipid biomarker signatures of intact sediments were biased towards the autochthonous source because many of the organic compounds indicative of degraded, terrigenous sources were protected from extraction and saponification by organo-mineral matrices. It is only after these protective matrices were removed by treatment with HCl and HF that these compounds became evident.

  14. Dark and baryonic matter in the MareNostrum Universe

    NASA Astrophysics Data System (ADS)

    Gottlöber, S.; Yepes, G.; Khalatyan, A.; Sevilla, R.; Turchaninov, V.

    2006-11-01

    We report some results from one of the largest hydrodynamical cosmological simulations of large scale structures that has been done up to date. The MareNostrum Universe SPH simulation consists of 2 billion particles (2 × 10243) in a cubic box of 500 h-1 Mpc on a side. This simulation has been done in the MareNostrum parallel supercomputer at the Barcelona SuperComputer Center. Due to the large simulated volume and good mass resolution, our simulated catalog of dark matter halos comprises more than half a million objects with masses larger than a typical Milky Way galaxy halo. From this dataset we have studied several statistical properties such as the halo mass function, the distribution of shapes of dark and gas components within halos, the baryon fraction, cumulative void volume etc. This simulation is particularly useful to study the large scale distribution of baryons in the universe as a function of temperature and density. In this paper we also show the time evolution of the gas fractions at large scales.

  15. Re-parameterization of a quasi-analytical algorithm for colored dissolved organic matter dominant inland waters

    NASA Astrophysics Data System (ADS)

    Ogashawara, Igor; Mishra, Deepak R.; Nascimento, Renata F. F.; Alcântara, Enner H.; Kampel, Milton; Stech, Jose L.

    2016-12-01

    Quasi-Analytical Algorithms (QAAs) are based on radiative transfer equations and have been used to derive inherent optical properties (IOPs) from the above surface remote sensing reflectance (Rrs) in aquatic systems in which phytoplankton is the dominant optically active constituents (OACs). However, Colored Dissolved Organic Matter (CDOM) and Non Algal Particles (NAP) can also be dominant OACs in water bodies and till now a QAA has not been parametrized for these aquatic systems. In this study, we compared the performance of three widely used QAAs in two CDOM dominated aquatic systems which were unsuccessful in retrieving the spectral shape of IOPS and produced minimum errors of 350% for the total absorption coefficient (a), 39% for colored dissolved matter absorption coefficient (aCDM) and 7566.33% for phytoplankton absorption coefficient (aphy). We re-parameterized a QAA for CDOM dominated (hereafter QAACDOM) waters which was able to not only achieve the spectral shape of the OACs absorption coefficients but also brought the error magnitude to a reasonable level. The average errors found for the 400-750 nm range were 30.71 and 14.51 for a, 14.89 and 8.95 for aCDM and 25.90 and 29.76 for aphy in Funil and Itumbiara Reservoirs, Brazil respectively. Although QAACDOM showed significant promise for retrieving IOPs in CDOM dominated waters, results indicated further tuning is needed in the estimation of a(λ) and aphy(λ). Successful retrieval of the absorption coefficients by QAACDOM would be very useful in monitoring the spatio-temporal variability of IOPS in CDOM dominated waters.

  16. A Possible Interpretation of Dark Energy and Matter of the Expanding Universe

    SciTech Connect

    Lehnert, B.

    2009-11-10

    At present the expanding universe is observed to be dominated by the not fully understood concepts of dark energy and matter, in a conceived almost flat Euclidian geometry. As one of the possible efforts to understand its global behaviour, the present paper attempts to explain these concepts in terms of the pressure force and gravity of a spherical photon gas cloud of zero point energy, in flat geometry. A difficult point concerns the frequency distribution of the zero point energy oscillations which leads to the unacceptable result of an infinite total energy. A modification of this distribution is therefore proposed which results in finite energy density. A corresponding equilibrium is investigated, as well as small dynamic deviations from it, to form a basis for a model of the expanding universe. Provided that the crucial points of the present approach hold true, the model satisfies the requirements of cosmic linear dimensions, results in an estimated acceleration of the expansion being of the order of the observed one, presents a possible solution of the coincidence problem of dark energy and matter, and provides one of the possible explanations of the observed excess of high-energy electrons and positrons in recent balloon and satellite experiments.

  17. The accretion history of dark matter haloes - I. The physical origin of the universal function

    NASA Astrophysics Data System (ADS)

    Correa, Camila A.; Wyithe, J. Stuart B.; Schaye, Joop; Duffy, Alan R.

    2015-06-01

    Understanding the universal accretion history of dark matter haloes is the first step towards determining the origin of their structure. We use the extended Press-Schechter formalism to derive the halo mass accretion history from the growth rate of initial density perturbations. We show that the halo mass history is well described by an exponential function of redshift in the high-redshift regime. However, in the low-redshift regime the mass history follows a power law because the growth of density perturbations is halted in the dark energy dominated era due to the accelerated expansion of the Universe. We provide an analytic model that follows the expression {M(z)=M0(1+z)^{af(M0)}e^{-f(M0)z}}, where M0 = M(z = 0), a depends on cosmology and f(M0) depends only on the linear matter power spectrum. The analytic model does not rely on calibration against numerical simulations and is suitable for any cosmology. We compare our model with the latest empirical models for the mass accretion history in the literature and find very good agreement. We provide numerical routines for the model online (available at https://bitbucket.org/astroduff/commah).

  18. A Universal Angular Momentum Profile for Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Liao, Shihong; Chen, Jianxiong; Chu, M.-C.

    2017-07-01

    The angular momentum distribution in dark matter halos and galaxies is a key ingredient in understanding their formation. Specifically, the internal distribution of angular momenta is closely related to the formation of disk galaxies. In this article, we use halos identified from a high-resolution simulation, the Bolshoi simulation, to study the spatial distribution of specific angular momenta, j(r,θ ). We show that by stacking halos with similar masses to increase the signal-to-noise ratio, the profile can be fitted as a simple function, j{(r,θ )={j}s{\\sin }2{(θ /{θ }s)(r/{r}s)}2/(1+r/{r}s)}4, with three free parameters, {j}s,{r}s, and {θ }s. Specifically, j s correlates with the halo mass M vir as {j}s\\propto {M}{vir}2/3, r s has a weak dependence on the halo mass as {r}s\\propto {M}{vir}0.040, and {θ }s is independent of M vir. This profile agrees with that from a rigid shell model, though its origin is unclear. Our universal specific angular momentum profile j(r,θ ) is useful in modeling the angular momenta of halos. Furthermore, by using an empirical stellar mass-halo mass relation, we can infer the average angular momentum distribution of a dark matter halo. The specific angular momentum-stellar mass relation within a halo computed from our profile is shown to share a similar shape as that from the observed disk galaxies.

  19. The VLT Weighs the Invisible Matter in the Universe

    NASA Astrophysics Data System (ADS)

    2000-12-01

    Shapes and Orientations of 76,000 Distant Galaxies Summary An international team of astronomers [1] has succeeded in mapping the "dark" (invisible) matter in the Universe, as seen in 50 different directions from the Earth. They find that, within the uncertainty, it is unlikely that mass alone would stop the current expansion of the Universe . This fundamental result is based on the powerful, but challenging method of "cosmic shear" . It depends on very accurate measurements of the apparent, weak distortion and preferential orientation of images of distant galaxies . This effect is caused by deflection of the light from those galaxies by the large mass concentrations in the Universe it encounters on its way to us. The larger these masses are, the larger are the apparent image distortions and the more pronounced are the alignments of neigbouring galaxy images. The new analysis was made possible by means of unique observational data, obtained under excellent conditions with the the ESO 8.2-m VLT ANTU telescope and the multi-mode FORS1 instrument at the Paranal Observatory . PR Photo 32/00 : Sky field with images of distant galaxies observed with the VLT for this research programme, and compared with a reconstructed map of the distribution of mass in this direction. The VLT Observations ESO PR Photo 32/00 ESO PR Photo 32/00 [Preview - JPEG: 400 x 252 pix - 35k] [Normal - JPEG: 800 x 504 pix - 232k] [Hi-Res - JPEG: 3000 x 1890 pix - 2.0Mb] Caption : PR Photo 32/00 shows an example of the mapping of the dark mass distribution in one of the 50 sky fields observed with the VLT and FORS1. To the left is the original image, a 36-min exposure in a near-infrared wavelength band. To the right is the reconstructed map of the mass (a "mass photo") in this direction, based on an analysis of the weak shear effect seen in the field; that is, on the measured elongations and directions of the axes of the galaxy images in this field. The brighter areas indicate the directions in which

  20. Universal Parametrization of Thermal Photon Production in Hadronic Matter

    NASA Astrophysics Data System (ADS)

    Heffernan, Matthew; Hohler, Paul; Rapp, Ralf

    2014-09-01

    As the production of photons and dileptons from high-energy collisions is able to provide information on the high temperature and high density phases of nuclear matter, an improved and universal parametrization of the rather involved microscopic calculations is key to honing the theory behind this production. We focus on photon emission rates from hadronic many-body calculations of the in-medium rho spectral function, which includes the effects of baryons and antibaryons. Across a range of temperatures from 0.1 to 0.18 GeV and baryon chemical potentials from 0 to 0.4 GeV, a parametrization of thermal photon rates for energies from 0.2 to 5 GeV is numerically determined through the use of nested fitting methods. This provides a fully functional description of thermal photon production largely within an unprecedented 20% of the calculated values from the spectral function, a significant reduction in error from available parametrizations. The contribution of photons and dileptons from pion-pion bremsstrahlung is evaluated for the importance of its contribution. The functional form, coupled with the comparison to the bremsstrahlung production of thermal photons, will provide a baseline for guiding future studies. As the production of photons and dileptons from high-energy collisions is able to provide information on the high temperature and high density phases of nuclear matter, an improved and universal parametrization of the rather involved microscopic calculations is key to honing the theory behind this production. We focus on photon emission rates from hadronic many-body calculations of the in-medium rho spectral function, which includes the effects of baryons and antibaryons. Across a range of temperatures from 0.1 to 0.18 GeV and baryon chemical potentials from 0 to 0.4 GeV, a parametrization of thermal photon rates for energies from 0.2 to 5 GeV is numerically determined through the use of nested fitting methods. This provides a fully functional description of

  1. Strangeness in the Nucleon, Cold Dark Matter in the Universe, and Neutrino Scattering off Liquid Argon

    SciTech Connect

    Papavassiliou, V.

    2010-03-30

    The strangeness content of the nucleon and the contribution of strange quarks to various nucleon quantum numbers, besides being of fundamental interest, also affects calculations of cross sections of processes that are important in searches for new physics. Here we focus on direct searches for cold dark matter, in the scenario in which the lightest supersymmetric neutral particle dominates the CDM density in the universe and point out that interpretation of searches, as well as the choice of optimal materials for future experiments, are hobbled by uncertainties in the contribution of strange quarks to the nucleon spin. We show how a future low-energy neutrino experiment using a liquid-Ar TPC can make important contributions in determining this quantity with much better precision and reduced theoretical uncertainties.

  2. Dominance and gene dosage balance in health and disease: why levels matter!

    PubMed

    Veitia, Reiner A; Birchler, James A

    2010-01-01

    The classical concept of genetic dominance is a simplification of a more quantitative reality. This is clearly exemplified by aneuploid syndromes, of which the best known case is trisomy 21. Moreover, there is an increasing number of clinical conditions due to reduced dosage (haploinsufficiency) of genes encoding transcription factors and other proteins involved in signal transduction and macromolecular complexes. In such genetic diseases, a high degree of phenotypic variability is observed, which calls for an explanation. The sources of dominance are heterogeneous and difficult to cover in a brief review. Here, we will focus on the molecular bases of dosage-sensitive syndromes from the perspective of the gene dosage balance hypothesis, which postulates that stoichiometric alterations of macromolecular complexes or cellular networks are responsible for dominant phenotypes, because of the existing non-linear relationships between the genotypic and phenotypic values with which they are associated.

  3. The Measure Matters: Language Dominance Profiles across Measures in Spanish-English Bilingual Children

    ERIC Educational Resources Information Center

    Bedore, Lisa M.; Pena, Elizabeth D.; Summers, Connie L.; Boerger, Karin M.; Resendiz, Maria D.; Greene, Kai; Bohman, Thomas M.; Gillam, Ronald B.

    2012-01-01

    The purpose of this study was to determine if different language measures resulted in the same classifications of language dominance and proficiency for a group of bilingual pre-kindergarteners and kindergarteners. Data were analyzed for 1029 Spanish-English bilingual pre-kindergarteners who spanned the full range of bilingual language…

  4. Dark matter electron anisotropy: A universal upper limit

    NASA Astrophysics Data System (ADS)

    Borriello, Enrico; Maccione, Luca; Cuoco, Alessandro

    2012-03-01

    We study the dipole anisotropy in the arrival directions of high energy CR electrons and positrons (CRE) of dark matter (DM) origin. We show that this quantity is very weakly model dependent and offers a viable criterion to discriminate among CRE from DM or from local discrete sources, like e.g. pulsars. In particular, we find that the maximum anisotropy which DM can provide is to a very good approximation a universal quantity and, as a consequence, if a larger anisotropy is detected, this would constitute a strong evidence for the presence of astrophysical local discrete CRE sources, whose anisotropy, instead, can be naturally larger than the DM upper limit. We further find that the main source of anisotropy from DM is given by the fluctuation in the number density of DM sub-structures in the vicinity of the observer and we thus devote special attention to the study of the variance in the sub-structures realization implementing a dedicated Montecarlo simulation. Such scenarios will be probed in the next years by Fermi-LAT, providing new hints, or constraints, about the nature of DM.

  5. Gravitons and dark matter in universal extra dimensions

    SciTech Connect

    Shah, Nausheen R.; Wagner, Carlos E. M.

    2006-11-15

    Models of universal extra dimensions (UED) at the TeV scale lead to the presence of Kaluza Klein (KK) excitations of the ordinary fermions and bosons of the standard model that may be observed at hadron and lepton colliders. A conserved discrete symmetry, KK-parity, ensures the stability of the lightest KK particle (LKP), which, if neutral, becomes a good dark matter particle. It has been recently shown that for a certain range of masses of the LKP a relic density consistent with the experimentally observed one may be obtained. These works, however, ignore the impact of KK graviton production at early times. Whether the G{sup 1} is the LKP or not, the G{sup n} tower thus produced can decay to the LKP, and depending on the reheating temperature, may lead to a modification of the relic density. In this article, we show that this effect may lead to a relevant modification of the range of KK masses consistent with the observed relic density. Additionally, if evidence for UED is observed experimentally, we find a stringent upper limit on the reheating temperature depending on the mass of the LKP observed.

  6. Gravitons and dark matter in universal extra dimensions.

    SciTech Connect

    Shah, N. R.; Wagner, C. E. M.; High Energy Physics; Univ. of Chicago; Enrico Femi Inst.; Kavli Inst. for Cosmological Physics

    2006-11-01

    Models of universal extra dimensions (UED) at the TeV scale lead to the presence of Kaluza Klein (KK) excitations of the ordinary fermions and bosons of the standard model that may be observed at hadron and lepton colliders. A conserved discrete symmetry, KK-parity, ensures the stability of the lightest KK particle (LKP), which, if neutral, becomes a good dark matter particle. It has been recently shown that for a certain range of masses of the LKP a relic density consistent with the experimentally observed one may be obtained. These works, however, ignore the impact of KK graviton production at early times. Whether the G{sup 1} is the LKP or not, the G{sup n} tower thus produced can decay to the LKP, and depending on the reheating temperature, may lead to a modification of the relic density. In this article, we show that this effect may lead to a relevant modification of the range of KK masses consistent with the observed relic density. Additionally, if evidence for UED is observed experimentally, we find a stringent upper limit on the reheating temperature depending on the mass of the LKP observed.

  7. SELF-SIMILAR DYNAMICAL RELAXATION OF DARK MATTER HALOS IN AN EXPANDING UNIVERSE

    SciTech Connect

    Lapi, A.; Cavaliere, A.

    2011-12-20

    We investigate the structure of cold dark matter halos using advanced models of spherical collapse and accretion in an expanding universe. These are based on solving time-dependent equations for the moments of the phase-space distribution function in the fluid approximation; our approach includes non-radial random motions and, most importantly, an advanced treatment of both dynamical relaxation effects that take place in the infalling matter: phase-mixing associated with shell crossing and collective collisions related to physical clumpiness. We find self-similar solutions for the spherically averaged profiles of mass density {rho}(r), pseudo phase-space density Q(r), and anisotropy parameter {beta}(r). These profiles agree with the outcomes of state-of-the-art N-body simulations in the radial range currently probed by the latter; at smaller radii, we provide specific predictions. In the perspective provided by our self-similar solutions, we link the halo structure to its two-stage growth history and propose the following picture. During the early fast collapse of the inner region dominated by a few merging clumps, efficient dynamical relaxation plays a key role in producing closely universal mass density and pseudo phase-space density profiles; in particular, these are found to depend only weakly on the detailed shape of the initial perturbation and the related collapse times. The subsequent inside-out growth of the outer regions feeds on the slow accretion of many small clumps and diffuse matter; thus the outskirts are only mildly affected by dynamical relaxation but are more sensitive to asymmetries and cosmological variance.

  8. Production of electron-positron pairs by a photon in the radiation-dominated universe

    SciTech Connect

    Tsaregorodtsev, L.I.

    1995-12-01

    The production of an arbitrary number of electron-positron pairs by a photon in a spatially flat Robertson-Walker universe with expansion law a(t) = a{sub o}{radical}t is considered. In Minkowski space, this process is forbidden by conservation laws. The total probability of the process and the mean number of Dirac particles produced as the result of photon decay are calculated and analyzed as functions of the primary-photon energy. The expressions obtained in this study are compared with the results of calculation of photon emission from the vacuum. The massless limit of the total probability of the process is considered. Numerical estimates are obtained for the mean number of particles produced in photon decays in the early universe. These estimates show that the production of Dirac particles in photon decays dominates over their production in photon emission from the vacuum and over their production from the vacuum of a free spinor field. 21 refs., 2 figs.

  9. Use of ESI-FTICR-MS to Characterize Dissolved Organic Matter in Headwater Streams Draining Forest-Dominated and Pasture-Dominated Watersheds

    PubMed Central

    Lu, YueHan; Li, Xiaping; Mesfioui, Rajaa; Bauer, James E.; Chambers, R. M.; Canuel, Elizabeth A.; Hatcher, Patrick G.

    2015-01-01

    Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) has proven to be a powerful technique revealing complexity and diversity of natural DOM molecules, but its application to DOM analysis in grazing-impacted agricultural systems remains scarce. In the present study, we presented a case study of using ESI-FTICR-MS in analyzing DOM from four headwater streams draining forest- or pasture-dominated watersheds in Virginia, USA. In all samples, most formulas were CHO compounds (71.8–87.9%), with other molecular series (CHOS, CHON, CHONS, and CHOP (N, S)) accounting for only minor fractions. All samples were dominated by molecules falling in the lignin-like region (H/C = 0.7–1.5, O/C = 0.1–0.67), suggesting the predominance of allochthonous, terrestrial plant-derived DOM. Relative to the two pasture streams, DOM formulas in the two forest streams were more similar, based on Jaccard similarity coefficients and nonmetric multidimensional scaling calculated from Bray-Curtis distance. Formulas from the pasture streams were characterized by lower proportions of aromatic formulas and lower unsaturation, suggesting that the allochthonous versus autochthonous contributions of organic matter to streams were modified by pasture land use. The number of condensed aromatic structures (CAS) was higher for the forest streams, which is possibly due to the controlled burning in the forest-dominated watersheds and suggests that black carbon was mobilized from soils to streams. During 15-day biodegradation experiments, DOM from the two pasture streams was altered to a greater extent than DOM from the forest streams, with formulas with H/C and O/C ranges similar to protein (H/C = 1.5–2.2, O/C = 0.3–0.67), lipid (H/C = 1.5–2.0, O/C = 0–0.3), and unsaturated hydrocarbon (H/C = 0.7–1.5, O/C = 0–0.1) being the most bioreactive groups. Aromatic compound formulas including CAS were preferentially removed during combined light

  10. The measure matters: Language dominance profiles across measures in Spanish-English bilingual children.

    PubMed

    Bedore, Lisa M; Peña, Elizabeth D; Summers, Connie L; Boerger, Karin M; Resendiz, Maria D; Greene, Kai; Bohman, Thomas M; Gillam, Ronald B

    2012-07-01

    The purpose of this study was to determine if different language measures resulted in the same classifications of language dominance and proficiency for a group of bilingual pre-kindergarteners and kindergarteners. Data were analyzed for 1029 Spanish-English bilingual pre-kindergarteners who spanned the full range of bilingual language proficiency. Parent questionnaires were used to quantify age of first exposure and current language use. Scores from a short test of semantic and morphosyntactic development in Spanish and English were used to quantify children's performance. Some children who were in the functionally monolingual range based on interview data demonstrated minimal knowledge of their other languages when tested. Current use accounted for more of the variance in language dominance than did age of first exposure. Results indicate that at different levels of language exposure children differed in their performance on semantic and morphosyntax tasks. These patterns suggest that it may be difficult to compare the results of studies that employ different measures of language dominance and proficiency. Current use is likely to be a useful metric of bilingual development that can be used to build a comprehensive picture of child bilingualism.

  11. Mothers matter! Maternal support, dominance status and mating success in male bonobos (Pan paniscus).

    PubMed

    Surbeck, Martin; Mundry, Roger; Hohmann, Gottfried

    2011-02-22

    Variation in male mating success is often related to rank differences. Males who are unable to monopolize oestrous females alone may engage in coalitions, thus enhancing their mating success. While studies on chimpanzees and dolphins suggest that coalitions are independent of kinship, information from female philopatric species shows the importance of kin support, especially from mothers, on the reproductive success of females. Therefore, one might expect a similar effect on sons in male philopatric species. We evaluate mating success determinants in male bonobos using data from nine male individuals from a wild population. Results reveal a steep, linear male dominance hierarchy and a positive correlation between dominance status and mating success. In addition to rank, the presence of mothers enhances the mating success of sons and reduces the proportion of matings by the highest ranking male. Mothers and sons have high association rates and mothers provide agonistic aid to sons in conflicts with other males. As bonobos are male-philopatric and adult females occupy high dominance status, maternal support extends into adulthood and females have the leverage to intervene in male conflicts. The absence of female support to unrelated males suggests that mothers gain indirect fitness benefits by supporting their sons.

  12. Mothers matter! Maternal support, dominance status and mating success in male bonobos (Pan paniscus)

    PubMed Central

    Surbeck, Martin; Mundry, Roger; Hohmann, Gottfried

    2011-01-01

    Variation in male mating success is often related to rank differences. Males who are unable to monopolize oestrous females alone may engage in coalitions, thus enhancing their mating success. While studies on chimpanzees and dolphins suggest that coalitions are independent of kinship, information from female philopatric species shows the importance of kin support, especially from mothers, on the reproductive success of females. Therefore, one might expect a similar effect on sons in male philopatric species. We evaluate mating success determinants in male bonobos using data from nine male individuals from a wild population. Results reveal a steep, linear male dominance hierarchy and a positive correlation between dominance status and mating success. In addition to rank, the presence of mothers enhances the mating success of sons and reduces the proportion of matings by the highest ranking male. Mothers and sons have high association rates and mothers provide agonistic aid to sons in conflicts with other males. As bonobos are male-philopatric and adult females occupy high dominance status, maternal support extends into adulthood and females have the leverage to intervene in male conflicts. The absence of female support to unrelated males suggests that mothers gain indirect fitness benefits by supporting their sons. PMID:20810444

  13. The measure matters: Language dominance profiles across measures in Spanish–English bilingual children*

    PubMed Central

    BEDORE, LISA M.; PEÑA, ELIZABETH D.; SUMMERS, CONNIE L.; BOERGER, KARIN M.; RESENDIZ, MARIA D.; GREENE, KAI; BOHMAN, THOMAS M.; GILLAM, RONALD B.

    2013-01-01

    The purpose of this study was to determine if different language measures resulted in the same classifications of language dominance and proficiency for a group of bilingual pre-kindergarteners and kindergarteners. Data were analyzed for 1029 Spanish–English bilingual pre-kindergarteners who spanned the full range of bilingual language proficiency. Parent questionnaires were used to quantify age of first exposure and current language use. Scores from a short test of semantic and morphosyntactic development in Spanish and English were used to quantify children’s performance. Some children who were in the functionally monolingual range based on interview data demonstrated minimal knowledge of their other languages when tested. Current use accounted for more of the variance in language dominance than did age of first exposure. Results indicate that at different levels of language exposure children differed in their performance on semantic and morphosyntax tasks. These patterns suggest that it may be difficult to compare the results of studies that employ different measures of language dominance and proficiency. Current use is likely to be a useful metric of bilingual development that can be used to build a comprehensive picture of child bilingualism. PMID:23565049

  14. Directional detection of dark matter in universal bound states

    SciTech Connect

    Laha, Ranjan

    2015-10-06

    It has been suggested that several small-scale structure anomalies in Λ CDM cosmology can be solved by strong self-interaction between dark matter particles. It was shown in Ref. [1] that the presence of a near threshold S-wave resonance can make the scattering cross section at nonrelativistic speeds come close to saturating the unitarity bound. This can result in the formation of a stable bound state of two asymmetric dark matter particles (which we call darkonium). Ref. [2] studied the nuclear recoil energy spectrum in dark matter direct detection experiments due to this incident bound state. Here we study the angular recoil spectrum, and show that it is uniquely determined up to normalization by the S-wave scattering length. Furthermore, observing this angular recoil spectrum in a dark matter directional detection experiment will uniquely determine many of the low-energy properties of dark matter independent of the underlying dark matter microphysics.

  15. Shape matters: Near-field fluid mechanics dominate the collective motions of ellipsoidal squirmers.

    PubMed

    Kyoya, K; Matsunaga, D; Imai, Y; Omori, T; Ishikawa, T

    2015-12-01

    Microswimmers show a variety of collective motions. Despite extensive study, questions remain regarding the role of near-field fluid mechanics in collective motion. In this paper, we describe precisely the Stokes flow around hydrodynamically interacting ellipsoidal squirmers in a monolayer suspension. The results showed that various collective motions, such as ordering, aggregation, and whirls, are dominated by the swimming mode and the aspect ratio. The collective motions are mainly induced by near-field fluid mechanics, despite Stokes flow propagation over a long range. These results emphasize the importance of particle shape in collective motion.

  16. Laser-matter interaction in cluster medium in the radiation dominated regime

    NASA Astrophysics Data System (ADS)

    Iwata, N.; Kishimoto, Y.; Wu, F.; Fukuda, Y.

    2016-03-01

    We study the interaction between laser and cluster medium in high intensity regime 1022-24 W/cm2 using a particle based integral code (EPIC3D). By introducing four targets consisting of the same mass, i.e. same packing fraction, but having different internal structure, we investigate the effect of cluster on the acceleration dynamics comparing with that of thin film. In the radiation pressure dominated regime, the cluster medium exhibits a higher maximum energy than that achieved by the simple piston mechanism due to the additional accerelation by the Coulomb explosion. The optimum cluster radius for ion acceleration is found to exist depending on the laser power irradiated.

  17. Drought-induced variability in dissolved organic matter composition in a marsh-dominated estuary

    NASA Astrophysics Data System (ADS)

    Medeiros, Patricia M.; Seidel, Michael; Dittmar, Thorsten; Whitman, William B.; Moran, Mary Ann

    2015-08-01

    The composition of dissolved organic matter (DOM) in an estuary characterized by extensive salt marsh vegetation was investigated at the molecular level using ultrahigh-resolution mass spectrometry and stable carbon isotope analyses. Samples from multiple seasons covered different hydrological regimes, including anomalously low-discharge conditions. The untargeted approach used allowed for identifying the DOM molecular signatures associated with different DOM sources in the estuary. DOM composition was strongly modulated by river discharge at monthly scales, with high river flow leading to significant increases in the terrigenous signature of the DOM throughout the estuary. During a severe/exceptional drought, estuarine DOM was imprinted with a distinct signature of marsh-derived compounds. The frequency of occurrence of anomalously low-discharge conditions seems to have increased over the last decades. If predictions of anthropogenically driven changes in hydroclimate are confirmed, they will likely be accompanied by changes in DOM composition in estuaries at multidecadal time scales.

  18. Relic abundance of dark matter in universal extra dimension models with right-handed neutrinos

    SciTech Connect

    Matsumoto, Shigeki; Sato, Joe; Yamanaka, Masato; Senami, Masato

    2009-04-17

    Relic abundance of dark matter is investigated in the framework of universal extra dimension models with right-handed neutrinos. These models are free from the serious Kaluza-Klein (KK) graviton problem that the original universal extra dimension model possesses. The first KK particle of the right-handed neutrino is a candidate for dark matter in this framework. When ordinary neutrino masses are large enough such as the degenerate mass spectrum case, the dark matter relic abundance can change significantly. The scale of the extra dimension consistent with cosmological observations can be 500 GeV in the minimal setup of universal extra dimension models with right-handed neutrinos.

  19. Fluorescence tracking of dissolved and particulate organic matter quality in a river-dominated estuary.

    PubMed

    Osburn, Christopher L; Handsel, Lauren T; Mikan, Molly P; Paerl, Hans W; Montgomery, Michael T

    2012-08-21

    Excitation-emission matrix (EEM) fluorescence was combined with parallel factor analysis (PARAFAC) to model base-extracted particulate (POM) and dissolved (DOM) organic matter quality in the Neuse River Estuary (NRE), North Carolina, before and after passage of Hurricane Irene in August 2011. Principle components analysis was used to determine that four of the PARAFAC components (C1-C3 and C6) were terrestrial sources to the NRE. One component (C4), prevalent in DOM of nutrient-impacted streams and estuaries and produced in phytoplankton cultures, was enriched in the POM and in surface sediment pore water DOM. One component (C5) was related to recent autochthonous production. Photoexposure of unfiltered Neuse River water caused an increase in slope ratio values (S(R)) which corresponded to an increase in the ratio C2:C3 for DOM, and the production of C4 fluorescence in both POM and DOM. Changes to the relative abundance of C4 in POM and DOM indicated that advection of pore water DOM from surface sediments into overlying waters could increase the autochthonous quality of DOM in shallow microtidal estuaries. Modeling POM and DOM simultaneously with PARAFAC is an informative technique that is applicable to assessments of estuarine water quality.

  20. Galaxy clusters and cold dark matter - A low-density unbiased universe?

    NASA Technical Reports Server (NTRS)

    Bahcall, Neta A.; Cen, Renyue

    1992-01-01

    Large-scale simulations of a universe dominated by cold dark matter (CDM) are tested against two fundamental properties of clusters of galaxies: the cluster mass function and the cluster correlation function. We find that standard biased CDM models are inconsistent with these observations for any bias parameter b. A low-density, low-bias CDM-type model, with or without a cosmological constant, appears to be consistent with both the cluster mass function and the cluster correlations. The low-density model agrees well with the observed correlation function of the Abell, Automatic Plate Measuring Facility (APM), and Edinburgh-Durham cluster catalogs. The model is in excellent agreement with the observed dependence of the correlation strength on cluster mean separation, reproducing the measured universal dimensionless cluster correlation. The low-density model is also consistent with other large-scale structure observations, including the APM angular galaxy-correlations, and for lambda = 1-Omega with the COBE results of the microwave background radiation fluctuations.

  1. Coexistence of matter dominated and accelerating solutions in f(G) gravity

    SciTech Connect

    Goheer, Naureen; Goswami, Rituparno; Ananda, Kishore; Dunsby, Peter K. S.

    2009-06-15

    Working within the theory of modified Gauss-Bonnet gravity, we show that Friedmann-Lemaitre-Robertson-Walker-like power-law solutions only exist for a very special class of f(G) theories. Furthermore, we point out that any transition from decelerated to accelerated expansion must pass through G=0, and no function f(G) that is differentiable at this point can admit both a decelerating power-law solution and any accelerating solution. This strongly constrains the cosmological viability of f(G) gravity, since it may not be possible to obtain an expansion history of the Universe which is compatible with observations. We explain why the same issue does not occur in f(R) gravity and discuss possible caveats for the case of f(G) gravity.

  2. Dissolved organic matter composition and biodegradability in a permafrost-dominated watershed network in central Siberia

    NASA Astrophysics Data System (ADS)

    Coble, A. A.; Rodriguez-Cardona, B.; Wymore, A.; Prokishkin, A. S.; Kolosov, R.; McDowell, W. H.

    2016-12-01

    Thawing permafrost soils can mobilize large quantities of dissolved organic matter (DOM) from soils to headwater streams, and DOM may undergo rapid transformations in streams and rivers in transit to the Arctic Ocean. With climate change an increased frequency of fire is also expected, which will further alter the DOM entering streams, and may contribute to changes in its biodegradability. Elucidating how DOM composition varies across a fire gradient within a river network underlain by continuous permafrost will therefore improve our understanding of the impact of climate change on Arctic ecosystems and its role in the global carbon cycle. To determine DOM composition we measured optical properties via excitation-emission matrices (EEMs) and subsequent parallel factor analysis across a spatially extensive collection of sites in central Siberia. Within a subset of streams in the Nizhnyaya Tunguska watershed network, we also measured biodegradable dissolved organic carbon (BDOC) incubated at in situ temperatures over a 7 day period during spring freshet on two dates in early June. Despite clear changes in optical properties of DOM and background DOC concentration along the fire gradient (range: 3 to >100 y since burn) BDOC did not vary systematically with years since fire for either incubation date. In the first incubation conducted near peak flow BDOC ranged from negligible to 7.6% (BDOC concentration = negligible to 1.4 mg C L-1) within a 7 day period. In the second incubation conducted 5 days later BDOC was negligible across all sites (as both a percentage and a concentration). Our results suggest that DOC exported from permafrost soils in the central Siberian plateau is relatively unreactive at in situ temperatures over 7 day time scales, which contrasts with previous studies conducted in watersheds underlain with Yedoma outcrops where biodegradability comprises a large fraction of DOC. Our preliminary results suggest that melting of permafrost soils in central

  3. Directional detection of dark matter in universal bound states

    DOE PAGES

    Laha, Ranjan

    2015-10-06

    It has been suggested that several small-scale structure anomalies in Λ CDM cosmology can be solved by strong self-interaction between dark matter particles. It was shown in Ref. [1] that the presence of a near threshold S-wave resonance can make the scattering cross section at nonrelativistic speeds come close to saturating the unitarity bound. This can result in the formation of a stable bound state of two asymmetric dark matter particles (which we call darkonium). Ref. [2] studied the nuclear recoil energy spectrum in dark matter direct detection experiments due to this incident bound state. Here we study the angularmore » recoil spectrum, and show that it is uniquely determined up to normalization by the S-wave scattering length. Furthermore, observing this angular recoil spectrum in a dark matter directional detection experiment will uniquely determine many of the low-energy properties of dark matter independent of the underlying dark matter microphysics.« less

  4. White Matter Abnormalities Track Disease Progression in PSEN1 Autosomal Dominant Alzheimer's Disease.

    PubMed

    Sánchez-Valle, Raquel; Monté, Gemma C; Sala-Llonch, Roser; Bosch, Beatriz; Fortea, Juan; Lladó, Albert; Antonell, Anna; Balasa, Mircea; Bargalló, Nuria; Molinuevo, José Luis

    2016-01-01

    PSEN1 mutations are the most frequent cause of autosomal dominant Alzheimer's disease (ADAD), and show nearly full penetrance. There is presently increasing interest in the study of biomarkers that track disease progression in order to test therapeutic interventions in ADAD. We used white mater (WM) volumetric characteristics and diffusion tensor imaging (DTI) metrics to investigate correlations with the normalized time to expected symptoms onset (relative age ratio) and group differences in a cohort of 36 subjects from PSEN1 ADAD families: 22 mutation carriers, 10 symptomatic (SMC) and 12 asymptomatic (AMC), and 14 non-carriers (NC). Subjects underwent a 3T MRI. WM morphometric data and DTI metrics were analyzed. We found that PSEN1 MC showed significant negative correlation between fractional anisotropy (FA) and the relative age ratio in the genus and body of corpus callosum and corona radiate (p <  0.05 Family-wise error correction (FWE) at cluster level) and positive correlation with mean diffusivity (MD), axial diffusivity (AxD), and radial diffusivity (RD) in the splenium of corpus callosum. SMC presented WM volume loss, reduced FA and increased MD, AxD, and RD in the anterior and posterior corona radiate, corpus callosum (p <  0.05 FWE) compared with NC. No significant differences were observed between AMC and NC in WM volume or DTI measures. These findings suggest that the integrity of the WM deteriorates linearly in PSEN1 ADAD from the early phases of the disease; thus DTI metrics might be useful to monitor the disease progression. However, the lack of significant alterations at the preclinical stages suggests that these indexes might not be good candidates for early markers of the disease.

  5. Fine organic particulate matter dominates indoor-generated PM2.5 in RIOPA homes.

    PubMed

    Polidori, Andrea; Turpin, Barbara; Meng, Qing Yu; Lee, Jong Hoon; Weisel, Clifford; Morandi, Maria; Colome, Steven; Stock, Thomas; Winer, Arthur; Zhang, Jim; Kwon, Jaymin; Alimokhtari, Shahnaz; Shendell, Derek; Jones, Jennifer; Farrar, Corice; Maberti, Silvia

    2006-07-01

    Residential indoor and outdoor fine particle (PM(2.5)) organic (OC) and elemental carbon (EC) concentrations (48 h) were measured at 173 homes in Houston, TX, Los Angeles County, CA, and Elizabeth, NJ as part of the Relationship of Indoor, Outdoor and Personal Air (RIOPA) study. The adsorption of organic vapors on the quartz fiber sampling filter (a positive artifact) was substantial indoors and out, accounting for 36% and 37% of measured OC at the median indoor (8.2 microg C/m(3)) and outdoor (5.0 microg C/m(3)) OC concentrations, respectively. Uncorrected, adsorption artifacts would lead to substantial overestimation of particulate OC both indoors and outdoors. After artifact correction, the mean particulate organic matter (OM=1.4 OC) concentration indoors (9.8 microg/m(3)) was twice the mean outdoor concentration (4.9 microg/m(3)). The mean EC concentration was 1.1 microg/m(3) both indoors and outdoors. OM accounted for 29%, 30% and 29% of PM(2.5) mass outdoors and 48%, 55% and 61% of indoor PM(2.5) mass in Los Angeles Co., Elizabeth and Houston study homes, respectively. Indirect evidence provided by species mass balance results suggests that PM(2.5) nitrate (not measured) was largely lost during outdoor-to-indoor transport, as reported by Lunden et al. This results in dramatic changes with outdoor-to-indoor transport in the mass and composition of ambient-generated PM(2.5) at California homes. On average, 71% to 76% of indoor OM was emitted or formed indoors, calculated by (1) Random Component Superposition (RCS) model and (2) non-linear fit of OC and air exchange rate data to the mass balance model. Assuming that all particles penetrate indoors (P=1) and there is no particle loss indoors (k=0), a lower bound estimate of 41% of indoor OM was indoor-generated (mean). OM appears to be the predominant species in indoor-generated PM(2.5), based on species mass balance results. Particulate OM emitted or formed indoors is substantial enough to alter the

  6. Probing bulk viscous matter-dominated models with gamma-ray bursts

    SciTech Connect

    Montiel, A.; Bretón, N. E-mail: nora@fis.cinvestav.mx

    2011-08-01

    In this paper we extend the range of consistency of a constant bulk viscosity model to redshifts up to z ∼ 8.1. In this model the dark sector of the cosmic substratum is a viscous fluid with pressure p = −ζθ, where θ is the fluid-expansion scalar and ζ is the coefficient of bulk viscosity. Using the sample of 59 high-redshift GRBs reported by Wei (2010), we calibrate GRBs at low redshifts with the Union 2 sample of SNe Ia, thus avoiding the circularity problem. Testing the constant bulk viscosity model with GRBs we found the best fit for the viscosity parameter ζ-tilde in the range 0 < ζ-tilde < 3, so that it be consistent with previous probes; we also determined the deceleration parameter q{sub 0} and the redshift of transition to accelerated expansion. Besides, we present an updated analysis of the model with CMB5-year data and CMB7-year data, as well as with the baryon acoustic peak BAO. From the statistics with CMB it turns out that the model does not describe in a feasible way to such a far epoch of recombination of the universe, but is in very good concordance for epochs as far as z ∼ 8.1 till present.

  7. CP violation and the matter-antimatter asymmetry of the Universe

    NASA Astrophysics Data System (ADS)

    Hambye, Thomas

    2012-03-01

    In our everyday environment one observes only matter. That's quite a fortunate situation! Any sizeable presence of antimatter on Earth, from the enormous energy it would release through annihilation with matter, would prevent us talking about it! For the physicist this fact, at first sight obvious, is nevertheless a kind of surprise: antimatter, which is observed in cosmic rays, in radioactive decays of nuclei, which has been copiously produced and extensively studied in accelerators and which is nowadays currently used in hospitals, turns out to have pretty much the same properties as matter. Moreover, the fact that matter dominates appears to be a general property of our Universe: no evidence of large quantities of antimatter has been observed at any distance from us. Why would matter have taken the advantage on antimatter? In this short review we explain how, through a limited number of basic elements, one can find answers to this question. Matter and antimatter have, in fact, not exactly the same properties: from laboratory experiments CP conservation is known not to be a fundamental law of nature. Dans notre vie de tous les jours nous n'appréhendons que de la matière et rien ne nous indique à première vue qu'il puisse exister de l'antimatière. Bienheureux sommes nous ! La présence d'une quelconque quantité macroscopique d'antimatière autour de nous, par l'énergie qu'elle dégagerait en s'annihilant avec la matière, nous empêcherait d'être là pour en parler ! Cet état de chose est cependant une surprise pour le physicien : l'antimatière qui est aujourd'hui bien connue — étant observée et utilisée tous les jours dans les rayons cosmiques, les processus radioactifs, les accélérateurs de particules et les hôpitaux — a des propriétés très similaires à celles de la matière. De plus le fait que la matière domine apparaît être une caractéristique générale de notre univers : aucune trace d'une grande quantité d'antimatière n'a

  8. [Mixed transcortical aphasia due to multiple deep white matter infarction in the dominant cerebral hemisphere: a case report].

    PubMed

    Sato, K; Sakajiri, K; Komai, K; Yoshikawa, H; Takamori, M; Notoya, M

    1997-08-01

    We report a case of mixed transcortical aphasia (MTA) due to multiple cerebral infarction in the dominant hemisphere in an 80-year-old right-handed woman without hemiplegia. Her spontaneous speech was markedly reduced and auditory comprehension, reading and writing were severely disturbed. Although the repetition of sentences (at most 3 words) was relatively preserved, her speech was echolalic. Brain MRI showed bilateral multiple deep white matter infarction and subcortical infarction of the left parietal lobe, including left angular gyrus, but no abnormal signal intensities were detected in either Wernicke's or Broca's area. SPECT indicated a significant decrease in mean cerebral blood flow in both hemispheres, but there was no focal hypoperfusion in either speech area. We thought that the focal hypoperfusion observed in the right cerebellum indicated crossed cerebellar diaschisis. Electroencephalogram showed a diffuse reduction in the incidence of alpha waves in the left cerebral hemisphere. From these findings, we suggest that widespread hypofunction in the dominant hemisphere was important for the occurrence of MTA.

  9. VARIATIONS IN A UNIVERSAL DARK MATTER PROFILE FOR DWARF SPHEROIDALS

    SciTech Connect

    Jardel, John R.; Gebhardt, Karl

    2013-09-20

    Using a newly developed modeling technique, we present orbit-based dynamical models of the Carina, Draco, Fornax, Sculptor, and Sextans dwarf spheroidal (dSph) galaxies. These models calculate the dark matter profiles non-parametrically without requiring any assumptions to be made about their profile shapes. By lifting this restriction, we discover a host of dark matter profiles in the dSphs that are different from the typical profiles suggested by both theorists and observers. However, when we scale these profiles appropriately and plot them on a common axis, they appear to follow an approximate r {sup –1} power law with considerable scatter.

  10. Variations in a Universal Dark Matter Profile for Dwarf Spheroidals

    NASA Astrophysics Data System (ADS)

    Jardel, John R.; Gebhardt, Karl

    2013-09-01

    Using a newly developed modeling technique, we present orbit-based dynamical models of the Carina, Draco, Fornax, Sculptor, and Sextans dwarf spheroidal (dSph) galaxies. These models calculate the dark matter profiles non-parametrically without requiring any assumptions to be made about their profile shapes. By lifting this restriction, we discover a host of dark matter profiles in the dSphs that are different from the typical profiles suggested by both theorists and observers. However, when we scale these profiles appropriately and plot them on a common axis, they appear to follow an approximate r -1 power law with considerable scatter.

  11. Teaching Criteria That Matter in University Academic Promotions

    ERIC Educational Resources Information Center

    Subbaye, Reshma; Vithal, Renuka

    2017-01-01

    While many universities have taken steps to recognise teaching in academic promotions, debate continues on the teaching criteria to be used and their evaluation. This article analyses the 10 criteria that inform the evaluation of teaching and eventual promotion decisions at a South African university: rationale for teaching, teaching methods,…

  12. Nevada Takes Personnel Matters Public with a University President's Dismissal

    ERIC Educational Resources Information Center

    Killough, Ashley C.

    2009-01-01

    In a daylong meeting broadcast online this month, David B. Ashley, the president of the University of Nevada at Las Vegas, was repeatedly grilled, and then publicly demoted, during a contentious gathering of the university system's Board of Regents. The dressing-down followed months of public disputes over the conduct of Mr. Ashley's wife and…

  13. University Rankings: Do They Matter in the UK?

    ERIC Educational Resources Information Center

    Broecke, Stijn

    2015-01-01

    This paper offers the first comprehensive analysis of the effect of changes in university rankings on applicant and institution behaviour in the UK. When their rank worsens, universities are found to experience small but statistically significant reductions in the number of applications received as well as in the average tariff score of applicants…

  14. Teaching Criteria That Matter in University Academic Promotions

    ERIC Educational Resources Information Center

    Subbaye, Reshma; Vithal, Renuka

    2017-01-01

    While many universities have taken steps to recognise teaching in academic promotions, debate continues on the teaching criteria to be used and their evaluation. This article analyses the 10 criteria that inform the evaluation of teaching and eventual promotion decisions at a South African university: rationale for teaching, teaching methods,…

  15. On the universality of Einstein(-Cartan) field equations in the presence of matter fields

    NASA Astrophysics Data System (ADS)

    Rubilar, Guillermo F.

    1998-01-01

    Within the context of gravity formulated as a gauge theory of the Lorentz group, we derive the field equations for a gravitational action consisting of a generic analytic function of the curvature scalar, in the presence of general matter fields. In the vacuum case we obtain universal equations in agreement with Ferraris et al. We also show explicit non-trivial examples of universal behaviour in the presence of matter fields, which in the general case produces a non-zero torsion field, leading to an Einstein-Cartan geometry and universal Einstein-Cartan field equations.

  16. White matter hyperintensities are a core feature of Alzheimer's disease: Evidence from the dominantly inherited Alzheimer network.

    PubMed

    Lee, Seonjoo; Viqar, Fawad; Zimmerman, Molly E; Narkhede, Atul; Tosto, Giuseppe; Benzinger, Tammie L S; Marcus, Daniel S; Fagan, Anne M; Goate, Alison; Fox, Nick C; Cairns, Nigel J; Holtzman, David M; Buckles, Virginia; Ghetti, Bernardino; McDade, Eric; Martins, Ralph N; Saykin, Andrew J; Masters, Colin L; Ringman, John M; Ryan, Natalie S; Förster, Stefan; Laske, Christoph; Schofield, Peter R; Sperling, Reisa A; Salloway, Stephen; Correia, Stephen; Jack, Clifford; Weiner, Michael; Bateman, Randall J; Morris, John C; Mayeux, Richard; Brickman, Adam M

    2016-06-01

    White matter hyperintensities (WMHs) are areas of increased signal on T2-weighted magnetic resonance imaging (MRI) scans that most commonly reflect small vessel cerebrovascular disease. Increased WMH volume is associated with risk and progression of Alzheimer's disease (AD). These observations are typically interpreted as evidence that vascular abnormalities play an additive, independent role contributing to symptom presentation, but not core features of AD. We examined the severity and distribution of WMH in presymptomatic PSEN1, PSEN2, and APP mutation carriers to determine the extent to which WMH manifest in individuals genetically determined to develop AD. The study comprised participants (n = 299; age = 39.03 ± 10.13) from the Dominantly Inherited Alzheimer Network, including 184 (61.5%) with a mutation that results in AD and 115 (38.5%) first-degree relatives who were noncarrier controls. We calculated the estimated years from expected symptom onset (EYO) by subtracting the affected parent's symptom onset age from the participant's age. Baseline MRI data were analyzed for total and regional WMH. Mixed-effects piece-wise linear regression was used to examine WMH differences between carriers and noncarriers with respect to EYO. Mutation carriers had greater total WMH volumes, which appeared to increase approximately 6 years before expected symptom onset. Effects were most prominent for the parietal and occipital lobe, which showed divergent effects as early as 22 years before estimated onset. Autosomal-dominant AD is associated with increased WMH well before expected symptom onset. The findings suggest the possibility that WMHs are a core feature of AD, a potential therapeutic target, and a factor that should be integrated into pathogenic models of the disease. Ann Neurol 2016;79:929-939. © 2016 American Neurological Association.

  17. White matter hyperintensities are a core feature of Alzheimer’s disease: Evidence from the Dominantly Inherited Alzheimer Network

    PubMed Central

    Lee, Seonjoo; Viqar, Fawad; Zimmerman, Molly E.; Narkhede, Atul; Tosto, Giuseppe; Benzinger, Tammie L.S.; Marcus, Daniel S.; Fagan, Anne M.; Goate, Alison; Fox, Nick C.; Cairns, Nigel J.; Holtzman, David M.; Buckles, Virginia; Ghetti, Bernardino; McDade, Eric; Martins, Ralph N.; Saykin, Andrew J.; Masters, Colin L.; Ringman, John M.; Ryan, Natalie S.; Förster, Stefan; Laske, Christoph; Schofield, Peter R.; Sperling, Reisa A.; Salloway, Stephen; Correia, Stephen; Jack, Clifford; Weiner, Michael; Bateman, Randall J.; Morris, John C.; Mayeux, Richard; Brickman, Adam M.

    2016-01-01

    Objective White matter hyperintensities(WMH) are areas of increased signal on magnetic resonance imaging(MRI) scans that most commonly reflect small vessel cerebrovascular disease. Increased WMH volume is associated with risk and progression of Alzheimer’s disease(AD). These observations are typically interpreted as evidence that vascular abnormalities play an additive, independent role contributing to symptom presentation, but not core features of AD. We examined the severity and distribution of WMH in presymptomatic PSEN1, PSEN2, and APP mutation carriers to determine the extent to which WMH manifest in individuals genetically-determined to develop AD. Methods The study comprised participants(n=299, age=39.03±10.13) from the Dominantly Inherited Alzheimer Network, including 184(61.5%) with a mutation that results in AD and 115(38.5%) first-degree relatives who were non-carrier controls. We calculated the estimated years from expected symptom onset(EYO) by subtracting the affected parent’s symptom onset age from the participant’s age. Baseline MRI data were analyzed for total and regional WMH. Mixed effects piecewise linear regression was used to examine WMH differences between carriers and non-carriers with respect to EYO. Results Mutation carriers had greater total WMH volumes, which appeared to increase approximately 6 years prior to expected symptom onset. The effects were most prominent for the parietal and occipital lobe, which showed divergent effects as early as 22 years prior to estimated onset. Interpretation Autosomal dominant AD is associated with increased WMH well before expected symptom onset. The findings suggest the possibility that WMH are a core feature of AD, a potential therapeutic target, and a factor that should be integrated into pathogenic models of the disease. PMID:27016429

  18. Mass discrepancy-acceleration relation: A universal maximum dark matter acceleration and implications for the ultralight scalar dark matter model

    NASA Astrophysics Data System (ADS)

    Ureña-López, L. Arturo; Robles, Victor H.; Matos, T.

    2017-08-01

    Recent analysis of the rotation curves of a large sample of galaxies with very diverse stellar properties reveals a relation between the radial acceleration purely due to the baryonic matter and the one inferred directly from the observed rotation curves. Assuming the dark matter (DM) exists, this acceleration relation is tantamount to an acceleration relation between DM and baryons. This leads us to a universal maximum acceleration for all halos. Using the latter in DM profiles that predict inner cores implies that the central surface density μDM=ρsrs must be a universal constant, as suggested by previous studies of selected galaxies, revealing a strong correlation between the density ρs and scale rs parameters in each profile. We then explore the consequences of the constancy of μDM in the context of the ultralight scalar field dark matter model (SFDM). We find that for this model μDM=648 M⊙ pc-2 and that the so-called WaveDM soliton profile should be a universal feature of the DM halos. Comparing with the data from the Milky Way and Andromeda satellites, we find that they are all consistent with a boson mass of the scalar field particle of the order of 10-21 eV /c2, which puts the SFDM model in agreement with recent cosmological constraints.

  19. Influence of Matter Creation on the Early Universe Stability

    NASA Astrophysics Data System (ADS)

    Montani, Giovanni; Nescatelli, Nicola

    The effects of the particles creation processes on the evolution of a spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) universe are investigated. Our approach is involved in the context of open thermodynamics systems choosing a natural phenomenological ansatz for the particles creation rate. There are reasons to believe that this model gives a simple and appropriate description of the gravitational stability concerning the isotropic model for the Early Universe considered both on a small and large scale. The prelude of our study is that the consideration of the particles production processes are supposed to play an relevant role in the perturbation theory arising in the Early Universe dynamics. We show how perturbations damp forwards in time or remain constant (as in the Cosmological Standard Model) and, differently from the standard analysis, we find instability backward in time from an initial condition on scalar perturbation.

  20. Faculty Salary at Korean Universities: Does Publication Matter?

    ERIC Educational Resources Information Center

    Jin, Jang C.; Cho, Jeung R.

    2015-01-01

    This paper investigates empirically the role of research publications in an academic reward structure in Korea. Our sample includes 145 universities and colleges in Korea. Publication data for the academic year of 2012 show that top-tier research schools published more in international journals, while domestic journal publications were dominated…

  1. Using Learning Technology in University Courses: Do Styles Matter?

    ERIC Educational Resources Information Center

    Vigentini, Lorenzo

    2009-01-01

    Purpose: The purpose of this paper is to explore the relevance of three different types of styles measure for students' learning in a large introductory university course in psychology, using information technology to enhance teaching. The paper examines the relationship between styles, the usage of learning technology, and academic performance in…

  2. Galaxy formation in an Omega = 1 cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Bardeen, James M.

    1986-01-01

    A model for galaxy formation is proposed which assumes that bright galaxies form where the primordial density fluctuations exceed a high threshold. Most of the mass in the universe is uncondensed or associated with low surface brightness galaxies. Physical mechanisms and predicitons for the galaxy-galaxy correlation function are discussed.

  3. Faculty Salary at Korean Universities: Does Publication Matter?

    ERIC Educational Resources Information Center

    Jin, Jang C.; Cho, Jeung R.

    2015-01-01

    This paper investigates empirically the role of research publications in an academic reward structure in Korea. Our sample includes 145 universities and colleges in Korea. Publication data for the academic year of 2012 show that top-tier research schools published more in international journals, while domestic journal publications were dominated…

  4. Using Learning Technology in University Courses: Do Styles Matter?

    ERIC Educational Resources Information Center

    Vigentini, Lorenzo

    2009-01-01

    Purpose: The purpose of this paper is to explore the relevance of three different types of styles measure for students' learning in a large introductory university course in psychology, using information technology to enhance teaching. The paper examines the relationship between styles, the usage of learning technology, and academic performance in…

  5. Galaxy formation in an Omega = 1 cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Bardeen, James M.

    1986-01-01

    A model for galaxy formation is proposed which assumes that bright galaxies form where the primordial density fluctuations exceed a high threshold. Most of the mass in the universe is uncondensed or associated with low surface brightness galaxies. Physical mechanisms and predicitons for the galaxy-galaxy correlation function are discussed.

  6. Does Gender Matter? University Library Access and Career Preparedness

    ERIC Educational Resources Information Center

    Smith, Daniella

    2015-01-01

    The purpose of this exploratory study was to examine how the gender of distance learning students related to variables such as the perception of the availability of library resources, technology available at home and work, technology provided by a university for distance learning, and career preparedness. A total of 166 master's students in the…

  7. Distribution, sources and biogeochemistry of organic matter in a mangrove dominated estuarine system (Indian Sundarbans) during the pre-monsoon

    NASA Astrophysics Data System (ADS)

    Ray, R.; Rixen, T.; Baum, A.; Malik, A.; Gleixner, G.; Jana, T. K.

    2015-12-01

    The sources and distribution of dissolved organic carbon (DOC), particulate organic carbon (POC) and dissolved inorganic carbon (DIC) in the Indian Sundarbans mangrove and Hooghly estuarine system were examined during the pre-monsoon (summer) 2014. DOC is the dominant form of organic matter (OM) in the studied estuarine waters and represents a mixture of mangrove and riverine sources. Microbial degradation of land derived OM results in a high pCO2 in the Hooghly estuarine waters while enrichment in δ13C-DIC ascribes to CO2 uptake by phytoplankton in the Sundarbans water. Higher δ15N in the particulate organic nitrogen (PON) of the mangrove and marine zone could be associated with enhanced phytoplankton production sustained by nitrate from mangrove derived OM decomposition and/or nitrate imported from the Bay of Bengal. Low organic carbon contents and elemental ratios (TN/TOC) indicate an intense mineralization and transformation of OM in the sediments, resulting insignificantly different OM compositions compared to those of the three major sources: land derived OM, mangrove leaf litter (Avicennia marina) and in situ phytoplankton production.

  8. Particle dark matter in the universe: at the brink of discovery?

    PubMed

    Sadoulet, Bernard

    2007-01-05

    The nature of dark matter is one of the central problems of cosmology, particle physics, and gravity. It may be made of still unknown particles produced in the early universe. Much progress has been made in attempts to detect these particles and in the development of the required experimental techniques. Results from direct searches, the Large Hadron Collider, and the Gamma-ray Large Area Space Telescope offer promising opportunities within the next decade to find the missing dark matter.

  9. Constraints on Universal Extra-Dimensional Dark Matter from Direct Detection Results

    NASA Astrophysics Data System (ADS)

    Torpin, Trevor; Duda, Gintaras

    2011-04-01

    Detection of dark matter is one of the most challenging and important problems in astro-particle physics. One theory that produces a viable particle dark matter candidate is Universal Extra Dimensions (UED), in which the existence of a 4th spatial dimension is theorized. The extra dimension is not seen because it is compactifed on a circular orbifold whose radius is too small to be observed with current technology. What separates this theory over other Kaluza-Klein-type theories is that UED allows all standard model particles and fields to propagate in the extra dimension. The dark matter candidate in UED theories is a stable particle known as the Lightest Kaluza-Klein Particle or LKP, and the LKP can exist with sufficient relic density to serve as the dark matter. This work will present bounds on UED model parameters from direct dark matter searches such as the CDMS II.

  10. Do baryons trace dark matter in the early universe?

    PubMed

    Grin, Daniel; Doré, Olivier; Kamionkowski, Marc

    2011-12-23

    Baryon-density perturbations of large amplitude may exist if they are compensated by dark-matter perturbations such that the total density is unchanged. Primordial abundances and galaxy clusters allow these compensated isocurvature perturbations (CIPs) to have amplitudes as large as ~10%. CIPs will modulate the power spectrum of cosmic microwave background (CMB) fluctuations--those due to the usual adiabatic perturbations--as a function of position on the sky. This leads to correlations between different spherical-harmonic coefficients of the temperature and/or polarization maps, and induces polarization B modes. Here, the magnitude of these effects is calculated and techniques to measure them are introduced. While a CIP of this amplitude can be probed on large scales with existing data, forthcoming CMB experiments should improve the sensitivity to CIPs by at least an order of magnitude.

  11. An Investigation on the Dominant Career Anchors of Faculty Members: The Case of Mersin University

    ERIC Educational Resources Information Center

    Unal, Burcu; Gizir, Sidika

    2014-01-01

    Due to social, economic, and political changes, as well as changing institutional priorities, the permeation of managerialism has impelled universities to redefine the roles and functions of its faculty members. Therefore, researchers from various disciplines have focused on the career choices and paths of such members. In this context, the…

  12. The Mira-Titan Universe. II. Matter Power Spectrum Emulation

    NASA Astrophysics Data System (ADS)

    Lawrence, Earl; Heitmann, Katrin; Kwan, Juliana; Upadhye, Amol; Bingham, Derek; Habib, Salman; Higdon, David; Pope, Adrian; Finkel, Hal; Frontiere, Nicholas

    2017-09-01

    We introduce a new cosmic emulator for the matter power spectrum covering eight cosmological parameters. Targeted at optical surveys, the emulator provides accurate predictions out to a wavenumber k∼ 5 Mpc‑1 and redshift z≤slant 2. In addition to covering the standard set of ΛCDM parameters, massive neutrinos and a dynamical dark energy of state are included. The emulator is built on a sample set of 36 cosmological models, carefully chosen to provide accurate predictions over the wide and large parameter space. For each model, we have performed a high-resolution simulation, augmented with 16 medium-resolution simulations and TimeRG perturbation theory results to provide accurate coverage over a wide k-range; the data set generated as part of this project is more than 1.2Pbytes. With the current set of simulated models, we achieve an accuracy of approximately 4%. Because the sampling approach used here has established convergence and error-control properties, follow-up results with more than a hundred cosmological models will soon achieve ∼ 1 % accuracy. We compare our approach with other prediction schemes that are based on halo model ideas and remapping approaches. The new emulator code is publicly available.

  13. Universe without dark energy: Cosmic acceleration from dark matter-baryon interactions

    NASA Astrophysics Data System (ADS)

    Berezhiani, Lasha; Khoury, Justin; Wang, Junpu

    2017-06-01

    Cosmic acceleration is widely believed to require either a source of negative pressure (i.e., dark energy), or a modification of gravity, which necessarily implies new degrees of freedom beyond those of Einstein gravity. In this paper we present a third possibility, using only dark matter (DM) and ordinary matter. The mechanism relies on the coupling between dark matter and ordinary matter through an effective metric. Dark matter couples to an Einstein-frame metric, and experiences a matter-dominated, decelerating cosmology up to the present time. Ordinary matter couples to an effective metric that depends also on the DM density, in such a way that it experiences late-time acceleration. Linear density perturbations are stable and propagate with arbitrarily small sound speed, at least in the case of "pressure" coupling. Assuming a simple parametrization of the effective metric, we show that our model can successfully match a set of basic cosmological observables, including luminosity distance, baryon acoustic oscillation measurements, angular-diameter distance to last scattering, etc. For the growth history of density perturbations, we find an intriguing connection between the growth factor and the Hubble constant. To get a growth history similar to the Λ CDM prediction, our model predicts a higher H0, closer to the value preferred by direct estimates. On the flip side, we tend to overpredict the growth of structures whenever H0 is comparable to the Planck preferred value. The model also tends to predict larger redshift-space distortions at low redshift than Λ CDM .

  14. Potential Rapid Effects on Soil Organic Matter Characteristics and Chemistry Following a Change in Dominant Litter Inputs

    NASA Astrophysics Data System (ADS)

    Crow, S. E.; Filley, T.; Conyers, G.; Stott, D.; McCormick, M.; Whigham, D.; Taylor, D.

    2006-12-01

    Changes in vegetation structure are expected in forests globally under predicted future climate scenarios. Shifts in type or quantity of litter inputs, which will be associated with changes in plant community, may influence soil organic matter (SOM) characteristics. We altered litter inputs in a mixed-deciduous forest at the Smithsonian Environmental Research Center beginning in May 2004: litter removal, leaf amendment, and wood amendment plots were established in three old (120-150 y) and three young (50-70 y) forests. Plots were amended with wood and leaves collected locally from the dominant tree species, tulip poplar (Lirodendron tulipifera). 0-5 cm A horizon soil was collected in November 2005, 18 months after initial treatment, and physically fractionated first by dispersal in HMP and size separation (53 μm) to remove silts and clays then the >53 μm fraction by density (1.4 g cm-3) in SPT to separate the organic debris (light fraction, LF) from the mineral material. Soil with the greatest amount of C present within the LF came from the wood amendment treatment (35.2 ± 0.1%), followed by the leaf amendment (27.7 ± 0.0%) and the litter removal (24.5 ± 0.0%) treatments. In a pattern opposite of the other treatments, leaf amended soil from the old sites had less C within LF than the young. Potentially, a priming effect from the leaf addition at the old sites resulted in increased decomposition of soil LF. While at the young sites, invasive earthworms potentially provided a rapid, direct mode for incorporation of fresh leaf inputs into LF. Preliminary data indicate differences in lignin and cutin/suberin decay rates during litter decomposition between old and young sites. An investigation into the biopolymer composition of LF will determine whether altering litter inputs will ultimately influence SOM dynamics at both the old and young forest sites.

  15. Simulation studies on matching of space-charge-dominated beams for the University of Maryland Electron Ring

    NASA Astrophysics Data System (ADS)

    Li, H.; Bernal, S.; Kishek, R. A.; Haber, I.; Zou, Y.; O'Shea, P. G.; Reiser, M.

    2004-02-01

    The physics of space-charge-dominated beams with very large tune shift has never been explored in existing machines. The University of Maryland Electron Ring (UMER), currently under construction, will study the nonlinear physics characteristics of intense space-charge-dominated beams on a scaled basis. The unique features of UMER challenge us to design the beam optics carefully. One of the most important issues is to match the beam from the electron gun through the injector into the ring lattice. This is the major topic of this paper. The physics background, matrix and linear envelope-code computations, and particle-in-cell simulations of beam transport over a long propagation distance in UMER are presented.

  16. Status Tracking and Reporting the Quality Matters Process at the University of North Georgia

    ERIC Educational Resources Information Center

    Lamson, Nina; Babb, David; Schmidt, Robert

    2016-01-01

    The University of North Georgia utilizes the internal Quality Matters (QM) process to review all their online courses. As our online course offerings have increased, the need to devise a system to track the QM process, ensure timely reviews, and begin recertification of previously reviewed courses was necessary. As a result, several reports have…

  17. Matter-antimatter separation in the early universe by rotating black holes

    NASA Technical Reports Server (NTRS)

    Leahy, D. A.

    1981-01-01

    Consideration of the effect of rotating black holes evaporating early in the universe shows that they would have produced oppositely directed neutrino and antineutrino currents, which push matter and antimatter apart. This separation mechanism is, however, too feeble to account for a present baryon-to-photon ratio of 10 to the -9th, and has no significant observational consequences.

  18. Status Tracking and Reporting the Quality Matters Process at the University of North Georgia

    ERIC Educational Resources Information Center

    Lamson, Nina; Babb, David; Schmidt, Robert

    2016-01-01

    The University of North Georgia utilizes the internal Quality Matters (QM) process to review all their online courses. As our online course offerings have increased, the need to devise a system to track the QM process, ensure timely reviews, and begin recertification of previously reviewed courses was necessary. As a result, several reports have…

  19. Universal soft matter template: from photonic to metamaterial applications

    NASA Astrophysics Data System (ADS)

    Umeton, Cesare; De Sio, Luciano; Caputo, Roberto; Ferjani, Sameh; Strangi, Giuseppe; Bartolino, Roberto

    2011-10-01

    We report on the realization and characterization of a polymeric template sculptured in photosensitive material, on a chemical inert surface. The structure is devoted to micro/nanoconfinement and stabilization of a wide range of organic and nano-particle components with selfarrangement properties at the nanoscale [1]. High quality morphology of a polymeric, micropatterned, array is obtained by combining a, nano-precision level, optical holographic setup and a multi-step chemico-physical process. The "universal" template represents the basic platform to be filled with different organic materials, which can also include metallic nano-particles. The long range self-organization is induced without making use of any kind of surface chemistry. Due to their capability of exhibiting self organization, light responsive Liquid Crystals (LC) [2] and short pitch Cholesterics LC [3] have been exploited, and experimental studies have been carried out in order to investigate the photo-optical and elecro-optical response of obtained composite structures for the realization of photonic devices. Finally, the possibility of including metallic nano-particles has been also investigated, with the aim of inducing a "metamaterial" behavior of the realized structure.

  20. Matter-Induced Neutrino Oscillation in Double Universal Seesaw Model

    NASA Astrophysics Data System (ADS)

    Sogami, I. S.; Shinohara, T.; Egawa, Y.

    1992-04-01

    The Mikheyev-Smirnov-Wolfenstein effect is investigated in an extended gauge field theory in which the universal seesaw mechanism is applied singly to the charged fermion sectors to lower their masses below the electroweak energy scale and doubly to the neutral fermion sector to make neutrinos superlight. At the first seesaw approximation, neutrinos are proved to have a distinctive spectrum consisting of doubly degenerate states with smaller mass m_{S} and a singlet state with larger mas m_{L}. The lepton mixing matrix is determined definitely in terms of the masses of charged leptons and down quarks, with a very small vacuum mixing angle sin theta = 0.043 +/- 0.004. The Schrödinger-like equation describing the spatial evolution of stationary neutrino flux is solved for globally-rotated-flavor wave functions. Comparison of its nonadiabatic solution with experimental results leads to an estimation m_{L}(2) - m_{S}(2) = (6 +/- 2) x 10(-6) eV(2) for the squared mass difference and a capture rate prediction of 74 +/- 12 SNU for the SAGE gallium experiment.

  1. Repulsive gravity induced by a conformally coupled scalar field implies a bouncing radiation-dominated universe

    NASA Astrophysics Data System (ADS)

    Antunes, V.; Novello, M.

    2017-04-01

    In the present work we revisit a model consisting of a scalar field with a quartic self-interaction potential non-minimally (conformally) coupled to gravity (Novello in Phys Lett 90A:347 1980). When the scalar field vacuum is in a broken symmetry state, an effective gravitational constant emerges which, in certain regimes, can lead to gravitational repulsive effects when only ordinary radiation is coupled to gravity. In this case, a bouncing universe is shown to be the only cosmological solution admissible by the field equations when the scalar field is in such broken symmetry state.

  2. Unified dark matter model in a singlet extension of the universal extra dimension model

    SciTech Connect

    Bai Yang; Han Zhenyu

    2009-05-01

    We propose a dark matter model with standard model singlet extension of the universal extra dimension model to explain the recent observations of ATIC, PPB-BETS, PAMELA, and DAMA. Other than the standard model fields propagating in the bulk of a five-dimensional space, one fermion field and one scalar field are introduced and both are standard model singlets. The zero mode of the new fermion is identified as the right-handed neutrino, while its first Klein-Kaluza (KK) mode is the lightest KK-odd particle and the dark matter candidate. The cosmic ray spectra from ATIC and PPB-BETS determine the dark matter particle mass and hence the fifth dimension compactification scale to be 1.0-1.6 TeV. The zero mode of the singlet scalar field with a mass below 1 GeV provides an attractive force between dark matter particles, which allows a Sommerfeld enhancement to boost the annihilation cross section in the Galactic halo to explain the PAMELA data. The DAMA annual modulation results are explained by coupling the same scalar field to the electron via a higher-dimensional operator. We analyze the model parameter space that can satisfy the dark matter relic abundance and accommodate all the dark matter detection experiments. We also consider constraints from the diffuse extragalactic gamma-ray background, which can be satisfied if the dark matter particle and the first KK mode of the scalar field have highly degenerate masses.

  3. Ghost dark matter

    SciTech Connect

    Furukawa, Tomonori; Yokoyama, Shuichiro; Ichiki, Kiyotomo; Sugiyama, Naoshi; Mukohyama, Shinji E-mail: shu@a.phys.nagoya-u.ac.jp E-mail: naoshi@a.phys.nagoya-u.ac.jp

    2010-05-01

    We revisit ghost dark matter, the possibility that ghost condensation may serve as an alternative to dark matter. In particular, we investigate the Friedmann-Robertson-Walker (FRW) background evolution and the large-scale structure (LSS) in the ΛGDM universe, i.e. a late-time universe dominated by a cosmological constant and ghost dark matter. The FRW background of the ΛGDM universe is indistinguishable from that of the standard ΛCDM universe if M∼>1eV, where M is the scale of spontaneous Lorentz breaking. From the LSS we find a stronger bound: M∼>10eV. For smaller M, ghost dark matter would have non-negligible sound speed after the matter-radiation equality, and thus the matter power spectrum would significantly differ from observation. These bounds are compatible with the phenomenological upper bound M∼<100GeV known in the literature.

  4. Heat death and oscillation in model universes containing interacting matter and radiation

    NASA Astrophysics Data System (ADS)

    Landsberg, P. T.; Reeves, G. A.

    1982-11-01

    Continuum and continuum-particle models for both oscillating and ever-expanding model universes are considered, with the consequences of various interactions between the components being traced and the connection with the irreversibility of oscillating models noted. It is for the first time shown that the relativistic equations allow the energy of an oscillating model universe to decrease by the end of a cycle, as is illustrated by a hypothetical model in which the matter temperature initially exceeds the radiation temperature. In addition, a novel continuum-particle model is introduced which is suitable for a study of universes with oscillation, or infinite expansion, and includes He formation and the effect of the Thomson interaction between matter and radiation.

  5. Relic abundance of dark matter in universal extra dimension models with right-handed neutrinos

    SciTech Connect

    Matsumoto, Shigeki; Sato, Joe; Yamanaka, Masato; Senami, Masato

    2007-08-15

    Relic abundance of dark matter is investigated in the framework of universal extra dimension models with right-handed neutrinos. These models are free from the serious Kaluza-Klein (KK) graviton problem that the original universal extra dimension model has. The first KK particle of the right-handed neutrino is a candidate for dark matter in this framework, and its relic abundance is determined by three processes, (1) the decay of the KK photon into the first KK right-handed neutrino in the late universe, (2) production of the first KK right-handed neutrino from the thermal bath in the early universe, and (3) the decay of higher KK right-handed neutrinos into the first KK right-handed neutrino in the late universe. When ordinary neutrino masses are large enough such as the degenerate mass spectrum case, the last process contributes to the abundance significantly, even if the reheating temperature is low. The scale of the extra dimension consistent with cosmological observations can be 500 GeV in the minimal setup of universal extra dimension models with right-handed neutrinos.

  6. Gravitationally neutral dark matter-dark antimatter universe crystal with epochs of decelerated and accelerated expansion

    NASA Astrophysics Data System (ADS)

    Gribov, I. A.; Trigger, S. A.

    2016-11-01

    A large-scale self-similar crystallized phase of finite gravitationally neutral universe (GNU)—huge GNU-ball—with spherical 2D-boundary immersed into an endless empty 3D- space is considered. The main principal assumptions of this universe model are: (1) existence of stable elementary particles-antiparticles with the opposite gravitational “charges” (M+gr and M -gr), which have the same positive inertial mass M in = |M ±gr | ≥ 0 and are equally presented in the universe during all universe evolution epochs; (2) the gravitational interaction between the masses of the opposite charges” is repulsive; (3) the unbroken baryon-antibaryon symmetry; (4) M+gr-M-gr “charges” symmetry, valid for two equally presented matter-antimatter GNU-components: (a) ordinary matter (OM)-ordinary antimatter (OAM), (b) dark matter (DM)-dark antimatter (DAM). The GNU-ball is weightless crystallized dust of equally presented, mutually repulsive (OM+DM) clusters and (OAM+DAM) anticlusters. Newtonian GNU-hydrodynamics gives the observable spatial flatness and ideal Hubble flow. The GNU in the obtained large-scale self-similar crystallized phase preserves absence of the cluster-anticluster collisions and simultaneously explains the observable large-scale universe phenomena: (1) the absence of the matter-antimatter clusters annihilation, (2) the self-similar Hubble flow stability and homogeneity, (3) flatness, (4) bubble and cosmic-net structures as 3D-2D-1D decrystallization phases with decelerative (a ≤ 0) and accelerative (a ≥ 0) expansion epochs, (5) the dark energy (DE) phenomena with Λ VACUUM = 0, (6) the DE and DM fine-tuning nature and predicts (7) evaporation into isolated huge M±gr superclusters without Big Rip.

  7. WIMP Dark Matter Limit-Direct Detection Data and Sensitivity Plots from the Cryogenic Dark Matter Search II and the University of California at Santa Barbara

    DOE Data Explorer

    Expectations for non-baryonic dark matter are founded principally in Big Bang nucleosynthesis calculations, which indicate that the missing mass of the universe is not likely to be baryonic. The supersymmetric standard model (SUSY) offers a promising framework for expectations of particle species which could satisfy the observed properties of dark matter. WIMPs are the most likely SUSY candidate for a dark matter particle. The High Energy Physics Group at University of California, Santa Barbara, is part of the CDMSII Collaboration and have provided the Interactive Plotter for WIMP Dark Matter Limit-Direct Detection Data on their website. They invite other collaborations working on dark matter research to submit datasets and, as a result, have more than 150 data sets now available for use with the plotting tool. The published source of the data is provided with each data set.

  8. Testing universal relations of neutron stars with a nonlinear matter-gravity coupling theory

    SciTech Connect

    Sham, Y.-H.; Lin, L.-M.; Leung, P. T. E-mail: lmlin@phy.cuhk.edu.hk

    2014-02-01

    Due to our ignorance of the equation of state (EOS) beyond nuclear density, there is still no unique theoretical model for neutron stars (NSs). It is therefore surprising that universal EOS-independent relations connecting different physical quantities of NSs can exist. Lau et al. found that the frequency of the f-mode oscillation, the mass, and the moment of inertia are connected by universal relations. More recently, Yagi and Yunes discovered the I-Love-Q universal relations among the mass, the moment of inertia, the Love number, and the quadrupole moment. In this paper, we study these universal relations in the Eddington-inspired Born-Infeld (EiBI) gravity. This theory differs from general relativity (GR) significantly only at high densities due to the nonlinear coupling between matter and gravity. It thus provides us an ideal case to test how robust the universal relations of NSs are with respect to the change of the gravity theory. Due to the apparent EOS formulation of EiBI gravity developed recently by Delsate and Steinhoff, we are able to study the universal relations in EiBI gravity using the same techniques as those in GR. We find that the universal relations in EiBI gravity are essentially the same as those in GR. Our work shows that, within the currently viable coupling constant, there exists at least one modified gravity theory that is indistinguishable from GR in view of the unexpected universal relations.

  9. A Universal Coupling Relation between Luminous and Dark Matter Surface Densities in Disk Rotating Galaxies

    NASA Astrophysics Data System (ADS)

    Giraud, Edmond

    2000-03-01

    The mutual dynamical evolution of visible and dark matter in spiral galaxies may have resulted in some kind of coupling between the distributions of visible and dark matter today. This conjecture is empirically explored in the present paper, where rotation curves of 60 spiral galaxies and universal rotation curves are fitted using dark halo models with a distribution that depends on the luminous mass distribution. It is shown that the dark matter profiles of any universal rotation curve can be decomposed into two components: (1) a main component, called ``coupled halo,'' and (2) a component having a gaslike distribution, negligible in bright galaxies, but of increasing significance toward faint galaxies. Once the disk component (stars, gas, and gaslike component) is subtracted, the dark halo integrated surface densities, σd(r), are in a plane (in log scale) σ2d(r)=σγσ(r), where the fundamental parameters are the disk integrated surface density, σ(r), and a surface density, σγ, which depends on the galaxy system only and characterizes the relative importance of the dark halo to the disk mass. This is the coupled halo. In the case of an exponential disk, the coupled halo has a central profile of the form ρ~r-1 and a flat curve at r>=ropt. The fact that the gaslike component decreases with luminosity suggests that it may be transformed into stars, and therefore could be dark baryons, possibly cold gas in the disk. In these models, the baryonic fraction (stars, gas, and gaslike component) is almost a constant over a range of 5 mag, that is, ~30% at 1.5 optical radii. The stellar fraction of baryonic matter increases with luminosity. The model predicts a large fraction of gaslike baryonic dark matter in faint spiral galaxies, i.e., in H I gas-rich systems. The mass fraction of this gaslike component is negligible in a galaxy like the Milky Way, and reaches half the halo mass in the faint, low surface brightness galaxy DDO 154. Some fine-tuning relations, which

  10. Heat death and oscillation in model universes containing interacting matter and radiation

    SciTech Connect

    Landsberg, P.T.; Reeves, G.A.

    1982-11-15

    The general thermodynamics of oscillating and ever expanding universes is studied by means of continuum matter-radiation cosmological models and their generalizations (see points (4)--(6) below), as follows: (1) The consequences of various interactions between the components are traced and the connection with the irreversibility of oscillating models is discussed. (2) ''Heat death'' characteristics (ever expanding case) have also been considered. (3) It is shown for the first time that the relativistic equations allow the energy of an oscillating model universe to decrease by the end of a cycle. This is illustrated by a hypothetical model in which the matter temperature initially exceeds the radiation temperature. (4) In addition, a new model, a continuum-particle model, has been introduced. This is suitable for a study of universes with oscillation, or indefinite expansion, and includes helium formation and the effect of the Thomson interaction between the matter and radiation. (5) It is found, as in earlier models, that energy is gained during a cycle. This corresponds to an entropy generation per baryon of 6.4 x 10/sup 6/ k. (6) At the present epoch with T/sub r/ = 2.70 K, the model predicts a nonstandard feature, namely a neutrino temperature slightly above this value at T/sub nue/ = T/sub numu/ = 2.74 K.

  11. Dark Energy and Dark Matter Phenomena and the Universe with Variable Gravitational Mass

    NASA Astrophysics Data System (ADS)

    Gorkavyi, N.

    2005-12-01

    Generation of high-frequency gravitational waves near the singularity is a crucial factor for understanding the origin and dynamics of the Universe. Emission of gravitational waves increases with a decreasing radius of collapsed object much faster than a gravitational force itself. Gravitationally unstable matter of the Universe will be completely converted into gravitational radiation during the Big Crunch. According to Misner, Thorne & Wheeler (Gravitation, 1977, p.959) plane gravitational waves have not gravitational mass or spacetime is flat everywhere outside the pulse. We can propose that the gravitational mass of the Universe is vanished after converting matter into gravitational waves. This hypothesis in the framework of Einstein's theory of gravitation can solve the problem of singularity without contradiction with theorems by Penrose-Hawking; explain the acceleration of our Universe as the effect of a retarded gravitational potential (Gorkavyi, BAAS, 2003, 35, #3) and the low quadrupole in fluctuations in CMB as result of blue-shift effect in a gravitational field. Proposed solution of dark energy problem free from coincidence problems. The hypothesis keeps best parts of Big Bang theory and inflation model without any unknown physical fields or new dimensions. According to this hypothesis a relic sea of high-frequency gravitational radiation in our Universe can be very dense. Interaction of relic gravitational waves with gravitational fields of galaxies and stars can create an additional dynamical effects like pressure of relic radiation that proportional to gravitational potential GM/(Rc2). This effect can be responsible for dark matter phenomena in galaxies and the Pioneer acceleration in the solar system (Gorkavyi, BAAS, 2005, 37, #2).

  12. The Connection between Galaxies and Dark Matter Structures in the Local Universe

    SciTech Connect

    Reddick, Rachel M.; Wechsler, Risa H.; Tinker, Jeremy L.; Behroozi, Peter S.

    2012-07-11

    We provide new constraints on the connection between galaxies in the local Universe, identified by the Sloan Digital Sky Survey (SDSS), and dark matter halos and their constituent substructures in the {Lambda}CDM model using WMAP7 cosmological parameters. Predictions for the abundance and clustering properties of dark matter halos, and the relationship between dark matter hosts and substructures, are based on a high-resolution cosmological simulation, the Bolshoi simulation. We associate galaxies with dark matter halos and subhalos using subhalo abundance matching, and perform a comprehensive analysis which investigates the underlying assumptions of this technique including (a) which halo property is most closely associated with galaxy stellar masses and luminosities, (b) how much scatter is in this relationship, and (c) how much subhalos can be stripped before their galaxies are destroyed. The models are jointly constrained by new measurements of the projected two-point galaxy clustering and the observed conditional stellar mass function of galaxies in groups. We find that an abundance matching model that associates galaxies with the peak circular velocity of their halos is in good agreement with the data, when scatter of 0.20 {+-} 0.03 dex in stellar mass at a given peak velocity is included. This confirms the theoretical expectation that the stellar mass of galaxies is tightly correlated with the potential wells of their dark matter halos before they are impacted by larger structures. The data put tight constraints on the satellite fraction of galaxies as a function of galaxy stellar mass and on the scatter between halo and galaxy properties, and rule out several alternative abundance matching models that have been considered. This will yield important constraints for galaxy formation models, and also provides encouraging indications that the galaxy - halo connection can be modeled with sufficient fidelity for future precision studies of the dark Universe.

  13. Visible and dark matter from a first-order phase transition in a baryon-symmetric universe

    DOE PAGES

    Petraki, Kalliopi; Trodden, Mark; Volkas, Raymond R.

    2012-02-28

    The similar cosmological abundances observed for visible and dark matter suggest a common origin for both. By viewing the dark matter density as a dark-sector asymmetry, mirroring the situation in the visible sector, we show that the visible and dark matter asymmetries may have arisen simultaneously through a first-order phase transition in the early universe. The additional scalar particles in the theory can mix with the standard Higgs boson and provide other striking signatures.

  14. Phantom of the Universe: A State-of-the-Art Planetarium Show on Dark Matter

    NASA Astrophysics Data System (ADS)

    Barnett, Michael

    2016-03-01

    Phantom of the Universe is a planetarium show premiering in 2016 that will showcase an exciting exploration of dark matter, from the Big Bang to the Large Hadron Collider. The show will reveal the first hints of its existence through the eyes of Fritz Zwicky. Viewers will marvel at the astral choreography witnessed by Vera Rubin in the Andromeda galaxy. They will plummet deep underground to see the most sensitive dark matter detector on Earth. From there, they will end the journey at the Large Hadron Collider, speeding alongside particles before they collide in visually stunning explosions of light and sound, and learning how scientists around the world are collaborating to track down the constituent of dark matter. The show will be offered to planetariums worldwide free of charge. It will feature music composed by Mickey Hart (Apocalypse Now, The Twilight Zone, The Grateful Dead) and narration by Academy-Award winning actress Tilda Swinton, and showcase the creativity and directing prowess of Joao Pequenao and the writing and producing talents of award-winning filmmaker, Carey Ann Strelecki. See a flattened preview (with resulting distortions) at: http://PhantomOfTheUniverse.com/

  15. Helium-3 in Milky Way Reveals Abundance of Matter in Early Universe

    NASA Astrophysics Data System (ADS)

    2002-01-01

    Astronomers using the National Science Foundation's 140 Foot Radio Telescope in Green Bank, West Virginia, were able to infer the amount of matter created by the Big Bang, and confirmed that it accounts for only a small portion of the effects of gravity observed in the Universe. The scientists were able to make these conclusions by determining the abundance of the rare element helium-3 (helium with only one neutron and two protons in its nucleus) in the Milky Way Galaxy. The NRAO 140 Foot Radio Telescope The NRAO 140-Foot Radio Telescope "Moments after the Big Bang, protons and neutrons began to combine to form helium-3 and other basic elements," said Robert Rood of the University of Virginia. "By accurately measuring the abundance of this primordial element in our Galaxy today, we were able infer just how much matter was created when the Universe was only a few minutes old." Rood and his colleagues, Thomas Bania from Boston University and Dana Balser from the National Radio Astronomy Observatory (NRAO), report their findings in the January 3 edition of the scientific journal Nature. Rood began searching for helium-3 in the Milky Way Galaxy in 1978. At that time, scientists believed that stars like our Sun synthesized helium-3 in their nuclear furnaces. Surprisingly, Rood's observations indicated that there was far less of this element in the Galaxy than the current models predicted. "If stars were indeed producing helium-3, as scientists believed, then we should have detected this element in much greater concentrations," he said. This unexpected discovery prompted Rood and his colleagues to broaden their search, and to look throughout the Milky Way for signs of stellar production of helium-3. Over the course of two decades, the researchers discovered that regardless of where they looked -- whether in the areas of sparse star formation like the outer edges of the Galaxy, or in areas of intense star formation near center of the Galaxy -- the relative abundance of

  16. Earth-mass dark-matter haloes as the first structures in the early Universe.

    PubMed

    Diemand, J; Moore, B; Stadel, J

    2005-01-27

    The Universe was nearly smooth and homogeneous before a redshift of z = 100, about 20 million years after the Big Bang. After this epoch, the tiny fluctuations imprinted upon the matter distribution during the initial expansion began to collapse because of gravity. The properties of these fluctuations depend on the unknown nature of dark matter, the determination of which is one of the biggest challenges in present-day science. Here we report supercomputer simulations of the concordance cosmological model, which assumes neutralino dark matter (at present the preferred candidate), and find that the first objects to form are numerous Earth-mass dark-matter haloes about as large as the Solar System. They are stable against gravitational disruption, even within the central regions of the Milky Way. We expect over 10(15) to survive within the Galactic halo, with one passing through the Solar System every few thousand years. The nearest structures should be among the brightest sources of gamma-rays (from particle-particle annihilation).

  17. Resonant sterile neutrino dark matter in the local and high-z Universe

    NASA Astrophysics Data System (ADS)

    Bozek, Brandon; Boylan-Kolchin, Michael; Horiuchi, Shunsaku; Garrison-Kimmel, Shea; Abazajian, Kevork; Bullock, James S.

    2016-06-01

    Sterile neutrinos comprise an entire class of dark matter models that, depending on their production mechanism, can be hot, warm, or cold dark matter (CDM). We simulate the Local Group and representative volumes of the Universe in a variety of sterile neutrino models, all of which are consistent with the possible existence of a radiative decay line at ˜3.5 keV. We compare models of production via resonances in the presence of a lepton asymmetry (suggested by Shi & Fuller 1999) to `thermal' models. We find that properties in the highly non-linear regime - e.g. counts of satellites and internal properties of haloes and subhaloes - are insensitive to the precise fall-off in power with wavenumber, indicating that non-linear evolution essentially washes away differences in the initial (linear) matter power spectrum. In the quasi-linear regime at higher redshifts, however, quantitative differences in the 3D matter power spectra remain, raising the possibility that such models can be tested with future observations of the Lyman-α forest. While many of the sterile neutrino models largely eliminate multiple small-scale issues within the CDM paradigm, we show that these models may be ruled out in the near future via discoveries of additional dwarf satellites in the Local Group.

  18. Matters Arising. Australian University Quality Agency Feedback in Relation to the Academic Engagement of International Students Enrolled in Onshore University Programmes

    ERIC Educational Resources Information Center

    Crossman, Joanna; Burdett, Jane

    2012-01-01

    It is now commonplace to find quality audit processes being applied in universities internationally as a means of assessing the quality of teaching and learning. This article draws upon a thematic analysis of 14 second-round Australian Universities Quality Agency reports in order to explore matters arising from the academic engagement of…

  19. Interacting Dark matter and Holographic dark energy in Bianchi type-V universe

    NASA Astrophysics Data System (ADS)

    Adhav, K. S.; Munde, S. L.; Tayade, G. B.; Bokey, V. D.

    2015-09-01

    The spatially homogeneous and anisotropic Bianchi type-V universe filled with interacting Dark matter and Holographic dark energy has been studied. The exact solutions of Einstein's field equations are obtained by (i) applying the special law of variation of Hubble parameter that yields constant values of the deceleration parameter and (ii) using a special form of deceleration parameter. It has been observed that for suitable choice of interaction between dark matter and holographic dark energy there is no coincidence problem (unlike CDM). Also, in all the resulting models the anisotropy of expansion dies out very quickly and attains isotropy after some finite time. The physical and geometrical aspects of the models are also discussed.

  20. Autosomal dominant polycystic kidney disease in University Clinic of Nephrology and Haemodialysis of Cotonou: clinical and genetical findings.

    PubMed

    Laleye, A; Awede, B; Agboton, B; Azonbakin, S; Biaou, O; Sagbo, G; Adjagba, M; Audrezet, M P; Ferec, C; Darboux, R

    2012-01-01

    Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease, but poorly studied in Africa. Its frequency in the University Clinic of Nephrology and Hemodialysis of Cotonou during the ten last years was 7 cases per year with a hospital prevalence estimated at 18 per 1000. The mean age of patients was 47.2 years extending from 29 to 70 years. Males were predominant with a sex ratio of 1.13. Family history was found in 47% of patients. The most common manifestations were lumbar pain (62%), high blood pressure (59%) urinary tract infections (53%), hematuria (46%), and abdominal masses (43%). Hepatic cysts were the most extra renal manifestations, found in 34% of cases. Renal failure was observed in 72% of patients of our series, six of them were under dialysis. Direct sequencing of polycystin 1 gene enabled us to identify some new mutations: 4 nonsense mutations (p.Q2824X exon 23, p.Q1651X exon 15, p.W1666X exon 15, p.R966W exon 12), a duplication (c_1761.1745 dup exon 9), a deletion (c.9397 + 1_9397 + 8del intron 26) and a deletion-insertion (c.7290_7291delins CTGCA exon 18).

  1. The World-Wide Effort to Understand the Visible Matter in Our Universe

    NASA Astrophysics Data System (ADS)

    Tribble, Robert E.

    2011-10-01

    A general goal in nuclear physics is to explain the origin, evolution, and structure of the visible matter in the universe. Today, nuclear physicists are working at a wide range of facilities around the world to provide information to help guide us to an understanding of this issue. I will provide a general overview of the field, which will focus on the important questions that are being addressed, the facilities that are being used to answer them, and a roadmap of the new construction projects that will define the field in the next decade.

  2. Soft CP violation and the global matter-antimatter symmetry of the universe

    NASA Technical Reports Server (NTRS)

    Senjanovic, G.; Stecker, F. W.

    1980-01-01

    Scenarios for baryon production are considered within the context of SU(5) and SO(10) grand unified theories where CP violation arises spontaneously. The spontaneous CP symmetry breaking then results in a matter-antimatter domain structure in the universe. Two possible, distinct types of theories of soft CP violation are defined. In the first type the CP nonconservation originates only from the breaking of SU(2) sub L X U(1) symmetry, and in the second type, even at the unification temperature scale, CP violation can emerge as a result of symmetry breaking by the vacuum expectation values of the superheavy Higgs sector scalars.

  3. Grand unification and possible matter-antimatter domain structure in the universe

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1981-01-01

    The theory and basic concepts for the development of a matter-antimatter domain cosmology are outlined within the framework of the grand unified gauge theory paradigm. It is shown how spontaneous CP symmetry breaking leads to such a domain sturcture in the universe. Astrophysical data such as the cosmic gamma-ray background spectrum, cosmic-ray p flux measurements, and galaxy clustering are found to favor this point of view. Future tests of this form of big-bang cosmology are suggested and discussed, including tests using deep underwater cosmic ray neutrino detectors.

  4. Quantum-Phase-Field Concept of Matter: Emergent Gravity in the Dynamic Universe

    NASA Astrophysics Data System (ADS)

    Steinbach, Ingo

    2017-01-01

    A monistic framework is set up where energy is the only fundamental substance. Different states of energy are ordered by a set of scalar fields. The dual elements of matter, mass and space, are described as volume- and gradient-energy contributions of the set of fields, respectively. Time and space are formulated as background-independent dynamic variables. The evolution equations of the body of the universe are derived from the first principles of thermodynamics. Gravitational interaction emerges from quantum fluctuations in finite space. Application to a large number of fields predicts scale separation in space and repulsive action of masses distant beyond a marginal distance. The predicted marginal distance is compared to the size of the voids in the observable universe.

  5. Exotic dense-matter states pumped by a relativistic laser plasma in the radiation-dominated regime.

    PubMed

    Colgan, J; Abdallah, J; Faenov, A Ya; Pikuz, S A; Wagenaars, E; Booth, N; Culfa, O; Dance, R J; Evans, R G; Gray, R J; Kaempfer, T; Lancaster, K L; McKenna, P; Rossall, A L; Skobelev, I Yu; Schulze, K S; Uschmann, I; Zhidkov, A G; Woolsey, N C

    2013-03-22

    In high-spectral resolution experiments with the petawatt Vulcan laser, strong x-ray radiation of KK hollow atoms (atoms without n = 1 electrons) from thin Al foils was observed at pulse intensities of 3 × 10(20) W/cm(2). The observations of spectra from these exotic states of matter are supported by detailed kinetics calculations, and are consistent with a picture in which an intense polychromatic x-ray field, formed from Thomson scattering and bremsstrahlung in the electrostatic fields at the target surface, drives the KK hollow atom production. We estimate that this x-ray field has an intensity of >5 × 10(18) W/cm(2) and is in the 3 keV range.

  6. University Programme Preferences of High School Science Students in Singapore and Reasons That Matter in Their Preferences: A Rasch Analysis

    ERIC Educational Resources Information Center

    Oon, Pey-Tee; Subramaniam, R.

    2015-01-01

    This study explored an under-researched area in science education--the university programmes preferred by high school students who take physical science subjects and the reasons that matter in their preferences. A total of 1,071 upper secondary and pre-university students in Singapore, who take physical science subjects among their range of…

  7. Investigating organic matter in Fanno Creek, Oregon, Part 1 of 3: Estimating annual foliar biomass for a deciduous-dominant urban riparian corridor

    NASA Astrophysics Data System (ADS)

    Sobieszczyk, Steven; Keith, Mackenzie K.; Rounds, Stewart A.; Goldman, Jami H.

    2014-11-01

    For this study, we explored the amount, type, and distribution of foliar biomass that is deposited annually as leaf litter to Fanno Creek and its floodplain in Portland, Oregon, USA. Organic matter is a significant contributor to the decreased dissolved oxygen concentrations observed in Fanno Creek each year and leaf litter is amongst the largest sources of organic matter to the stream channel and floodplain. Using a combination of field measurements and light detection and ranging (LiDAR) point cloud data, the annual foliar biomass was estimated for 13 stream reaches along the creek. Biomass estimates were divided into two sets: (1) the annual foliage available from the entire floodplain overstory canopy, and (2) the annual foliage overhanging the stream, which likely contributes leaf litter directly to the creek each year. Based on these computations, an estimated 991 (±22%) metric tons (tonnes, t) of foliar biomass is produced annually above the floodplain, with about 136 t (±24%) of that foliage falling directly into Fanno Creek. The distribution of foliar biomass varies by reach, with between 150 and 640 t/km2 produced along the floodplain and between 400 and 1100 t/km2 available over the channel. Biomass estimates vary by reach based primarily on the density of tree cover, with forest-dominant reaches containing more mature deciduous trees with broader tree canopies than either wetland or urban-dominant reaches, thus supplying more organic material to the creek. By quantifying the foliar biomass along Fanno Creek we have provided a reach-scale assessment of terrestrial organic matter loading, thereby providing land managers useful information for planning future restoration efforts.

  8. Investigating organic matter in Fanno Creek, Oregon, Part 1 of 3: estimating annual foliar biomass for a deciduous-dominant urban riparian corridor

    USGS Publications Warehouse

    Sobieszczyk, Steven; Keith, Mackenzie K.; Rounds, Stewart A.; Goldman, Jami H.

    2014-01-01

    For this study, we explored the amount, type, and distribution of foliar biomass that is deposited annually as leaf litter to Fanno Creek and its floodplain in Portland, Oregon, USA. Organic matter is a significant contributor to the decreased dissolved oxygen concentrations observed in Fanno Creek each year and leaf litter is amongst the largest sources of organic matter to the stream channel and floodplain. Using a combination of field measurements and light detection and ranging (LiDAR) point cloud data, the annual foliar biomass was estimated for 13 stream reaches along the creek. Biomass estimates were divided into two sets: (1) the annual foliage available from the entire floodplain overstory canopy, and (2) the annual foliage overhanging the stream, which likely contributes leaf litter directly to the creek each year. Based on these computations, an estimated 991 (±22%) metric tons (tonnes, t) of foliar biomass is produced annually above the floodplain, with about 136 t (±24%) of that foliage falling directly into Fanno Creek. The distribution of foliar biomass varies by reach, with between 150 and 640 t/km2 produced along the floodplain and between 400 and 1100 t/km2 available over the channel. Biomass estimates vary by reach based primarily on the density of tree cover, with forest-dominant reaches containing more mature deciduous trees with broader tree canopies than either wetland or urban-dominant reaches, thus supplying more organic material to the creek. By quantifying the foliar biomass along Fanno Creek we have provided a reach-scale assessment of terrestrial organic matter loading, thereby providing land managers useful information for planning future restoration efforts.

  9. Detection prospects for high energy neutrino sources from the anisotropic matter distribution in the local Universe

    NASA Astrophysics Data System (ADS)

    Mertsch, Philipp; Rameez, Mohamed; Tamborra, Irene

    2017-03-01

    Constraints on the number and luminosity of the sources of the cosmic neutrinos detected by IceCube have been set by targeted searches for point sources. We set complementary constraints by using the 2MASS Redshift Survey (2MRS) catalogue, which maps the matter distribution of the local Universe. Assuming that the distribution of the neutrino sources follows that of matter, we look for correlations between ``warm'' spots on the IceCube skymap and the 2MRS matter distribution. Through Monte Carlo simulations of the expected number of neutrino multiplets and careful modelling of the detector performance (including that of IceCube-Gen2), we demonstrate that sources with local density exceeding 10-6 Mpc-3 and neutrino luminosity Lν lesssim 1042 erg s-1 (1041 erg s-1) will be efficiently revealed by our method using IceCube (IceCube-Gen2). At low luminosities such as will be probed by IceCube-Gen2, the sensitivity of this analysis is superior to requiring statistically significant direct observation of a point source.

  10. Large-scale rotational perturbations of a Friedmann universe with collisionless matter and primordial magnetic fields

    NASA Astrophysics Data System (ADS)

    Rebhan, Anton

    1992-06-01

    The dynamical equations for rotational (vector) perturbations of a Friedmann-Robertson-Walker universe containing a perfect fluid of massive matter and radiation together with relativistic collisionless matter are established. These equations have solutions which remain regular as the initial singularity is approached, in contrast to the purely perfect-fluid case, where small rotational perturbations cannot coexist with a Friedmann-type singularity due to the Helmholtz-Kelvin circulation theorem. With collisionless matter present (e.g., gravitons after the Planck era), this obstruction is circumvented, and solutions which exhibit a growing mode of vorticity on superhorizon scales are obtained. The anisotropies in the cosmic microwave background caused by these small vector perturbations are analyzed, and limits on admissible primordial vorticity are derived. In the radiation era, large-scale vorticity gives rise to large-scale primordial magnetic fields, which are shown potentially to have the right magnitude to act as seed fields for galactic dynamo action and thereby to explain the presently observed galactic magnetic fields.

  11. Scalar and vector perturbations in a universe with discrete and continuous matter sources

    NASA Astrophysics Data System (ADS)

    Eingorn, Maxim; Kiefer, Claus; Zhuk, Alexander

    2016-09-01

    We study a universe filled with dust-like matter in the form of discrete inhomogeneities (e.g., galaxies and their groups and clusters) and two sets of perfect fluids with linear and nonlinear equations of state, respectively. The background spacetime geometry is defined by the FLRW metric. In the weak gravitational field limit, we develop the first-order scalar and vector cosmological perturbation theory. Our approach works at all cosmological scales (i.e. sub-horizon and super-horizon ones) and incorporates linear and nonlinear effects with respect to energy density fluctuations. We demonstrate that the scalar perturbation (i.e. the gravitational potential) as well as the vector perturbation can be split into individual contributions from each matter source. Each of these contributions satisfies its own equation. The velocity-independent parts of the individual gravitational potentials are characterized by a finite time-dependent Yukawa interaction range being the same for each individual contribution. We also obtain the exact form of the gravitational potential and vector perturbation related to the discrete matter sources. The self-consistency of our approach is thoroughly checked. The derived equations can form the theoretical basis for numerical simulations for a wide class of cosmological models.

  12. Undulant Universe

    SciTech Connect

    Barenboim, Gabriela; Mena, Olga; Quigg, Chris; /Fermilab

    2004-12-01

    If the equation of state for ''dark energy'' varies periodically, the expansion of the Universe may have undergone alternating eras of acceleration and deceleration. We examine a specific form that survives existing observational tests, does not single out the present state of the Universe as exceptional, and suggests a future much like the matter-dominated past: a smooth expansion without a final inflationary epoch.

  13. Composition and distribution of particulate matter (PM10) in a mechanically ventilated University building

    NASA Astrophysics Data System (ADS)

    Ali, Mohamed Yasreen Mohamed; Hanafiah, Marlia Mohd; Latif, Mohd Talib

    2016-11-01

    This study analyses the composition and distribution of particulate matter (PM10) in the Biology department building, in UKM. PM10 were collected using SENSIDYNE Gillian GilAir-5 Personal Air Sampling System, a low-volume sampler, whereas the concentration of heavy metals was determined using Inductively coupled plasma-mass spectrometry (ICP-MS). The concentration of PM10 recorded in the mechanically ventilated building ranges from 89 µgm-3 to 910 µgm-3. The composition of the selected heavy metals in PM10 were dominated by zinc, followed by copper, lead and cadmium. It was found that the present of indoor-related particulate matter were originated from the poorly maintained ventilation system, the activity of occupants and typical office equipments such as printers and photocopy machines. The haze event occured during sampling periods was also affected the PM10 concentration in the building. This results can serve as a starting point to assess the potential human health damage using the life cycle impact assessment, expressed in term of disability adjusted life year (DALY).

  14. Quantitative and qualitative characteristics of dissolved organic matter from eight dominant aquatic macrophytes in Lake Dianchi, China.

    PubMed

    Qu, Xiaoxia; Xie, Li; Lin, Ying; Bai, Yingchen; Zhu, Yuanrong; Xie, Fazhi; Giesy, John P; Wu, Fengchang

    2013-10-01

    The aim of this research was to determine and compare the quantitative and qualitative characteristics of dissolved organic matters (DOM) from eight aquatic macrophytes in a eutrophic lake. C, H, N, and P in ground dry leaves and C, N, and P in DOM of the species were determined, and C/N, C/P, C/H, DOC/C, TDN/N, TDP/P, DOC/TDN, and DOC/TDP were calculated. Chemical structures of the DOM were characterized by the use of multiple techniques including UV-visible, FT-IR, and (13)C CP/MAS spectra. The results showed subtle differences in quantity and quality of DOM among species and life-forms. Except oriental pepper which had a C/H of 0.7, C/H of all the other species was 0.6. C/N and C/P of ground leaves was 10.5-17.3 and 79.4-225.3, respectively, which were greater in floating and submerged species than in the others. Parrot feather also had a small C/P (102.8). DOC/C, TDN/N, and TDP/P were 7.6-16.8, 5.5-22.6, and 22.9-45.6 %, respectively. Except C/N in emergent and riparian species, C/N in the other species and C/P in all the species were lower in their DOM than in the ground leaves. DOM of the macrophytes had a SUVA254 value of 0.83-1.80. The FT-IR and (13)C NMR spectra indicated that the DOM mainly contained polysaccharides and/or amino acids/proteins. Percent of carbohydrates in the DOM was 37.3-66.5 % and was highest in parrot feather (66.5 %) and crofton weed (61.5 %). DOM of water hyacinth, water lettuce, and sago pondweed may have the greatest content of proteins. Aromaticity of the DOM was from 6.9 % in water lettuce to 17.8 % in oriental pepper. DOM of the macrophytes was also different in polarity and percent of Ar-OH. Distinguished characteristics in quantity and quality of the macrophyte-derived DOM may induce unique environmental consequences in the lake systems.

  15. Scale invariance and universality of force networks in static granular matter.

    PubMed

    Ostojic, Srdjan; Somfai, Ellák; Nienhuis, Bernard

    2006-02-16

    Force networks form the skeleton of static granular matter. They are the key factor that determines mechanical properties such as stability, elasticity and sound transmission, which are important for civil engineering and industrial processing. Previous studies have focused on investigations of the global structure of external forces (the boundary condition) and on the probability distribution of individual contact forces. So far, however, precise knowledge of the disordered spatial structure of the force network has remained elusive. Here we report that molecular dynamics simulations of realistic granular packings reveal scale invariance of clusters of particles interacting by means of relatively strong forces. Despite visual variation, force networks for various values of the confining pressure and other parameters have identical scaling exponents and scaling function, thereby determining a universality class. Unexpectedly, the flat ensemble of force configurations (a simple generalization of equilibrium statistical mechanics) belongs to this universality class, whereas some widely studied simplified models do not. This implies that the elasticity of the grains and their geometrical disorder do not affect the universal mechanical properties.

  16. Dispersion Distance and the Matter Distribution of the Universe in Dispersion Space.

    PubMed

    Masui, Kiyoshi Wesley; Sigurdson, Kris

    2015-09-18

    We propose that "standard pings," brief broadband radio impulses, can be used to study the three-dimensional clustering of matter in the Universe even in the absence of redshift information. The dispersion of radio waves as they travel through the intervening plasma can, like redshift, be used as a cosmological distance measure. Because of inhomogeneities in the electron density along the line of sight, dispersion is an imperfect proxy for radial distance and we show that this leads to calculable dispersion-space distortions in the apparent clustering of sources. Fast radio bursts (FRBs) are a new class of radio transients that are the prototypical standard ping and, due to their high observed dispersion, have been interpreted as originating at cosmological distances. The rate of fast radio bursts has been estimated to be several thousand over the whole sky per day and, if cosmological, the sources of these events should trace the large-scale structure of the Universe. We calculate the dispersion-space power spectra for a simple model where electrons and FRBs are biased tracers of the large-scale structure of the Universe, and we show that the clustering signal could be measured using as few as 10 000 events. Such a survey is in line with what may be achieved with upcoming wide-field radio telescopes.

  17. Fluxes of dissolved organic matter and mineral weathering products from Corn Belt landscapes dominated by subsurface drainage: large-scale soil and hydrologic change

    NASA Astrophysics Data System (ADS)

    Jelinski, N. A.; Yoo, K.; Strock, J.; Dalzell, B. J.; Finlay, J. C.

    2011-12-01

    The human alteration of agricultural landscapes is one of the most important factors in pedologic and geomorphic change, and can influence hydrology and aquatic chemistry at large scales. Most of the Midwestern Corn Belt that is currently dominated by subsurface tile drainage (such as southern Minnesota) was historically prairie and wetland which had hydrologic flow-paths through organic-rich surface soil horizons, a condition that favored the export of dissolved organic matter. When hydrology is altered through subsurface drainage, adsorption of organic materials to mineral surfaces and increases in mineral weathering may result because more water is flowing through subsurface mineral soils. We suggest that the alteration of hydrologic flowpaths in agricultural landscapes can dramatically alter the rate of mineral weathering as well as surface export of weathering products and dissolved organic matter. This could be at least one contributing factor to observed increases in Mississippi River alkalinity over the past four decades. Here, we examine trends in dissolved organic carbon, total dissolved nitrogen, dissolved organic nitrogen, total suspended solids, and indicators of mineral weathering (Si, Ca, Na, K) from subsurface drainage systems located in southwestern MN. Then, using a simple conceptual model, we estimate the effects of subsurface drainage on the regional fluxes of these parameters and present directions for future research.

  18. String cloud and domain walls with quark matter for a higher dimensional FRW universe in self creation cosmology

    NASA Astrophysics Data System (ADS)

    Halife, Caǧlar; Sezgin, Aygün

    2016-04-01

    In this study, we research a higher dimensional flat Friedmann-Robertson-Walker (FRW) universe in Barber-s second theory when strange quark matter (SQM) and normal matter (NM) are attached to the string cloud and domain walls. We obtain zero string tension density for this model. We obtain dust quark matter solutions. This result agrees with Kiran and Reddy, Krori et al, Sahoo and Mishra and Reddy. In our solutions the quark matter transforms to other particles over time. We also obtain two different solutions for domain walls with quark and normal matters by using a deceleration parameter. Also, the features of the obtained solutions are discussed and some physical and kinematical quantities are generalized and discussed. Our results are consistent with Yılmaz, Adcox et al and Back et al in four and five dimensions.

  19. A Place for Materials Science: University of Pennsylvania's Laboratory for Research on the Structure of Matter

    NASA Astrophysics Data System (ADS)

    Shields, Brittany

    2013-03-01

    The University of Pennsylvania's Laboratory for Research on the Structure of Matter (LRSM) opened its doors in 1965. Constructed to house cutting-edge research on Materials Science, the LRSM building was designed to foster interdisciplinary research among physicists, chemists and metallurgical engineers. Each of the five floors of the new building included a central facility, including a high magnetic field center, an analytical chemistry research center and an electron microscopy center. While primarily funded by the Department of Defense's Advanced Research Projects Agency, the LRSM also was also partly sponsored by industry. The LRSM received funding from Philadelphia Electric Company, General Electric Company, and IBM, among others. In this paper, I will study how the building was designed to encourage interdisciplinary collaboration, while also becoming a place of intersection among academic, private, and governmental interests. This project is a collaboration with Hyungsub Choi.

  20. Dark Matter and Super Symmetry: Exploring and Explaining the Universe with Simulations at the LHC

    SciTech Connect

    Gutsche, Oliver

    2016-07-10

    The Large Hadron Collider (LHC) at CERN in Geneva, Switzerland, is one of the largest machines on this planet. It is built to smash protons into each other at unprecedented energies to reveal the fundamental constituents of our universe. The 4 detectors at the LHC record multi-petabyte datasets every year. The scientific analysis of this data requires equally large simulation datasets of the collisions based on the theory of particle physics, the Standard Model. The goal is to verify the validity of the Standard Model or of theories that extend the Model like the concepts of Supersymmetry and an explanation of Dark Matter. I will give an overview of the nature of simulations needed to discover new particles like the Higgs boson in 2012, and review the different areas where simulations are indispensable: from the actual recording of the collisions to the extraction of scientific results to the conceptual design of improvements to the LHC and its experiments.

  1. Coupled dark matter-dark energy in light of near universe observations

    SciTech Connect

    Honorez, Laura Lopez; Mena, Olga E-mail: beth.ann.reid@gmail.com E-mail: liciaverde@gmail.com

    2010-09-01

    Cosmological analysis based on currently available observations are unable to rule out a sizeable coupling among the dark energy and dark matter fluids. We explore a variety of coupled dark matter-dark energy models, which satisfy cosmic microwave background constraints, in light of low redshift and near universe observations. We illustrate the phenomenology of different classes of dark coupling models, paying particular attention in distinguishing between effects that appear only on the expansion history and those that appear in the growth of structure. We find that while a broad class of dark coupling models are effectively models where general relativity (GR) is modified — and thus can be probed by a combination of tests for the expansion history and the growth of structure —, there is a class of dark coupling models where gravity is still GR, but the growth of perturbations is, in principle modified. While this effect is small in the specific models we have considered, one should bear in mind that an inconsistency between reconstructed expansion history and growth may not uniquely indicate deviations from GR. Our low redshift constraints arise from cosmic velocities, redshift space distortions and dark matter abundance in galaxy voids. We find that current data constrain the dimensionless coupling to be |ξ| < 0.2, but prospects from forthcoming data are for a significant improvement. Future, precise measurements of the Hubble constant, combined with high-precision constraints on the growth of structure, could provide the key to rule out dark coupling models which survive other tests. We shall exploit as well weak equivalence principle violation arguments, which have the potential to highly disfavour a broad family of coupled models.

  2. Statistics of dark matter substructure - I. Model and universal fitting functions

    NASA Astrophysics Data System (ADS)

    Jiang, Fangzhou; van den Bosch, Frank C.

    2016-05-01

    We present a new, semi-analytical model describing the evolution of dark matter subhaloes. The model uses merger trees constructed using the method of Parkinson et al. to describe the masses and redshifts of subhaloes at accretion, which are subsequently evolved using a simple model for the orbit-averaged mass-loss rates. The model is extremely fast, treats subhaloes of all orders, accounts for scatter in orbital properties and halo concentrations, uses a simple recipe to convert subhalo mass to maximum circular velocity, and considers subhalo disruption. The model is calibrated to accurately reproduce the average subhalo mass and velocity functions in numerical simulations. We demonstrate that, on average, the mass fraction in subhaloes is tightly correlated with the `dynamical age' of the host halo, defined as the number of halo dynamical times that have elapsed since its formation. Using this relation, we present universal fitting functions for the evolved and unevolved subhalo mass and velocity functions that are valid for a broad range in host halo mass, redshift and Λ cold dark matter cosmology.

  3. The universe in a box - Thermal effects in the standard cold dark matter scenario

    NASA Technical Reports Server (NTRS)

    Cen, R. Y.; Ostriker, Jeremiah P.; Jameson, Anthony; Liu, Feng

    1990-01-01

    An attempt is made to compute the evolution of a representative piece of the universe at a minimal resolution of a flux-based mesh code coupled with a standard particle-mesh dark matter code. It is found that, on scales greater than 1/h Mpc, dark matter is more clumped than gas. Bremsstrahlung and Compton cooling are unimportant on scales of 1 Mpc or greater. Shocks gradually heat the gas, leaving most of it in voids at T = 10 exp 3.5 K or less, but with a small fraction reaching T = 10 million K or more. Ultraviolet and soft X-ray emission from the heated gas is significant, providing an important part of the background radiation field and significant ionizing of the intergalactic medium. The mean induced Delta T/T for microwave background radiation in the Rayleigh-Jeans part of the spectrum is 1.1 x 10 to the -6th with fluctuation of 5.6 x 10 to the -7th on arcmin scales and a mean y parameter of 5.5 x 10 to the -7th, which is potentially detectable by the COBE satellite.

  4. The coyote universe III: simulation suite and precision emulator for the nonlinear matter power spectrum

    SciTech Connect

    Heitmann, Katrin; White, Martin; Higdon, David; Wagner, Christian; Lawrence, Earl; Habib, Salman; Williams, Brian

    2009-01-01

    Ongoing and future large scale structure surveys targeted at the investigation of dark energy will enter the nonlinear regime of structure formation. In order to fully exploit the newly available information from this regime and to extract cosmological constraints. very accurate theoretical predictions are needed. Such predictions can currently only be obtained from costly precision N-body simulations. We have recently shown that it is possible to obtain predictions for the nonlinear matter power spectrum at the level of one-percent accuracy and that we can build a precise prediction scheme for the nonlinear power spectrum from a small set of cosmological models. In this paper we introduce the 'Coyote Universe' simulation suite which comprises more than 800 N-body simulations at different force and mass resolutions, spanning 38 wCDM cosmologies. This large simulation suite enables us to construct a prediction scheme for the nonlinear matter power spectrum accurate at the 1% level out to k {approx_equal} 1 hMpc{sup -1}.

  5. THE COYOTE UNIVERSE. II. COSMOLOGICAL MODELS AND PRECISION EMULATION OF THE NONLINEAR MATTER POWER SPECTRUM

    SciTech Connect

    Heitmann, Katrin; Higdon, David; Williams, Brian J.; Lawrence, Earl; White, Martin; Habib, Salman; Wagner, Christian

    2009-11-01

    The power spectrum of density fluctuations is a foundational source of cosmological information. Precision cosmological probes targeted primarily at investigations of dark energy require accurate theoretical determinations of the power spectrum in the nonlinear regime. To exploit the observational power of future cosmological surveys, accuracy demands on the theory are at the 1% level or better. Numerical simulations are currently the only way to produce sufficiently error-controlled predictions for the power spectrum. The very high computational cost of (precision) N-body simulations is a major obstacle to obtaining predictions in the nonlinear regime, while scanning over cosmological parameters. Near-future observations, however, are likely to provide a meaningful constraint only on constant dark energy equation of state, 'wCDM', cosmologies. In this paper, we demonstrate that a limited set of only 37 cosmological models-the 'Coyote Universe' suite-can be used to predict the nonlinear matter power spectrum to 1% over a prior parameter range set by current cosmic microwave background observations. This paper is the second in a series of three, with the final aim to provide a high-accuracy prediction scheme for the nonlinear matter power spectrum for wCDM cosmologies.

  6. The Coyote Universe. II. Cosmological Models and Precision Emulation of the Nonlinear Matter Power Spectrum

    NASA Astrophysics Data System (ADS)

    Heitmann, Katrin; Higdon, David; White, Martin; Habib, Salman; Williams, Brian J.; Lawrence, Earl; Wagner, Christian

    2009-11-01

    The power spectrum of density fluctuations is a foundational source of cosmological information. Precision cosmological probes targeted primarily at investigations of dark energy require accurate theoretical determinations of the power spectrum in the nonlinear regime. To exploit the observational power of future cosmological surveys, accuracy demands on the theory are at the 1% level or better. Numerical simulations are currently the only way to produce sufficiently error-controlled predictions for the power spectrum. The very high computational cost of (precision) N-body simulations is a major obstacle to obtaining predictions in the nonlinear regime, while scanning over cosmological parameters. Near-future observations, however, are likely to provide a meaningful constraint only on constant dark energy equation of state, "wCDM", cosmologies. In this paper, we demonstrate that a limited set of only 37 cosmological models—the "Coyote Universe" suite—can be used to predict the nonlinear matter power spectrum to 1% over a prior parameter range set by current cosmic microwave background observations. This paper is the second in a series of three, with the final aim to provide a high-accuracy prediction scheme for the nonlinear matter power spectrum for wCDM cosmologies.

  7. The Coyote Universe II: Cosmological Models and Precision Emulation of the Nonlinear Matter Power Spectrum

    SciTech Connect

    Heitmann, Katrin; Habib, Salman; Higdon, David; Williams, Brian J; White, Martin; Wagner, Christian

    2008-01-01

    The power spectrum of density fluctuations is a foundational source of cosmological information. Precision cosmological probes targeted primarily at investigations of dark energy require accurate theoretical determinations of the power spectrum in the nonlinear regime. To exploit the observational power of future cosmological surveys, accuracy demands on the theory are at the one percent level or better. Numerical simulations are currently the only way to produce sufficiently error-controlled predictions for the power spectrum. The very high computational cost of (precision) N-body simulations is a major obstacle to obtaining predictions in the nonlinear regime, while scanning over cosmological parameters. Near-future observations, however, are likely to provide a meaningful constraint only on constant dark energy equation of state 'wCDM' cosmologies. In this paper we demonstrate that a limited set of only 37 cosmological models -- the 'Coyote Universe' suite -- can be used to predict the nonlinear matter power spectrum at the required accuracy over a prior parameter range set by cosmic microwave background observations. This paper is the second in a series of three, with the final aim to provide a high-accuracy prediction scheme for the nonlinear matter power spectrum for wCDM cosmologies.

  8. Soil organic matter in the Moscow State University botanical garden on the Vorob'evy Hills

    NASA Astrophysics Data System (ADS)

    Rozanova, M. S.; Prokof'eva, T. V.; Lysak, L. V.; Rakhleeva, A. A.

    2016-09-01

    Humification conditions and humus status parameters in arboretum soils of the Moscow State University botanical garden on the Vorob'evy Hills have been studied. Although microbiological activity is reduced, the warm and mild climate in the city, the eutrophication of soils (due to atmospheric fallouts and dissolution of construction waste inclusions), the retention of plant waste on the soil surface, and the presence of abundant primary destructors (mesofauna) have resulted in the formation of organic matter with specific characteristics. During the 60 years that have elapsed since the arboretum establishment, soils with a high content (up to 10-14%) of humate humus (CHA/CFA > 1) characterized by a higher degree of humification than in the control soils under herbaceous vegetation have been developed in the area. Large reserves of organic carbon have been noted not only in the upper 30-cm-thick soil layer, but also in the 1-m-thick layer due to organic matter of buried and technogenic horizons.

  9. Mirror world and superstring-inspired hidden sector of the Universe, dark matter and dark energy

    NASA Astrophysics Data System (ADS)

    Das, C. R.; Laperashvili, L. V.; Nielsen, H. B.; Tureanu, A.

    2011-09-01

    We develop a concept of parallel existence of the ordinary (O) and hidden (H) worlds. We compare two cases: (1) when the hidden sector of the Universe is a mirror counterpart of the ordinary world, and (2) when it is a superstring-inspired shadow world described, in contrast to the mirror world, by a symmetry group (or by a chain of groups), which does not coincide with the ordinary world symmetry group. We construct a cosmological model assuming the existence of the superstring-inspired E6 unification, broken at the early stage of the Universe to SO(10)×U(1)Z—in the O-world, and to SU(6)'×SU(2)θ'—in the H-world. As a result, we obtain the low-energy symmetry group GSM'×SU(2)θ' in the shadow world, instead of the standard model group GSM existing in the O-world. The additional non-Abelian SU(2)θ' group with massless gauge fields, ”thetons,” is responsible for dark energy. Considering a quintessence model of cosmology with an inflaton σ and an axion aθ, which is a pseudo Nambu-Goldstone boson induced by the SU(2)θ'-group anomaly, we explain the origin of dark energy, dark matter and ordinary matter. In the present model we review all cosmological epochs (inflation, reheating, recombination and nucleosynthesis), and give our version of the baryogenesis. The cosmological constant problem is also briefly discussed.

  10. Impact of organic matter source and quality on living benthic foraminiferal distribution on a river-dominated continental margin: A study of the Portuguese Margin.

    NASA Astrophysics Data System (ADS)

    Bonnin, Jerome; Dessandier, Pierre-Antoine; Kim, Jung-Hyun; Deflandre, Bruno; Gremare, Antoine; Sinninghe-Damsté, Jaap

    2016-04-01

    Living (rose Bengal stained) benthic foraminifera were investigated on surface sediments from 23 stations from the river-dominated north-western Portuguese margin. Samples were collected in March 2011, following the period of the maximum rainfall over the Iberian Peninsula, between 20 and 2000 m water depth along five cross-margin transects. Four of them are located off the Douro, Mondego, Tagus and Sado rivers and one off the Estremadura coast. The major objectives of this study are hence 1) to compare the influence of the rivers on the distribution of benthic foraminifera and 2) assess the impact of organic matter of various origin and quality on the benthic micro faunas. To do this, sedimentological and biogeochemical characteristics of the sediments were identified by measuring grain size, oxygen penetration depth (OPD), total organic carbon (TOC) content, stable carbon isotopic composition of TOC (δ13CTOC) and concentration of pigments and amino acids. Based on the principal component (PCA) and cluster analyses of the environmental data, three major geographical groups are identified: (1) deep stations, (2) coastal and mid-slopestations, and (3) shelf stations under river influence.At the deepest stations, species are associated with high organic matter (OM) quantity but low OM quality, where Uvigerina mediterranea, Hoeglundina elegans and agglutinated species such as Reophax scorpiurus or Bigenerina nodosaria are dominant. All stations off the Sado River, which is the most affected area by the anthropogenic influence, are also characterized by high quantity but low quality of OM with the minimum faunal density and diversity within the study area. Mid-slope stations are associated with low OM content and coarse sediments (Q50) with the predominance of N. scaphum. Shallow shelf stations close to the Douro and Tagus river mouths show a dominance of taxa (e.g. Ammonia beccarii, Bulimina aculeata, Eggerelloides scaber, Nonion scaphum, Cancris auriculus and

  11. Impact of organic matter source and quality on living benthic foraminiferal distribution on a river-dominated continental margin: A study of the Portuguese margin

    NASA Astrophysics Data System (ADS)

    Dessandier, Pierre-Antoine; Bonnin, Jérôme; Kim, Jung-Hyun; Bichon, Sabrina; Deflandre, Bruno; Grémare, Antoine; Sinninghe Damsté, Jaap S.

    2016-06-01

    Living (rose Bengal stained) benthic foraminifera were investigated on surface sediments from 23 stations from the river-dominated northwestern Portuguese margin. Samples were collected in March 2011, following the period of the maximum rainfall over the Iberian Peninsula, between 20 and 2000 m water depth along five cross-margin transects. Four of them are located off the Douro, Mondego, Tagus, and Sado Rivers and one off the Estremadura coast. The major objectives of this study are (1) to assess the impact of organic matter of various origin and quality on the benthic foraminifera and (2) to investigate the spatial differences of faunal distribution from coastal waters to the deep sea under river influences. To do this, sedimentological and biogeochemical characteristics of the sediments were identified by measuring grain size, oxygen penetration depth, total organic carbon (TOC) content, stable carbon isotopic composition of TOC (δ13CTOC) and concentration of pigments and amino acids. Based on the principal component and cluster analyses of the environmental data, three major geographical groups are identified: (1) deep stations, (2) coastal and middle slope stations, and (3) shelf stations under river influence. At the deepest stations, species are associated with high organic matter (OM) quantity but low OM quality, where Uvigerina mediterranea, Hoeglundina elegans, and agglutinated species such as Reophax scorpiurus or Bigenerina nodosaria are dominant. All stations off the Sado River, which is the most affected area by the anthropogenic influence, are also characterized by high quantity but low quality of OM with the minimum faunal density and diversity within the study area. Middle slope stations are associated with low OM content and coarse sediments (Q50) with the predominance of N. scaphum. Shallow shelf stations close to the Douro and Tagus River mouths show a dominance of taxa (e.g., Ammonia beccarii, Bulimina aculeata, Eggerelloides scaber, Nonion

  12. THE ACCRETION OF DARK MATTER SUBHALOS WITHIN THE COSMIC WEB: PRIMORDIAL ANISOTROPIC DISTRIBUTION AND ITS UNIVERSALITY

    SciTech Connect

    Kang, Xi; Wang, Peng

    2015-11-01

    The distribution of galaxies displays anisotropy on different scales and it is often referred to as galaxy alignment. To understand the origin of galaxy alignments on small scales, one must investigate how galaxies were accreted in the early universe and quantify their primordial anisotropy at the time of accretion. In this paper we use N-body simulations to investigate the accretion of subhalos, focusing on their alignment with halo shape and the orientation of mass distribution on the large scale, defined using the Hessian matrix of the density field. The large/small (e1/e3) eigenvalues of the Hessian matrix define the fast/slow collapse direction of matter on the large scale. We find that: (1) the halo major axis is well aligned with the e3 (slow collapse) direction, and it is stronger for massive halos; (2) subhalos are predominantly accreted along the major axis of the host halo, and the alignment increases with the host halo mass. Most importantly, this alignment is universal; (3) accretion of subhalos with respect to the e3 direction is not universal. In massive halos, subhalos are accreted along the e3 (even more strongly than the alignment with the halo major axis), but in low-mass halos subhalos are accreted perpendicular to e3. The transitional mass is lower at high redshift. The last result well explains the puzzling correlation (both in recent observations and simulations) that massive galaxies/halos have their spin perpendicular to the filament, and the spin of low-mass galaxies/halos is slightly aligned with the filament, under the assumption that the orbital angular momentum of subhalos is converted to halo spin.

  13. The Accretion of Dark Matter Subhalos within the Cosmic Web: Primordial Anisotropic Distribution and its Universality

    NASA Astrophysics Data System (ADS)

    Kang, Xi; Wang, Peng

    2015-11-01

    The distribution of galaxies displays anisotropy on different scales and it is often referred to as galaxy alignment. To understand the origin of galaxy alignments on small scales, one must investigate how galaxies were accreted in the early universe and quantify their primordial anisotropy at the time of accretion. In this paper we use N-body simulations to investigate the accretion of subhalos, focusing on their alignment with halo shape and the orientation of mass distribution on the large scale, defined using the Hessian matrix of the density field. The large/small (e1/e3) eigenvalues of the Hessian matrix define the fast/slow collapse direction of matter on the large scale. We find that: (1) the halo major axis is well aligned with the e3 (slow collapse) direction, and it is stronger for massive halos; (2) subhalos are predominantly accreted along the major axis of the host halo, and the alignment increases with the host halo mass. Most importantly, this alignment is universal; (3) accretion of subhalos with respect to the e3 direction is not universal. In massive halos, subhalos are accreted along the e3 (even more strongly than the alignment with the halo major axis), but in low-mass halos subhalos are accreted perpendicular to e3. The transitional mass is lower at high redshift. The last result well explains the puzzling correlation (both in recent observations and simulations) that massive galaxies/halos have their spin perpendicular to the filament, and the spin of low-mass galaxies/halos is slightly aligned with the filament, under the assumption that the orbital angular momentum of subhalos is converted to halo spin.

  14. 75 FR 26822 - In the Matter of: Universal Property Development & Acquisition Corp.; Order of Suspension of Trading

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-12

    ... [Federal Register Volume 75, Number 91 (Wednesday, May 12, 2010)] [Notices] [Page 26822] [FR Doc No: 2010-11401] SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] In the Matter of: Universal Property Development & Acquisition Corp.; Order of Suspension of Trading May 10, 2010. It appears to...

  15. 77 FR 4389 - In the Matter of Tornado Gold International Corp., Twin Faces East Entertainment Corp., Universal...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-27

    ... From the Federal Register Online via the Government Publishing Office SECURITIES AND EXCHANGE COMMISSION In the Matter of Tornado Gold International Corp., Twin Faces East Entertainment Corp., Universal... that there is a lack of current and accurate information concerning the securities of Tornado...

  16. 77 FR 16890 - In the Matter of ProElite, Inc. and Universal Guardian Holdings, Inc.: Order of Suspension of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-22

    ... From the Federal Register Online via the Government Publishing Office ] SECURITIES AND EXCHANGE COMMISSION In the Matter of ProElite, Inc. and Universal Guardian Holdings, Inc.: Order of Suspension of... current and accurate information concerning the securities of ProElite, Inc. because it has not filed any...

  17. Singularity free N-body simulations called 'Dynamic Universe Model' don't require dark matter

    NASA Astrophysics Data System (ADS)

    Naga Parameswara Gupta, Satyavarapu

    For finding trajectories of Pioneer satellite (Anomaly), New Horizons satellite going to Pluto, the Calculations of Dynamic Universe model can be successfully applied. No dark matter is assumed within solar system radius. The effect on the masses around SUN shows as though there is extra gravitation pull toward SUN. It solves the Dynamics of Extra-solar planets like Planet X, satellite like Pioneer and NH for 3-Position, 3-velocity 3-accelaration for their masses, considering the complex situation of Multiple planets, Stars, Galaxy parts and Galaxy centre and other Galaxies Using simple Newtonian Physics. It already solved problems Missing mass in Galaxies observed by galaxy circular velocity curves successfully. Singularity free Newtonian N-body simulations Historically, King Oscar II of Sweden an-nounced a prize to a solution of N-body problem with advice given by Güsta Mittag-Leffler in 1887. He announced `Given a system of arbitrarily many mass points that attract each according to Newton's law, under the assumption that no two points ever collide, try to find a representation of the coordinates of each point as a series in a variable that is some known function of time and for all of whose values the series converges uniformly.'[This is taken from Wikipedia]. The announced dead line that time was1st June 1888. And after that dead line, on 21st January 1889, Great mathematician Poincaré claimed that prize. Later he himself sent a telegram to journal Acta Mathematica to stop printing the special issue after finding the error in his solution. Yet for such a man of science reputation is important than money. [ Ref Book `Celestial mechanics: the waltz of the planets' By Alessandra Celletti, Ettore Perozzi, page 27]. He realized that he has been wrong in his general stability result! But till now nobody could solve that problem or claimed that prize. Later all solutions resulted in singularities and collisions of masses, given by many people

  18. Bianchi type-I universe in f(R, T) modified gravity with quark matter and Λ

    NASA Astrophysics Data System (ADS)

    Ćaǧlar, Halife; Aygün, Sezgin

    2017-02-01

    In this study, we investigate homogeneous and anisotropic Bianchi type I universe in the presence of quark matter source in f(R, T) gravity (Harko et al. in Phys. Rev. D 84:024020, 2011) with cosmological constant Λ (where R is the Ricci scalar and T is the trace of the energy momentum tensor). For this aim we have used the anisotropy feature of Bianchi type I universe and equation of states (EoS) of quark matter. We explore the exact solution f(R,T)=R+2f(T) model for Bianchi type I universe model. When t→∞, we get very small cosmological constant value, this result agrees with recent observations.

  19. Reionization in a cold dark matter universe: The feedback of galaxy formation on the intergalactic medium

    NASA Technical Reports Server (NTRS)

    Shapiro, Paul R.; Giroux, Mark L.; Babul, Arif

    1994-01-01

    We study the coupled evolution of the intergalactic medium (IGM) and the emerging structure in the universe in the context of the cold dark matter (CDM) model, with a special focus on the consequences of imposing reionization and the Gunn-Peterson constraint as a boundary condition on the model. We have calculated the time-varying density of the IGM by coupling our detailed, numerical calculations of the thermal and ionization balance and radiative transfer in a uniform, spatially averaged IGM of H and He, including the mean opacity of an evolving distribution of gas clumps which correspond to quasar absorption line clouds, to the linearized equations for the growth of density fluctuations in both the gaseous and dark matter components in a CDM universe. We use the linear growth equations to identify the fraction of the gas which must have collapsed out at each epoch, an approach similar in spirit to the so-called Press-Schechter formalism. We identify the IGM density with the uncollapsed baryon fraction. The collapsed fraction is postulated to be a source of energy injection into the IGM, by radiation or bulk hydrodynamical heating (e.g., via shocks) or both, at a rate which is marginally enough to satisfy the Gunn-Peterson constraint at z less than 5. Our results include the following: (1) We find that the IGM in a CDM model must have contained a substantial fraction of the total baryon density of the universe both during and after its reionization epoch. (2) As a result, our previous conclusion that the observed Quasi-Stellar Objects (QSOs) at high redshift are not sufficient to ionize the IGM enough to satisfy the Gunn-Peterson constraint is confirmed. (3) We predict a detectable He II Gunn-Peterson effect at 304(1 + z) A in the spectra of quasars at a range of redshift z greater than or approx. 3, depending on the nature of the sources of IGM reionization. (4) We find, moreover, that a CDM model with high bias parameter b (i.e., b greater than or approx. 2

  20. Reionization in a cold dark matter universe: The feedback of galaxy formation on the intergalactic medium

    NASA Technical Reports Server (NTRS)

    Shapiro, Paul R.; Giroux, Mark L.; Babul, Arif

    1994-01-01

    We study the coupled evolution of the intergalactic medium (IGM) and the emerging structure in the universe in the context of the cold dark matter (CDM) model, with a special focus on the consequences of imposing reionization and the Gunn-Peterson constraint as a boundary condition on the model. We have calculated the time-varying density of the IGM by coupling our detailed, numerical calculations of the thermal and ionization balance and radiative transfer in a uniform, spatially averaged IGM of H and He, including the mean opacity of an evolving distribution of gas clumps which correspond to quasar absorption line clouds, to the linearized equations for the growth of density fluctuations in both the gaseous and dark matter components in a CDM universe. We use the linear growth equations to identify the fraction of the gas which must have collapsed out at each epoch, an approach similar in spirit to the so-called Press-Schechter formalism. We identify the IGM density with the uncollapsed baryon fraction. The collapsed fraction is postulated to be a source of energy injection into the IGM, by radiation or bulk hydrodynamical heating (e.g., via shocks) or both, at a rate which is marginally enough to satisfy the Gunn-Peterson constraint at z less than 5. Our results include the following: (1) We find that the IGM in a CDM model must have contained a substantial fraction of the total baryon density of the universe both during and after its reionization epoch. (2) As a result, our previous conclusion that the observed Quasi-Stellar Objects (QSOs) at high redshift are not sufficient to ionize the IGM enough to satisfy the Gunn-Peterson constraint is confirmed. (3) We predict a detectable He II Gunn-Peterson effect at 304(1 + z) A in the spectra of quasars at a range of redshift z greater than or approx. 3, depending on the nature of the sources of IGM reionization. (4) We find, moreover, that a CDM model with high bias parameter b (i.e., b greater than or approx. 2

  1. Does the Choice of University Matter? A Study of the Differences across UK Universities in Life Sciences Students' Degree Performance.

    ERIC Educational Resources Information Center

    Bratti, Massimiliano

    2002-01-01

    Investigates differences across UK universities in 1993 life-sciences students' degree performance using individual-level data from the universities' Statistical Record. Analyzes differences across universities by specifying and estimating a subject-specific production function. Even after including a wide range of controls for the quality of…

  2. Sources and detection of dark matter in the universe. Proceedings. Workshop on Primordial Black Holes and Hawking Radiation and 3rd International Symposium on Sources and Detection of Dark Matter in the Universe, Marina del Rey, CA (USA), 17 - 20 Feb 1998.

    NASA Astrophysics Data System (ADS)

    1998-12-01

    The following topics were dealt with: early universe and cosmological constants of the universe, large scale nature of the universe, gravitational lensing and microlensing, formation of primordial black holes, Hawking radiation, current search for primordial black holes, theoretical studies of particle dark matter, and experimental progress on the search for dark matter elementary particles.

  3. The correlation between emotional intelligence and gray matter volume in university students.

    PubMed

    Tan, Yafei; Zhang, Qinglin; Li, Wenfu; Wei, Dongtao; Qiao, Lei; Qiu, Jiang; Hitchman, Glenn; Liu, Yijun

    2014-11-01

    A number of recent studies have investigated the neurological substrates of emotional intelligence (EI), but none of them have considered the neural correlates of EI that are measured using the Schutte Self-Report Emotional Intelligence Scale (SSREIS). This scale was developed based on the EI model of Salovey and Mayer (1990). In the present study, SSREIS was adopted to estimate EI. Meanwhile, magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) were used to evaluate the gray matter volume (GMV) of 328 university students. Results found positive correlations between Monitor of Emotions and VBM measurements in the insula and orbitofrontal cortex. In addition, Utilization of Emotions was positively correlated with the GMV in the parahippocampal gyrus, but was negatively correlated with the VBM measurements in the fusiform gyrus and middle temporal gyrus. Furthermore, Social Ability had volume correlates in the vermis. These findings indicate that the neural correlates of the EI model, which primarily focuses on the abilities of individuals to appraise and express emotions, can also regulate and utilize emotions to solve problems. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. The Coyote Universe. III. Simulation Suite and Precision Emulator for the Nonlinear Matter Power Spectrum

    NASA Astrophysics Data System (ADS)

    Lawrence, Earl; Heitmann, Katrin; White, Martin; Higdon, David; Wagner, Christian; Habib, Salman; Williams, Brian

    2010-04-01

    Many of the most exciting questions in astrophysics and cosmology, including the majority of observational probes of dark energy, rely on an understanding of the nonlinear regime of structure formation. In order to fully exploit the information available from this regime and to extract cosmological constraints, accurate theoretical predictions are needed. Currently, such predictions can only be obtained from costly, precision numerical simulations. This paper is the third in a series aimed at constructing an accurate calibration of the nonlinear mass power spectrum on Mpc scales for a wide range of currently viable cosmological models, including dark energy models with w ≠ -1. The first two papers addressed the numerical challenges and the scheme by which an interpolator was built from a carefully chosen set of cosmological models. In this paper, we introduce the "Coyote Universe" simulation suite which comprises nearly 1000 N-body simulations at different force and mass resolutions, spanning 38 w CDM cosmologies. This large simulation suite enables us to construct a prediction scheme, or emulator, for the nonlinear matter power spectrum accurate at the percent level out to k ~= 1 h Mpc-1. We describe the construction of the emulator, explain the tests performed to ensure its accuracy, and discuss how the central ideas may be extended to a wider range of cosmological models and applications. A power spectrum emulator code is released publicly as part of this paper.

  5. DARK MATTER DECAY AND ANNIHILATION IN THE LOCAL UNIVERSE: CLUES FROM FERMI

    SciTech Connect

    Cuesta, A. J.; Zandanel, F.; Prada, F.; Jeltema, T. E.; Yepes, G.; Klypin, A.; Hoffman, Y.; Gottloeber, S.; Sanchez-Conde, M. A.; Pfrommer, C. E-mail: fabio@iaa.es

    2011-01-01

    We present all-sky simulated Fermi maps of {gamma}-rays from dark matter (DM) decay and annihilation in the local universe. The DM distribution is obtained from a constrained cosmological simulation of the neighboring large-scale structure provided by the CLUES project. The DM fields of density and density squared are then taken as an input for the Fermi observation simulation tool to predict the {gamma}-ray photon counts that Fermi would detect in 5 years of an all-sky survey for given DM models. Signal-to-noise ratio (S/N) sky maps have also been obtained by adopting the current Galactic and isotropic diffuse background models released by the Fermi Collaboration. We point out the possibility for Fermi to detect a DM {gamma}-ray signal in local extragalactic structures. In particular, we conclude here that Fermi observations of nearby clusters (e.g., Virgo and Coma) and filaments are expected to give stronger constraints on decaying DM compared to previous studies. As an example, we find a significant S/N in DM models with a decay rate fitting the positron excess as measured by PAMELA. This is the first time that DM filaments are shown to be promising targets for indirect detection of DM. On the other hand, the prospects for detectability of annihilating DM in local extragalactic structures are less optimistic even with extreme cross-sections. We make the DM density and density squared maps publicly available online.

  6. The evolving intergalactic medium - The uncollapsed baryon fraction in a cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Shapiro, Paul R.; Giroux, Mark L.; Babul, Arif

    1991-01-01

    The time-varying density of the intergalactic medium (IGM) is calculated by coupling detailed numerical calculations of the thermal and ionization balance and radiative transfer in a uniform IGM of H and He to the linearized equations for the growth of density fluctuations in both gases and a dark component in a cold dark matter universe. The IGM density is identified with the collapsed baryon fraction. It is found that even if the IGM is never reheated, a significant fraction of the baryons remain uncollapsed at redshifts of four. If instead the collapsed fraction releases enough ionizing radiation or thermal energy to reionize the IGM by z greater than four as required by the Gunn-Peterson (GP) constraint, the uncollapsed fraction at z of four is even higher. The known quasar distribution is insufficient to supply the ionizing radiation necessary to satisfy the GP constraint in this case and, if stars are instead responsible, a substantial metallicity must have been produced by z of four.

  7. The evolving intergalactic medium - The uncollapsed baryon fraction in a cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Shapiro, Paul R.; Giroux, Mark L.; Babul, Arif

    1991-01-01

    The time-varying density of the intergalactic medium (IGM) is calculated by coupling detailed numerical calculations of the thermal and ionization balance and radiative transfer in a uniform IGM of H and He to the linearized equations for the growth of density fluctuations in both gases and a dark component in a cold dark matter universe. The IGM density is identified with the collapsed baryon fraction. It is found that even if the IGM is never reheated, a significant fraction of the baryons remain uncollapsed at redshifts of four. If instead the collapsed fraction releases enough ionizing radiation or thermal energy to reionize the IGM by z greater than four as required by the Gunn-Peterson (GP) constraint, the uncollapsed fraction at z of four is even higher. The known quasar distribution is insufficient to supply the ionizing radiation necessary to satisfy the GP constraint in this case and, if stars are instead responsible, a substantial metallicity must have been produced by z of four.

  8. Making the Best of a World Dominated by League Tables? New Developments in the International Ranking of Universities

    ERIC Educational Resources Information Center

    Observatory on Borderless Higher Education, 2010

    2010-01-01

    Two interesting initiatives have started to develop more balanced international league tables of universities. The first initiative is being taken by UK magazine the Times Higher Education (THE), which recently entered into a collaboration with both the international academic community and research-metrics company Thomsons Reuters to create an…

  9. Making the Best of a World Dominated by League Tables? New Developments in the International Ranking of Universities

    ERIC Educational Resources Information Center

    Observatory on Borderless Higher Education, 2010

    2010-01-01

    Two interesting initiatives have started to develop more balanced international league tables of universities. The first initiative is being taken by UK magazine the Times Higher Education (THE), which recently entered into a collaboration with both the international academic community and research-metrics company Thomsons Reuters to create an…

  10. Cultivating Self-Worth among Dislocated Tibetan Undergraduate Students in a Chinese Han-Dominated National Key University

    ERIC Educational Resources Information Center

    Yi, Lin; Wang, Lili

    2012-01-01

    Drawing upon fieldwork conducted with a group of dislocated Tibetan undergraduate students of the "neidi ban" program in a Han-predominated university, this paper examines the ways in which these students make sense of their worlds. To achieve this, they have actively and engagingly organized a series of symbolically meaningful…

  11. Dark matter in ghost-free bigravity theory: From a galaxy scale to the universe

    NASA Astrophysics Data System (ADS)

    Aoki, Katsuki; Maeda, Kei-ichi

    2014-12-01

    We study the origin of dark matter based on the ghost-free bigravity theory with twin matter fluids. The present cosmic acceleration can be explained by the existence of graviton mass, while dark matter is required in several cosmological situations (the galactic missing mass, the cosmic structure formation and the cosmic microwave background observation). Assuming that the Compton wavelength of the massive graviton is shorter than a galactic scale, we show the bigravity theory can explain dark matter by twin matter fluid as well as the cosmic acceleration by tuning appropriate coupling constants.

  12. The closed-universe recollapse conjecture

    NASA Astrophysics Data System (ADS)

    Barrow, John D.; Galloway, Gregory J.; Tipler, Frank J.

    1986-12-01

    It is widely believed that all expanding S3 closed universes that satisfy the standard energy conditions recollapse to a second singularity. The authors show that this is false even for Friedmann universes: they construct an ever-expanding S3 Friedmann universe in which the matter tensor satisfies the strong, weak and dominant energy conditions and the generic condition. The authors prove a general recollapse theorem for Friedmann universes: if the positive pressure criterion, dominant energy condition and matter regularity condition hold, then an S3 Friedmann universe must recollapse. The authors show that all known vacuum solutions with Cauchy surface topology S3 or S2×S1 recollapse, and they conjecture that this is a property of all vacuum solutions of Einstein's equations with such Cauchy surfaces. The authors consider a number of Kantowski-Sachs and Bianchi IX universes with various matter tensors, and formulate a new recollapse conjecture for matter-filled universes.

  13. The X-Shooter Lens Survey - I. Dark matter domination and a Salpeter-type initial mass function in a massive early-type galaxy

    NASA Astrophysics Data System (ADS)

    Spiniello, C.; Koopmans, L. V. E.; Trager, S. C.; Czoske, O.; Treu, T.

    2011-11-01

    -derived mass limit. We conclude that this very massive early-type galaxy is dark-matter-dominated inside one effective radius, consistent with the trend recently found from massive Sloan Lens ACS (SLACS) galaxies, with a total density slope shallower than isothermal and an IMF normalization consistent with Salpeter.

  14. In-situ, satellite measurement and model evidence for a~dominant regional contribution to fine particulate matter levels in the Paris Megacity

    NASA Astrophysics Data System (ADS)

    Beekmann, M.; Prévôt, A. S. H.; Drewnick, F.; Sciare, J.; Pandis, S. N.; Denier van der Gon, H. A. C.; Crippa, M.; Freutel, F.; Poulain, L.; Ghersi, V.; Rodriguez, E.; Beirle, S.; Zotter, P.; von der Weiden-Reinmüller, S.-L.; Bressi, M.; Fountoukis, C.; Petetin, H.; Szidat, S.; Schneider, J.; Rosso, A.; El Haddad, I.; Megaritis, A.; Zhang, Q. J.; Michoud, V.; Slowik, J. G.; Moukhtar, S.; Kolmonen, P.; Stohl, A.; Eckhardt, S.; Borbon, A.; Gros, V.; Marchand, N.; Jaffrezo, J. L.; Schwarzenboeck, A.; Colomb, A.; Wiedensohler, A.; Borrmann, S.; Lawrence, M.; Baklanov, A.; Baltensperger, U.

    2015-03-01

    A detailed characterization of air quality in Paris (France), a megacity of more than 10 million inhabitants, during two one month intensive campaigns and from additional one year observations, revealed that about 70% of the fine particulate matter (PM) at urban background is transported on average into the megacity from upwind regions. This dominant influence of regional sources was confirmed by in-situ measurements during short intensive and longer term campaigns, aerosol optical depth (AOD) measurements from ENVISAT, and modeling results from PMCAMx and CHIMERE. While advection of sulfate is well documented for other megacities, there was surprisingly high contribution from long-range transport for both nitrate and organic aerosol. The origin of organic PM was investigated by a comprehensive analysis of aerosol mass spectrometer (AMS), radiocarbon and tracer measurements during two intensive campaigns. Primary fossil fuel combustion emissions contributed less than 20% in winter and 40% in summer to carbonaceous fine PM, unexpectedly little for a megacity. Cooking activities and, during winter, residential wood burning are the major primary organic PM sources. This analysis suggests that the major part of secondary organic aerosol is of modern origin, i.e. from biogenic precursors and from wood burning. Black carbon concentrations are on the lower end of values encountered in megacities worldwide, but still represent an issue for air quality. These comparatively low air pollution levels are due to a combination of low emissions per inhabitant, flat terrain, and a meteorology that is in general not conducive to local pollution build-up. This revised picture of a megacity only controlling part of its own average and peak PM levels has important implications for air pollution regulation policies.

  15. Equation of state, universal profiles, scaling and macroscopic quantum effects in warm dark matter galaxies

    NASA Astrophysics Data System (ADS)

    de Vega, H. J.; Sanchez, N. G.

    2017-02-01

    The Thomas-Fermi approach to galaxy structure determines self-consistently and non-linearly the gravitational potential of the fermionic warm dark matter (WDM) particles given their quantum distribution function f( E). This semiclassical framework accounts for the quantum nature and high number of DM particles, properly describing gravitational bounded and quantum macroscopic systems as neutron stars, white dwarfs and WDM galaxies. We express the main galaxy magnitudes as the halo radius r_h , mass M_h , velocity dispersion and phase space density in terms of the surface density which is important to confront to observations. From these expressions we derive the general equation of state for galaxies, i.e., the relation between pressure and density, and provide its analytic expression. Two regimes clearly show up: (1) Large diluted galaxies for M_h ≳ 2.3 × 10^6 M_⊙ and effective temperatures T_0 > 0.017 K described by the classical self-gravitating WDM Boltzman gas with a space-dependent perfect gas equation of state, and (2) Compact dwarf galaxies for 1.6 × 10^6 M_⊙ ≳ M_h ≳ M_{h,min} ˜eq 3.10 × 10^4 (2 {keV}/m)^{16/5} M_⊙, T_0 < 0.011 K described by the quantum fermionic WDM regime with a steeper equation of state close to the degenerate state. In particular, the T_0 = 0 degenerate or extreme quantum limit yields the most compact and smallest galaxy. In the diluted regime, the halo radius r_h , the squared velocity v^2(r_h) and the temperature T_0 turn to exhibit square-root of M_h scaling laws. The normalized density profiles ρ (r)/ρ (0) and the normalized velocity profiles v^2(r)/ v^2(0) are universal functions of r/r_h reflecting the WDM perfect gas behavior in this regime. These theoretical results contrasted to robust and independent sets of galaxy data remarkably reproduce the observations. For the small galaxies, 10^6 ≳ M_h ≥ M_{h,min} , the equation of state is galaxy mass dependent and the density and velocity profiles are not

  16. Finding the Axion: The Search for the Dark Matter of the Universe

    SciTech Connect

    Carosi, G

    2006-11-03

    The nature of dark matter has been a mystery for over 70 years. One plausible candidate is the axion, an extremely light and weakly interacting particle, which results from the Peccei-Quinn solution to the strong CP problem. In this proceedings I will briefly review the evidence for dark matter as well as the motivation for the existence of the axion as a prime dark matter candidate. I will then discuss the experimental methods to search for axion dark matter focusing on a sensitive cavity experiment (ADMX) being run at Lawrence Livermore National Laboratory.

  17. Dark Matter annihilations in halos and high-redshift sources of reionization of the universe

    SciTech Connect

    Poulin, Vivian; Serpico, Pasquale D.; Lesgourgues, Julien E-mail: Pasquale.Serpico@lapth.cnrs.fr

    2015-12-01

    It is well known that annihilations in the homogeneous fluid of dark matter (DM) can leave imprints in the cosmic microwave background (CMB) anisotropy power spectrum. However, the relevance of DM annihilations in halos for cosmological observables is still subject to debate, with previous works reaching different conclusions on this point. Also, all previous studies used a single type of parameterization for the astrophysical reionization, and included no astrophysical source for the heating of the intergalactic medium. In this work, we revisit these problems. When standard approaches are adopted, we find that the ionization fraction does exhibit a very particular (and potentially constraining) pattern, but the currently measurable τ{sub reio} is left almost unchanged: in agreement with most of the previous literature, for plausible halo models we find that the modification of the signal with respect to the one coming from annihilations in the smooth background is tiny, below cosmic variance within currently allowed parameter space. However, if different and probably more realistic treatments of the astrophysical sources of reionization and heating are adopted, a more pronounced effect of the DM annihilation in halos is possible. We thus conclude that within currently adopted baseline models the impact of the virialised DM structures cannot be uncovered by CMB power spectra measurements, but a larger impact is possible if peculiar models are invoked for the redshift evolution of the DM annihilation signal or different assumptions are made for the astrophysical contributions. A better understanding (both theoretical and observational) of the reionization and temperature history of the universe, notably via the 21 cm signal, seems the most promising way for using halo formation as a tool in DM searches, improving over the sensitivity of current cosmological probes.

  18. Dark Matter annihilations in halos and high-redshift sources of reionization of the universe

    NASA Astrophysics Data System (ADS)

    Poulin, Vivian; Serpico, Pasquale D.; Lesgourgues, Julien

    2015-12-01

    It is well known that annihilations in the homogeneous fluid of dark matter (DM) can leave imprints in the cosmic microwave background (CMB) anisotropy power spectrum. However, the relevance of DM annihilations in halos for cosmological observables is still subject to debate, with previous works reaching different conclusions on this point. Also, all previous studies used a single type of parameterization for the astrophysical reionization, and included no astrophysical source for the heating of the intergalactic medium. In this work, we revisit these problems. When standard approaches are adopted, we find that the ionization fraction does exhibit a very particular (and potentially constraining) pattern, but the currently measurable τreio is left almost unchanged: in agreement with most of the previous literature, for plausible halo models we find that the modification of the signal with respect to the one coming from annihilations in the smooth background is tiny, below cosmic variance within currently allowed parameter space. However, if different and probably more realistic treatments of the astrophysical sources of reionization and heating are adopted, a more pronounced effect of the DM annihilation in halos is possible. We thus conclude that within currently adopted baseline models the impact of the virialised DM structures cannot be uncovered by CMB power spectra measurements, but a larger impact is possible if peculiar models are invoked for the redshift evolution of the DM annihilation signal or different assumptions are made for the astrophysical contributions. A better understanding (both theoretical and observational) of the reionization and temperature history of the universe, notably via the 21 cm signal, seems the most promising way for using halo formation as a tool in DM searches, improving over the sensitivity of current cosmological probes.

  19. Quasidecoupled state for dark matter in nonstandard thermal histories

    NASA Astrophysics Data System (ADS)

    Waldstein, Isaac Raj; Erickcek, Adrienne L.; Ilie, Cosmin

    2017-06-01

    Dark matter drops out of kinetic equilibrium with standard model particles when the momentum-transfer rate equals the expansion rate. In a radiation-dominated universe, this occurs at essentially the same time as dark matter kinetically decouples from the plasma. Dark matter may also fall out of kinetic equilibrium with standard model particles during an early matter-dominated era (EMDE), which occurs when the energy content of the Universe is dominated by either a decaying oscillating scalar field or a semistable massive particle before big bang nucleosynthesis. Until now, it has been assumed that kinetic decoupling during an EMDE happens similarly to the way it does in a radiation-dominated era. We show that this is not the case. By studying the evolution of the dark matter temperature, we establish a quasidecoupled state for dark matter in an EMDE, during which the dark matter temperature cools faster than the plasma temperature but slower than it would cool if the dark matter were fully decoupled. The dark matter does not fully decouple until the EMDE ends and the Universe becomes radiation dominated. We also extend the criteria for quasidecoupling to other nonstandard thermal histories and consider how quasidecoupling affects the free-streaming length of dark matter.

  20. The Spheronic Toy Universe: How Special Relativity may be Visualised to Emerge from a Wave-Nature of Matter

    NASA Astrophysics Data System (ADS)

    Schmid, Manfred; Kroupa, Pavel

    2014-08-01

    We construct an idealised universe for didactic purposes. This universe is assumed to consist of absolute Euclidean space and to be filled with a classical medium which allows for sound waves. A known solution to the wave equation describing the dynamics of the medium is a standing spherical wave. Although this is a problem of classical mechanics, we demonstrate that the Lorentz transformation is required to generate a moving solution from the stationary one. Both solutions are here collectively referred to as "spherons". These spherons exhibit properties which have analogues in the physical description of matter with rest mass, among them de Broglie like phase waves and at the same time "relativistic" effects such as contraction and a speed limit. This leads to a theory of special relativity by assuming the point of view of an observer made of such spheronic "matter". The argument made here may thus be useful as a visualisation or didactic approach to the real universe, in which matter has wave-like properties and obeys the laws of special relativity.

  1. Growth of the nonbaryonic dark matter theory

    NASA Astrophysics Data System (ADS)

    Peebles, P. J. E.

    2017-03-01

    The evidence that has accumulated since the 1930s is that the mass of the Universe is dominated by an exotic nonbaryonic form of matter largely draped around the galaxies. This dark matter approximates an initially low-pressure gas of particles that interact only with gravity, but we know little more than that. Searches for detection thus must follow many difficult paths to a great discovery: what the Universe is made of.

  2. The spin and shape of dark matter haloes in the Millennium simulation of a Λ cold dark matter universe

    NASA Astrophysics Data System (ADS)

    Bett, Philip; Eke, Vincent; Frenk, Carlos S.; Jenkins, Adrian; Helly, John; Navarro, Julio

    2007-03-01

    We investigate the spins and shapes of over a million dark matter haloes identified at z = 0 in the Millennium simulation. Our sample spans halo masses ranging from dwarf galaxies to rich galaxy clusters. The very large dynamic range of this Λ cold dark matter cosmological simulation enables the distribution of spins and shapes and their variation with halo mass and environment to be characterized with unprecedented precision. We compare results for haloes identified using three different algorithms, and investigate (and remove) biases in the estimate of angular momentum introduced both by the algorithm itself and by numerical effects. We introduce a novel halo definition called the TREE halo, based on the branches of the halo merger trees, which is more appropriate for comparison with real astronomical objects than the traditional `friends-of-friends' and `spherical overdensity' (SO) algorithms. We find that for this many objects, the traditional lognormal function is no longer an adequate description of the distribution, P(λ), of the dimensionless spin parameter λ, and we provide a different function that gives a better fit for TREE and SO haloes. The variation in spin with halo mass is weak but detectable, although the trend depends strongly on the halo definition used. For the entire population of haloes, we find median values of λmed = 0.0367-0.0429, depending on the definition of a halo. The haloes exhibit a range of shapes, with a preference for prolateness over oblateness. More-massive haloes tend to be less spherical and more prolate. We find that the more-spherical haloes have less coherent rotation in the median, and those closest to being spherical have a spin independent of mass (λmed ~ 0.033). The most-massive haloes have a spin independent of shape (λmed ~ 0.032). The majority of haloes have their angular momentum vector aligned with their minor axis and perpendicular to their major axis. We find a general trend for higher spin haloes to be

  3. ISO confirms that the normal matter in the Universe is not enough to cause a Big Crunch

    NASA Astrophysics Data System (ADS)

    1999-03-01

    Deuterium, an isotope of hydrogen, is a key element for astronomers studying the origin of the Universe. All the deuterium that can be detected today was produced a few minutes after the Big Bang, during a process called primordial nucleosynthesis --in which a few other elements, like hydrogen and helium,were also made. Apart from the Big Bang, there are no other known sources of deuterium in the Universe. Thus, astronomers regard deuterium as a 'fossil element' that holds a lot of cosmological information. Specifically, the abundance of deuterium in the new-born Universe is directly related to the total amount of existing normal matter -the so-called 'baryonic' matter--, the value upon which depends the ultimate fate of our Universe. According to the most accepted theories, if the total amount of matter exceeds a certain number, known as the critical density, in the far future the Universe will stop expanding and will collapse into a 'Big Crunch'; otherwise, the expansion will continue forever. But measuring the abundance of primordial deuterium is not easy. It started off at one value at the time of the Big Bang -10 to 15 billion years ago-, but has since diminished significantly because it is destroyed by nuclear reactions in the interior of the stars. Astronomers, therefore, have measured different values for deuterium in different places and are trying to extrapolate back in time to the deuterium abundance at the Big Bang. The new result obtained by the international team led by Chris Wright (School of Physics, University College, Canberra, Australia) and Ewine van Dishoeck (Leiden University Observatory, The Netherlands), using the Long Wavelength Spectrometer (LWS) on board ISO, allows for the first time to infer the deuterium abundance in an actively star forming region, the Orion Bar in the Orion nebula, about 1,500 light-years away. The deuterium they measured was locked up in the primary deuterium bearing molecule in the Universe, hydrogen deuteride (HD

  4. Hints about Dark, Light-Bending Matter in the Distant Universe

    NASA Astrophysics Data System (ADS)

    1997-07-01

    New infrared observations of a gravitational lens About 20 cases of gravitationally lensed (GL) quasars are known. This special physical effect, also known as a cosmic mirage, occurs when the rays of light of a distant quasar on their way to us pass near a massive object, for instance a galaxy. As a result, two or more images of the same quasar will be seen near each other. This phenomenon is described in more detail in the Appendix. A new study by a group of three European astronomers, headed by Frederic Courbin ( Institut d'Astrophysique, Universite de Liege, Belgium, and Observatoire de Paris-Meudon, France) [1], has led to the discovery of the object responsible for the double images of a remote quasar in the gravitational lens HE 1104-1805 . The investigation is based on infrared observations at the ESO La Silla Observatory in Chile and the `lensing system' turns out to be a distant, massive galaxy. Nevertheless, the geometry of the object is unusual and an additional gravitational lens of `dark' (invisible) matter may possibly be involved. This gravitational lens is also particularly well suited for future cosmological studies that aim at the determination of the Hubble constant and the expansion rate of the Universe. A new and detailed study of gravitational lenses It is rare among the relatively few, confirmed cases of gravitational lensing in the distant Universe, that the distribution of matter in the lensing system is well known. However, it is exactly this information that is needed to derive cosmological parameters by means of photometric monitoring of the brightness of the individual images in a gravitational lens [2]. The three astronomers have therefore undertaken a detailed study of some previously known gravitational lenses (or good candidate objects) with the primary aim to detect and map the associated lensing matter (refered to as the gravitational deflector or lensing object ). This is observationally quite difficult and time-consuming since

  5. Student Graduation in Spain: To What Extent Does University Expenditure Matter?

    ERIC Educational Resources Information Center

    García-Estevez, Javier; Duch-Brown, Néstor

    2014-01-01

    Graduation rates (GRs) remain one of the most frequently applied measures of institutional performance. This paper analyzes the relationship between university characteristics and GRs in Spain, using a dataset for the entire public university system over the period 1998-2008. Since we observe the same university over several years, we address the…

  6. What Matters Most: Factors Influencing the University Application Choice Decisions of Korean International Students and Parents

    ERIC Educational Resources Information Center

    Parslow, Breanna

    2014-01-01

    The purpose of this study is to determine factors influencing Korean parents' and students' university application choice decisions in three international schools in the Republic of Korea (South). Institutional and individual factors that influenced Korean students' university application choice decisions and their parents' university application…

  7. Student Graduation in Spain: To What Extent Does University Expenditure Matter?

    ERIC Educational Resources Information Center

    García-Estevez, Javier; Duch-Brown, Néstor

    2014-01-01

    Graduation rates (GRs) remain one of the most frequently applied measures of institutional performance. This paper analyzes the relationship between university characteristics and GRs in Spain, using a dataset for the entire public university system over the period 1998-2008. Since we observe the same university over several years, we address the…

  8. Universities' Access to Research Funds: Do Institutional Features and Strategies Matter?

    ERIC Educational Resources Information Center

    Rossi, Federica

    2009-01-01

    Competitively allocated research funds, from both public and private sources, constitute an increasing share of university revenues. The article investigates empirically, using data on the Italian university system, whether structural and strategic features of universities--such as size, age and especially the importance that they assign to their…

  9. University Leaders and University Performance in the United Kingdom: Is It "Who" Leads, or "Where" They Lead that Matters Most?

    ERIC Educational Resources Information Center

    Breakwell, Glynis M.; Tytherleigh, Michelle Y.

    2010-01-01

    With key performance indicators (KPIs) part of everyday life in the higher education (HE) sector, universities have become increasingly concerned with league tables and performance indicator-led strategy and planning. The choice an institution makes concerning the KPIs it wishes to be evaluated on depends on its mission and objectives, with a Head…

  10. University Leaders and University Performance in the United Kingdom: Is It "Who" Leads, or "Where" They Lead that Matters Most?

    ERIC Educational Resources Information Center

    Breakwell, Glynis M.; Tytherleigh, Michelle Y.

    2010-01-01

    With key performance indicators (KPIs) part of everyday life in the higher education (HE) sector, universities have become increasingly concerned with league tables and performance indicator-led strategy and planning. The choice an institution makes concerning the KPIs it wishes to be evaluated on depends on its mission and objectives, with a Head…

  11. Autosomal dominant

    MedlinePlus

    ... whether the trait is dominant or recessive. A single abnormal gene on one of the first 22 nonsex ( autosomal ) chromosomes from either parent can cause an autosomal disorder. Dominant inheritance means ...

  12. Probing dark matter, galaxies and the expansion history of the Universe with Lyα in absorption and emission

    NASA Astrophysics Data System (ADS)

    Haehnelt, M. G.

    2010-05-01

    Lyα radiation is an important diagnostic tool in a wide range of astrophysical environments. I will first describe here how measurements of the matter power spectrum on small scales from Lyα forest data constrain the mass of dark matter particles. I then will report on an ambitious program of searching for very faint spatially extended Lyα emission at z ˜ 3 which has led to the discovery of a new population of faint Lyα emitters which I will argue should be identified with the long searched for host galaxies of damped Lyα absorbers. Finally, I will discuss the possibility of measuring the redshift drift of Lyα absorption features and therefore the change of the expansion rate of the Universe in real time with the ultra-stable high-resolution spectrograph CODEX proposed for the E-ELT.

  13. Cardiomyopathy confers susceptibility to particulate matter-induced oxidative stress, vagal dominance, arrhythmia, pulmonary inflammation in heart failure-prone rats

    EPA Science Inventory

    Acute exposure to ambient fine particulate matter (PM2.5) is tied to cardiovascular morbidity and mortality, especially among those with prior cardiac injury. The mechanisms and pathophysiologic events precipitating these outcomes remain poorly understood but may involve inflamm...

  14. Cardiomyopathy confers susceptibility to particulate matter-induced oxidative stress, vagal dominance, arrhythmia, pulmonary inflammation in heart failure-prone rats

    EPA Science Inventory

    Acute exposure to ambient fine particulate matter (PM2.5) is tied to cardiovascular morbidity and mortality, especially among those with prior cardiac injury. The mechanisms and pathophysiologic events precipitating these outcomes remain poorly understood but may involve inflamm...

  15. The Coyote Universe. I. Precision Determination of the Nonlinear Matter Power Spectrum

    NASA Astrophysics Data System (ADS)

    Heitmann, Katrin; White, Martin; Wagner, Christian; Habib, Salman; Higdon, David

    2010-05-01

    Near-future cosmological observations targeted at investigations of dark energy pose stringent requirements on the accuracy of theoretical predictions for the nonlinear clustering of matter. Currently, N-body simulations comprise the only viable approach to this problem. In this paper, we study various sources of computational error and methods to control them. By applying our methodology to a large suite of cosmological simulations we show that results for the (gravity-only) nonlinear matter power spectrum can be obtained at 1% accuracy out to k ~ 1 h Mpc-1. The key components of these high accuracy simulations are precise initial conditions, very large simulation volumes, sufficient mass resolution, and accurate time stepping. This paper is the first in a series of three; the final aim is a high-accuracy prediction scheme for the nonlinear matter power spectrum that improves current fitting formulae by an order of magnitude.

  16. THE COYOTE UNIVERSE. I. PRECISION DETERMINATION OF THE NONLINEAR MATTER POWER SPECTRUM

    SciTech Connect

    Heitmann, Katrin; White, Martin; Wagner, Christian; Habib, Salman; Higdon, David

    2010-05-20

    Near-future cosmological observations targeted at investigations of dark energy pose stringent requirements on the accuracy of theoretical predictions for the nonlinear clustering of matter. Currently, N-body simulations comprise the only viable approach to this problem. In this paper, we study various sources of computational error and methods to control them. By applying our methodology to a large suite of cosmological simulations we show that results for the (gravity-only) nonlinear matter power spectrum can be obtained at 1% accuracy out to k {approx} 1 h Mpc{sup -1}. The key components of these high accuracy simulations are precise initial conditions, very large simulation volumes, sufficient mass resolution, and accurate time stepping. This paper is the first in a series of three; the final aim is a high-accuracy prediction scheme for the nonlinear matter power spectrum that improves current fitting formulae by an order of magnitude.

  17. Cosmological explosions from cold dark matter perturbations

    NASA Technical Reports Server (NTRS)

    Scherrer, Robert J.

    1992-01-01

    The cosmological-explosion model is examined for a universe dominated by cold dark matter in which explosion seeds are produced from the growth of initial density perturbations of a given form. Fragmentation of the exploding shells is dominated by the dark-matter potential wells rather than the self-gravity of the shells, and particular conditions are required for the explosions to bootstrap up to very large scales. The final distribution of dark matter is strongly correlated with the baryons on small scales, but uncorrelated on large scales.

  18. Cosmological explosions from cold dark matter perturbations

    NASA Technical Reports Server (NTRS)

    Scherrer, Robert J.

    1992-01-01

    The cosmological-explosion model is examined for a universe dominated by cold dark matter in which explosion seeds are produced from the growth of initial density perturbations of a given form. Fragmentation of the exploding shells is dominated by the dark-matter potential wells rather than the self-gravity of the shells, and particular conditions are required for the explosions to bootstrap up to very large scales. The final distribution of dark matter is strongly correlated with the baryons on small scales, but uncorrelated on large scales.

  19. Hydrodynamic vacuum sources of dark matter self-generation in an accelerating universe without a Big Bang

    SciTech Connect

    Chefranov, S. G.; Novikov, E. A.

    2010-11-15

    We have obtained a generalization of the hydrodynamic theory of vacuum in the context of general relativity. While retaining the Lagrangian character of general relativity, the new theory provides a natural alternative to the view that the singularity is inevitable in general relativity and the theory of a hot Universe. We show that the macroscopic source-sink motion as a whole of ordinary (dark) matter that emerges during the production of particles out of the vacuum can be a new source of gravitational vacuum polarization (determining the variability of the cosmological term in general relativity). We have removed the well-known problems of the cosmological constant by refining the physical nature of dark energy associated precisely with this hydrodynamically initiated variability of the vacuum energy density. A new exact solution of the modified general relativity equations that contains no free (fitting) parameter additional to those available in general relativity has been obtained. It corresponds to the continuous and metric-affecting production of ultralight dark matter particles (with mass m{sub 0} = ({h_bar}/c{sup 2}) {approx} 3 x 10{sup -66} g, k is the gravitational constant) out of the vacuum, with its density {rho}{sub 0}, constant during the exponential expansion of a spatially flat Universe, being retained. This solution is shown to be stable in the regime of cosmological expansion in the time interval -{infinity} < t < t{sub max}, when t = 0 corresponds to the present epoch and t{sub max}= 2/3H{sub 0}c{Omega}{sub 0m} {approx} 38 x 10{sup 9} yr at {Omega}{sub 0m} = {rho}{sub 0}/{rho}{sub c} {approx} 0.28 (H{sub 0} is the Hubble constant, {rho}{sub c} is the critical density). For t > t{sub max}, the solution becomes exponentially unstable and characterizes the inverse process of dark matter particle absorption by the vacuum in the regime of contraction of the Universe. We consider the admissibility of the fact that scalar massive photon pairs can be

  20. Criticality and big brake singularities in the tachyonic evolutions of closed Friedmann universes with cold dark matter

    NASA Astrophysics Data System (ADS)

    Horváth, Zsolt; Keresztes, Zoltán; Kamenshchik, Alexander Yu.; Gergely, László Á.

    2015-05-01

    The evolution of a closed Friedmann universe filled by a tachyon scalar field with a trigonometric potential and cold dark matter (CDM) is investigated. A subset of the evolutions consistent to 1 σ confidence level with the Union 2.1 supernova data set is identified. The evolutions of the tachyon field are classified. Some of them evolve into a de Sitter attractor, while others proceed through a pseudotachyonic regime into a sudden future singularity. Critical evolutions leading to big brake singularities in the presence of CDM are found and a new type of cosmological evolution characterized by singularity avoidance in the pseudotachyon regime is presented.

  1. The GAPS Experiment: A Search for Dark Matter Using Low Energy Antiprotons and Antideuterons [University of Hawaii Co-I

    NASA Astrophysics Data System (ADS)

    von Doetinchem, Philip

    This is a Co-I proposal in support of the PI lead proposal entitled "The GAPS experiment: a search for dark matter using low energy antiprotons and antideuterons" submitted by Prof. Charles Hailey, Columbia University. Our proposed program would support the Umiversity of Hawaii at Manoa tasks on the GAPS experiment as detailed in our task statement. The primary focus of this work is the calibration and test of the Si(Li) detector modules, instrument simulation and support of the flight program and scientific analysis.

  2. Dark matter dynamics and indirect detection

    SciTech Connect

    Bertone, Gianfranco; Merritt, David; /Rochester Inst. Tech.

    2005-04-01

    Non-baryonic, or ''dark'', matter is believed to be a major component of the total mass budget of the universe. We review the candidates for particle dark matter and discuss the prospects for direct detection (via interaction of dark matter particles with laboratory detectors) and indirect detection (via observations of the products of dark matter self-annihilations), focusing in particular on the Galactic center, which is among the most promising targets for indirect detection studies. The gravitational potential at the Galactic center is dominated by stars and by the supermassive black hole, and the dark matter distribution is expected to evolve on sub-parsec scales due to interaction with these components. We discuss the dominant interaction mechanisms and show how they can be used to rule out certain extreme models for the dark matter distribution, thus increasing the information that can be gleaned from indirect detection searches.

  3. How Public Universities Close Budget Gaps Matters for States. Schools in Crisis: Making Ends Meet

    ERIC Educational Resources Information Center

    Kinne, Alicia; Roza, Marguerite; Murphy, Patrick; Gross, Betheny

    2012-01-01

    When the Great Recession took its toll on state budgets, public universities felt the pain. Many public universities attempted to offset reductions in state funds by raising tuition, shifting admission spots to more out-of-state students, and, in some cases, increasing enrollment. For a given budget gap, these three strategies should be weighted…

  4. Who Matters to Universities? A Stakeholder Perspective on Humanities, Arts and Social Sciences Valorisation

    ERIC Educational Resources Information Center

    Benneworth, Paul; Jongbloed, Ben W.

    2010-01-01

    Valorisation is at the centre of many debates on the future of academic research. But valorisation has largely become narrowly understood in terms of universities' economic contributions through patenting, licensing, spin-off formation and technology transfer. This emergent restrictive definition of universities' societal impacts is a worrying…

  5. Universal Design for Instruction: A Matter of Equitable Access to Learning

    ERIC Educational Resources Information Center

    DeVore, Simone; Stuart, Shannon; Riall, Ann

    2008-01-01

    Universal design for instruction is an inclusive teaching model that the authors advocate for responding to the diverse learning needs of students in today's postsecondary classrooms. The goal of universally designed courses is to allow all students to have available a menu of choices by which they can access curriculum content, engage in learning…

  6. Academic Identity Tensions in the Public University: Which Values Really Matter?

    ERIC Educational Resources Information Center

    Winter, Richard P.; O'Donohue, Wayne

    2012-01-01

    Our study explores the relationship between values and academic identity in the public university. Framing the study is the proposition public universities face academic identity tensions arising from pressures to combine and sustain competing and contradictory managerial (economic) and academic (professional) values systems. Academic responses to…

  7. Ratings of University Teacher Instruction: How Much Do Student and Course Characteristics Really Matter?

    ERIC Educational Resources Information Center

    Beran, Tanya; Violato, Claudio

    2005-01-01

    Several student and course characteristics were examined in relation to student ratings of instruction. Students at a major Canadian university completed the Universal Student Ratings of Instruction instrument at the end of every course over a three-year period, providing 371,131 student ratings. Analyses of between-group differences indicate that…

  8. Ratings of University Teacher Instruction: How Much Do Student and Course Characteristics Really Matter?

    ERIC Educational Resources Information Center

    Beran, Tanya; Violato, Claudio

    2005-01-01

    Several student and course characteristics were examined in relation to student ratings of instruction. Students at a major Canadian university completed the Universal Student Ratings of Instruction instrument at the end of every course over a three-year period, providing 371,131 student ratings. Analyses of between-group differences indicate that…

  9. Evolution of Private Universities in Nigeria: Matters Arising and the Way Forward

    ERIC Educational Resources Information Center

    Ige, Akindele M.

    2013-01-01

    Many issues such as the increasing cases of unsatisfied demand for admission, moral decadence among students, incessant strikes, student unrest and cultism, among others necessitated the establishment of private alongside the federal and state universities in Nigeria. It is however expected that the advent of private universities will provide…

  10. Academic Identity Tensions in the Public University: Which Values Really Matter?

    ERIC Educational Resources Information Center

    Winter, Richard P.; O'Donohue, Wayne

    2012-01-01

    Our study explores the relationship between values and academic identity in the public university. Framing the study is the proposition public universities face academic identity tensions arising from pressures to combine and sustain competing and contradictory managerial (economic) and academic (professional) values systems. Academic responses to…

  11. Uncovering Reading Habits of University Students in Uganda: Does ICT Matter?

    ERIC Educational Resources Information Center

    Mlay, Samali V.; Sabi, Humphrey M.; Tsuma, Clive K.; Langmia, Kehbuma

    2015-01-01

    This paper investigates how Information and Communication Technology (ICT) can improve reading habits among university students. We also investigated the influence of home culture, school culture and disposable income on reading habit. Our main objective was to assess the effect of ICT on the reading habit of particularly university students in…

  12. Semidegenerate Self-Gravitating System of Fermion as Dark Matter on Galaxies i: Universality Laws

    NASA Astrophysics Data System (ADS)

    Fraga, Bernardo M. O.; Argüelles, Carlos; Ruffini, Remo; Siutsou, Ivan

    2015-01-01

    We present a unified model for galactic Dark Matter (DM) halos as well as galactic DM central cores (alternatively to the central Supermassive Black Hole scenario), based on systems of self-gravitating fermions at finite temperatures. This work will deal mainly with the halo part, leaving the core description to another part of this proceedings...

  13. Depression and College Stress among University Undergraduates: Do Mattering and Self-Esteem Make a Difference?

    ERIC Educational Resources Information Center

    Dixon, Sarah K.; Kurpius, Sharon E. Robinson

    2008-01-01

    Depression and college stress, major concerns among undergraduates, are potentially related to self-esteem and mattering. This study investigated the interrelationships among these four variables. Participants included college students (199 males and 256 females) between the ages of 18 and 23. Significant sex differences were found with women…

  14. Depression and College Stress among University Undergraduates: Do Mattering and Self-Esteem Make a Difference?

    ERIC Educational Resources Information Center

    Dixon, Sarah K.; Kurpius, Sharon E. Robinson

    2008-01-01

    Depression and college stress, major concerns among undergraduates, are potentially related to self-esteem and mattering. This study investigated the interrelationships among these four variables. Participants included college students (199 males and 256 females) between the ages of 18 and 23. Significant sex differences were found with women…

  15. Matter antimatter domains: A possible solution to the CP domain wall problem in the early universe

    NASA Technical Reports Server (NTRS)

    Mohanty, A. K.; Stecker, F. W.

    1984-01-01

    An SU(5) grand unified theory model is used to show how the degeneracy between vacua with different spontaneously broken charge parity can be dynamically lifted by a condensate of heavy fermion pairs. This drives a phase transition to a unique vacuum state with definite charge parity. The transition eliminates the domain walls in a matter antimatter symmetric domain cosmology.

  16. Dark matter: theoretical perspectives.

    PubMed Central

    Turner, M S

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that (i) there are no dark-matter candidates within the "standard model" of particle physics, (ii) there are several compelling candidates within attractive extensions of the standard model of particle physics, and (iii) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for "new physics." The compelling candidates are a very light axion (10(-6)-10(-4) eV), a light neutrino (20-90 eV), and a heavy neutralino (10 GeV-2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos. PMID:11607395

  17. Dark matter: Theoretical perspectives

    SciTech Connect

    Turner, M.S. . Enrico Fermi Inst. Fermi National Accelerator Lab., Batavia, IL )

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for new physics.'' The compelling candidates are: a very light axion ( 10[sup [minus]6] eV--10[sup [minus]4] eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos.

  18. Dark matter: Theoretical perspectives

    SciTech Connect

    Turner, M.S. |

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for ``new physics.`` The compelling candidates are: a very light axion ( 10{sup {minus}6} eV--10{sup {minus}4} eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos.

  19. Dark matter: Theoretical perspectives

    SciTech Connect

    Turner, M.S. Fermi National Accelerator Lab., Batavia, IL )

    1993-06-01

    The author both reviews and makes the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that (i) there are no dark-matter candidates within the [open quotes]standard model[close quotes] of particle physics, (ii) there are several compelling candidates within attractive extensions of the standard model of particle physics, and (iii) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for [open quotes]new physics.[close quotes] The compelling candidates are a very light axion (10[sup [minus]6]--10[sup [minus]4] eV), a light neutrino (20--90 eV), and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. The author briefly mentions more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos. 119 refs.

  20. Using Dark Matter Haloes to Learn about Cosmic Acceleration: A New Proposal for a Universal Mass Function

    NASA Technical Reports Server (NTRS)

    Prescod-Weinstein, Chanda; Afshordi, Niayesh

    2011-01-01

    Structure formation provides a strong test of any cosmic acceleration model because a successful dark energy model must not inhibit or overpredict the development of observed large-scale structures. Traditional approaches to studies of structure formation in the presence of dark energy or a modified gravity implement a modified Press-Schechter formalism, which relates the linear overdensities to the abundance of dark matter haloes at the same time. We critically examine the universality of the Press-Schechter formalism for different cosmologies, and show that the halo abundance is best correlated with spherical linear overdensity at 94% of collapse (or observation) time. We then extend this argument to ellipsoidal collapse (which decreases the fractional time of best correlation for small haloes), and show that our results agree with deviations from modified Press-Schechter formalism seen in simulated mass functions. This provides a novel universal prescription to measure linear density evolution, based on current and future observations of cluster (or dark matter) halo mass function. In particular, even observations of cluster abundance in a single epoch will constrain the entire history of linear growth of cosmological of perturbations.

  1. Information Dominance

    DTIC Science & Technology

    1997-11-01

    Information dominance may be defined as superiority in the generation, manipulation, and use of information sufficient to afford its possessors... information dominance at the strategic level: knowing oneself and one’s enemy; and, at best, inducing them to see things as one does.

  2. On 3+1 Dimensional Friedman-Robertson-Walker Universes with Matter

    NASA Astrophysics Data System (ADS)

    Christodoulakis, T.; Helias, C.; Kevrekidis, P. G.; Kevrekidis, I. G.; Papadopoulos, G.

    We examine the dynamical behavior of matter coupled to gravity in the context of a linear Klein-Gordon equation coupled to a Friedman-Robertson-Walker metric. The resulting ordinary differential equations can be decoupled, the effect of gravity being traced in rendering the equation for the scalar field nonlinear. We obtain regular (in the mass-less case) and asymptotic (in the massive case) solutions for the resulting matter field and discuss their ensuing finite time blowup in the light of earlier findings. Finally, some potentially interesting connections of these blowups with features of focusing in the theory of nonlinear partial differential equations are outlined, suggesting the potential relevance of a nonlinear theory of quantum cosmology.

  3. Sterile neutrino dark matter with supersymmetry

    NASA Astrophysics Data System (ADS)

    Shakya, Bibhushan; Wells, James D.

    2017-08-01

    Sterile neutrino dark matter, a popular alternative to the WIMP paradigm, has generally been studied in non-supersymmetric setups. If the underlying theory is supersymmetric, we find that several interesting and novel dark matter features can arise. In particular, in scenarios of freeze-in production of sterile neutrino dark matter, its superpartner, the sterile sneutrino, can play a crucial role in early Universe cosmology as the dominant source of cold, warm, or hot dark matter, or of a subdominant relativistic population of sterile neutrinos that can contribute to the effective number of relativistic degrees of freedom Neff during big bang nucleosynthesis.

  4. Dominant dark matter and a counter-rotating disc: MUSE view of the low-luminosity S0 galaxy NGC 5102

    NASA Astrophysics Data System (ADS)

    Mitzkus, Martin; Cappellari, Michele; Walcher, C. Jakob

    2017-02-01

    The kinematics and stellar populations of the low-mass nearby S0 galaxy NGC 5102 are studied from integral field spectra taken with the Multi-Unit Spectroscopic Explorer. The kinematic maps reveal for the first time that NGC 5102 has the characteristic 2σ peaks indicative of galaxies with counter-rotating discs. This interpretation is quantitatively confirmed by fitting two kinematic components to the observed spectra. Through stellar population analysis, we confirm the known young stellar population in the centre and find steep age and metallicity gradients. We construct axisymmetric Jeans anisotropic models of the stellar dynamics to investigate the initial mass function (IMF) and the dark matter halo of the galaxy. The models show that this galaxy is quite different from all galaxies previously studied with a similar approach: even within the half-light radius, it cannot be approximated with the self-consistent mass-follows-light assumption. Including a Navarro, Frenk & White dark matter halo, we need a heavy IMF and a dark matter fraction of 0.37 ± 0.04 within a sphere of one Re radius to describe the stellar kinematics. The more general model with a free slope of the dark matter halo shows that slope and IMF are degenerate, but indicates that a light weight IMF (Chabrier-like) and a higher dark matter fraction, with a steeper (contracted) halo, fit the data better. Regardless of the assumptions about the halo profile, we measure the slope of the total mass density to be -1.75 ± 0.04. This is shallower than the slope of -2 of an isothermal halo and shallower than published slopes for more massive early-type galaxies.

  5. An Inquiry-based Undergraduate Course Investigating Unseen Matter in the Universe

    NASA Astrophysics Data System (ADS)

    Lovell, A. J.; Greenstein, G. S.

    1999-05-01

    We present a new inquiry-based college astronomy course, devoted to the investigation of unseen matter. This course takes advantage of a ``technology classroom," set up to facilitate both the seminar/discussion format of the course and the use of computers for hands-on investigation of astronomical data. Students make use of software, to learn about calculation of mass via measurements of orbiting astronomical bodies, with the ultimate goal of discovering and investigating dark matter. The initial investigation is of a system with at least two visible, moving objects. After the students have employed Keplerian and Newtonian physics to estimate the mass of the central body in this simple case, they learn to employ spectral lines and Doppler shifts to determine masses in the case where the bodies do not appear to move. Ultimately, they employ Doppler velocities to determine extended masses, such as a circumstellar disk or a galaxy. Real astronomical data are presented, or, where real data does not exist, it is simulated in physically realistic fashion. Course software acts as both a visual aid and a data-gathering tool to assist the students in their inquiries. Once they have ``discovered" dark matter, then they form groups and embark on research projects to investigate how to account for it. This phase of the course will allow them to encounter a wider range of data, spanning the electromagnetic spectrum. The course culminates in a conference in which each group presents their findings to the entire class, and the instructors summarize topics not investigated by students. In this poster, we present details of the course and demonstrate the associated software.

  6. The Biomedical Doctorate in the Contemporary University: Education or Training and Why It Matters

    ERIC Educational Resources Information Center

    Kemp, Matthew W.; Newnham, John P.; Chapman, Elaine

    2012-01-01

    The form and function(s) of doctoral education continue to be a subject of much debate by stakeholders internal and external to the university. Notable concerns driving this debate derive from a seemingly discursive array of factors including increasing student numbers, increased understanding of the economic value of doctoral graduates,…

  7. When Does Race Matter? Race, Sex, and Dating at an Elite University

    ERIC Educational Resources Information Center

    McClintock, Elizabeth Aura

    2010-01-01

    This paper unites quantitative and qualitative data from the College Social Life Survey (n = 732) to describe and explain patterns of racial homophily in undergraduate sexual/romantic relationships at an elite university, a closed social setting. It expands the literature on interracial romantic unions by comparing homophily in hookups…

  8. Business Students' Perceptions of Best University Professors: Does Gender Role Matter?

    ERIC Educational Resources Information Center

    Das, Mallika; Das, Hari

    2001-01-01

    Investigated the relationship between gender and gender role of students and their "best" university professors. Surveys of Canadian college students indicated that there was a strong relationship between students' gender and gender role and the gender and perceived gender role of their best instructors. Masculinity was valued more by…

  9. Attitudes and Interests among University Students in Introductory Nonmajor Science Courses: Does Gender Matter?

    ERIC Educational Resources Information Center

    Desy, Elizabeth; Peterson, Scott; Brockman, Vicky

    2009-01-01

    Attitudes toward science may develop as early as middle school and often differ between genders. Do these gender-based differences in attitude persist into the college years? In a survey of 376 university students, male students reported a stronger self-concept, more motivation, and more enjoyment of science than did female students, and female…

  10. Why Academic Depth and Rigour in University-Based Coursework Matters for Prospective Teachers

    ERIC Educational Resources Information Center

    Rusznyak, Lee; Balfour, Robert; Van Vollenhoven, Willie; Sosibo, Lungi

    2016-01-01

    This special issue of "Perspectives in Education" arises from a symposium entitled "Academic depth and rigour in initial teacher education" jointly organised by four universities in South Africa. The symposium, held in October 2014, attracted 125 delegates from 18 South African higher education institutions (HEIs).…

  11. Business Students' Perceptions of Best University Professors: Does Gender Role Matter?

    ERIC Educational Resources Information Center

    Das, Mallika; Das, Hari

    2001-01-01

    Investigated the relationship between gender and gender role of students and their "best" university professors. Surveys of Canadian college students indicated that there was a strong relationship between students' gender and gender role and the gender and perceived gender role of their best instructors. Masculinity was valued more by…

  12. Why Academic Depth and Rigour in University-Based Coursework Matters for Prospective Teachers

    ERIC Educational Resources Information Center

    Rusznyak, Lee; Balfour, Robert; Van Vollenhoven, Willie; Sosibo, Lungi

    2016-01-01

    This special issue of "Perspectives in Education" arises from a symposium entitled "Academic depth and rigour in initial teacher education" jointly organised by four universities in South Africa. The symposium, held in October 2014, attracted 125 delegates from 18 South African higher education institutions (HEIs).…

  13. The Biomedical Doctorate in the Contemporary University: Education or Training and Why It Matters

    ERIC Educational Resources Information Center

    Kemp, Matthew W.; Newnham, John P.; Chapman, Elaine

    2012-01-01

    The form and function(s) of doctoral education continue to be a subject of much debate by stakeholders internal and external to the university. Notable concerns driving this debate derive from a seemingly discursive array of factors including increasing student numbers, increased understanding of the economic value of doctoral graduates,…

  14. College and University Mergers: Recent Trends. Policy Matters: A Higher Education Policy Brief

    ERIC Educational Resources Information Center

    McBain, Lesley

    2009-01-01

    Given the current economic turbulence characterized, in part, by unprecedented business consolidations, talk of mergers has spread to higher education. At first glance, merger discussions may seem more appropriate to the corporate world than academe because American colleges and universities were not created in accordance with a centralized…

  15. When Culture and Learning Styles Matter: A Canadian University with Middle-Eastern Students

    ERIC Educational Resources Information Center

    Lemke-Westcott, Tracey; Johnson, Brad

    2013-01-01

    Transnational branch campuses of universities are a growing phenomenon, particularly in the Middle-East. The cultures of home institutions and host countries are often foreign to each other. The result is a cultural and learning style gap between faculty and students impacting students' learning and teachers' effectiveness. A pilot study of the…

  16. Factors Influencing Student Satisfaction in Universities in the Gulf Region: Does Gender of Students Matter?

    ERIC Educational Resources Information Center

    Parahoo, Sanjai K.; Harvey, Heather L.; Tamim, Rana M.

    2013-01-01

    While various research studies have focused on antecedents and consequences of student satisfaction, few studies have done so in the Gulf region. The objective of the present study was therefore to design and empirically examine a model of student satisfaction in a private university in the Gulf region that operates in a high-technology-enabled…

  17. When Does Race Matter? Race, Sex, and Dating at an Elite University

    ERIC Educational Resources Information Center

    McClintock, Elizabeth Aura

    2010-01-01

    This paper unites quantitative and qualitative data from the College Social Life Survey (n = 732) to describe and explain patterns of racial homophily in undergraduate sexual/romantic relationships at an elite university, a closed social setting. It expands the literature on interracial romantic unions by comparing homophily in hookups…

  18. Sharing but not caring: dark matter and the baryon asymmetry of the universe

    SciTech Connect

    Bernal, Nicolás; Fong, Chee Sheng; Fonseca, Nayara

    2016-09-02

    We consider scenarios where Dark Matter (DM) particles carry baryon and/or lepton numbers, which can be defined if there exist operators connecting the dark to the visible sector. As a result, the DM fields become intimately linked to the Standard Model (SM) ones and can be maximally asymmetric just like the ordinary matter. In particular, we discuss minimal scenarios where the DM is a complex scalar or a Dirac fermion coupled to operators with nonzero baryon and/or lepton numbers, and that consist of only SM fields. We consider an initial asymmetry stored in either the SM or the DM sector; the main role of these operators is to properly share the asymmetry between the two sectors, in accordance with observations. After the chemical decoupling, the DM and SM sectors do not care about each other as there is only an ineffective communication between them. Once the DM mass is specified, the Wilson coefficients of these operators are fixed by the requirement of the correct transfer of the asymmetry. We study the phenomenology of this framework at colliders, direct detection and indirect detection experiments. In particular, the LHC phenomenology is very rich and can be tested in different channels such as the two same-sign leptons with two jets, monojet and monojet with a monolepton.

  19. Evidence of turbulence-like universality in the formation of galaxy-sized dark matter haloes

    NASA Astrophysics Data System (ADS)

    Caretta, C. A.; Rosa, R. R.; de Campos Velho, H. F.; Ramos, F. M.; Makler, M.

    2008-08-01

    Context: Although the theoretical understanding of nonlinear gravitational clustering has greatly advanced in the last decades, in particular by improvements in numerical N-body simulations, the physics behind this process is not fully elucidated. Aims: The main goal of this work is the study of the possibility of a turbulent-like physical process in the formation of structures, galaxies and clusters of galaxies, by the action of gravity alone. Methods: We use simulation data from the Virgo Consortium, in ten redshift snapshots (from 0 to 10). From this we identify galaxy-sized and cluster-sized dark matter haloes, by using a FoF algorithm and applying a boundedness criterion, and study the gravitational potential energy spectra. Results: We find that the galaxy-sized halo energy spectrum follows closely a Kolmogorov power law, similar to the behaviour of dynamically turbulent processes in fluids. Conclusions: This means that the gravitational clustering of dark matter may admit a turbulent-like representation. Part of the calculations made use of the NEC SX4/8A supercomputer at the CeNaPAD Ambiental, CPTEC/INPE, Brasil.

  20. Fractal analysis of the dark matter and gas distributions in the Mare-Nostrum universe

    SciTech Connect

    Gaite, José

    2010-03-01

    We develop a method of multifractal analysis of N-body cosmological simulations that improves on the customary counts-in-cells method by taking special care of the effects of discreteness and large scale homogeneity. The analysis of the Mare-Nostrum simulation with our method provides strong evidence of self-similar multifractal distributions of dark matter and gas, with a halo mass function that is of Press-Schechter type but has a power-law exponent -2, as corresponds to a multifractal. Furthermore, our analysis shows that the dark matter and gas distributions are indistinguishable as multifractals. To determine if there is any gas biasing, we calculate the cross-correlation coefficient, with negative but inconclusive results. Hence, we develop an effective Bayesian analysis connected with information theory, which clearly demonstrates that the gas is biased in a long range of scales, up to the scale of homogeneity. However, entropic measures related to the Bayesian analysis show that this gas bias is small (in a precise sense) and is such that the fractal singularities of both distributions coincide and are identical. We conclude that this common multifractal cosmic web structure is determined by the dynamics and is independent of the initial conditions.

  1. Sharing but not caring: dark matter and the baryon asymmetry of the universe

    NASA Astrophysics Data System (ADS)

    Bernal, Nicolás; Fong, Chee Sheng; Fonseca, Nayara

    2016-09-01

    We consider scenarios where Dark Matter (DM) particles carry baryon and/or lepton numbers, which can be defined if there exist operators connecting the dark to the visible sector. As a result, the DM fields become intimately linked to the Standard Model (SM) ones and can be maximally asymmetric just like the ordinary matter. In particular, we discuss minimal scenarios where the DM is a complex scalar or a Dirac fermion coupled to operators with nonzero baryon and/or lepton numbers, and that consist of only SM fields. We consider an initial asymmetry stored in either the SM or the DM sector; the main role of these operators is to properly share the asymmetry between the two sectors, in accordance with observations. After the chemical decoupling, the DM and SM sectors do not care about each other as there is only an ineffective communication between them. Once the DM mass is specified, the Wilson coefficients of these operators are fixed by the requirement of the correct transfer of the asymmetry. We study the phenomenology of this framework at colliders, direct detection and indirect detection experiments. In particular, the LHC phenomenology is very rich and can be tested in different channels such as the two same-sign leptons with two jets, monojet and monojet with a monolepton.

  2. University Programme Preferences of High School Science Students in Singapore and Reasons that Matter in their Preferences: A Rasch analysis

    NASA Astrophysics Data System (ADS)

    Oon, Pey-Tee; Subramaniam, R.

    2015-01-01

    This study explored an under-researched area in science education-the university programmes preferred by high school students who take physical science subjects and the reasons that matter in their preferences. A total of 1,071 upper secondary and pre-university students in Singapore, who take physical science subjects among their range of subjects, participated in this study. A survey method was adopted and the Rasch model was used to analyse the data. Overall, Business Studies was ranked as the predominant choice; nonetheless, scientific programmes such as Science, Engineering, and Mathematics are generally still well liked by the students. When gender differences were examined, we found that students largely followed gender-typical programme preferences, in which males tend to incline towards Engineering while females tend to incline towards Arts and Social Sciences. Students prefer a university programme based on their individual interest and ability, with career aspiration and remuneration coming next. Interestingly, females place greater emphasis on career aspiration than males. Some implications of the study are discussed.

  3. PIC Code Simulations Of A Space-Charge-Dominated Beam In The Quadrupole Channel Of The University Of Maryland E-Ring.

    NASA Astrophysics Data System (ADS)

    Kishek, Rami; Bernal, Santiago; Reiser, Martin; Venturini, Marco; Haber, Irving

    1998-11-01

    Self-consistent numerical simulations using the WARP particle-in-cell code are applied to study the evolution of the space-charge-dominated beam in the University of Maryland Electron Ring [1]. The simulations are compared to experimental measurements on an existing prototype injector. Both the simulations and the experimental data are used to understand the evolution of density waves formed in a beam not in local thermal equilibrium. The simulations also explore the sensitivity of the downstream density distribution to the initial distribution upstream and to intercepting the beam with an aperture. Simulations of the entire ring lattice, in the presence of magnet nonlinearities and dispersion, reveal only a modest increase in emittance over 10-20 turns. Various beam and lattice errors are considered and their contribution to the emittance growth is evaluated. Simulation results are compared to analytic theory when possible. [1] M. Reiser, et. al., Fusion Engineering and Design 32-33, 293 (1996). * Research Supported by US Department of Energy under contract DE-FG02-94ER40855.

  4. A PHOTON-DOMINATED REGION MODEL FOR THE FIR MID-J CO LADDER WITH UNIVERSAL ROTATIONAL TEMPERATURE IN STAR FORMING REGIONS

    SciTech Connect

    Lee, Seokho; Park, Yong-Sun; Lee, Jeong-Eun; Bergin, Edwin A.

    2014-08-01

    A photon-dominated region (PDR) is one of the leading candidate mechanisms for the origin of warm CO gas with near universal ∼300 K rotational temperature inferred from the CO emission detected toward embedded protostars by Herschel/PACS. We have developed a PDR model in general coordinates, where we can use the most adequate coordinate system for an embedded protostar having outflow cavity walls, to solve chemistry and gas energetics self-consistently for given UV radiation fields with different spectral shapes. Simple one-dimensional tests and applications show that FIR mid-J (14 ≤ J ≤ 24) CO lines are emitted from close to the surface of a dense region exposed to high UV fluxes. We apply our model to HH46 and find that the UV-heated outflow cavity wall can reproduce the mid-J CO transitions observed by Herschel/PACS. A model with UV radiation corresponding to a blackbody of 10,000 K results in a rotational temperature lower than 300 K, while models with the Draine interstellar radiation field and the 15,000 K blackbody radiation field predict a rotational temperature similar to the observed one.

  5. Tidal features of classical Milky Way satellites in a Λ cold dark matter universe

    NASA Astrophysics Data System (ADS)

    Wang, M.-Y.; Fattahi, Azadeh; Cooper, Andrew P.; Sawala, Till; Strigari, Louis E.; Frenk, Carlos S.; Navarro, Julio F.; Oman, Kyle; Schaller, Matthieu

    2017-07-01

    We use the APOSTLE (A Project Of Simulating The Local Environment) cosmological hydrodynamic simulations to examine the effects of tidal stripping on cold dark matter subhaloes that host three of the most luminous Milky Way dwarf satellite galaxies: Fornax, Sculptor and Leo I. We identify simulated satellites that match the observed spatial and kinematic distributions of stars in these galaxies, and track their evolution after infall. We find ˜30 per cent of subhaloes hosting satellites with present-day stellar mass 106-108 M⊙ experience >20 per cent stellar mass-loss after infall. Fornax analogues have earlier infall times compared to Sculptor and Leo I analogues. Star formation in Fornax analogues continues for ˜3-6 Gyr after infall, whereas Sculptor and Leo I analogues stop forming stars <2-3 Gyr after infall. Fornax analogues typically show more significant stellar mass-loss and exhibit stellar tidal tails, whereas Sculptor and Leo I analogues, which are more deeply embedded in their host dark matter haloes at infall, do not show substantial mass-loss due to tides. When additionally comparing the orbital motion of the host subaloes to the measured proper motion of Fornax, we find the matching more difficult; host subhaloes tend to have pericentres smaller than that measured for Fornax itself. From the kinematic and orbital data, we estimate that Fornax has lost 10-20 per cent of its infall stellar mass. Our best estimate for the surface brightness of a stellar tidal stream associated with Fornax is Σ ˜ 32.6 mag arcsec-2, which may be detectable with deep imaging surveys such as DES and LSST.

  6. Universal slip dynamics in metallic glasses and granular matter - linking frictional weakening with inertial effects

    NASA Astrophysics Data System (ADS)

    Denisov, Dmitry V.; Lőrincz, Kinga A.; Wright, Wendelin J.; Hufnagel, Todd C.; Nawano, Aya; Gu, Xiaojun; Uhl, Jonathan T.; Dahmen, Karin A.; Schall, Peter

    2017-03-01

    Slowly strained solids deform via intermittent slips that exhibit a material-independent critical size distribution. Here, by comparing two disparate systems - granular materials and bulk metallic glasses - we show evidence that not only the statistics of slips but also their dynamics are remarkably similar, i.e. independent of the microscopic details of the material. By resolving and comparing the full time evolution of avalanches in bulk metallic glasses and granular materials, we uncover a regime of universal deformation dynamics. We experimentally verify the predicted universal scaling functions for the dynamics of individual avalanches in both systems, and show that both the slip statistics and dynamics are independent of the scale and details of the material structure and interactions, thus settling a long-standing debate as to whether or not the claim of universality includes only the slip statistics or also the slip dynamics. The results imply that the frictional weakening in granular materials and the interplay of damping, weakening and inertial effects in bulk metallic glasses have strikingly similar effects on the slip dynamics. These results are important for transferring experimental results across scales and material structures in a single theory of deformation dynamics.

  7. Universal slip dynamics in metallic glasses and granular matter – linking frictional weakening with inertial effects

    PubMed Central

    Denisov, Dmitry V.; Lőrincz, Kinga A.; Wright, Wendelin J.; Hufnagel, Todd C.; Nawano, Aya; Gu, Xiaojun; Uhl, Jonathan T.; Dahmen, Karin A.; Schall, Peter

    2017-01-01

    Slowly strained solids deform via intermittent slips that exhibit a material-independent critical size distribution. Here, by comparing two disparate systems - granular materials and bulk metallic glasses - we show evidence that not only the statistics of slips but also their dynamics are remarkably similar, i.e. independent of the microscopic details of the material. By resolving and comparing the full time evolution of avalanches in bulk metallic glasses and granular materials, we uncover a regime of universal deformation dynamics. We experimentally verify the predicted universal scaling functions for the dynamics of individual avalanches in both systems, and show that both the slip statistics and dynamics are independent of the scale and details of the material structure and interactions, thus settling a long-standing debate as to whether or not the claim of universality includes only the slip statistics or also the slip dynamics. The results imply that the frictional weakening in granular materials and the interplay of damping, weakening and inertial effects in bulk metallic glasses have strikingly similar effects on the slip dynamics. These results are important for transferring experimental results across scales and material structures in a single theory of deformation dynamics. PMID:28262791

  8. CURRICULUM MATTERS: The Foundation Programme in Science and Engineering at Loughborough University of Technology

    NASA Astrophysics Data System (ADS)

    Stewart, Mary

    1996-01-01

    University Foundation courses in Engineering were run for the first time in the 1988-9 academic year. The Science and the Engineering faculties at Loughborough University of Technology instigated a Foundation Programme in Science and Engineering at the start of the 1991-2 academic year. Of the 100 or so students on the programme four on average go on to continue their studies in physics. This year sees the first two graduates in the physics department to have come via the Foundation route. One studied PE, Sports Science and Physics and the other Engineering Physics. Both of them achieved lower second class honours degrees. There is an extremely heterogeneous intake into the Foundation Programme and a multitude of exit routes, currently up to 30 different science or engineering degrees. These two factors provide interesting challenges to the course planners in terms of both the choice of course content and the teaching styles adopted. The lecturer responsible for the physics input to the programme believes that the use of Resource- Based Learning materials may be a partial solution to the problems faced by students with non-standard entry qualifications. Such materials are being produced by the FLAP (Flexible Learning Approach to Physics) team, of which she has been a member since 1989. The Foundation Programme continues to evolve and is being redesigned to fit the University's plans for semesterization, which will be put into effect from October 1995.

  9. Universal slip dynamics in metallic glasses and granular matter - linking frictional weakening with inertial effects.

    PubMed

    Denisov, Dmitry V; Lőrincz, Kinga A; Wright, Wendelin J; Hufnagel, Todd C; Nawano, Aya; Gu, Xiaojun; Uhl, Jonathan T; Dahmen, Karin A; Schall, Peter

    2017-03-06

    Slowly strained solids deform via intermittent slips that exhibit a material-independent critical size distribution. Here, by comparing two disparate systems - granular materials and bulk metallic glasses - we show evidence that not only the statistics of slips but also their dynamics are remarkably similar, i.e. independent of the microscopic details of the material. By resolving and comparing the full time evolution of avalanches in bulk metallic glasses and granular materials, we uncover a regime of universal deformation dynamics. We experimentally verify the predicted universal scaling functions for the dynamics of individual avalanches in both systems, and show that both the slip statistics and dynamics are independent of the scale and details of the material structure and interactions, thus settling a long-standing debate as to whether or not the claim of universality includes only the slip statistics or also the slip dynamics. The results imply that the frictional weakening in granular materials and the interplay of damping, weakening and inertial effects in bulk metallic glasses have strikingly similar effects on the slip dynamics. These results are important for transferring experimental results across scales and material structures in a single theory of deformation dynamics.

  10. Indoor air quality in university classrooms and relative environment in terms of mass concentrations of particulate matter.

    PubMed

    Gaidajis, George; Angelakoglou, Komninos

    2009-10-01

    The mass concentrations of coarse (PM10) and fine (PM2.5) particulate matter were measured in different classrooms and relevant indoors areas of Democritus University, School of Engineering, Xanthi, with portable aerosol monitoring equipment. Two sampling campaigns were conducted in different seasons. The results indicated that the average concentrations in classrooms ranged from 32-188 microg/m3 and 25-151 microg/m3 for PM10 and PM2.5, respectively. Concentration levels above 300 microg/m3 were usually recorded, while the PM2.5/PM10 ratio was about 0.8. As expected, PM10 and PM2.5 average concentrations were significantly higher in the open-access meeting place of common use, indicating the significance of student trespassing and occasional smoking in the deterioration of indoors air quality.

  11. Exact solutions of bulk viscous with string cloud attached to strange quark matter for higher dimensional FRW universe in Lyra geometry

    SciTech Connect

    Çağlar, Halife; Aygün, Sezgin

    2016-03-25

    In this study, we have investigated bulk viscous with strange quark matter attached to the string cloud for higher dimensional Friedman-Robertson-Walker (FRW) universe in Lyra geometry. By using varying deceleration parameter and conservation equations we have solved Einstein Field Equations (EFE’s) and obtained generalized exact solutions for our model. Also we have found that string is not survived for bulk viscous with strange quark matter attached to the string cloud in framework higher dimensional FRW universe in Lyra geometry. This result agrees with Kiran and Reddy, Krori et al, Sahoo and Mishra and Mohanty et al. in four and five dimensions.

  12. Exact solutions of bulk viscous with string cloud attached to strange quark matter for higher dimensional FRW universe in Lyra geometry

    NASA Astrophysics Data System (ADS)

    Ćaǧlar, Halife; Aygün, Sezgin

    2016-03-01

    In this study, we have investigated bulk viscous with strange quark matter attached to the string cloud for higher dimensional Friedman-Robertson-Walker (FRW) universe in Lyra geometry. By using varying deceleration parameter and conservation equations we have solved Einstein Field Equations (EFE's) and obtained generalized exact solutions for our model. Also we have found that string is not survived for bulk viscous with strange quark matter attached to the string cloud in framework higher dimensional FRW universe in Lyra geometry. This result agrees with Kiran and Reddy, Krori et al, Sahoo and Mishra and Mohanty et al. in four and five dimensions.

  13. What are the Building Blocks of Our UNIVERSE?

    NASA Astrophysics Data System (ADS)

    Wali, Kameshwar C.

    We are living in a Golden Age of Astronomy. Cosmological Parameters are found with an unprecedented accuracy comparable to high energy physics. Yet, the known form of matter forms only a small fraction of the total energy density of the universe. Also, a mysterious dark energy dominates the universe and causes acceleration in the rate of expansion. These findings raise new questions concerning the ultimate constitution of matter in the universe.

  14. The evolution of X-ray clusters in a cold plus hot dark matter universe

    NASA Technical Reports Server (NTRS)

    Bryan, Greg L.; Klypin, Anatoly; Loken, Chris; Norman, Michael L.; Burns, Jack O.

    1994-01-01

    We present the first self-consistently computed results on the evolution of X-ray properties of galaxy clusters in a cold + hot dark matter (CHDM) model. We have performed a hydrodynamic plus N-body simulation for the COBE-compatible CHDM model with standard mass components: Omega(sub hot) = 0.3, Omega (sub cold) = 0.6 and Omega(sub baryon) = 0.1 (h = 0.5). In contrast with the CDM model, which fails to reproduce the observed temperature distribution function dN/dT (Bryan et al. 1994b), the CHDM model fits the observational dN/dT quite well. Our results on X-ray luminosity are less firm but even more intriguing. We find that the resulting X-ray luminosity functions at redshifts z = 0.0, 0.2, 0.4, 0.7 are well fit by observations, where they overlap. The fact that both temperatures and luminosities provide a reasonable fit to the available observational data indicates that, unless we are missing some essential physics, there is neither room nor need for a large fraction of gas in rich clusters: 10% (or less) in baryons is sufficient to explain their X-ray properties. We also see a tight correlation between X-ray luminosity and gas temperature.

  15. The evolution of X-ray clusters in a cold plus hot dark matter universe

    NASA Technical Reports Server (NTRS)

    Bryan, Greg L.; Klypin, Anatoly; Loken, Chris; Norman, Michael L.; Burns, Jack O.

    1994-01-01

    We present the first self-consistently computed results on the evolution of X-ray properties of galaxy clusters in a cold + hot dark matter (CHDM) model. We have performed a hydrodynamic plus N-body simulation for the COBE-compatible CHDM model with standard mass components: Omega(sub hot) = 0.3, Omega (sub cold) = 0.6 and Omega(sub baryon) = 0.1 (h = 0.5). In contrast with the CDM model, which fails to reproduce the observed temperature distribution function dN/dT (Bryan et al. 1994b), the CHDM model fits the observational dN/dT quite well. Our results on X-ray luminosity are less firm but even more intriguing. We find that the resulting X-ray luminosity functions at redshifts z = 0.0, 0.2, 0.4, 0.7 are well fit by observations, where they overlap. The fact that both temperatures and luminosities provide a reasonable fit to the available observational data indicates that, unless we are missing some essential physics, there is neither room nor need for a large fraction of gas in rich clusters: 10% (or less) in baryons is sufficient to explain their X-ray properties. We also see a tight correlation between X-ray luminosity and gas temperature.

  16. The other side of bulge formation in a Λ cold dark matter cosmology: bulgeless galaxies in the local Universe

    NASA Astrophysics Data System (ADS)

    Fontanot, Fabio; De Lucia, Gabriella; Wilman, David; Monaco, Pierluigi

    2011-09-01

    We study the physical properties, formation histories and environment of galaxies without a significant 'classical' spheroidal component, as predicted by semi-analytical models of galaxy formation and evolution. This work is complementary to the analysis presented in De Lucia et al., where we focus on the relative contribution of various physical mechanisms responsible for bulge assembly in a Λ cold dark matter cosmology. We find that the fraction of bulgeless galaxies is a strong decreasing function of stellar mass: they represent a negligible fraction of the galaxy population with M★ > 1012 M⊙, but dominate at M★ < 1010 M⊙. We find a clear dichotomy in this galaxy population, between central galaxies of low-mass dark matter haloes and satellite galaxies in massive groups/clusters. We show that bulgeless galaxies are relatively young systems, that assemble most of their mass at low redshift, but they can also host very old stellar populations. Since galaxy-galaxy mergers are assumed to lead to the formation of a spheroidal component, in our models these galaxies form preferentially in low-mass haloes that host a small number of satellites galaxies. We show that the adopted modelling for galaxy mergers represents a key ingredient in determining the actual number of bulgeless galaxies. Our results show that these galaxies are not a rare population in theoretical models: at z ˜ 0, galaxies with no classical bulge (but often including galaxies with the equivalent of pseudo-bulges) account for up to 14 per cent of the galaxies with 1011 < M★/M⊙ < 1012.

  17. Ambient Fine Particulate Matter Air Pollution and Physical Activity: A Longitudinal Study of University Retirees in Beijing, China.

    PubMed

    Yu, Hongjun; An, Ruopeng; Andrade, Flavia

    2017-07-01

    We examined the longitudinal relationship between ambient fine particulate matter (PM2.5) air pollution and physical activity-related health behaviors among university retirees in Beijing, China. Annual health surveys of retirees were conducted at Tsinghua University during 2011-2016. We conducted linear individual fixed-effect regression analyses to estimate the impact of ambient PM2.5 concentration on physical activity-related health behaviors among survey participants, adjusting for various time-variant individual characteristics and environmental measures. An increase in ambient PM2.5 concentration by one standard deviation (56.6 μg/m³) was associated with a reduction in weekly total hours of walking by 4.69 (95% confidence interval=1.30-8.08), a reduction in leisure-time Physical Activity Scale for the Elderly (PASE) score by 71.16 (28.91-113.41), and a reduction in total PASE score by 110.67 (59.25-162.08). An increase in ambient PM2.5 concentration by one standard deviation was associated with an increase in daily average hours of nighttime/daytime sleeping by 1.75 (1.24-2.26). The impact of ambient PM2.5 concentration on weekly hours of walking tended to be greater among men than among women. Air pollution significantly discouraged Chinese older adults from engaging in daily physical activities. Policy interventions are needed to reduce air pollution in China's urban areas.

  18. A tale of oblivion: Ida Noddack and the ‘universal abundance’ of matter

    PubMed Central

    Santos, Gildo Magalhães

    2014-01-01

    Ida Noddack was a German chemist who in 1925, with her husband Walter Noddack, discovered element 75 (rhenium) and possibly element 43 (technetium). She is also known to have anticipated, by nine years, the possibility of nuclear fission. This article focuses on Ida's hypothesis that all elements are present in any mineral. Ida related the relative abundance of the elements in the Universe to hypothetical properties of the atomic nuclei. This allowed her to speculate about a different Periodic Table in which isotopes might be the cause of unexpected features of periodicity. Ida Noddack faced many professional obstacles because of her scientific nonconformity and gender, the resentment of physicists against intrusion in their field, and the overall difficulty of research under and after the Nazi regime.

  19. Spatial and dynamical properties of voids in a Λ cold dark matter universe

    NASA Astrophysics Data System (ADS)

    Padilla, N. D.; Ceccarelli, L.; Lambas, D. G.

    2005-11-01

    We study the statistical properties of voids in the distribution of mass, dark-matter haloes and galaxies (BJ < -16) in a Λ cold dark matter (ΛCDM)numerical simulation populated with galaxies using a semi-analytic galaxy formation model (GALFORM, Cole et al.). We find that the properties of voids selected from GALFORM galaxies are compatible with those of voids identified from a population of haloes with mass M > 1011.5h-1Msolar, similar to the median halo mass, Mmed= 1011.3h-1Msolar. We also find that the number density of galaxy- and halo-defined voids can be up to two orders of magnitude higher than mass-defined voids for large void radii, however, we observe that this difference is reduced to about half an order of magnitude when the positions are considered in redshift space. As expected, there are outflow velocities that show their maximum at larger void-centric distances for larger voids. We find a linear relation for the maximum outflow velocity, vmax=v0rvoid. The void-centric distance where this maximum occurs follows a suitable power-law fit of the form log(dvmax)=(rvoid/A)B. At sufficiently large distances, we find mild infall motions on to the subdense regions. The galaxy velocity field around galaxy-defined voids is consistent with the results of haloes with masses above the median, showing milder outflows than the mass around mass-defined voids. We find that a similar analysis in redshift space would make both outflows and infalls appear with a lower amplitude. We also find that the velocity dispersion of galaxies and haloes is larger in the direction parallel to the void walls by ~=10-20 per cent. Given that voids are by definition subdense regions, the cross-correlation function between galaxy-defined voids and galaxies is close to ξ=-1 out to separations comparable to the void size, and at larger separations the correlation function level increases, approaching the values of the auto-correlation function of galaxies. The cross

  20. The coyote universe extended: Precision emulation of the matter power spectrum

    SciTech Connect

    Heitmann, Katrin; Kwan, Juliana; Habib, Salman; Lawrence, Earl; Higdon, David

    2014-01-01

    Modern sky surveys are returning precision measurements of cosmological statistics such as weak lensing shear correlations, the distribution of galaxies, and cluster abundance. To fully exploit these observations, theorists must provide predictions that are at least as accurate as the measurements, as well as robust estimates of systematic errors that are inherent to the modeling process. In the nonlinear regime of structure formation, this challenge can only be overcome by developing a large-scale, multi-physics simulation capability covering a range of cosmological models and astrophysical processes. As a first step to achieving this goal, we have recently developed a prediction scheme for the matter power spectrum (a so-called emulator), accurate at the 1% level out to k ∼ 1 Mpc{sup –1} and z = 1 for wCDM cosmologies based on a set of high-accuracy N-body simulations. It is highly desirable to increase the range in both redshift and wavenumber and to extend the reach in cosmological parameter space. To make progress in this direction, while minimizing computational cost, we present a strategy that maximally reuses the original simulations. We demonstrate improvement over the original spatial dynamic range by an order of magnitude, reaching k ∼ 10 h Mpc{sup –1}, a four-fold increase in redshift coverage, to z = 4, and now include the Hubble parameter as a new independent variable. To further the range in k and z, a new set of nested simulations run at modest cost is added to the original set. The extension in h is performed by including perturbation theory results within a multi-scale procedure for building the emulator. This economical methodology still gives excellent error control, ∼5% near the edges of the domain of applicability of the emulator. A public domain code for the new emulator is released as part of the work presented in this paper.

  1. The Coyote Universe Extended: Precision Emulation of the Matter Power Spectrum

    NASA Astrophysics Data System (ADS)

    Heitmann, Katrin; Lawrence, Earl; Kwan, Juliana; Habib, Salman; Higdon, David

    2014-01-01

    Modern sky surveys are returning precision measurements of cosmological statistics such as weak lensing shear correlations, the distribution of galaxies, and cluster abundance. To fully exploit these observations, theorists must provide predictions that are at least as accurate as the measurements, as well as robust estimates of systematic errors that are inherent to the modeling process. In the nonlinear regime of structure formation, this challenge can only be overcome by developing a large-scale, multi-physics simulation capability covering a range of cosmological models and astrophysical processes. As a first step to achieving this goal, we have recently developed a prediction scheme for the matter power spectrum (a so-called emulator), accurate at the 1% level out to k ~ 1 Mpc-1 and z = 1 for wCDM cosmologies based on a set of high-accuracy N-body simulations. It is highly desirable to increase the range in both redshift and wavenumber and to extend the reach in cosmological parameter space. To make progress in this direction, while minimizing computational cost, we present a strategy that maximally reuses the original simulations. We demonstrate improvement over the original spatial dynamic range by an order of magnitude, reaching k ~ 10 h Mpc-1, a four-fold increase in redshift coverage, to z = 4, and now include the Hubble parameter as a new independent variable. To further the range in k and z, a new set of nested simulations run at modest cost is added to the original set. The extension in h is performed by including perturbation theory results within a multi-scale procedure for building the emulator. This economical methodology still gives excellent error control, ~5% near the edges of the domain of applicability of the emulator. A public domain code for the new emulator is released as part of the work presented in this paper.

  2. Benefit incidence analysis of healthcare in Bangladesh - equity matters for universal health coverage.

    PubMed

    Khan, Jahangir A M; Ahmed, Sayem; MacLennan, Mary; Sarker, Abdur Razzaque; Sultana, Marufa; Rahman, Hafizur

    2017-04-01

    Equity in access to and utilization of healthcare is an important goal for any health system and an essential prerequisite for achieving Universal Health Coverage for any country. This study investigated the extent to which health benefits are distributed across socioeconomic groups; and how different types of providers contribute to inequity in health benefits of Bangladesh. The distribution of health benefits across socioeconomic groups was estimated using concentration indices. Health benefits from three types of formal providers were analysed (public, private and NGO providers), separated into rural and urban populations. Decomposition of concentration indices into types of providers quantified the relative contribution of providers to the overall distribution of benefits across socioeconomic groups. Eventually, the distribution of benefits was compared to the distribution of healthcare need (proxied by 'self-reported illness and symptoms') across socioeconomic groups. Data from the latest Household Income and Expenditure Survey, 2010 and WHO-CHOICE were used. An overall pro-rich distribution of healthcare benefits was observed (CI = 0.229, t -value = 9.50). Healthcare benefits from private providers (CI = 0.237, t -value = 9.44) largely favoured the richer socioeconomic groups. Little evidence of inequity in benefits was found in public (CI = 0.044, t -value = 2.98) and NGO (CI = 0.095, t -value = 0.54) providers. Private providers contributed by 95.9% to overall inequity. The poorest socioeconomic group with 21.8% of the need for healthcare received only 12.7% of the benefits, while the richest group with 18.0% of the need accounted for 32.8% of the health benefits. Overall healthcare benefits in Bangladesh were pro-rich, particularly because of health benefits from private providers. Public providers were observed to contribute relatively slightly to inequity. The poorest (richest) people with largest (least) need for

  3. An Investigation of University Student and K-12 Teacher Reasoning about Key Ideas in the Development of the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Robertson, Amy D.

    2011-01-01

    This dissertation describes a systematic investigation of university student and K-12 teacher reasoning about key ideas relevant to the development of a particulate model for matter. Written assessments and individual demonstration interviews have been used to study the reasoning of introductory and sophomore-level physics students, introductory…

  4. An Investigation of University Student and K-12 Teacher Reasoning about Key Ideas in the Development of the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Robertson, Amy D.

    2011-01-01

    This dissertation describes a systematic investigation of university student and K-12 teacher reasoning about key ideas relevant to the development of a particulate model for matter. Written assessments and individual demonstration interviews have been used to study the reasoning of introductory and sophomore-level physics students, introductory…

  5. University Students' Satisfaction with their Academic Studies: Personality and Motivation Matter

    PubMed Central

    Wach, F.-Sophie; Karbach, Julia; Ruffing, Stephanie; Brünken, Roland; Spinath, Frank M.

    2016-01-01

    Although there is consensus about the importance of students' satisfaction with their academic studies as one facet of academic success, little is known about the determinants of this significant outcome variable. Past research rarely investigated the predictive power of multiple predictors simultaneously. Hence, we examined how demographic variables, personality, cognitive and achievement-related variables (intelligence, academic achievement), as well as various motivational constructs were associated with three different dimensions of satisfaction (satisfaction with study content, satisfaction with the conditions of the academic program, satisfaction with the ability to cope with academic stress) assessed approximately 2 years apart. Analyzing data of a sample of university students (N = 620; Mage = 20.77; SDage = 3.22) using structural equation modeling, our results underline the significance of personality and motivational variables: Neuroticism predicted satisfaction with academic studies, but its relevance varied between outcome dimensions. Regarding the predictive validity of motivational variables, the initial motivation for enrolling in a particular major was correlated with two dimensions of subsequent satisfaction with academic studies. In contrast, the predictive value of cognitive and achievement-related variables was relatively low, with academic achievement only related to satisfaction with the conditions of the academic program after controlling for the prior satisfaction level. PMID:26909049

  6. University Students' Satisfaction with their Academic Studies: Personality and Motivation Matter.

    PubMed

    Wach, F-Sophie; Karbach, Julia; Ruffing, Stephanie; Brünken, Roland; Spinath, Frank M

    2016-01-01

    Although there is consensus about the importance of students' satisfaction with their academic studies as one facet of academic success, little is known about the determinants of this significant outcome variable. Past research rarely investigated the predictive power of multiple predictors simultaneously. Hence, we examined how demographic variables, personality, cognitive and achievement-related variables (intelligence, academic achievement), as well as various motivational constructs were associated with three different dimensions of satisfaction (satisfaction with study content, satisfaction with the conditions of the academic program, satisfaction with the ability to cope with academic stress) assessed approximately 2 years apart. Analyzing data of a sample of university students (N = 620; M age = 20.77; SD age = 3.22) using structural equation modeling, our results underline the significance of personality and motivational variables: Neuroticism predicted satisfaction with academic studies, but its relevance varied between outcome dimensions. Regarding the predictive validity of motivational variables, the initial motivation for enrolling in a particular major was correlated with two dimensions of subsequent satisfaction with academic studies. In contrast, the predictive value of cognitive and achievement-related variables was relatively low, with academic achievement only related to satisfaction with the conditions of the academic program after controlling for the prior satisfaction level.

  7. A new observation of a cosmic microwave background radiation supports my idea that a balance universe model between stellar matter and dark matter is like Chinese TaiJi Model

    NASA Astrophysics Data System (ADS)

    Cao, Dayong

    2014-03-01

    Einstein's equation gives a balance model of the universe. However it is not a steady model. As we know, there is a large amount of dark matter around stars and galaxies. This dark matter structure is very special. A new balance model of the universe, includes the dark matter, needed to be looked for. The stellar matter is a positive of Einstein's model. The dark matter is a negative of Einstein's model by ``mass-energy coordinate'' system because it has a space-time center. http://meetings.aps.org/link/BAPS.2010.SES.FC.9, Both of them build up a Dynamic Steady Balance Universal TaiJi Model without cosmological constant. http://meetings.aps.org/link/BAPS.2010.DNP.FE.9, So the map of CMB is like the Chinese TaiJi map. And there may be a ``hot spot'' across ``Axis of Evil'' and opposite to the ``cold spot.'' http://www.dailymail.co.uk/sciencetech/article-2430415, So there is a negative black-body radiation. A positive black-body radiation and a negative black-body radiation also builds up a balance model such as TaiJi Model. http://meetings.aps.org/link/BAPS.2012.APR.K1.78, The paper supposes that dark negative heat never spontaneously flows from a hot substance to a cold substance in dark matter system. The negative second law of thermodynamics and the second law of thermodynamics build up a balance model such as TaiJi Model too. AEEA

  8. Dark Matters

    ScienceCinema

    Joseph Silk

    2016-07-12

    One of the greatest mysteries in the cosmos is that it is mostly dark.  Astronomers and particle physicists today are seeking to unravel the nature of this mysterious, but pervasive dark matter which has profoundly influenced the formation of structure in the universe.  I will describe the complex interplay between galaxy formation and dark matter detectability and review recent attempts to measure particle dark matter by direct and indirect means.

  9. Superheavy thermal dark matter and primordial asymmetries

    NASA Astrophysics Data System (ADS)

    Bramante, Joseph; Unwin, James

    2017-02-01

    The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important consequence of late time dilution, is that a smaller dark matter annihilation cross section is needed to obtain the observed dark matter relic density. For cosmologies with high scale baryogenesis, followed by radiation-dominated dark matter freeze-out, we show that the perturbative unitarity mass bound on thermal relic dark matter is relaxed to 1010 GeV. We proceed to study superheavy asym-metric dark matter models, made possible by a sizable entropy injection after dark matter freeze-out, and identify how the Affleck-Dine mechanism would generate the baryon and dark asymmetries.

  10. Does mentoring matter: results from a survey of faculty mentees at a large health sciences university

    PubMed Central

    Feldman, Mitchell D.; Arean, Patricia A.; Marshall, Sally J.; Lovett, Mark; O'Sullivan, Patricia

    2010-01-01

    Background To determine the characteristics associated with having a mentor, the association of mentoring with self-efficacy, and the content of mentor–mentee interactions at the University of California, San Francisco (UCSF), we conducted a baseline assessment prior to implementing a comprehensive faculty mentoring program. Method We surveyed all prospective junior faculty mentees at UCSF. Mentees completed a web-based, 38-item survey including an assessment of self-efficacy and a needs assessment. We used descriptive and inferential statistics to determine the association between having a mentor and gender, ethnicity, faculty series, and self-efficacy. Results Our respondents (n=464, 56%) were 53% female, 62% white, and 7% from underrepresented minority groups. More than half of respondents (n=319) reported having a mentor. There were no differences in having a mentor based on gender or ethnicity (p≥0.05). Clinician educator faculty with more teaching and patient care responsibilities were statistically significantly less likely to have a mentor compared with faculty in research intensive series (p<0.001). Having a mentor was associated with greater satisfaction with time allocation at work (p<0.05) and with higher academic self-efficacy scores, 6.07 (sd = 1.36) compared with those without a mentor, 5.33 (sd = 1.35, p<0.001). Mentees reported that they most often discussed funding with the mentors, but rated highest requiring mentoring assistance with issues of promotion and tenure. Conclusion Findings from the UCSF faculty mentoring program may assist other health science institutions plan similar programs. Mentoring needs for junior faculty with greater teaching and patient care responsibilities must be addressed. PMID:20431710

  11. Cardiomyopathy confers susceptibility to particulate matter-induced oxidative stress, vagal dominance, arrhythmia and pulmonary inflammation in heart failure-prone rats.

    PubMed

    Carll, Alex P; Haykal-Coates, Najwa; Winsett, Darrell W; Hazari, Mehdi S; Ledbetter, Allen D; Richards, Judy H; Cascio, Wayne E; Costa, Daniel L; Farraj, Aimen K

    2015-02-01

    Acute exposure to ambient fine particulate matter (PM2.5) is tied to cardiovascular morbidity and mortality, especially among those with prior cardiac injury. The mechanisms and pathophysiological events precipitating these outcomes remain poorly understood but may involve inflammation, oxidative stress, arrhythmia and autonomic nervous system imbalance. Cardiomyopathy results from cardiac injury, is the leading cause of heart failure, and can be induced in heart failure-prone rats through sub-chronic infusion of isoproterenol (ISO). To test whether cardiomyopathy confers susceptibility to inhaled PM2.5 and can elucidate potential mechanisms, we investigated the cardiophysiologic, ventilatory, inflammatory and oxidative effects of a single nose-only inhalation of a metal-rich PM2.5 (580 µg/m(3), 4 h) in ISO-pretreated (35 days × 1.0 mg/kg/day sc) rats. During the 5 days post-treatment, ISO-treated rats had decreased HR and BP and increased pre-ejection period (PEP, an inverse correlate of contractility) relative to saline-treated rats. Before inhalation exposure, ISO-pretreated rats had increased PR and ventricular repolarization time (QT) and heterogeneity (Tp-Te). Relative to clean air, PM2.5 further prolonged PR-interval and decreased systolic BP during inhalation exposure; increased tidal volume, expiratory time, heart rate variability (HRV) parameters of parasympathetic tone and atrioventricular block arrhythmias over the hours post-exposure; increased pulmonary neutrophils, macrophages and total antioxidant status one day post-exposure; and decreased pulmonary glutathione peroxidase 8 weeks after exposure, with all effects occurring exclusively in ISO-pretreated rats but not saline-pretreated rats. Ultimately, our findings indicate that cardiomyopathy confers susceptibility to the oxidative, inflammatory, ventilatory, autonomic and arrhythmogenic effects of acute PM2.5 inhalation.

  12. Universality for quintessence

    NASA Astrophysics Data System (ADS)

    Cicciarella, F.; Pieroni, M.

    2017-08-01

    Several recent works suggested the possibility of describing inflation by means of a renormalization group equation. In this paper we discuss the application of these methods to models of quintessence. In this framework a period of exponential expansion corresponds to the slow evolution of the scalar field in the neighborhood of a fixed point. A minimal set of universality classes for models of quintessence is defined and the transition from a matter dominated to quintessence dominated universe is studied. Models in which quintessence is non-minimally coupled with gravity are also discussed. We show that the formalism proves to be extremely convenient to describe quintessence and moreover we find that in most of the models discussed in this work quintessence naturally takes over ordinary matter.

  13. Dark matter candidates

    SciTech Connect

    Turner, M.S.

    1989-01-01

    One of the simplest, yet most profound, questions we can ask about the Universe is, how much stuff is in it, and further what is that stuff composed of. Needless to say, the answer to this question has very important implications for the evolution of the Universe, determining both the ultimate fate and the course of structure formation. Remarkably, at this late date in the history of the Universe we still do not have a definitive answer to this simplest of questions---although we have some very intriguing clues. It is known with certainty that most of the material in the Universe is dark, and we have the strong suspicion that the dominant component of material in the Cosmos is not baryons, but rather is exotic relic elementary particles left over from the earliest, very hot epoch of the Universe. If true, the Dark Matter question is a most fundamental one facing both particle physics and cosmology. The leading particle dark matter candidates are: the axion, the neutralino, and a light neutrino species. All three candidates are accessible to experimental tests, and experiments are now in progress. In addition, there are several dark horse, long shot, candidates, including the superheavy magnetic monopole and soliton stars. 13 refs.

  14. Rotation of the Universe at different cosmological epochs

    NASA Astrophysics Data System (ADS)

    Chechin, L. M.

    2016-06-01

    A step-by-step foundation for the differential character of the Universe's rotation is presented. First, invoking the concept of spacetime foam with spin, it is reasonable to assume that the very early Universe can be described by the Dirac equation. Second, it is shown using the Ehrenfest theorem that, from a classical point of view, the early Universe can be described by the Papapetrou equations. Third, it is stressed that our Universe can perform only rotational motion. It is shown based on the spin part of the Papapetrou equations that the Universe's rotation depends appreciably on the physical properties of a specific cosmological epoch. The rotational angular velocity is calculated for three basic cosmological epochs: the matter-dominated epoch, the transition period (from domination of matter to domination of vacuum), and the vacuum-dominated epoch.

  15. Universality of dark matter haloes shape over six decades in mass: insights from the Millennium XXL and SBARBINE simulations

    NASA Astrophysics Data System (ADS)

    Bonamigo, Mario; Despali, Giulia; Limousin, Marceau; Angulo, Raul; Giocoli, Carlo; Soucail, Geneviève

    2015-05-01

    For the last 30 yr many observational and theoretical evidences have shown that galaxy clusters are not spherical objects, and that their shape is much better described by a triaxial geometry. With the advent of multiwavelength data of increasing quality, triaxial investigations of galaxy clusters is gathering a growing interest from the community, especially in the time of `precision cosmology'. In this work, we aim to provide the first statistically significant predictions in the unexplored mass range above 3 × 1014 M⊙h-1, using haloes from two redshift snapshots (z = 0 and z = 1) of the Millennium XXL simulation. The size of this cosmological dark matter-only simulation (4.1 Gpc) allows the formation of a statistically significant number of massive cluster scale haloes (≈500 with M > 2× 1015 M⊙ h-1, and 780 000 with M > 1014 M⊙ h-1). Besides, we aim to extend this investigation to lower masses in order to look for universal predictions across nearly six orders of magnitude in mass, from 1010 to almost 1016 M⊙ h-1. For this purpose we use the SBARBINE simulations, allowing us to model haloes of masses starting from ≈1010 M⊙ h-1. We use an elliptical overdensity method to select haloes and compute the shapes of the unimodal ones (approximately 50 per cent), while we discard the more unrelaxed. The minor to major and intermediate to major axis ratio distributions are found to be well described by simple universal functional forms that do not depend on cosmology or redshift. Our results extend the findings of Jing & Suto to a higher precision and a wider range of mass. This `recipe' is made available to the community in this paper and in a dedicated web page.

  16. X-ray clusters from a high-resolution hydrodynamic PPM simulation of the cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Bryan, Greg L.; Cen, Renyue; Norman, Michael L.; Ostriker, Jermemiah P.; Stone, James M.

    1994-01-01

    A new three-dimensional hydrodynamic code based on the piecewise parabolic method (PPM) is utilized to compute the distribution of hot gas in the standard Cosmic Background Explorer (COBE)-normalized cold dark matter (CDM) universe. Utilizing periodic boundary conditions, a box with size 85 h(exp-1) Mpc, having cell size 0.31 h(exp-1) Mpc, is followed in a simulation with 270(exp 3)=10(exp 7.3) cells. Adopting standard parameters determined from COBE and light-element nucleosynthesis, Sigma(sub 8)=1.05, Omega(sub b)=0.06, we find the X-ray-emitting clusters, compute the luminosity function at several wavelengths, the temperature distribution, and estimated sizes, as well as the evolution of these quantities with redshift. The results, which are compared with those obtained in the preceding paper (Kang et al. 1994a), may be used in conjuction with ROSAT and other observational data sets. Overall, the results of the two computations are qualitatively very similar with regard to the trends of cluster properties, i.e., how the number density, radius, and temeprature depend on luminosity and redshift. The total luminosity from clusters is approximately a factor of 2 higher using the PPM code (as compared to the 'total variation diminishing' (TVD) code used in the previous paper) with the number of bright clusters higher by a similar factor. The primary conclusions of the prior paper, with regard to the power spectrum of the primeval density perturbations, are strengthened: the standard CDM model, normalized to the COBE microwave detection, predicts too many bright X-ray emitting clusters, by a factor probably in excess of 5. The comparison between observations and theoretical predictions for the evolution of cluster properties, luminosity functions, and size and temperature distributions should provide an important discriminator among competing scenarios for the development of structure in the universe.

  17. X-ray clusters from a high-resolution hydrodynamic PPM simulation of the cold dark matter universe

    NASA Technical Reports Server (NTRS)

    Bryan, Greg L.; Cen, Renyue; Norman, Michael L.; Ostriker, Jermemiah P.; Stone, James M.

    1994-01-01

    A new three-dimensional hydrodynamic code based on the piecewise parabolic method (PPM) is utilized to compute the distribution of hot gas in the standard Cosmic Background Explorer (COBE)-normalized cold dark matter (CDM) universe. Utilizing periodic boundary conditions, a box with size 85 h(exp-1) Mpc, having cell size 0.31 h(exp-1) Mpc, is followed in a simulation with 270(exp 3)=10(exp 7.3) cells. Adopting standard parameters determined from COBE and light-element nucleosynthesis, Sigma(sub 8)=1.05, Omega(sub b)=0.06, we find the X-ray-emitting clusters, compute the luminosity function at several wavelengths, the temperature distribution, and estimated sizes, as well as the evolution of these quantities with redshift. The results, which are compared with those obtained in the preceding paper (Kang et al. 1994a), may be used in conjuction with ROSAT and other observational data sets. Overall, the results of the two computations are qualitatively very similar with regard to the trends of cluster properties, i.e., how the number density, radius, and temeprature depend on luminosity and redshift. The total luminosity from clusters is approximately a factor of 2 higher using the PPM code (as compared to the 'total variation diminishing' (TVD) code used in the previous paper) with the number of bright clusters higher by a similar factor. The primary conclusions of the prior paper, with regard to the power spectrum of the primeval density perturbations, are strengthened: the standard CDM model, normalized to the COBE microwave detection, predicts too many bright X-ray emitting clusters, by a factor probably in excess of 5. The comparison between observations and theoretical predictions for the evolution of cluster properties, luminosity functions, and size and temperature distributions should provide an important discriminator among competing scenarios for the development of structure in the universe.

  18. How universal are human mate choices? Size does not matter when Hadza foragers are choosing a mate.

    PubMed

    Sear, Rebecca; Marlowe, Frank W

    2009-10-23

    It has been argued that size matters on the human mate market: both stated preferences and mate choices have been found to be non-random with respect to height and weight. But how universal are these patterns? Most of the literature on human mating patterns is based on post-industrial societies. Much less is known about mating behaviour in more traditional societies. Here we investigate mate choice by analysing whether there is any evidence for non-random mating with respect to size and strength in a forager community, the Hadza of Tanzania. We test whether couples assort for height, weight, body mass index (BMI), per cent fat and grip strength. We test whether there is a male-taller norm. Finally, we test for an association between anthropometric variables and number of marriages. Our results show no evidence for assortative mating for height, weight, BMI or per cent fat; no evidence for a male-taller norm and no evidence that number of marriages is associated with our size variables. Hadza couples may assort positively for grip strength, but grip strength does not affect the number of marriages. Overall we conclude that, in contrast to post-industrial societies, mating appears to be random with respect to size in the Hadza.

  19. How universal are human mate choices? Size does not matter when Hadza foragers are choosing a mate

    PubMed Central

    Sear, Rebecca; Marlowe, Frank W.

    2009-01-01

    It has been argued that size matters on the human mate market: both stated preferences and mate choices have been found to be non-random with respect to height and weight. But how universal are these patterns? Most of the literature on human mating patterns is based on post-industrial societies. Much less is known about mating behaviour in more traditional societies. Here we investigate mate choice by analysing whether there is any evidence for non-random mating with respect to size and strength in a forager community, the Hadza of Tanzania. We test whether couples assort for height, weight, body mass index (BMI), per cent fat and grip strength. We test whether there is a male-taller norm. Finally, we test for an association between anthropometric variables and number of marriages. Our results show no evidence for assortative mating for height, weight, BMI or per cent fat; no evidence for a male-taller norm and no evidence that number of marriages is associated with our size variables. Hadza couples may assort positively for grip strength, but grip strength does not affect the number of marriages. Overall we conclude that, in contrast to post-industrial societies, mating appears to be random with respect to size in the Hadza. PMID:19570778

  20. When matter matters

    SciTech Connect

    Easson, Damien A.; Sawicki, Ignacy; Vikman, Alexander E-mail: ignacy.sawicki@uni-heidelberg.de

    2013-07-01

    We study a recently proposed scenario for the early universe:Subluminal Galilean Genesis. We prove that without any other matter present in the spatially flat Friedmann universe, the perturbations of the Galileon scalar field propagate with a speed at most equal to the speed of light. This proof applies to all cosmological solutions — to the whole phase space. However, in a more realistic situation, when one includes any matter which is not directly coupled to the Galileon, there always exists a region of phase space where these perturbations propagate superluminally, indeed with arbitrarily high speed. We illustrate our analytic proof with numerical computations. We discuss the implications of this result for the possible UV completion of the model.

  1. Imperfect Dark Matter

    SciTech Connect

    Mirzagholi, Leila; Vikman, Alexander E-mail: alexander.vikman@lmu.de

    2015-06-01

    We consider cosmology of the recently introduced mimetic matter with higher derivatives (HD). Without HD this system describes irrotational dust—Dark Matter (DM) as we see it on cosmologically large scales. DM particles correspond to the shift-charges—Noether charges of the shifts in the field space. Higher derivative corrections usually describe a deviation from the thermodynamical equilibrium in the relativistic hydrodynamics. Thus we show that mimetic matter with HD corresponds to an imperfect DM which: i) renormalises the Newton's constant in the Friedmann equations, ii) has zero pressure when there is no extra matter in the universe, iii) survives the inflationary expansion which puts the system on a dynamical attractor with a vanishing shift-charge, iv) perfectly tracks any external matter on this attractor, v) can become the main (and possibly the only) source of DM, provided the shift-symmetry in the HD terms is broken during some small time interval in the radiation domination époque. In the second part of the paper we present a hydrodynamical description of general anisotropic and inhomogeneous configurations of the system. This imperfect mimetic fluid has an energy flow in the field's rest frame. We find that in the Eckart and in the Landau-Lifshitz frames the mimetic fluid possesses nonvanishing vorticity appearing already at the first order in the HD. Thus, the structure formation and gravitational collapse should proceed in a rather different fashion from the simple irrotational DM models.

  2. Dark Matter

    SciTech Connect

    Bashir, A.; Cotti, U.; De Leon, C. L.; Raya, A; Villasenor, L.

    2008-07-02

    One of the biggest scientific mysteries of our time resides in the identification of the particles that constitute a large fraction of the mass of our Universe, generically known as dark matter. We review the observations and the experimental data that imply the existence of dark matter. We briefly discuss the properties of the two best dark-matter candidate particles and the experimental techniques presently used to try to discover them. Finally, we mention a proposed project that has recently emerged within the Mexican community to look for dark matter.

  3. ETHOS—an effective theory of structure formation: From dark particle physics to the matter distribution of the Universe

    NASA Astrophysics Data System (ADS)

    Cyr-Racine, Francis-Yan; Sigurdson, Kris; Zavala, Jesús; Bringmann, Torsten; Vogelsberger, Mark; Pfrommer, Christoph

    2016-06-01

    We formulate an effective theory of structure formation (ETHOS) that enables cosmological structure formation to be computed in almost any microphysical model of dark matter physics. This framework maps the detailed microphysical theories of particle dark matter interactions into the physical effective parameters that shape the linear matter power spectrum and the self-interaction transfer cross section of nonrelativistic dark matter. These are the input to structure formation simulations, which follow the evolution of the cosmological and galactic dark matter distributions. Models with similar effective parameters in ETHOS but with different dark particle physics would nevertheless result in similar dark matter distributions. We present a general method to map an ultraviolet complete or effective field theory of low-energy dark matter physics into parameters that affect the linear matter power spectrum and carry out this mapping for several representative particle models. We further propose a simple but useful choice for characterizing the dark matter self-interaction transfer cross section that parametrizes self-scattering in structure formation simulations. Taken together, these effective parameters in ETHOS allow the classification of dark matter theories according to their structure formation properties rather than their intrinsic particle properties, paving the way for future simulations to span the space of viable dark matter physics relevant for structure formation.

  4. Algorithms for computing parsimonious evolutionary scenarios for genome evolution, the last universal common ancestor and dominance of horizontal gene transfer in the evolution of prokaryotes.

    PubMed

    Mirkin, Boris G; Fenner, Trevor I; Galperin, Michael Y; Koonin, Eugene V

    2003-01-06

    Comparative analysis of sequenced genomes reveals numerous instances of apparent horizontal gene transfer (HGT), at least in prokaryotes, and indicates that lineage-specific gene loss might have been even more common in evolution. This complicates the notion of a species tree, which needs to be re-interpreted as a prevailing evolutionary trend, rather than the full depiction of evolution, and makes reconstruction of ancestral genomes a non-trivial task. We addressed the problem of constructing parsimonious scenarios for individual sets of orthologous genes given a species tree. The orthologous sets were taken from the database of Clusters of Orthologous Groups of proteins (COGs). We show that the phyletic patterns (patterns of presence-absence in completely sequenced genomes) of almost 90% of the COGs are inconsistent with the hypothetical species tree. Algorithms were developed to reconcile the phyletic patterns with the species tree by postulating gene loss, COG emergence and HGT (the latter two classes of events were collectively treated as gene gains). We prove that each of these algorithms produces a parsimonious evolutionary scenario, which can be represented as mapping of loss and gain events on the species tree. The distribution of the evolutionary events among the tree nodes substantially depends on the underlying assumptions of the reconciliation algorithm, e.g. whether or not independent gene gains (gain after loss after gain) are permitted. Biological considerations suggest that, on average, gene loss might be a more likely event than gene gain. Therefore different gain penalties were used and the resulting series of reconstructed gene sets for the last universal common ancestor (LUCA) of the extant life forms were analysed. The number of genes in the reconstructed LUCA gene sets grows as the gain penalty increases. However, qualitative examination of the LUCA versions reconstructed with different gain penalties indicates that, even with a gain penalty

  5. Algorithms for computing parsimonious evolutionary scenarios for genome evolution, the last universal common ancestor and dominance of horizontal gene transfer in the evolution of prokaryotes

    PubMed Central

    Mirkin, Boris G; Fenner, Trevor I; Galperin, Michael Y; Koonin, Eugene V

    2003-01-01

    Background Comparative analysis of sequenced genomes reveals numerous instances of apparent horizontal gene transfer (HGT), at least in prokaryotes, and indicates that lineage-specific gene loss might have been even more common in evolution. This complicates the notion of a species tree, which needs to be re-interpreted as a prevailing evolutionary trend, rather than the full depiction of evolution, and makes reconstruction of ancestral genomes a non-trivial task. Results We addressed the problem of constructing parsimonious scenarios for individual sets of orthologous genes given a species tree. The orthologous sets were taken from the database of Clusters of Orthologous Groups of proteins (COGs). We show that the phyletic patterns (patterns of presence-absence in completely sequenced genomes) of almost 90% of the COGs are inconsistent with the hypothetical species tree. Algorithms were developed to reconcile the phyletic patterns with the species tree by postulating gene loss, COG emergence and HGT (the latter two classes of events were collectively treated as gene gains). We prove that each of these algorithms produces a parsimonious evolutionary scenario, which can be represented as mapping of loss and gain events on the species tree. The distribution of the evolutionary events among the tree nodes substantially depends on the underlying assumptions of the reconciliation algorithm, e.g. whether or not independent gene gains (gain after loss after gain) are permitted. Biological considerations suggest that, on average, gene loss might be a more likely event than gene gain. Therefore different gain penalties were used and the resulting series of reconstructed gene sets for the last universal common ancestor (LUCA) of the extant life forms were analysed. The number of genes in the reconstructed LUCA gene sets grows as the gain penalty increases. However, qualitative examination of the LUCA versions reconstructed with different gain penalties indicates that, even

  6. Isocurvature cold dark matter fluctuations

    NASA Technical Reports Server (NTRS)

    Efstathiou, G.; Bond, J. R.

    1986-01-01

    According to Preskill et al. (1983), the axion field represents a particularly attractive candidate for the dark matter in the universe. In many respects it behaves like other forms of cold dark matter, such as massive gravitinos, photinos, and monopoles. It is, however, a pseudo-Goldstone boson of very low mass, and it is only because of rapid coherent oscillations of the field that it can dominate the mass density of the universe. In the present paper it is assumed that the isocurvature mode is dominant. The linear evolution calculations conducted do not depend upon specific details of particle physics. For this reason, the conducted discussion is applicable to any cold dark matter model with isocurvature perturbations. The results of the study lead to the conclusion that scale-invariant isocurvature perturbations do not seem an attractive possibility for the origin of large-scale structure. The findings strengthen the review that primordial adiabatic perturbations were the dominant fluctuations in the early stages of the Big Bang.

  7. Isocurvature cold dark matter fluctuations

    NASA Technical Reports Server (NTRS)

    Efstathiou, G.; Bond, J. R.

    1986-01-01

    According to Preskill et al. (1983), the axion field represents a particularly attractive candidate for the dark matter in the universe. In many respects it behaves like other forms of cold dark matter, such as massive gravitinos, photinos, and monopoles. It is, however, a pseudo-Goldstone boson of very low mass, and it is only because of rapid coherent oscillations of the field that it can dominate the mass density of the universe. In the present paper it is assumed that the isocurvature mode is dominant. The linear evolution calculations conducted do not depend upon specific details of particle physics. For this reason, the conducted discussion is applicable to any cold dark matter model with isocurvature perturbations. The results of the study lead to the conclusion that scale-invariant isocurvature perturbations do not seem an attractive possibility for the origin of large-scale structure. The findings strengthen the review that primordial adiabatic perturbations were the dominant fluctuations in the early stages of the Big Bang.

  8. The matter distribution in the local Universe as derived from galaxy groups in SDSS DR12 and 2MRS

    NASA Astrophysics Data System (ADS)

    Saulder, Christoph; van Kampen, Eelco; Chilingarian, Igor V.; Mieske, Steffen; Zeilinger, Werner W.

    2016-11-01

    Context. Friends-of-friends algorithms are a common tool to detect galaxy groups and clusters in large survey data. In order to be as precise as possible, they have to be carefully calibrated using mock catalogues. Aims: We create an accurate and robust description of the matter distribution in the local Universe using the most up-to-date available data. This will provide the input for a specific cosmological test planned as follow-up to this work, and will be useful for general extragalactic and cosmological research. Methods: We created a set of galaxy group catalogues based on the 2MRS and SDSS DR12 galaxy samples using a friends-of-friends based group finder algorithm. The algorithm was carefully calibrated and optimised on a new set of wide-angle mock catalogues from the Millennium simulation, in order to provide accurate total mass estimates of the galaxy groups taking into account the relevant observational biases in 2MRS and SDSS. Results: We provide four different catalogues: (i) a 2MRS based group catalogue; (ii) an SDSS DR12 based group catalogue reaching out to a redshift z = 0.11 with stellar mass estimates for 70% of the galaxies; (iii) a catalogue providing additional fundamental plane distances for all groups of the SDSS catalogue that host elliptical galaxies; (iv) a catalogue of the mass distribution in the local Universe based on a combination of our 2MRS and SDSS catalogues. Conclusions: While motivated by a specific cosmological test, three of the four catalogues that we produced are well suited to act as reference databases for a variety of extragalactic and cosmological science cases. Our catalogue of fundamental plane distances for SDSS groups provides further added value to this paper. The full catalogues (Tables A.1 to A.8) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A14

  9. Particle physics in the very early universe

    NASA Technical Reports Server (NTRS)

    Schramm, D. N.

    1981-01-01

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

  10. Particle physics in the very early universe

    NASA Technical Reports Server (NTRS)

    Schramm, D. N.

    1981-01-01

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

  11. The Nature of Damped Lyα Systems and Their Hosts in the Standard Cold Dark Matter Universe

    NASA Astrophysics Data System (ADS)

    Cen, Renyue

    2012-04-01

    Using adaptive mesh refinement cosmological hydrodynamic simulations with a physically motivated supernova feedback prescription, we show that the standard cold dark matter model can account for extant observed properties of damped Lyα systems (DLAs). With detailed examination of DLAs identified for each redshift snapshot through ray tracing through the simulation volumes containing thousands of galaxies, we find the following: (1) While DLA hosts roughly trace the overall population of galaxies at all redshifts, they are always gas-rich and have tendencies of being slightly smaller and bluer. (2) The history of DLA evolution is cosmological in nature and reflects primarily the evolution of the underlying cosmic density, galaxy size, and galaxy interactions. With higher density and more interactions at high redshift the size of DLAs is a larger fraction of their virial radius. (3) The variety of DLAs at high redshift is richer with a large contribution coming from galactic aqueducts, created through close galaxy interactions. The portion of gaseous disks of galaxies where most stars reside makes a relatively small contribution to DLA incidence at z = 3-4. (4) The majority of DLAs arise in halos of mass Mh = 1010-1012 M ⊙ at z = 1.6-4, as these galaxies dominate the overall population of galaxies then. At z = 3-4, 20%-30% of DLA hosts are Lyman break galaxies (LBGs), 10%-20% are due to galaxies more massive than LBGs, and 50%-70% are from smaller galaxies. (5) Galactic winds play an indispensable role in shaping the kinematic properties of DLAs. Specifically, the high velocity width DLAs are a mixture of those arising in high-mass, high velocity dispersion halos and those arising in smaller mass systems where cold gas clouds are entrained to high velocities by galactic winds. (6) In agreement with observations, we see a weak but noticeable evolution in DLA metallicity. The metallicity distribution centers at [Z/H] = -1.5 to -1 and spans more than three decades at

  12. Imaging the early universe

    SciTech Connect

    Krupa, Tyler J.

    2000-07-01

    An international team of cosmologists has released the first detailed images of the universe in its infancy. The images reveal the structure that existed when the universe was a tiny fraction of its current age and 1,000 times smaller and hotter than it is today. Research carried out as part of this project is shedding light on some of cosmology's long-standing mysteries, such as the nature of the matter and energy that dominate intergalactic space and whether space is ''curved'' or ''flat.''(c) 2000 Optical Society of America.

  13. Class of solutions of the Wheeler-DeWitt equation in the Friedmann-Robertson-Walker universe

    NASA Astrophysics Data System (ADS)

    Vieira, H. S.; Bezerra, V. B.

    2016-07-01

    We show that the solutions of the Wheeler-DeWitt equation in a homogeneous and isotropic universe are given by triconfluent Heun functions for the spatially closed, flat, and open geometries of the Friedmann-Robertson-Walker universe filled with different forms of energy. In a matter-dominated universe, we find the polynomial solution and the energy density spectrum. In the cases of radiation-dominated and vacuum universes, there are no polynomial solutions as shown.

  14. Brain Dominance Theory and the Missouri Public School Curriculum as Perceived by College Freshmen at Southwest Missouri State University. A Field Study.

    ERIC Educational Resources Information Center

    Hough, David

    To clarify the perceptions of college freshmen regarding the kind of teaching they experienced in public schools and how those experiences relate to the split-brain theory, a study surveyed 241 first-semester college freshmen from the fall of 1984 to the fall of 1987 at Southwest Missouri State University. Only students who had completed at least…

  15. Invisible matter.

    NASA Astrophysics Data System (ADS)

    Dolgov, A. D.

    These lectures have been given to particle physicists, mostly experimentalists and very briefly and at a pedestrian level review the problems of dark matter. The content of the lectures is the following: 1. Introduction. 2. Cosmological background. 3. Luminous matter. 4. Primordial nucleosynthesis and the total amount of baryons. 5. Gravitating invisible matter. 6. Baryonic crisis. 7. Inflationary omega. 8. Intermediate summary. 9. Possible forms of dark matter. 10. Structure formation: basic assumptions. 11. Structure formations: basics of the theory. 12. Evolution of perturbations with different forms of dark matter. 13. Conclusion. The presentation and conclusion reflect personal view of the author that a considerable amount of invisible energy in the universe is in the form of vacuum energy (cosmological constant) and possibly in the form of a classical field which adjusts vacuum energy to the value permitted and requested by astronomical data.

  16. THE NATURE OF DAMPED Ly{alpha} SYSTEMS AND THEIR HOSTS IN THE STANDARD COLD DARK MATTER UNIVERSE

    SciTech Connect

    Cen Renyue

    2012-04-01

    Using adaptive mesh refinement cosmological hydrodynamic simulations with a physically motivated supernova feedback prescription, we show that the standard cold dark matter model can account for extant observed properties of damped Ly{alpha} systems (DLAs). With detailed examination of DLAs identified for each redshift snapshot through ray tracing through the simulation volumes containing thousands of galaxies, we find the following: (1) While DLA hosts roughly trace the overall population of galaxies at all redshifts, they are always gas-rich and have tendencies of being slightly smaller and bluer. (2) The history of DLA evolution is cosmological in nature and reflects primarily the evolution of the underlying cosmic density, galaxy size, and galaxy interactions. With higher density and more interactions at high redshift the size of DLAs is a larger fraction of their virial radius. (3) The variety of DLAs at high redshift is richer with a large contribution coming from galactic aqueducts, created through close galaxy interactions. The portion of gaseous disks of galaxies where most stars reside makes a relatively small contribution to DLA incidence at z = 3-4. (4) The majority of DLAs arise in halos of mass M{sub h} = 10{sup 10}-10{sup 12} M{sub Sun} at z = 1.6-4, as these galaxies dominate the overall population of galaxies then. At z = 3-4, 20%-30% of DLA hosts are Lyman break galaxies (LBGs), 10%-20% are due to galaxies more massive than LBGs, and 50%-70% are from smaller galaxies. (5) Galactic winds play an indispensable role in shaping the kinematic properties of DLAs. Specifically, the high velocity width DLAs are a mixture of those arising in high-mass, high velocity dispersion halos and those arising in smaller mass systems where cold gas clouds are entrained to high velocities by galactic winds. (6) In agreement with observations, we see a weak but noticeable evolution in DLA metallicity. The metallicity distribution centers at [Z/H] = -1.5 to -1 and

  17. A balance for dark matter bound states

    NASA Astrophysics Data System (ADS)

    Nozzoli, F.

    2017-05-01

    Massive particles with self interactions of the order of 0.2 barn/GeV are intriguing Dark Matter candidates from an astrophysical point of view. Current and past experiments for direct detection of massive Dark Matter particles are focusing to relatively low cross sections with ordinary matter, however they cannot rule out very large cross sections, σ/M > 0.01 barn/GeV, due to atmosphere and material shielding. Cosmology places a strong indirect limit for the presence of large interactions among Dark Matter and baryons in the Universe, however such a limit cannot rule out the existence of a small sub-dominant component of Dark Matter with non negligible interactions with ordinary matter in our galactic halo. Here, the possibility of the existence of bound states with ordinary matter, for a similar Dark Matter candidate with not negligible interactions, is considered. The existence of bound states, with binding energy larger than ∼ 1 meV, would offer the possibility to test in laboratory capture cross sections of the order of a barn (or larger). The signature of the detection for a mass increasing of cryogenic samples, due to the possible particle accumulation, would allow the investigation of these Dark Matter candidates with mass up to the GUT scale. A proof of concept for a possible detection set-up and the evaluation of some noise sources are described.

  18. University Handbook. University of Wisconsin, Whitewater.

    ERIC Educational Resources Information Center

    Wisconsin Univ., Whitewater.

    The University of Wisconsin-Whitewater's handbook is divided into major sections dealing with: the university; business services; university services; student matters; curricular matters; and personnel matters. Various topics are covered, including: tuition for senior citizens, medical insurance, risk management, degree requirements, student…

  19. Confronting recent results from selected direct and indirect dark matter searches and the Higgs boson with supersymmetric models with non-universal gaugino masses

    SciTech Connect

    Spies, A.; Anton, G. E-mail: gisela.anton@physik.uni-erlangen.de

    2013-06-01

    In this paper we study a class of supersymmetric models with non-universal gaugino masses that arise from a mixture of SU(5) singlet and non-singlet representations, i.e. a combination of 1, 24, 75 and 200. Based on these models we calculate the expected dark matter signatures within the linear combination 1 ⊕ 24 ⊕ 75 ⊕ 200. We confront the model predictions with the detected boson as well as current experimental limits from selected indirect and direct dark matter search experiments ANTARES respective IceCube and XENON. We comment on the detection/exclusion capability of the future XENON 1t project. For the investigated parameter span we could not find a SU(5) singlet model that fulfils the Higgs mass and the relic density constraint. In contrary, allowing a mixture of 1 ⊕ 24 ⊕ 75 ⊕ 200 enables a number of models fulfilling these constraints.

  20. The distribution of the dark matter in galaxies as the imprint of its Nature

    NASA Astrophysics Data System (ADS)

    Frigerio Martins, Christiane

    2009-03-01

    The standard framework within which cosmological measurements are confronted and interpreted nowadays, called Lambda Cold Dark Matter, presents a Universe dominated by unknown forms of energy and matter. My Thesis is devoted to investigate the distribution of dark matter in galaxies and addresses the fact that the local universe-the small objects that orbit galaxies and the galaxy cores-turns out to be a marvelous laboratory for examining the nature of dark matter and the fundamental physics involved in structure formation and evolution. I develop tests, based on mass modeling of rotation curves, for the validation of dark matter models on galactic scales. These tests have been applied in analyzing the phenomenology of the cusp vs core controversy, and the phenomenon of non-Keplerian rotation curves as modification of the laws of gravity. I further investigate the properties and scaling laws of dark matter halos. My conclusion is that galactic observations provide strong imprints on the nature of dark matter.

  1. Deformed matter bounce with dark energy epoch

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-09-01

    We extend the loop quantum cosmology matter bounce scenario in order to include a dark energy era, which ends abruptly at a rip singularity where the scale factor and the Hubble rate diverge. In the "deformed matter bounce scenario," the Universe is contracting from an initial noncausal matter dominated era until it reaches a minimal radius. After that it expands in a decelerating way, until at late times, where it expands in an accelerating way, and thus the model is described by a dark energy era that follows the matter dominated era. Depending on the choice of the free parameters of the model, the dark energy era is quintessential as what follows the matter domination era, and eventually it crosses the phantom divide line and becomes phantom. At the end of the dark energy era, a rip singularity exists, where the scale factor and Hubble rate diverge; however, the physical system cannot reach the singularity, since the effective energy density and pressure become complex. This indicates two things, first that the ordinary loop quantum cosmology matter bounce evolution stops, thus ending the infinite repetition of the ordinary matter bounce scenario. Second, the fact that both the pressure and the density become complex probably indicates that the description of the cosmic evolution within the theoretical context of loop quantum cosmology ceases to describe the physics of the system and possibly a more fundamental theory of quantum gravity is needed near the would be rip singularity. We describe the qualitative features of the model, and we also investigate how this cosmology could be realized by a viscous fluid in the context of loop quantum cosmology. In addition to this, we show how this deformed model can be realized by a canonical scalar field filled Universe, in the context of loop quantum cosmology. Finally, we demonstrate how the model can be generated by a vacuum F (R ) gravity.

  2. Resurrection of neutrinos as dark matter

    SciTech Connect

    Schramm, D.N.

    1986-05-01

    It is shown that new observations of large scale structure in the universe (voids, foam, and large-scale velocity fields) are best understood if the dominant matter of the universe is in the form of massive (9eV less than or equal to m/sub nu/ less than or equal to 35 eV) neutrinos. Cold dark matter, even with biasing, seems unable to duplicate the combination of these observations (although a fine-tuned loophole with cold matter and percolated explosions may also marginally work.) The previous fatal problems of galaxy formation with neutrinos can be remedied by combining them with either cosmic strings or explosive galaxy formation. The former naturally gives the scale-free correlation function for galaxies, clusters, and superclusters, and gives large, but not necessarily spherical voids. The latter naturally gives spherical voids, but requires fine tuning and percolation to get the large scales and the scale-free correlation function. 39 refs.

  3. Prospects for detecting supersymmetric dark matter in the Galactic halo.

    PubMed

    Springel, V; White, S D M; Frenk, C S; Navarro, J F; Jenkins, A; Vogelsberger, M; Wang, J; Ludlow, A; Helmi, A

    2008-11-06

    Dark matter is the dominant form of matter in the Universe, but its nature is unknown. It is plausibly an elementary particle, perhaps the lightest supersymmetric partner of known particle species. In this case, annihilation of dark matter in the halo of the Milky Way should produce gamma-rays at a level that may soon be observable. Previous work has argued that the annihilation signal will be dominated by emission from very small clumps (perhaps smaller even than the Earth), which would be most easily detected where they cluster together in the dark matter haloes of dwarf satellite galaxies. Here we report that such small-scale structure will, in fact, have a negligible impact on dark matter detectability. Rather, the dominant and probably most easily detectable signal will be produced by diffuse dark matter in the main halo of the Milky Way. If the main halo is strongly detected, then small dark matter clumps should also be visible, but may well contain no stars, thereby confirming a key prediction of the cold dark matter model.

  4. Dark Matter Core Defies Explanation

    NASA Image and Video Library

    2017-09-28

    NASA image release March 2, 2012 This composite image shows the distribution of dark matter, galaxies, and hot gas in the core of the merging galaxy cluster Abell 520, formed from a violent collision of massive galaxy clusters. The natural-color image of the galaxies was taken with NASA's Hubble Space Telescope and with the Canada-France-Hawaii Telescope in Hawaii. Superimposed on the image are "false-colored" maps showing the concentration of starlight, hot gas, and dark matter in the cluster. Starlight from galaxies, derived from observations by the Canada-France-Hawaii Telescope, is colored orange. The green-tinted regions show hot gas, as detected by NASA's Chandra X-ray Observatory. The gas is evidence that a collision took place. The blue-colored areas pinpoint the location of most of the mass in the cluster, which is dominated by dark matter. Dark matter is an invisible substance that makes up most of the universe's mass. The dark-matter map was derived from the Hubble Wide Field Planetary Camera 2 observations, by detecting how light from distant objects is distorted by the cluster galaxies, an effect called gravitational lensing. The blend of blue and green in the center of the image reveals that a clump of dark matter resides near most of the hot gas, where very few galaxies are found. This finding confirms previous observations of a dark-matter core in the cluster. The result could present a challenge to basic theories of dark matter, which predict that galaxies should be anchored to dark matter, even during the shock of a collision. Abell 520 resides 2.4 billion light-years away. To read more go to: www.nasa.gov/mission_pages/hubble/science/dark-matter-cor... Credit: NASA, ESA, CFHT, CXO, M.J. Jee (University of California, Davis), and A. Mahdavi (San Francisco State University) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and

  5. Differences in brain activation between tremor- and nontremor-dominant Parkinson disease.

    PubMed

    Prodoehl, Janey; Planetta, Peggy J; Kurani, Ajay S; Comella, Cynthia L; Corcos, Daniel M; Vaillancourt, David E

    2013-01-01

    OBJECTIVE To compare differences in functional brain activity between tremor- and nontremor-dominant subtypes of Parkinson disease (PD) using functional magnetic resonance imaging. DESIGN In our study, patients with tremor-dominant PD and those with nontremor-dominant PD performed a grip task, and the results obtained were compared using voxelwise analysis. Areas of the brain that were significantly different were then examined using a region-of-interest analysis to compare these patients with healthy controls. Voxel-based morphometry was used to determine macroscopic differences in gray and white matter volume between patient groups. SETTING University-affiliated research institution. PARTICIPANTS A total of 20 drug-naive patients with PD (10 with tremor-dominant PD and 10 with nontremor-dominant PD) and a total of 20 healthy controls. MAIN OUTCOME MEASURES Blood oxygenation level-dependent activation and percent signal change. RESULTS Robust findings across both voxelwise and region-of-interest analyses showed that, compared with patients with tremor-dominant PD, patients with nontremor-dominant PD had reduced activation in the ipsilateral dorsolateral prefrontal cortex, the globus pallidus interna, and the globus pallidus externa. Region-of-interest analyses confirmed that patients with nontremor-dominant PD had reduced activity in the ipsilateral dorsolateral prefrontal cortex, the globus pallidus interna, and the globus pallidus externa compared with patients with tremor-dominant PD and healthy controls. Patients with tremor-dominant PD had increased activity in the contralateral dorsolateral prefrontal cortex compared with patients with nontremor-dominant PD and healthy controls. These results could not be explained by differences in gray or white matter volume. CONCLUSIONS Reduced brain activity occurs in the prefrontal cortex and globus pallidus of patients with nontremor-dominant PD compared with both patients with tremor-dominant PD and healthy controls

  6. New constraints on dark matter production during kination

    NASA Astrophysics Data System (ADS)

    Redmond, Kayla; Erickcek, Adrienne L.

    2017-08-01

    Our ignorance of the period between the end of inflation and the beginning of big bang nucleosynthesis limits our understanding of the origins and evolution of dark matter. One possibility is that the Universe's energy density was dominated by a fast-rolling scalar field while the radiation bath was hot enough to thermally produce dark matter. We investigate the evolution of the dark matter density and derive analytic expressions for the dark matter relic abundance generated during such a period of kination. Kination scenarios in which dark matter does not reach thermal equilibrium require ⟨σ v ⟩<2.7 ×10-38 cm3 s-1 to generate the observed dark matter density while allowing the Universe to become radiation dominated by a temperature of 3 MeV. Kination scenarios in which dark matter does reach thermal equilibrium require ⟨σ v ⟩>3 ×10-26 cm3 s-1 in order to generate the observed dark matter abundance. We use observations of dwarf spheroidal galaxies by the Fermi Gamma-Ray Telescope and observations of the Galactic Center by the High Energy Stereoscopic System to constrain these kination scenarios. Combining the unitarity constraint on ⟨σ v ⟩ with these observational constraints sets a lower limit on the temperature at which the Universe can become radiation dominated following a period of kination if ⟨σ v ⟩>3 ×10-31 cm3 s-1 . This lower limit is between 0.05 and 1 GeV, depending on the dark matter annihilation channel.

  7. Do Tutors Matter? Assessing the Impact of Tutors on First-Year Academic Performance at a South African University

    ERIC Educational Resources Information Center

    McKay, Tracey Morton

    2016-01-01

    This research sought to determine if a teaching intervention using tutors in a South African university could promote epistemological access to university for first-year students. Although hiring, developing and managing tutors takes money, time and energy, the effectiveness of tutors in the South African context is underreported. The first-year…

  8. Tuition-Setting Authority and Deregulation at State Colleges and Universities. Policy Matters: A Higher Education Policy Brief

    ERIC Educational Resources Information Center

    McBain, Lesley

    2010-01-01

    State support for public colleges and universities is based on a historic relationship; these institutions were established to perform the public service mission of predominantly educating residents from local and state-wide communities at a lower price than private, independent colleges and universities. In return, the states appropriated funds…

  9. Tuition-Setting Authority and Deregulation at State Colleges and Universities. Policy Matters: A Higher Education Policy Brief

    ERIC Educational Resources Information Center

    McBain, Lesley

    2010-01-01

    State support for public colleges and universities is based on a historic relationship; these institutions were established to perform the public service mission of predominantly educating residents from local and state-wide communities at a lower price than private, independent colleges and universities. In return, the states appropriated funds…

  10. Reasoning Using Particulate Nature of Matter: An Example of a Sociochemical Norm in a University-Level Physical Chemistry Class

    ERIC Educational Resources Information Center

    Becker, Nicole; Rasmussen, Chris; Sweeney, George; Wawro, Megan; Towns, Marcy; Cole, Renee

    2013-01-01

    In college level chemistry courses, reasoning using molecular and particulate descriptions of matter becomes central to understanding physical and chemical properties. In this study, we used a qualitative approach to analyzing classroom discourse derived from Toulmin's model of argumentation in order to describe the ways in which students develop…

  11. High-energy cosmic antiparticle excess vs. isotropic gamma-ray background problem in decaying dark matter Universe

    NASA Astrophysics Data System (ADS)

    Alekseev, V. V.; Belotsky, K. M.; Bogomolov, Yu V.; Budaev, R. I.; Dunaeva, O. A.; Kirillov, A. A.; Kuznetsov, A. V.; Laletin, M. N.; Lukyanov, A. D.; Malakhov, V. V.; Mayorov, A. G.; Mayorova, M. A.; Mosichkin, A. F.; Okrugin, A. A.; Rodenko, S. A.; Shitova, A. M.

    2016-02-01

    We are going to show that any conventional decaying dark matter model, providing an explanation of cosmic antiparticle excess observed by PAMELA and AMS-02, inevitably faces the contradiction with isotropic diffuse gamma-ray background, measured by FERMI/LAT.

  12. Reasoning Using Particulate Nature of Matter: An Example of a Sociochemical Norm in a University-Level Physical Chemistry Class

    ERIC Educational Resources Information Center

    Becker, Nicole; Rasmussen, Chris; Sweeney, George; Wawro, Megan; Towns, Marcy; Cole, Renee

    2013-01-01

    In college level chemistry courses, reasoning using molecular and particulate descriptions of matter becomes central to understanding physical and chemical properties. In this study, we used a qualitative approach to analyzing classroom discourse derived from Toulmin's model of argumentation in order to describe the ways in which students develop…

  13. Local heating of matter in the early universe owing to the interaction of the Higgs field with a scalar field

    NASA Astrophysics Data System (ADS)

    Belotsky, K. M.; Golikova, Yu. A.; Rubin, S. G.

    2017-07-01

    It is shown that the formation of primordialmassive black holes may be accompanied by a local heating of matter. The proposed heating mechanism is based on the interaction of the Higgs field with a scalar field that is responsible for the formation of black holes.

  14. Strongly baryon-dominated disk galaxies at the peak of galaxy formation ten billion years ago

    NASA Astrophysics Data System (ADS)

    Genzel, R.; Schreiber, N. M. Förster; Übler, H.; Lang, P.; Naab, T.; Bender, R.; Tacconi, L. J.; Wisnioski, E.; Wuyts, S.; Alexander, T.; Beifiori, A.; Belli, S.; Brammer, G.; Burkert, A.; Carollo, C. M.; Chan, J.; Davies, R.; Fossati, M.; Galametz, A.; Genel, S.; Gerhard, O.; Lutz, D.; Mendel, J. T.; Momcheva, I.; Nelson, E. J.; Renzini, A.; Saglia, R.; Sternberg, A.; Tacchella, S.; Tadaki, K.; Wilman, D.

    2017-03-01

    In the cold dark matter cosmology, the baryonic components of galaxies—stars and gas—are thought to be mixed with and embedded in non-baryonic and non-relativistic dark matter, which dominates the total mass of the galaxy and its dark-matter halo. In the local (low-redshift) Universe, the mass of dark matter within a galactic disk increases with disk radius, becoming appreciable and then dominant in the outer, baryonic regions of the disks of star-forming galaxies. This results in rotation velocities of the visible matter within the disk that are constant or increasing with disk radius—a hallmark of the dark-matter model. Comparisons between the dynamical mass, inferred from these velocities in rotational equilibrium, and the sum of the stellar and cold-gas mass at the peak epoch of galaxy formation ten billion years ago, inferred from ancillary data, suggest high baryon fractions in the inner, star-forming regions of the disks. Although this implied baryon fraction may be larger than in the local Universe, the systematic uncertainties (owing to the chosen stellar initial-mass function and the calibration of gas masses) render such comparisons inconclusive in terms of the mass of dark matter. Here we report rotation curves (showing rotation velocity as a function of disk radius) for the outer disks of six massive star-forming galaxies, and find that the rotation velocities are not constant, but decrease with radius. We propose that this trend arises because of a combination of two main factors: first, a large fraction of the massive high-redshift galaxy population was strongly baryon-dominated, with dark matter playing a smaller part than in the local Universe; and second, the large velocity dispersion in high-redshift disks introduces a substantial pressure term that leads to a decrease in rotation velocity with increasing radius. The effect of both factors appears to increase with redshift. Qualitatively, the observations suggest that baryons in the early

  15. Strongly baryon-dominated disk galaxies at the peak of galaxy formation ten billion years ago.

    PubMed

    Genzel, R; Schreiber, N M Förster; Übler, H; Lang, P; Naab, T; Bender, R; Tacconi, L J; Wisnioski, E; Wuyts, S; Alexander, T; Beifiori, A; Belli, S; Brammer, G; Burkert, A; Carollo, C M; Chan, J; Davies, R; Fossati, M; Galametz, A; Genel, S; Gerhard, O; Lutz, D; Mendel, J T; Momcheva, I; Nelson, E J; Renzini, A; Saglia, R; Sternberg, A; Tacchella, S; Tadaki, K; Wilman, D

    2017-03-15

    In the cold dark matter cosmology, the baryonic components of galaxies-stars and gas-are thought to be mixed with and embedded in non-baryonic and non-relativistic dark matter, which dominates the total mass of the galaxy and its dark-matter halo. In the local (low-redshift) Universe, the mass of dark matter within a galactic disk increases with disk radius, becoming appreciable and then dominant in the outer, baryonic regions of the disks of star-forming galaxies. This results in rotation velocities of the visible matter within the disk that are constant or increasing with disk radius-a hallmark of the dark-matter model. Comparisons between the dynamical mass, inferred from these velocities in rotational equilibrium, and the sum of the stellar and cold-gas mass at the peak epoch of galaxy formation ten billion years ago, inferred from ancillary data, suggest high baryon fractions in the inner, star-forming regions of the disks. Although this implied baryon fraction may be larger than in the local Universe, the systematic uncertainties (owing to the chosen stellar initial-mass function and the calibration of gas masses) render such comparisons inconclusive in terms of the mass of dark matter. Here we report rotation curves (showing rotation velocity as a function of disk radius) for the outer disks of six massive star-forming galaxies, and find that the rotation velocities are not constant, but decrease with radius. We propose that this trend arises because of a combination of two main factors: first, a large fraction of the massive high-redshift galaxy population was strongly baryon-dominated, with dark matter playing a smaller part than in the local Universe; and second, the large velocity dispersion in high-redshift disks introduces a substantial pressure term that leads to a decrease in rotation velocity with increasing radius. The effect of both factors appears to increase with redshift. Qualitatively, the observations suggest that baryons in the early (high

  16. Life in the fast lane: The dark-matter distribution in the most massive galaxy clusters in the Universe at z>0.5

    NASA Astrophysics Data System (ADS)

    Ebeling, Harald

    2003-07-01

    We propose two-filter ACS observations of a complete sample of 12 very X-ray luminous galaxy clusters at 0.5universe. Our sample includes the famous systems Cl0016+16 and MS0451-03; all other clusters are new discoveries from the MACS survey. Being the counterparts of the best-studied systems at lower and higher redshift and comprising ALL massive clusters at 0.50.5. HST's unique capabilities will allow us to: 1} measure accurately the clusters' dark matter distribution on scales from tens to more than 500/h_50 kpc from observations of strong and weak gravitational lensing, 2} use galaxy-galaxy lensing to measure the shape, extent, and mass content of the dark-matter halos of both cluster and field galaxies, and 3} study the color morphology of mergers and the star formation history of galaxies in a high-density environment. The proposed observations are complemented by Chandra observations of all our targets {all 12 awarded, 11 executed to date} which provide independent constraints on the dark matter and gas distribution in the cluster cores, as well a by extensive groundbased observations of weak lensing on yet larger scales, galaxy dynamics, and the SZ effect.

  17. Life in the fast lane: The dark-matter distribution in the most massive galaxy clusters in the Universe at z>0.5

    NASA Astrophysics Data System (ADS)

    Ebeling, Harald

    2004-07-01

    We propose two-filter ACS observations of a complete sample of 12 very X-ray luminous galaxy clusters at 0.5universe. Our sample includes the famous systems Cl0016+16 and MS0451-03; all other clusters are new discoveries from the MACS survey. Being the counterparts of the best-studied systems at lower and higher redshift and comprising ALL massive clusters at 0.50.5. HST's unique capabilities will allow us to: 1} measure accurately the clusters' dark matter distribution on scales from tens to more than 500/h_50 kpc from observations of strong and weak gravitational lensing, 2} use galaxy-galaxy lensing to measure the shape, extent, and mass content of the dark-matter halos of both cluster and field galaxies, and 3} study the color morphology of mergers and the star formation history of galaxies in a high-density environment. The proposed observations are complemented by Chandra observations of all our targets {all 12 awarded, 11 executed to date} which provide independent constraints on the dark matter and gas distribution in the cluster cores, as well a by extensive groundbased observations of weak lensing on yet larger scales, galaxy dynamics, and the SZ effect.

  18. Cosmology with a stiff matter era

    NASA Astrophysics Data System (ADS)

    Chavanis, Pierre-Henri

    2015-11-01

    We consider the possibility that the Universe is made of a dark fluid described by a quadratic equation of state P =K ρ2 , where ρ is the rest-mass density and K is a constant. The energy density ɛ =ρ c2+K ρ2 is the sum of two terms: a rest-mass term ρ c2 that mimics "dark matter" (P =0 ) and an internal energy term u =K ρ2=P that mimics a "stiff fluid" (P =ɛ ) in which the speed of sound is equal to the speed of light. In the early universe, the internal energy dominates and the dark fluid behaves as a stiff fluid (P ˜ɛ , ɛ ∝a-6). In the late universe, the rest-mass energy dominates and the dark fluid behaves as pressureless dark matter (P ≃0 , ɛ ∝a-3). We provide a simple analytical solution of the Friedmann equations for a universe undergoing a stiff matter era, a dark matter era, and a dark energy era due to the cosmological constant. This analytical solution generalizes the Einstein-de Sitter solution describing the dark matter era, and the Λ CDM model describing the dark matter era and the dark energy era. Historically, the possibility of a primordial stiff matter era first appeared in the cosmological model of Zel'dovich where the primordial universe is assumed to be made of a cold gas of baryons. A primordial stiff matter era also occurs in recent cosmological models where dark matter is made of relativistic self-gravitating Bose-Einstein condensates (BECs). When the internal energy of the dark fluid mimicking stiff matter is positive, the primordial universe is singular like in the standard big bang theory. It expands from an initial state with a vanishing scale factor and an infinite density. We consider the possibility that the internal energy of the dark fluid is negative (while, of course, its total energy density is positive), so that it mimics anti-stiff matter. This happens, for example, when the BECs have an attractive self-interaction with a negative scattering length. In that case, the primordial universe is nonsingular and

  19. Maverick dark matter at colliders

    NASA Astrophysics Data System (ADS)

    Beltrán, Maria; Hooper, Dan; Kolb, Edward W.; Krusberg, Zosia A. C.; Tait, Tim M. P.

    2010-09-01

    Assuming that dark matter is a weakly interacting massive particle (WIMP) species X produced in the early Universe as a cold thermal relic, we study the collider signal of pp or pbar{p} rightarrow bar{X}X + jets and its distinguishability from standard-model background processes associated with jets and missing energy. We assume that the WIMP is the sole particle related to dark matter within reach of the LHC — a “maverick” particle — and that it couples to quarks through a higher dimensional contact interaction. We simulate the WIMP final-state signal Xbar{X} + jets and dominant standard-model (SM) background processes and find that the dark-matter production process results in higher energies for the colored final state partons than do the standard-model background processes. As a consequence, the detectable signature of maverick dark matter is an excess over standard-model expectations of events consisting of large missing transverse energy, together with large leading jet transverse momentum and scalar sum of the transverse momenta of the jets. Existing Tevatron data and forthcoming LHC data can constrain (or discover!) maverick dark matter.

  20. Secretly asymmetric dark matter

    NASA Astrophysics Data System (ADS)

    Agrawal, Prateek; Kilic, Can; Swaminathan, Sivaramakrishnan; Trendafilova, Cynthia

    2017-01-01

    We study a mechanism where the dark matter number density today arises from asymmetries generated in the dark sector in the early Universe, even though the total dark matter number remains zero throughout the history of the Universe. The dark matter population today can be completely symmetric, with annihilation rates above those expected from thermal weakly interacting massive particles. We give a simple example of this mechanism using a benchmark model of flavored dark matter. We discuss the experimental signatures of this setup, which arise mainly from the sector that annihilates the symmetric component of dark matter.

  1. PeV-scale dark matter as a thermal relic of a decoupled sector

    NASA Astrophysics Data System (ADS)

    Berlin, Asher; Hooper, Dan; Krnjaic, Gordan

    2016-09-01

    In this letter, we consider a class of scenarios in which the dark matter is part of a heavy hidden sector that is thermally decoupled from the Standard Model in the early universe. The dark matter freezes-out by annihilating to a lighter, metastable state, whose subsequent abundance can naturally come to dominate the energy density of the universe. When this state decays, it reheats the visible sector and dilutes all relic abundances, thereby allowing the dark matter to be orders of magnitude heavier than the weak scale. For concreteness, we consider a simple realization with a Dirac fermion dark matter candidate coupled to a massive gauge boson that decays to the Standard Model through its kinetic mixing with hypercharge. We identify viable parameter space in which the dark matter can be as heavy as ∼1-100 PeV without being overproduced in the early universe.

  2. PeV-scale dark matter as a thermal relic of a decoupled sector

    DOE PAGES

    Berlin, Asher; Hooper, Dan; Krnjaic, Gordan

    2016-06-21

    We consider a class of scenarios in which the dark matter is part of a heavy hidden sector that is thermally decoupled from the Standard Model in the early universe. The dark matter freezes-out by annihilating to a lighter, metastable state, whose subsequent abundance can naturally come to dominate the energy density of the universe. Moreover, when this state decays, it reheats the visible sector and dilutes all relic abundances, thereby allowing the dark matter to be orders of magnitude heavier than the weak scale. For concreteness, we consider a simple realization with a Dirac fermion dark matter candidate coupledmore » to a massive gauge boson that decays to the Standard Model through its kinetic mixing with hypercharge. Finally, we identify viable parameter space in which the dark matter can be as heavy as ~1-100 PeV without being overproduced in the early universe.« less

  3. X-ray clusters of galaxies as tracers of structure in the Universe.

    PubMed

    Borgani, S; Guzzo, L

    2001-01-04

    Clusters of galaxies are visible tracers of the network of matter in the Universe, marking the high-density regions where filaments of dark matter join together. When observed at X-ray wavelengths these clusters shine like cosmic lighthouses, as a consequence of the hot gas trapped within their gravitational potential wells. The X-ray emission is linked directly to the total mass of a cluster, and so can be used to investigate the mass distribution for a sizeable fraction of the Universe. The picture that has emerged from recent studies is remarkably consistent with the predictions for a low-density Universe dominated by cold dark matter.

  4. Do closed universes recollapse?

    NASA Astrophysics Data System (ADS)

    Tipler, Frank J.

    The conditions for recollapse in universes with compact maximal hypersurfaces are investigated theoretically, reviewing the results of recent investigations. The importance of recollapse for observational astrophysics is briefly discussed, and particular attention is given to the implications of maximal hypersurfaces and to recollapse in S3 Friedmann universes. It is conjectured that all globally hyperbolic C2 maximally extended spatially homogeneous closed universes with S3 or S2 x S1 topology and with stress-energy tensors obeying the strong-energy, positive-pressure, dominant-energy, and matter-regularity conditions do expand from an all-encompassing initial singularity to a maximal hypersurface and then recollapse to an all-encompassing final singularity.

  5. Not Merely a Matter of Academics: Student Experiences of a South African University as Study-Abroad Destination

    ERIC Educational Resources Information Center

    Paola, R. J.; Lemmer, E. M.

    2013-01-01

    Study abroad programmes attract considerable numbers of American college students; however, very few select an African country as their study-abroad destination. This article explores the experiences of American undergraduates who made the uncommon choice of a South African university as destination for a mid-length immersion type programme. The…

  6. Understanding First-Year Persistence at a Micropolitan University: Do Geographic Characteristics of Students' Home City Matter?

    ERIC Educational Resources Information Center

    Williams, James E.; Luo, Mingchu

    2010-01-01

    This study analyzed data of two freshmen cohorts to examine the effect existence of students' home city geographic characteristics on first-year persistence at a micropolitan university. The geographic factors including proximity and urbanicity of students' home city were combined with the other factors of students' background characteristics,…

  7. Predicting College Math Success: Do High School Performance and Gender Matter? Evidence from Sultan Qaboos University in Oman

    ERIC Educational Resources Information Center

    Islam, M. Mazharul; Al-Ghassani, Asma

    2015-01-01

    The objective of this study was to evaluate the performance of students of college of Science of Sultan Qaboos University (SQU) in Calculus I course, and examine the predictive validity of student's high school performance and gender for Calculus I success. The data for the study was extracted from students' database maintained by the Deanship of…

  8. The Fall of the Faculty: The Rise of the All-Administrative University and Why It Matters

    ERIC Educational Resources Information Center

    Ginsberg, Benjamin

    2011-01-01

    Until very recently, American universities were led mainly by their faculties, which viewed intellectual production and pedagogy as the core missions of higher education. Today, as Benjamin Ginsberg warns in this eye-opening, controversial book, "deanlets"--administrators and staffers often without serious academic backgrounds or experience--are…

  9. 77 FR 46684 - In the Matter of: Universal Industries Limited, Inc., 3050 SW 14th Place Unit 3, Boynton Beach...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-06

    ... convicted of violating Section 38 of the Arms Export Control Act (22 U.S.C. 2778 (2000)) (``AECA.... 2401-2420 (2000)) (``EAA''). Since August 21, 2001, the EAA has been in lapse and the President... Powers Act (50 U.S.C. 1701 et seq. (2000)). I have received notice of Universal's conviction...

  10. The Fall of the Faculty: The Rise of the All-Administrative University and Why It Matters

    ERIC Educational Resources Information Center

    Ginsberg, Benjamin

    2011-01-01

    Until very recently, American universities were led mainly by their faculties, which viewed intellectual production and pedagogy as the core missions of higher education. Today, as Benjamin Ginsberg warns in this eye-opening, controversial book, "deanlets"--administrators and staffers often without serious academic backgrounds or experience--are…

  11. Does Structural Development Matter? The Third Mission through Teaching and R&D at Finnish Universities of Applied Sciences

    ERIC Educational Resources Information Center

    Kohtamäki, Vuokko

    2015-01-01

    The latest policy trends of higher education institutions (HEIs) have increasingly highlighted the importance of external stakeholders' expertise and resources. This paper investigated how the third mission through teaching and research and development (R&D) at Finnish universities of applied sciences (UASs) is influenced by the structural…

  12. Does Structural Development Matter? The Third Mission through Teaching and R&D at Finnish Universities of Applied Sciences

    ERIC Educational Resources Information Center

    Kohtamäki, Vuokko

    2015-01-01

    The latest policy trends of higher education institutions (HEIs) have increasingly highlighted the importance of external stakeholders' expertise and resources. This paper investigated how the third mission through teaching and research and development (R&D) at Finnish universities of applied sciences (UASs) is influenced by the structural…

  13. Not Merely a Matter of Academics: Student Experiences of a South African University as Study-Abroad Destination

    ERIC Educational Resources Information Center

    Paola, R. J.; Lemmer, E. M.

    2013-01-01

    Study abroad programmes attract considerable numbers of American college students; however, very few select an African country as their study-abroad destination. This article explores the experiences of American undergraduates who made the uncommon choice of a South African university as destination for a mid-length immersion type programme. The…

  14. Redshift and structure formation in a spatially flat inhomogeneous universe

    NASA Astrophysics Data System (ADS)

    Moffat, J. W.; Tatarski, D. C.

    1992-05-01

    We study a spherically symmetric Tolman-Bondi cosmological model with globally flat spatial sections t=const. We consider the model valid for the description of the Universe after matter starts to dominate. The redshift and cosmological observations in the model are examined and a simple scenario of the changes in the structure formation when compared to the standard flat Friedmann-Robertson-Walker universe is proposed. This scenario is based on the fact that in our model different parts of the Universe spend unequal periods of time in the matter-dominated era. The correction to the cold-dark-matter spatial two-point correlation function is derived. Specific cases are examined corresponding to observationally based distributions of the density. We show that this not only leads to no contradictions, but significantly improves the fit of theoretically predicted correlation functions to observations.

  15. Can inflation take place in a closed universe admitting creation?

    NASA Astrophysics Data System (ADS)

    Wolf, C.

    1988-08-01

    The possibility of inflation taking place in a closed universe which admits the creation of matter is discussed. It is found that a nonconservative ansatz with matter in the form of ultrarelativistic particles and false vacuum leads to inflation for all spatial topologies provided the creation parameter is not too large. It is demonstrated that, if creation becomes dominant, inflation does not result for any of the spatial topologies.

  16. Quantum matter bounce with a dark energy expanding phase

    NASA Astrophysics Data System (ADS)

    Colin, Samuel; Pinto-Neto, Nelson

    2017-09-01

    Analyzing quantum cosmological scenarios containing one scalar field with exponential potential, we have obtained a universe model which realizes a classical dust contraction from very large scales, the initial repeller of the model, and moves to a stiff matter contraction near the singularity, which is avoided due to a quantum bounce. The universe is then launched in a stiff matter expanding phase, which then moves to a dark energy era, finally returning to the dust expanding phase, the final attractor of the model. Hence, one has obtained a nonsingular cosmological model where a single scalar field can describe both the matter contracting phase of a bouncing model, necessary to give an almost scale invariant spectrum of scalar cosmological perturbations, and a transient expanding dark energy phase. As the universe is necessarily dust dominated in the far past, usual adiabatic vacuum initial conditions can be easily imposed in this era, avoiding the usual issues appearing when dark energy is considered in bouncing models.

  17. Primordial magnetic fields from the post-inflationary universe

    SciTech Connect

    Kobayashi, Takeshi

    2014-05-01

    We explore cosmological magnetogenesis in the post-inflationary universe, when the inflaton oscillates around its potential minimum and the universe is effectively dominated by cold matter. During this epoch prior to reheating, large-scale magnetic fields can be significantly produced by the cosmological background. By considering magnetogenesis both during and after inflation, we demonstrate that magnetic fields stronger than 10{sup −15} G can be generated on Mpc scales without having strong couplings in the theory, or producing too large electric fields that would dominate the universe.

  18. Dark matter haloes: a multistream view

    NASA Astrophysics Data System (ADS)

    Ramachandra, Nesar S.; Shandarin, Sergei F.

    2017-09-01

    Mysterious dark matter constitutes about 85 per cent of all masses in the Universe. Clustering of dark matter plays a dominant role in the formation of all observed structures on scales from a fraction to a few hundreds of Mega-parsecs. Galaxies play a role of lights illuminating these structures so they can be observed. The observations in the last several decades have unveiled opulent geometry of these structures currently known as the cosmic web. Haloes are the highest concentrations of dark matter and host luminous galaxies. Currently the most accurate modelling of dark matter haloes is achieved in cosmological N-body simulations. Identifying the haloes from the distribution of particles in N-body simulations is one of the problems attracting both considerable interest and efforts. We propose a novel framework for detecting potential dark matter haloes using the field unique for dark matter-multistream field. The multistream field emerges at the non-linear stage of the growth of perturbations because the dark matter is collisionless. Counting the number of velocity streams in gravitational collapses supplements our knowledge of spatial clustering. We assume that the virialized haloes have convex boundaries. Closed and convex regions of the multistream field are hence isolated by imposing a positivity condition on all three eigenvalues of the Hessian estimated on the smoothed multistream field. In a single-scale analysis of high multistream field resolution and low softening length, the halo substructures with local multistream maxima are isolated as individual halo sites.

  19. Fine-tuning challenges for the matter bounce scenario

    NASA Astrophysics Data System (ADS)

    Levy, Aaron M.

    2017-01-01

    A bouncing universe with a long period of contraction during which the average density is pressureless (the same equation of state as matter) as cosmologically observable scales exit the Hubble horizon has been proposed as an explanation for producing a nearly scale-invariant spectrum of adiabatic scalar perturbations. A well-known problem with this scenario is that, unless suppressed, the energy density associated with anisotropy grows to dominate that of the pressureless matter, so the matter-like phase is unstable. Previous models introduced an ekpyrotic phase after the matter-like phase to prevent the anisotropy from generating chaotic mixmaster behavior. In this work, though, we point out that, unless the anisotropy is suppressed first, the matter-like phase will never start and that suppressing the anisotropy requires extraordinary, exponential fine-tuning.

  20. Problems of modern cosmology: how dominant is the vacuum?

    PubMed

    Overduin, J; Priester, W

    2001-06-01

    It would be hard to find a cosmologist today who does not believe that the vast bulk of the Universe (95% or more) is hidden from our eyes. We review the evidence for this remarkable consensus, and for the latest proposal, that the mysterious dark matter consists of as many as four separate ingredients: baryons, massive neutrinos, new "exotic" dark matter particles, and vacuum energy, also known as the cosmological constant (lambda). Of these, only baryons fit within standard theoretical physics; the others, if their existence is confirmed, will mean rewriting textbooks. Fresh experimental evidence has recently appeared for and against all four components, so that the subject is in a state of turmoil and excitement. The past 3 years in particular have seen the fourth (vacuum) component come into new prominence, largely at the expense of the third (exotic dark matter). We conclude our review by exploring the possibility that the energy density of the vacuum is in fact so dominant as to leave little room for significant amounts of exotic dark matter.

  1. Does Gender of Administrator Matter? National Study Explores U.S. University Administrators' Attitudes About Retaining Women Professors in STEM.

    PubMed

    Williams, Wendy M; Mahajan, Agrima; Thoemmes, Felix; Barnett, Susan M; Vermeylen, Francoise; Cash, Brian M; Ceci, Stephen J

    2017-01-01

    Omnipresent calls for more women in university administration presume women will prioritize using resources and power to increase female representation, especially in STEM fields where women are most underrepresented. However, empirical evidence is lacking for systematic differences in female vs. male administratorsŠ attitudes. Do female administrators agree on which strategies are best, and do men see things differently? We explored United States college and university administratorsŠ opinions regarding strategies, policies, and structural changes in their organizations designed to increase women professorsŠ representation and retention in STEM fields. A comprehensive review of past research yielded a database of potentially-effective, recommended policies. A survey based on these policies was sent to provosts, deans, associate deans, and department chairs of STEM fields at 96 public and private research universities across the U.S. These administrators were asked to rate the quality and feasibility of each strategy; 474 provided data, of which 334 contained complete numerical data used in the analyses. Our data revealed that female (vs. male) administrators believed the 44 strategies were higher in quality overall-but not higher in feasibility-with 9 strategies perceived differently by women and men, after imposing conservative statistical controls. There was broad general agreement on the relative-quality rankings of the 44 strategies. Women (vs. men) gave higher quality ratings to increasing the value of teaching, service, and administrative experience in tenure/promotion decisions, increasing flexibility of federal-grant funding to accommodate mothers, conducting gender-equity research, and supporting shared tenure lines enabling work-life balance. Women (vs. men) believed it was more feasible for men to stop the tenure clock for 1 year for childrearing and for universities to support requests for shared tenure lines, but less feasible for women to

  2. Does Gender of Administrator Matter? National Study Explores U.S. University Administrators' Attitudes About Retaining Women Professors in STEM

    PubMed Central

    Williams, Wendy M.; Mahajan, Agrima; Thoemmes, Felix; Barnett, Susan M.; Vermeylen, Francoise; Cash, Brian M.; Ceci, Stephen J.

    2017-01-01

    Omnipresent calls for more women in university administration presume women will prioritize using resources and power to increase female representation, especially in STEM fields where women are most underrepresented. However, empirical evidence is lacking for systematic differences in female vs. male administratorsŠ attitudes. Do female administrators agree on which strategies are best, and do men see things differently? We explored United States college and university administratorsŠ opinions regarding strategies, policies, and structural changes in their organizations designed to increase women professorsŠ representation and retention in STEM fields. A comprehensive review of past research yielded a database of potentially-effective, recommended policies. A survey based on these policies was sent to provosts, deans, associate deans, and department chairs of STEM fields at 96 public and private research universities across the U.S. These administrators were asked to rate the quality and feasibility of each strategy; 474 provided data, of which 334 contained complete numerical data used in the analyses. Our data revealed that female (vs. male) administrators believed the 44 strategies were higher in quality overall—but not higher in feasibility—with 9 strategies perceived differently by women and men, after imposing conservative statistical controls. There was broad general agreement on the relative-quality rankings of the 44 strategies. Women (vs. men) gave higher quality ratings to increasing the value of teaching, service, and administrative experience in tenure/promotion decisions, increasing flexibility of federal-grant funding to accommodate mothers, conducting gender-equity research, and supporting shared tenure lines enabling work-life balance. Women (vs. men) believed it was more feasible for men to stop the tenure clock for 1 year for childrearing and for universities to support requests for shared tenure lines, but less feasible for women

  3. Anisotropic universe with anisotropic sources

    SciTech Connect

    Aluri, Pavan K.; Panda, Sukanta; Sharma, Manabendra; Thakur, Snigdha E-mail: sukanta@iiserb.ac.in E-mail: snigdha@iiserb.ac.in

    2013-12-01

    We analyze the state space of a Bianchi-I universe with anisotropic sources. Here we consider an extended state space which includes null geodesics in this background. The evolution equations for all the state observables are derived. Dynamical systems approach is used to study the evolution of these equations. The asymptotic stable fixed points for all the evolution equations are found. We also check our analytic results with numerical analysis of these dynamical equations. The evolution of the state observables are studied both in cosmic time and using a dimensionless time variable. Then we repeat the same analysis with a more realistic scenario, adding the isotropic (dust like dark) matter and a cosmological constant (dark energy) to our anisotropic sources, to study their co-evolution. The universe now approaches a de Sitter space asymptotically dominated by the cosmological constant. The cosmic microwave background anisotropy maps due to shear are also generated in this scenario, assuming that the universe contains anisotropic matter along with the usual (dark) matter and vacuum (dark) energy since decoupling. We find that they contribute dominantly to the CMB quadrupole. We also constrain the current level of anisotropy and also search for any cosmic preferred axis present in the data. We use the Union 2 Supernovae data to this extent. An anisotropy axis close to the mirror symmetry axis seen in the cosmic microwave background data from Planck probe is found.

  4. The dark matter annihilation boost from low-temperature reheating

    NASA Astrophysics Data System (ADS)

    Erickcek, Adrienne L.

    2015-11-01

    The evolution of the Universe between inflation and the onset of big bang nucleosynthesis is difficult to probe and largely unconstrained. This ignorance profoundly limits our understanding of dark matter: we cannot calculate its thermal relic abundance without knowing when the Universe became radiation dominated. Fortunately, small-scale density perturbations provide a probe of the early Universe that could break this degeneracy. If dark matter is a thermal relic, density perturbations that enter the horizon during an early matter-dominated era grow linearly with the scale factor prior to reheating. The resulting abundance of substructure boosts the annihilation rate by several orders of magnitude, which can compensate for the smaller annihilation cross sections that are required to generate the observed dark matter density in these scenarios. In particular, thermal relics with masses less than a TeV that thermally and kinetically decouple prior to reheating may already be ruled out by Fermi-LAT observations of dwarf spheroidal galaxies. Although these constraints are subject to uncertainties regarding the internal structure of the microhalos that form from the enhanced perturbations, they open up the possibility of using gamma-ray observations to learn about the reheating of the Universe.

  5. General Relativistic Radiation Pressure Supported Stars as Quasar Central Engines in an Universe Which is Recycling Matter

    NASA Astrophysics Data System (ADS)

    Mitra, Abhas

    2011-11-01

    Hoyle & Folwler (1963a,b) suggested that quasars may contain Radiation Pressure Supported Stars (RPSS), which are quasi-Newtonian (surface redshitf z ≪ 1) and supermassive. This proposal however did not work and one of the reasons was that such quasi-Newtonian PRSSs are unstable to gravitational contraction to become extremely general relativistic RPSSs. And since trapped surfaces are not allowed, (Mitra 2009a) these relativistic RPSSs are bound to hover around their instantaneous "Schwarzschild Radius" Rs = 2GM/c2. In view of the fact that they have z ≫ 1, they appear as "Black Holes" (BH) to distant observers. However since, they are always radiating, in a strict sense, they are always contracting. During such extreme compatification, RPSSs are likely to acquire extremely large magnetic field due to magnetic flux freezing, and hence they have strong magnetosphere around them by which they may arrest the accretion disk surrounding them at "Alfven Radius", Ra ≫ Rs. In contrast, for an accreting Schwarzschild black hole, one expects the inner edge of the accretion disk to be at Ri = 3Rs. Consequently, such ultramagnetized RPSSs have been nick named as Magnetospheric Eternally Collapsing Objects" (MECOs). Microlensing studies of several quasar structures have shown that indeed Ri ˜ 35Rs rather that R1 = 3Rs, and which confirms that quasars harbor MECOs rather than true black holes (Schild et al. 2006, 2008, Lovegrove et al. 2011). Further the recent proof that the true BHs have M = 0 confirms that the BH candidates are not true BHs (Mitra 2004a,b; 2009b). Here we highlight the facts (i) outflows from quasars and (ii) their ability to recycle cosmic matter for having new stars and galaxies are best understood by realizing that they contain MECOs rather than true BHs.

  6. Do Babies Matter? The Effect of Family Formation on Men and Women in Science

    SciTech Connect

    Mary Ann Mason

    2007-10-30

    Mary Ann Mason, Professor of Social Welfare and Law at the University of California, Berkeley, presents "Do Babies Matter? The Effect of Family Formation on Men and Women in Science." In her talk, she discusses the difficulties of women who have a career in science or in other male-dominated professions.

  7. Do Babies Matter? The Effect of Family Formation on Men and Women in Science

    ScienceCinema

    Mary Ann Mason

    2016-07-12

    Mary Ann Mason, Professor of Social Welfare and Law at the University of California, Berkeley, presents "Do Babies Matter? The Effect of Family Formation on Men and Women in Science." In her talk, she discusses the difficulties of women who have a career in science or in other male-dominated professions.

  8. Undulant Universe: Expansion with alternating eras of acceleration and deceleration

    SciTech Connect

    Barenboim, Gabriela; Requejo, Olga Mena; Quigg, Chris

    2005-03-15

    If the equation of state for 'dark energy' varies periodically, the expansion of the Universe may have undergone alternating eras of acceleration and deceleration. We examine a specific form that survives existing observational tests, does not single out the present state of the Universe as exceptional, and suggests a future much like the matter-dominated past: a smooth expansion without a final inflationary epoch.

  9. Does information entropy play a role in the expansion and acceleration of the Universe?

    NASA Astrophysics Data System (ADS)

    Pandey, Biswajit

    2017-10-01

    We propose an interpretation of the expansion and acceleration of the Universe from an information theoretic viewpoint. We obtain the time evolution of the configuration entropy of the mass distribution in a static Universe and show that the process of gravitational instability leads to a rapid dissipation of configuration entropy during the growth of the density fluctuations making such a Universe entropically unfavourable. We find that in an expanding Universe, the configuration entropy rate is governed by the expansion rate of the Universe and the growth rate of density fluctuations. The configuration entropy rate becomes smaller but still remains negative in a matter dominated Universe and eventually becomes zero at some future time in a $\\Lambda$ dominated Universe. The configuration entropy may have a connection to the dark energy and possibly plays a driving role in the current accelerating expansion of the Universe leading the Universe to its maximum entropy configuration.

  10. Dynamic Matter

    NASA Astrophysics Data System (ADS)

    Hohner, Jack

    2003-05-01

    First postulate: Following the Big Bang, quarks, born from zero point mass, did not acquire a constant size. They are growing. Atomic distances remain relative to increasing quark diameter resulting in molecular density remaining constant. Current rate of quark growth results in an increase of Earth radius of approximately 2.8 cm/year. The perpetual growth is sustained by the conversion of space to matter. The equality of space to matter is algebraically derived from Newton's law of gravity. There results an inward flow of space at each quark. This creates a vector field of space flowing inward at the Earth. Next postulate: Einstein space curvature is actually inward flow of space. Although this appears as an ether theory, it does not conflict with relativity. The combined vector fields of all stars in the universe create a scalar field equal to C. Inward velocity of space at the surface of the Earth is calculated at 1.46 cm/sec. This is derived from space curvature formula from relativity. This value accelerates toward the nucleus of each atom until it terminates at C at the diameter of a quark. These two predictions of the velocity C demonstrate why it is the universal constant. This work predicts the gravitational constant from a derivation based on C. Several unifying aspects emerge including; equivalence principle, 5 dimensions, time, strong nuclear force, decreasing rotational velocity of Earth, dark matter, red shift and quantum mechanics. This theory is an extension of Einstein and Newton.

  11. Dynamics in a Maximally Symmetric Universe

    NASA Astrophysics Data System (ADS)

    Bewketu, Asnakew

    2016-03-01

    Our present understanding of the evolution of the universe relies upon the Friedmann- Robertson- Walker cosmological models. This model is so successful that it is now being considered as the Standard Model of Cosmology. So in this work we derive the Fried- mann equations using the Friedmann-Robertson-Walker metric together with Einstein field equation and then we give a simple method to reduce Friedmann equations to a second order linear differential equation when it is supplemented with a time dependent equation of state. Furthermore, as illustrative examples, we solve this equation for some specific time dependent equation of states. And also by using the Friedmann equations with some time dependent equation of state we try to determine the cosmic scale factor(the rate at which the universe expands) and age of the Friedmann universe, for the matter dominated era, radiation dominated era and for both matter and radiation dominated era by considering different cases. We have finally discussed the observable quantities that can be evidences for the accelerated expansion of the Friedmann universe. I would like to acknowledge Addis Ababa University for its financial and material support to my work on the title mentioned above.

  12. The influence of the environmental history on quenching star formation in a Λ cold dark matter universe

    NASA Astrophysics Data System (ADS)

    Hirschmann, Michaela; De Lucia, Gabriella; Wilman, Dave; Weinmann, Simone; Iovino, Angela; Cucciati, Olga; Zibetti, Stefano; Villalobos, Álvaro

    2014-11-01

    We present a detailed analysis of the influence of the environment and of the environmental history on quenching star formation in central and satellite galaxies in the local Universe. We take advantage of publicly available galaxy catalogues obtained from applying a galaxy formation model to the Millennium simulation. In addition to halo mass, we consider the local density of galaxies within various fixed scales. Comparing our model predictions to observational data [Sloan Digital Sky Survey (SDSS)], we demonstrate that the models are failing to reproduce the observed density dependence of the quiescent galaxy fraction in several aspects: for most of the stellar mass ranges and densities explored, models cannot reproduce the observed similar behaviour of centrals and satellites, they slightly underestimate the quiescent fraction of centrals and significantly overestimate that of satellites. We show that in the models, the density dependence of the quiescent central galaxies is caused by a fraction of `backsplash' centrals which have been satellites in the past. The observed stronger density dependence on scales of 0.2-1 Mpc may, however, indicate additional environmental processes working on central galaxies. Turning to satellite galaxies, the density dependence of their quiescent fractions reflects a dependence on the time spent orbiting within a parent halo, correlating strongly with halo mass and distance from the halo centre. Comparisons with observational estimates suggest relatively long gas consumption time-scales of roughly 5 Gyr in low-mass satellite galaxies. The quenching time-scales decrease with increasing satellite stellar mass. Overall, a change in modelling both internal processes and environmental processes is required for improving currently used galaxy formation models.

  13. Flooded Dark Matter and S level rise

    NASA Astrophysics Data System (ADS)

    Randall, Lisa; Scholtz, Jakub; Unwin, James

    2016-03-01

    Most dark matter models set the dark matter relic density by some interaction with Standard Model particles. Such models generally assume the existence of Standard Model particles early on, with the dark matter relic density a later consequence of those interactions. Perhaps a more compelling assumption is that dark matter is not part of the Standard Model sector and a population of dark matter too is generated at the end of inflation. This democratic assumption about initial conditions does not necessarily provide a natural value for the dark matter relic density, and furthermore superficially leads to too much entropy in the dark sector relative to ordinary matter. We address the latter issue by the late decay of heavy particles produced at early times, thereby associating the dark matter relic density with the lifetime of a long-lived state. This paper investigates what it would take for this scenario to be compatible with observations in what we call Flooded Dark Matter (FDM) models and discusses several interesting consequences. One is that dark matter can be very light and furthermore, light dark matter is in some sense the most natural scenario in FDM as it is compatible with larger couplings of the decaying particle. A related consequence is that the decay of the field with the smallest coupling and hence the longest lifetime dominates the entropy and possibly the matter content of the Universe, a principle we refer to as "Maximum Baroqueness". We also demonstrate that the dark sector should be colder than the ordinary sector, relaxing the most stringent free-streaming constraints on light dark matter candidates. We will discuss the potential implications for the core-cusp problem in a follow-up paper. The FDM framework will furthermore have interesting baryogenesis implications. One possibility is that dark matter is like the baryon asymmetry and both are simultaneously diluted by a late entropy dump. Alternatively, FDM is compatible with an elegant non

  14. From superstrings theory to the dark matter in galaxies

    SciTech Connect

    Matos, Tonatiuh

    1999-10-25

    Starting from the effective action of the low energy limit of superstrings theory, I find an exact solution of the field equations which geodesics behavie exactly as the trajectories of stars arround of a spiral galaxy. Here dark matter is of dilatonic origin. It is remarkable that the energy density of this space-time is the same as the used by astronomers to model galaxy stability. Some remarks about a universe dominated by dilatons are pointed out.

  15. Growth of matter perturbation in quintessence cosmology

    NASA Astrophysics Data System (ADS)

    Mulki, Fargiza A. M.; Wulandari, Hesti R. T.

    2017-01-01

    Big bang theory states that universe emerged from singularity with very high temperature and density, then expands homogeneously and isotropically. This theory gives rise standard cosmological principle which declares that universe is homogeneous and isotropic on large scales. However, universe is not perfectly homogeneous and isotropic on small scales. There exist structures starting from clusters, galaxies even to stars and planetary system scales. Cosmological perturbation theory is a fundamental theory that explains the origin of structures. According to this theory, the structures can be regarded as small perturbations in the early universe, which evolves as the universe expands. In addition to the problem of inhomogeneities of the universe, observations of supernovae Ia suggest that our universe is being accelerated. Various models of dark energy have been proposed to explain cosmic acceleration, one of them is cosmological constant. Because of several problems arise from cosmological constant, the alternative models have been proposed, one of these models is quintessence. We reconstruct growth of structure model following quintessence scenario at several epochs of the universe, which is specified by the effective equation of state parameters for each stage. Discussion begins with the dynamics of quintessence, in which exponential potential is analytically derived, which leads to various conditions of the universe. We then focus on scaling and quintessence dominated solutions. Subsequently, we review the basics of cosmological perturbation theory and derive formulas to investigate how matter perturbation evolves with time in subhorizon scales which leads to structure formation, and also analyze the influence of quintessence to the structure formation. From analytical exploration, we obtain the growth rate of matter perturbation and the existence of quintessence as a dark energy that slows down the growth of structure formation of the universe.

  16. Dynamics of dark energy with a coupling to dark matter

    SciTech Connect

    Boehmer, Christian G.; Caldera-Cabral, Gabriela; Maartens, Roy; Lazkoz, Ruth

    2008-07-15

    Dark energy and dark matter are the dominant sources in the evolution of the late universe. They are currently only indirectly detected via their gravitational effects, and there could be a coupling between them without violating observational constraints. We investigate the background dynamics when dark energy is modeled as exponential quintessence and is coupled to dark matter via simple models of energy exchange. We introduce a new form of dark sector coupling, which leads to a more complicated dynamical phase space and has a better physical motivation than previous mathematically similar couplings.

  17. Modified gravity and its reconstruction from the universe expansion history

    NASA Astrophysics Data System (ADS)

    Nojiri, Shin'ichi; Odintsov, Sergei D.

    2007-05-01

    We develop the reconstruction program for the number of modified gravities: scalar-tensor theory, f(R), F(G) and string-inspired, scalar-Gauss-Bonnet gravity. The known (classical) universe expansion history is used for the explicit and successful reconstruction of some versions (of special form or with specific potentials) from all above modified gravities. It is demonstrated that cosmological sequence of matter dominance, deceleration-acceleration transition and acceleration era may always emerge as cosmological solutions of such theory. Moreover, the late-time dark energy FRW universe may have the approximate or exact ΓCDM form consistent with three years WMAP data. The principal possibility to extend this reconstruction scheme to include the radiation dominated era and inflation is briefly mentioned. Finally, it is indicated how even modified gravity which does not describe the matter-dominated epoch may have such a solution before acceleration era at the price of the introduction of compensating dark energy.

  18. Dark matter and cosmological nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Schramm, D. N.

    1986-01-01

    Existing dark matter problems, i.e., dynamics, galaxy formation and inflation, are considered, along with a model which proposes dark baryons as the bulk of missing matter in a fractal universe. It is shown that no combination of dark, nonbaryonic matter can either provide a cosmological density parameter value near unity or, as in the case of high energy neutrinos, allow formation of condensed matter at epochs when quasars already existed. The possibility that correlations among galactic clusters are scale-free is discussed. Such a distribution of matter would yield a fractal of 1.2, close to a one-dimensional universe. Biasing, cosmic superstrings, and percolated explosions and hot dark matter are theoretical approaches that would satisfy the D = 1.2 fractal model of the large-scale structure of the universe and which would also allow sufficient dark matter in halos to close the universe.

  19. Dark matter and cosmological nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Schramm, D. N.

    1986-01-01

    Existing dark matter problems, i.e., dynamics, galaxy formation and inflation, are considered, along with a model which proposes dark baryons as the bulk of missing matter in a fractal universe. It is shown that no combination of dark, nonbaryonic matter can either provide a cosmological density parameter value near unity or, as in the case of high energy neutrinos, allow formation of condensed matter at epochs when quasars already existed. The possibility that correlations among galactic clusters are scale-free is discussed. Such a distribution of matter would yield a fractal of 1.2, close to a one-dimensional universe. Biasing, cosmic superstrings, and percolated explosions and hot dark matter are theoretical approaches that would satisfy the D = 1.2 fractal model of the large-scale structure of the universe and which would also allow sufficient dark matter in halos to close the universe.

  20. Interstellar Matters

    NASA Astrophysics Data System (ADS)

    Verschuur, Gerrit L.

    In this provocative new book, radio astronomer and author Gerrit L. Verschuur describes the phenomena of scientific curiosity and discovery by following the exciting story of interstellar matter. The discovery of "stuff between the stars" was the result of decades of work by hundreds of astronomers, and the evolving recognition of its existence has profoundly changed the way we view the Universe. Verschuur begins with E.E. Barnard, who puzzled for a quarter century over the interpretation of photographs of dark patches between the stars. Verschuur then traces the tortuous path to acceptance of the existence of interstellar matter. He shares with us the thrill of discovery that motivates astronomers, the use of metaphors and modeling by scientist, and other tricks of the astronomical trade. Finally, we learn about the modern study of interstellar matter: the discovery of complex organic molecules between the stars and how they may have seeded the early earth with the precursors for life, new insights into star formation, the structure of the Milky Way and the elusive interstellar magnetic field. More than a history, Interstellar Matters is a detective story that evokes the excitement and serendipity of science against the background of a century of shared effort by the world community of astronomers. From the reviews: "I can't imagine anyone interested in astronomy who won't enjoy this book - it's chocked full of science, personalities and insights. We are products of the stuff between the stars - Verschuur tells the fascinating story of how its existence was discovered. Interstellar Matters is his best book, I think. It's certainly one of the best astronomy popularizations I've read." Leif J. Robinson, Sky and Teleskope#1

  1. Operation DOMINIC. Project Stemwinder

    DTIC Science & Technology

    1985-09-01

    Sampling was accomplished by the RB - 57 aircraft. The detonations Investigated were all air bursts over water during Operation Dominic I at Christmas...limits. III. Stem Cloud Penetration» An RB - 57 aircraft was available for stem penetration missions Irae- dlately following seven of the Dominic ...OPERATION DOMINIC Project Stemwinder (WT-2060)(EX) EXTRACTED VERSION I in 0) o < i D < G. J. Ferber Atmospheric Radioactivity Research

  2. Big Questions: Dark Matter

    ScienceCinema

    Lincoln, Don

    2016-07-12

    Carl Sagan's oft-quoted statement that there are "billions and billions" of stars in the cosmos gives an idea of just how much "stuff" is in the universe. However scientists now think that in addition to the type of matter with which we are familiar, there is another kind of matter out there. This new kind of matter is called "dark matter" and there seems to be five times as much as ordinary matter. Dark matter interacts only with gravity, thus light simply zips right by it. Scientists are searching through their data, trying to prove that the dark matter idea is real. Fermilab's Dr. Don Lincoln tells us why we think this seemingly-crazy idea might not be so crazy after all.

  3. Big Questions: Dark Matter

    SciTech Connect

    Lincoln, Don

    2013-12-05

    Carl Sagan's oft-quoted statement that there are "billions and billions" of stars in the cosmos gives an idea of just how much "stuff" is in the universe. However scientists now think that in addition to the type of matter with which we are familiar, there is another kind of matter out there. This new kind of matter is called "dark matter" and there seems to be five times as much as ordinary matter. Dark matter interacts only with gravity, thus light simply zips right by it. Scientists are searching through their data, trying to prove that the dark matter idea is real. Fermilab's Dr. Don Lincoln tells us why we think this seemingly-crazy idea might not be so crazy after all.

  4. The cosmological constant and cold dark matter

    NASA Astrophysics Data System (ADS)

    Efstathiou, G.; Sutherland, W. J.; Maddox, S. J.

    1990-12-01

    It is argued here that the success of the cosmological cold dark matter (CDM) model can be retained and the new observations of very large scale cosmological structures can be accommodated in a spatially flat cosmology in which as much as 80 percent of the critical density is provided by a positive cosmological constant. In such a universe, expansion was dominated by CDM until a recent epoch, but is now governed by the cosmological constant. This constant can also account for the lack of fluctuations in the microwave background and the large number of certain kinds of objects found at high redshift.

  5. Selection Rule for Enhanced Dark Matter Annihilation.

    PubMed

    Das, Anirban; Dasgupta, Basudeb

    2017-06-23

    We point out a selection rule for enhancement (suppression) of odd (even) partial waves of dark matter coannihilation or annihilation using the Sommerfeld effect. Using this, the usually velocity-suppressed p-wave annihilation can dominate the annihilation signals in the present Universe. The selection mechanism is a manifestation of the exchange symmetry of identical incoming particles, and generic for multistate DM with off-diagonal long-range interactions. As a consequence, the relic and late-time annihilation rates are parametrically different and a distinctive phenomenology, with large but strongly velocity-dependent annihilation rates, is predicted.

  6. Selection Rule for Enhanced Dark Matter Annihilation

    NASA Astrophysics Data System (ADS)

    Das, Anirban; Dasgupta, Basudeb

    2017-06-01

    We point out a selection rule for enhancement (suppression) of odd (even) partial waves of dark matter coannihilation or annihilation using the Sommerfeld effect. Using this, the usually velocity-suppressed p -wave annihilation can dominate the annihilation signals in the present Universe. The selection mechanism is a manifestation of the exchange symmetry of identical incoming particles, and generic for multistate DM with off-diagonal long-range interactions. As a consequence, the relic and late-time annihilation rates are parametrically different and a distinctive phenomenology, with large but strongly velocity-dependent annihilation rates, is predicted.

  7. Long-lived light mediator to dark matter and primordial small scale spectrum

    SciTech Connect

    Zhang, Yue

    2015-05-06

    We calculate the early universe evolution of perturbations in the dark matter energy density in the context of simple dark sector models containing a GeV scale light mediator. We consider the case that the mediator is long-lived, with lifetime up to a second, and before decaying it temporarily dominates the energy density of the universe. We show that for primordial perturbations that enter the horizon around this period, the interplay between linear growth during matter domination and collisional damping can generically lead to a sharp peak in the spectrum of dark matter density perturbation. As a result, the population of the smallest DM halos gets enhanced. Possible implications of this scenario are discussed.

  8. Long-lived light mediator to dark matter and primordial small scale spectrum

    SciTech Connect

    Zhang, Yue

    2015-05-01

    We calculate the early universe evolution of perturbations in the dark matter energy density in the context of simple dark sector models containing a GeV scale light mediator. We consider the case that the mediator is long-lived, with lifetime up to a second, and before decaying it temporarily dominates the energy density of the universe. We show that for primordial perturbations that enter the horizon around this period, the interplay between linear growth during matter domination and collisional damping can generically lead to a sharp peak in the spectrum of dark matter density perturbation. As a result, the population of the smallest DM halos gets enhanced. Possible implications of this scenario are discussed.

  9. The matter-ekpyrotic bounce scenario in Loop Quantum Cosmology

    NASA Astrophysics Data System (ADS)

    Haro, Jaume; Amorós, Jaume; Aresté Saló, Llibert

    2017-09-01

    We will perform a detailed study of the matter-ekpyrotic bouncing scenario in Loop Quantum Cosmology using the methods of the dynamical systems theory. We will show that when the background is driven by a single scalar field, at very late times, in the contracting phase, all orbits depict a matter dominated Universe, which evolves to an ekpyrotic phase. After the bounce the Universe enters in the expanding phase, where the orbits leave the ekpyrotic regime going to a kination (also named deflationary) regime. Moreover, this scenario supports the production of heavy massive particles conformally coupled with gravity, which reheats the universe at temperatures compatible with the nucleosynthesis bounds and also the production of massless particles non-conformally coupled with gravity leading to very high reheating temperatures but ensuring the nucleosynthesis success. Dealing with cosmological perturbations, these background dynamics produce a nearly scale invariant power spectrum for the modes that leave the Hubble radius, in the contracting phase, when the Universe is quasi-matter dominated, whose spectral index and corresponding running is compatible with the recent experimental data obtained by PLANCK's team.

  10. Genetic Dominance & Cellular Processes

    ERIC Educational Resources Information Center

    Seager, Robert D.

    2014-01-01

    In learning genetics, many students misunderstand and misinterpret what "dominance" means. Understanding is easier if students realize that dominance is not a mechanism, but rather a consequence of underlying cellular processes. For example, metabolic pathways are often little affected by changes in enzyme concentration. This means that…

  11. Genetic Dominance & Cellular Processes

    ERIC Educational Resources Information Center

    Seager, Robert D.

    2014-01-01

    In learning genetics, many students misunderstand and misinterpret what "dominance" means. Understanding is easier if students realize that dominance is not a mechanism, but rather a consequence of underlying cellular processes. For example, metabolic pathways are often little affected by changes in enzyme concentration. This means that…

  12. PAL Measures Language Dominance.

    ERIC Educational Resources Information Center

    Gil, Sylvia

    The Primary Acquisition of Languages Oral Language Dominance Measure (PAL) developed by the El Paso Independent School District determines a child's structural proficiency in English and Spanish and measures language dominance to aid in placing pupils in bilingual programs. PAL consists of four components, including an examiner's manual containing…

  13. Dark matter in voids

    NASA Astrophysics Data System (ADS)

    Fong, Richard; Doroshkevich, Andrei G.; Turchaninov, Victor I.

    1995-07-01

    The theory of the formation of large-scale structure in the universe through the action of gravitational instability imply the existence of substantial amounts of baryonic dark matter, of the order of 50% of the total baryon content in the universe, in the ``voids'' or under-dense regions seen in the large-scale distribution of galaxies. We discuss also the large-scale structure of dark matter expected in voids and the present and future possibilities for the observation of this baryonic dark matter in ``voids.''

  14. Evolution of perturbations in an inflationary universe

    NASA Technical Reports Server (NTRS)

    Frieman, J. A.; Will, C. M.

    1982-01-01

    The evolution of inhomogeneous density perturbations in a model of the very early universe that is dominated for a time by a constant energy density of a false quantum-mechanical vacuum is analyzed. During this period, the universe inflates exponentially and supercools exponentially, until a phase transition back to the true vacuum reheats the matter and radiation. Focus is on the physically measurable, coordinate-independent modes of inhomogeneous perturbations of this model and it is found that all modes either are constant or are exponentially damped during the inflationary era.

  15. Cosmology with Mimetic Matter

    SciTech Connect

    Chamseddine, Ali H.; Mukhanov, Viatcheslav; Vikman, Alexander E-mail: viatcheslav.Mukhanov@lmu.de

    2014-06-01

    We consider minimal extensions of the recently proposed Mimetic Dark Matter and show that by introducing a potential for the mimetic non-dynamical scalar field we can mimic nearly any gravitational properties of the normal matter. In particular, the mimetic matter can provide us with inflaton, quintessence and even can lead to a bouncing nonsingular universe. We also investigate the behaviour of cosmological perturbations due to a mimetic matter. We demonstrate that simple mimetic inflation can produce red-tilted scalar perturbations which are largely enhanced over gravity waves.

  16. Lindquist-Wheeler formulation of lattice universes

    NASA Astrophysics Data System (ADS)

    Liu, Rex G.

    2015-09-01

    This paper examines the properties of "lattice universes" wherein point masses are arranged in a regular lattice on spacelike hypersurfaces; open, flat, and closed universes are considered. The universes are modeled using the Lindquist-Wheeler (LW) approximation scheme, which approximates the space-time in each lattice cell by Schwarzschild geometry. Extending Lindquist and Wheeler's work, we derive cosmological scale factors describing the evolution of all three types of universes, and we use these scale factors to show that the universes' dynamics strongly resemble those of Friedmann-Lemaître-Robertson-Walker (FLRW) universes. In particular, we use the scale factors to make more salient the resemblance between Clifton and Ferreira's Friedmann-like equations for the LW models and the actual Friedmann equations of FLRW space-times. Cosmological redshifts for such universes are then determined numerically, using a modification of Clifton and Ferreira's approach; the redshifts are found to closely resemble their FLRW counterparts, though with certain differences attributable to the "lumpiness" in the underlying matter content. Most notably, the LW redshifts can differ from their FLRW counterparts by as much as 30%, even though they increase linearly with FLRW redshifts, and they exhibit a nonzero integrated Sachs-Wolfe effect, something which would not be possible in matter-dominated FLRW universes without a cosmological constant.

  17. X-ray clusters in a cold dark matter + lambda universe: A direct, large-scale, high-resolution, hydrodynamic simulation

    NASA Technical Reports Server (NTRS)

    Cen, Renyue; Ostriker, Jeremiah P.

    1994-01-01

    A new, three-dimensional, shock-capturing, hydrodynamic code is utilized to determine the distribution of hot gas in a cold dark matter (CDM) + lambda model universe. Periodic boundary conditions are assumed: a box with size 85/h Mpc, having cell size 0.31/h Mpc, is followed in a simulation with 270(exp 3) = 10(exp 7.3) cells. We adopt omega = 0.45, lambda = 0.55, h identically equal to H/100 km/s/Mpc = 0.6, and then, from the cosmic background explorer (COBE) and light element nucleosynthesis, sigma(sub 8) = 0.77, omega(sub b) = 0.043. We identify the X-ray emitting clusters in the simulation box, compute the luminosity function at several wavelength bands, the temperature function and estimated sizes, as well as the evolution of these quantities with redshift. This open model succeeds in matching local observations of clusters in contrast to the standard omega = 1, CDM model, which fails. It predicts an order of magnitude decline in the number density of bright (h nu = 2-10 keV) clusters from z = 0 to z = 2 in contrast to a slight increase in the number density for standard omega = 1, CDM model. This COBE-normalized CDM + lambda model produces approximately the same number of X-ray clusters having L(sub x) greater than 10(exp 43) erg/s as observed. The background radiation field at 1 keV due to clusters is approximately the observed background which, after correction for numerical effects, again indicates that the model is consistent with observations.

  18. X-ray clusters in a cold dark matter + lambda universe: A direct, large-scale, high-resolution, hydrodynamic simulation

    NASA Technical Reports Server (NTRS)

    Cen, Renyue; Ostriker, Jeremiah P.

    1994-01-01

    A new, three-dimensional, shock-capturing, hydrodynamic code is utilized to determine the distribution of hot gas in a cold dark matter (CDM) + lambda model universe. Periodic boundary conditions are assumed: a box with size 85/h Mpc, having cell size 0.31/h Mpc, is followed in a simulation with 270(exp 3) = 10(exp 7.3) cells. We adopt omega = 0.45, lambda = 0.55, h identically equal to H/100 km/s/Mpc = 0.6, and then, from the cosmic background explorer (COBE) and light element nucleosynthesis, sigma(sub 8) = 0.77, omega(sub b) = 0.043. We identify the X-ray emitting clusters in the simulation box, compute the luminosity function at several wavelength bands, the temperature function and estimated sizes, as well as the evolution of these quantities with redshift. This open model succeeds in matching local observations of clusters in contrast to the standard omega = 1, CDM model, which fails. It predicts an order of magnitude decline in the number density of bright (h nu = 2-10 keV) clusters from z = 0 to z = 2 in contrast to a slight increase in the number density for standard omega = 1, CDM model. This COBE-normalized CDM + lambda model produces approximately the same number of X-ray clusters having L(sub x) greater than 10(exp 43) erg/s as observed. The background radiation field at 1 keV due to clusters is approximately the observed background which, after correction for numerical effects, again indicates that the model is consistent with observations.

  19. Inflaton dark matter from incomplete decay

    NASA Astrophysics Data System (ADS)

    Bastero-Gil, Mar; Cerezo, Rafael; Rosa, João G.

    2016-05-01

    We show that the decay of the inflaton field may be incomplete, while nevertheless successfully reheating the Universe and leaving a stable remnant that accounts for the present dark matter abundance. We note, in particular, that since the mass of the inflaton decay products is field dependent, one can construct models, endowed with an appropriate discrete symmetry, where inflaton decay is kinematically forbidden at late times and only occurs during the initial stages of field oscillations after inflation. We show that this is sufficient to ensure the transition to a radiation-dominated era and that inflaton particles typically thermalize in the process. They eventually decouple and freeze out, yielding a thermal dark matter relic. We discuss possible implementations of this generic mechanism within consistent cosmological and particle physics scenarios, for both single-field and hybrid inflation.

  20. Human brain structure predicts individual differences in preconscious evaluation of facial dominance and trustworthiness.

    PubMed

    Getov, Spas; Kanai, Ryota; Bahrami, Bahador; Rees, Geraint

    2015-05-01

    Social cues conveyed by the human face, such as eye gaze direction, are evaluated even before they are consciously perceived. While there is substantial individual variability in such evaluation, its neural basis is unknown. Here we asked whether individual differences in preconscious evaluation of social face traits were associated with local variability in brain structure. Adult human participants (n = 36) monocularly viewed faces varying in dominance and trustworthiness, which were suppressed from awareness by a dynamic noise pattern shown to the other eye. The time taken for faces to emerge from suppression and become visible (t2e) was used as a measure of potency in competing for visual awareness. Both dominant and untrustworthy faces resulted in slower t2e than neutral faces, with substantial individual variability in these effects. Individual differences in t2e were correlated with gray matter volume in right insula for dominant faces, and with gray matter volume in medial prefrontal cortex, right temporoparietal junction and bilateral fusiform face area for untrustworthy faces. Thus, individual differences in preconscious social processing can be predicted from local brain structure, and separable correlates for facial dominance and untrustworthiness suggest distinct mechanisms of preconscious processing. © The Author (2014). Published by Oxford University Press.

  1. Neutrinos and dark matter

    SciTech Connect

    Ibarra, Alejandro

    2015-07-15

    Neutrinos could be key particles to unravel the nature of the dark matter of the Universe. On the one hand, sterile neutrinos in minimal extensions of the Standard Model are excellent dark matter candidates, producing potentially observable signals in the form of a line in the X-ray sky. On the other hand, the annihilation or the decay of dark matter particles produces, in many plausible dark matter scenarios, a neutrino flux that could be detected at neutrino telescopes, thus providing non-gravitational evidence for dark matter. More conservatively, the non-observation of a significant excess in the neutrino fluxes with respect to the expected astrophysical backgrounds can be used to constrain dark matter properties, such as the self-annihilation cross section, the scattering cross section with nucleons and the lifetime.

  2. Complex Dark Matter

    ScienceCinema

    Lincoln, Don

    2016-07-12

    After a century of study, scientists have come to the realization that the ordinary matter made of atoms is a minority in the universe. In order to explain observations, it appears that there exists a new and undiscovered kind of matter, called dark matter, that is five times more prevalent than ordinary matter. The evidence for this new matter’s existence is very strong, but scientists know only a little about its nature. In today’s video, Fermilab’s Dr. Don Lincoln talks about an exciting and unconventional idea, specifically that dark matter might have a very complex set of structures and interactions. While this idea is entirely speculative, it is an interesting hypothesis and one that scientists are investigating.

  3. Direct search for dark matter

    SciTech Connect

    Yoo, Jonghee; /Fermilab

    2009-12-01

    Dark matter is hypothetical matter which does not interact with electromagnetic radiation. The existence of dark matter is only inferred from gravitational effects of astrophysical observations to explain the missing mass component of the Universe. Weakly Interacting Massive Particles are currently the most popular candidate to explain the missing mass component. I review the current status of experimental searches of dark matter through direct detection using terrestrial detectors.

  4. Cosmology and Structure Formation with Scalar Field Dark Matter

    NASA Astrophysics Data System (ADS)

    Rindler-Daller, Tanja; Li, Bohua; Shapiro, Paul R.

    2013-04-01

    The exploration of the nature of the cosmological dark matter is an ongoing hot topic in modern cosmology and particle physics. Suggested candidates include ultra-light particles which are described by a real or complex scalar field. Previous literature has revealed the richness of this candidate in terms of its power to explain astrophysical and cosmological observations, from the background cosmological evolution to galactic rotation curves. However, a lot of research remains to be done to find out which parts of the parameter space of this kind of dark matter is able to explain observations on all scales consistently. In this talk, we will present our current and ongoing work on the study of complex scalar field dark matter (SFDM). We find that this SFDM underwent three distinctive states in the early Universe, a scalar-field dominated, a radiation-dominated and a matter-dominated phase. The timing and longevity of each phase places important first constraints on the parameters of the model. For this SFDM model, we revisit classical problems of structure formation theory, like the tophat collapse, the problem of virial shocks, and the cosmological infall problem for an isolated halo, in order to find viable model parameters which match the constraints from cosmology.

  5. Thermal dark matter from a highly decoupled sector

    SciTech Connect

    Berlin, Asher; Hooper, Dan; Krnjaic, Gordan

    2016-11-17

    It has recently been shown that if the dark matter is in thermal equilibrium with a sector that is highly decoupled from the Standard Model, it can freeze out with an acceptable relic abundance, even if the dark matter is as heavy as ~1–100 PeV. In such scenarios, both the dark and visible sectors are populated after inflation, but with independent temperatures. The lightest particle in the dark sector will be generically long-lived and can come to dominate the energy density of the Universe. Upon decaying, these particles can significantly reheat the visible sector, diluting the abundance of dark matter and thus allowing for dark matter particles that are much heavier than conventional WIMPs. In this study, we present a systematic and pedagogical treatment of the cosmological history in this class of models, emphasizing the simplest scenarios in which a dark matter candidate annihilates into hidden sector particles which then decay into visible matter through the vector, Higgs, or lepton portals. In each case, we find ample parameter space in which very heavy dark matter particles can provide an acceptable thermal relic abundance. We also discuss possible extensions of models featuring these dynamics.

  6. Evidence for dark matter interactions in cosmological precision data?

    SciTech Connect

    Lesgourgues, Julien; Marques-Tavares, Gustavo; Schmaltz, Martin E-mail: gusmt@stanford.edu

    2016-02-01

    We study a two-parameter extension of the cosmological standard model ΛCDM in which cold dark matter interacts with a new form of dark radiation. The two parameters correspond to the energy density in the dark radiation fluid ΔN{sub fluid} and the interaction strength between dark matter and dark radiation. The interactions give rise to a very weak ''dark matter drag'' which damps the growth of matter density perturbations throughout radiation domination, allowing to reconcile the tension between predictions of large scale structure from the CMB and direct measurements of σ{sub 8}. We perform a precision fit to Planck CMB data, BAO, large scale structure, and direct measurements of the expansion rate of the universe today. Our model lowers the χ-squared relative to ΛCDM by about 12, corresponding to a preference for non-zero dark matter drag by more than 3σ. Particle physics models which naturally produce a dark matter drag of the required form include the recently proposed non-Abelian dark matter model in which the dark radiation corresponds to massless dark gluons.

  7. Dragging force on galaxies due to streaming dark matter

    NASA Technical Reports Server (NTRS)

    Hara, Tetsuya; Miyoshi, Shigeru

    1990-01-01

    It has been reported that galaxies in large regions (approx. 10(exp 2) Mpc), including some clusters of galaxies, may be streaming coherently with velocities up to 600 km/sec or more with respect to the rest frame determined by the microwave background radiation. On the other hand, it is suggested that the dominant mass component of the universe is dark matter. Because we can only speculate the motion of dark matter from the galaxy motions, much attention should be paid to the correlation of velocities between the observed galaxies and cold dark matter. So the authors investigated whether such coherent large-scale streaming velocities are due to dark matter or only to baryonic objects which may be formed by piling up of gases due to some explosive events. It seems that, although each galaxy will not follow the motion of dark matter, clusters of galaxies may represent the velocity field of dark matter. The origin of the velocity field of dark matter would be due to the initial adiabatic perturbations and, in fact, the observed peculiar velocities of clusters are within the allowed region constrained from the isotropy of the microwave background radiation.

  8. Experimental constraint on dark matter detection with optical atomic clocks

    NASA Astrophysics Data System (ADS)

    Wcisło, P.; Morzyński, P.; Bober, M.; Cygan, A.; Lisak, D.; Ciuryło, R.; Zawada, M.

    2016-12-01

    The total mass density of the Universe appears to be dominated by dark matter. However, beyond its gravitational interactions at the galactic scale, little is known about its nature1. Several proposals have been advanced in recent years for the detection of dark matter2-4. In particular, a network of atomic clocks could be used to search for transient indicators of hypothetical dark matter5 in the form of stable topological defects; for example, monopoles, strings or domain walls6. The clocks become desynchronized when a dark-matter object sweeps through the network. This pioneering approach5 requires a comparison between at least two distant optical atomic clocks7-9. Here, by exploiting differences in the susceptibilities of the atoms and the cavity to the fine-structure constant10,11, we show that a single optical atomic clock12 is already sensitive to dark-matter events. This implies that existing optical atomic clocks13,14 can serve as a global topological-defect dark-matter observatory, without any further developments in experimental apparatus or the need for long phase-noise-compensated optical-fibre links15. Using optical atomic clocks, we explored a new dimension of astrophysical observations by constraining the strength of atomic coupling to hypothetical dark-matter cosmic objects. Under the conditions of our experiments, the degree of constraint was found to exceed the previously reported limits16 by more than three orders of magnitude.

  9. Thermal dark matter from a highly decoupled sector

    NASA Astrophysics Data System (ADS)

    Berlin, Asher; Hooper, Dan; Krnjaic, Gordan

    2016-11-01

    It has recently been shown that if the dark matter is in thermal equilibrium with a sector that is highly decoupled from the Standard Model, it can freeze out with an acceptable relic abundance, even if the dark matter is as heavy as ˜1 - 100 PeV . In such scenarios, both the dark and visible sectors are populated after inflation, but with independent temperatures. The lightest particle in the dark sector will be generically long-lived and can come to dominate the energy density of the Universe. Upon decaying, these particles can significantly reheat the visible sector, diluting the abundance of dark matter and thus allowing for dark matter particles that are much heavier than conventional WIMPs. In this paper, we present a systematic and pedagogical treatment of the cosmological history in this class of models, emphasizing the simplest scenarios in which a dark matter candidate annihilates into hidden sector particles which then decay into visible matter through the vector, Higgs, or lepton portals. In each case, we find ample parameter space in which very heavy dark matter particles can provide an acceptable thermal relic abundance. We also discuss possible extensions of models featuring these dynamics.

  10. How did matter gain the upper hand over antimatter?

    SciTech Connect

    Quinn, Helen; /SLAC

    2009-01-30

    Antimatter exists! We routinely make it in laboratories. For every familiar particle type we find a matching antiparticle with opposite charge, but exactly the same mass. For example, a positron with positive charge has the same mass as an electron; an antiproton with negative charge has the same mass as a proton. Antimatter occurs naturally all over the universe wherever high-energy particles collide. The laws of physics for antimatter are very, very similar to those for antimatter--so far we know only one tiny difference in them, a detail of the weak interactions of quarks that earned Makoto Kobayashi and Toshihide Maskawa a share of the 2008 Nobel Prize for Physics. Our understanding of the early Universe also tells us that after inflation ended equal amounts of matter and antimatter were produced. Today there's a lot of matter in the universe, but very little antimatter. This leaves a big question for cosmology. How did matter gain the upper hand over antimatter? It's a question at the root of our existence. Without this excess, there would be no stars, no Earth, and no us! When a particle meets its antiparticle, they annihilate each other in a flash of radiation. This process removed all the antimatter and most of the matter as the universe expanded and cooled. All that's left today is the excess amount of matter when destruction began to dominate over production. To get from equality to inequality for matter and antimatter requires a difference in the laws of physics between them and some special situation where it affects the balance between them. But, when we try to use the tiny difference we know about between quark and antiquark weak interactions to generate the imbalance, it doesn't work. We find a way that it can indeed give a small excess of matter over antimatter, but not nearly enough to give us all the matter we see in our universe. We can patch up the theory by adding unknown particles to it to make a scenario that works. Indeed we can do that in

  11. Death, dying, and domination.

    PubMed

    Spindelman, Marc

    2008-06-01

    This Article critiques conventional liberal arguments for the right to die on liberal grounds. It contends that these arguments do not go far enough to recognize and address private, and in particular structural, forms of domination. It presents an alternative that does, which is thus more respectful of true freedom in the context of death and dying, and also more consistent with liberalism. After discussing obstacles to the achievement of a right to die that encompasses freedom from both public and private domination, the Article closes with a significant reform project within bioethics that might help bring it about.

  12. Autosomal dominant vitreoretinochoroidopathy (ADVIRC).

    PubMed Central

    Blair, N P; Goldberg, M F; Fishman, G A; Salzano, T

    1984-01-01

    We report the second family recognised to have autosomal dominant vitreoretinochoroidopathy. The clinical features were (1) autosomal dominant inheritance; (2) peripheral, coarse pigmentary degeneration of the fundus for 360 degrees, with a relatively discrete posterior border in the equatorial region (this finding may be pathognomonic); (3) superficial punctate yellowish-white opacities in the retina; (4) various vascular abnormalities; (5) breakdown of the blood-retinal barrier; (6) retinal neovascularisation; (7) vitreous abnormalities; and (8) choroidal atrophy. Visual reduction was mainly due to macular oedema or vitreous haemorrhage. Images PMID:6689931

  13. Apical Dominance in Plants

    ERIC Educational Resources Information Center

    Tucker, D. J.

    1974-01-01

    Describes a tentative hypothesis for the control of plant branching (apical dominance). Explores the mechanism by which apical buds inhibit the growth of axillary buds on the same shoot. Presents an up-to-date picture of the problem and gives economic implications of the study. (BR)

  14. Convection dominated problems

    NASA Technical Reports Server (NTRS)

    Peraire, J.; Morgan, K.; Zienkiewicz, O. C.

    1986-01-01

    The paper surveys the last ten years of activity of the INME Swansea, dealing with problems of convection dominated flow. The basic explicit/implicit characteristic Galerkin process and its application to adaptive mesh refinement used in the solution of realistic problems is focused on.

  15. Communication and Cultural Domination.

    ERIC Educational Resources Information Center

    Schiller, Herbert I.

    Communications and the flow of messages and imagery within and between nations--especially between developed and dominated states--have assumed a special significance in the years since the second World War. During this period, although more than 90 countries have achieved political independence, at least two-thirds of the world's nations have…

  16. Autosomal dominant genes (image)

    MedlinePlus

    ... disease. One of the parents will have the disease (since it is dominant) in this mode of inheritance and that person is called the CARRIER. Only one parent must be a carrier in order for the child to inherit the disease.

  17. Iron dominated magnets

    SciTech Connect

    Fischer, G.E.

    1985-07-01

    These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided.

  18. Sterile neutrinos as subdominant warm dark matter

    SciTech Connect

    Palazzo, A.; Cumberbatch, D.; Slosar, A.; Silk, J.

    2007-11-15

    In light of recent findings which seem to disfavor a scenario with (warm) dark matter entirely constituted of sterile neutrinos produced via the Dodelson-Widrow mechanism, we investigate the constraints attainable for this mechanism by relaxing the usual hypothesis that the relic neutrino abundance must necessarily account for all of the dark matter. We first study how to reinterpret the limits attainable from x-ray nondetection and Lyman-{alpha} forest measurements in the case that sterile neutrinos constitute only a fraction f{sub s} of the total amount of dark matter. Then, assuming that sterile neutrinos are generated in the early universe solely through the Dodelson-Widrow mechanism, we show how the x-ray and Lyman-{alpha} results jointly constrain the mass-mixing parameters governing their production. Furthermore, we show how the same data allow us to set a robust upper limit f{sub s} < or approx. 0.7 at the 2{sigma} level, rejecting the case of dominant dark matter (f{sub s}=1) at the {approx}3{sigma} level.

  19. A Universe without Weak Interactions

    SciTech Connect

    Harnik, Roni; Kribs, Graham D.; Perez, Gilad

    2006-04-07

    A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical ''Weakless Universe'' is matched to our Universe by simultaneously adjusting Standard Model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the Weakless Universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multi-parameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe.

  20. Nonlinear evolution of dark matter subhalos and applications to warm dark matter

    SciTech Connect

    Pullen, Anthony R.; Moustakas, Leonidas A.; Benson, Andrew J.

    2014-09-01

    We describe the methodology to include nonlinear evolution, including tidal effects, in the computation of subhalo distribution properties in both cold (CDM) and warm (WDM) dark matter universes. Using semi-analytic modeling, we include effects from dynamical friction, tidal stripping, and tidal heating, allowing us to dynamically evolve the subhalo distribution. We calibrate our nonlinear evolution scheme to the CDM subhalo mass function in the Aquarius N-body simulation, producing a subhalo mass function within the range of simulations. We find tidal effects to be the dominant mechanism of nonlinear evolution in the subhalo population. Finally, we compute the subhalo mass function for m {sub χ} = 1.5 keV WDM including the effects of nonlinear evolution, and compare radial number densities and mass density profiles of subhalos in CDM and WDM models. We show that all three signatures differ between the two dark matter models, suggesting that probes of substructure may be able to differentiate between them.

  1. Is the Universe logotropic?

    NASA Astrophysics Data System (ADS)

    Chavanis, Pierre-Henri

    2015-07-01

    We consider the possibility that the universe is made of a single dark fluid described by a logotropic equation of state P = A ln( ρ/ρ*, where ρ is the rest-mass density, ρ * is a reference density, and A is the logotropic temperature. The energy density ɛ is the sum of two terms: a rest-mass energy term ρ c 2 that mimics dark matter and an internal energy term u( ρ) = - P( ρ) - A that mimics dark energy. This decomposition leads to a natural, and physical, unification of dark matter and dark energy, and elucidates their mysterious nature. In the early universe, the rest-mass energy dominates and the dark fluid behaves as pressureless dark matter ( P ≃ 0, ɛ ∝ a -3. In the late universe, the internal energy dominates and the dark fluid behaves as dark energy ( P ˜ - ɛ, ɛ ∝ ln a. The logotropic model depends on a single parameter B = A / ρ Λ c 2 (dimensionless logotropic temperature), where ρ Λ = 6.72 × 10-24 g m-3 is the cosmological density. For B = 0, we recover the ΛCDM model with a different justification. For B > 0, we can describe deviations from the ΛCDM model. Using cosmological constraints, we find that 0 ≤ B ≤ 0.09425. We consider the possibility that dark matter halos are described by the same logotropic equation of state. When B > 0, pressure gradients prevent gravitational collapse and provide halo density cores instead of cuspy density profiles, in agreement with the observations. The universal rotation curve of logotropic dark matter halos is consistent with the observational Burkert profile (Burkert, Astrophys. J. 447, L25 (1995)) up to the halo radius. It decreases as r -1 at large distances, similarly to the profile of dark matter halos close to the core radius (Burkert, arXiv:1501.06604). Interestingly, if we assume that all the dark matter halos have the same logotropic temperature B, we find that their surface density Σ 0 = ρ0 r h is constant. This result is in agreement with the observations (Donato et al., Mon

  2. Supersymmetric Dark Matter and Prospects for its Detection

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takahiro

    Dark matter is a prominent and dominant form of matter in the Universe. Yet, despite various intense efforts, its nongravitational effects have not been observed. In this dissertation, we explore the nature of such elusive particles within a supersymmetric SU(3)C ⊗ SU(2)L ⊗ U(1)Y gauge theory. Although large regions of parameter space within supersymmetric models have been excluded by recent results from collider experiments and direct and indirect dark matter searches, we find that there is a wide range of viable parameter space once the requirements of minimal flavor violation and mass universality are relaxed. In particular, we focus on a class of models in which electroweak-scale Majorana dark matter has interactions with the Standard Model sector via relatively light charged scalars with large chiral mixing and CP-violation. Our model is shown to lead to enhanced dark matter pair annihilation, and is constrained by precise measurements of the lepton dipole moments. We illustrate that our model satisfies all constraints, including the observed thermal relic density, and investigate prospects for the detection of dark matter annihilation products. We also examine the effects of chiral mixing and CP-violationn on the variation in the ratio of the flux of monoenergetic photons from annihilation to two photons relative to that from annihilation to a photon and a Z boson, as well as the helicity asymmetry in the diphoton final state. We also find the most general spectrum for internal bremsstrahlung, which interpolates between the regimes dominated by virtual internal bremsstrahlung and by final state radiation, and that it provides distinctive gamma-ray signals, which could potentially be observed in the near future.

  3. Warm dark matter

    SciTech Connect

    Horiuchi, Shunsaku

    2016-06-21

    The cold dark matter paradigm has been extremely successful in explaining the large-scale structure of the Universe. However, it continues to face issues when confronted by observations on sub-Galactic scales. A major caveat, now being addressed, has been the incomplete treatment of baryon physics. We first summarize the small-scale issues surrounding cold dark matter and discuss the solutions explored by modern state-of-the-art numerical simulations including treatment of baryonic physics. We identify the too big to fail in field galaxies as among the best targets to study modifications to dark matter, and discuss the particular connection with sterile neutrino warm dark matter. We also discuss how the recently detected anomalous 3.55 keV X-ray lines, when interpreted as sterile neutrino dark matter decay, provide a very good description of small-scale observations of the Local Group.

  4. Complex Dark Matter

    SciTech Connect

    Lincoln, Don

    2015-04-16

    After a century of study, scientists have come to the realization that the ordinary matter made of atoms is a minority in the universe. In order to explain observations, it appears that there exists a new and undiscovered kind of matter, called dark matter, that is five times more prevalent than ordinary matter. The evidence for this new matter’s existence is very strong, but scientists know only a little about its nature. In today’s video, Fermilab’s Dr. Don Lincoln talks about an exciting and unconventional idea, specifically that dark matter might have a very complex set of structures and interactions. While this idea is entirely speculative, it is an interesting hypothesis and one that scientists are investigating.

  5. Light domain walls, massive neutrinos and the large scale structure of the Universe

    NASA Technical Reports Server (NTRS)

    Massarotti, Alessandro

    1991-01-01

    Domain walls generated through a cosmological phase transition are considered, which interact nongravitationally with light neutrinos. At a redshift z greater than or equal to 10(exp 4), the network grows rapidly and is virtually decoupled from the matter. As the friction with the matter becomes dominant, a comoving network scale close to that of the comoving horizon scale at z of approximately 10(exp 4) gets frozen. During the later phases, the walls produce matter wakes of a thickness d of approximately 10h(exp -1)Mpc, that may become seeds for the formation of the large scale structure observed in the Universe.

  6. The phenomenology of maverick dark matter

    NASA Astrophysics Data System (ADS)

    Krusberg, Zosia Anna Celina

    Astrophysical observations from galactic to cosmological scales point to a substantial non-baryonic component to the universe's total matter density. Although very little is presently known about the physical properties of dark matter, its existence offers some of the most compelling evidence for physics beyond the standard model (BSM). In the weakly interacting massive particle (WIMP) scenario, the dark matter consists of particles that possess weak-scale interactions with the particles of the standard model, offering a compelling theoretical framework that allows us to understand the relic abundance of dark matter as a natural consequence of the thermal history of the early universe. From the perspective of particle physics phenomenology, the WIMP scenario is appealing for two additional reasons. First, many theories of BSM physics contain attractive WIMP candidates. Second, the weak-scale interactions between WIMPs and standard model particles imply the possibility of detecting scatterings between relic WIMPs and detector nuclei in direct detection experiments, products of WIMP annihilations at locations throughout the galaxy in indirect detection programs, and WIMP production signals at high-energy particle colliders. In this work, we use an effective field theory approach to study model-independent dark matter phenomenology in direct detection and collider experiments. The maverick dark matter scenario is defined by an effective field theory in which the WIMP is the only new particle within the energy range accessible to the Large Hadron Collider (LHC). Although certain assumptions are necessary to keep the problem tractable, we describe our WIMP candidate generically by specifying only its spin and dominant interaction form with standard model particles. Constraints are placed on the masses and coupling constants of the maverick WIMPs using the Wilkinson Microwave Anisotropy Probe (WMAP) relic density measurement and direct detection exclusion data from both

  7. Galactic Dark Matter

    NASA Astrophysics Data System (ADS)

    Burch, Benjamin P.

    The precise phase-space distribution and properties of Galactic dark matter necessary for its direct and indirect detection are currently unknown. Since the distributions of normal and dark matter in the Milky Way are coupled to each other as they both move in the same gravitational potential, constraints on the distribution and properties of dark matter can be derived by studying the distribution of visible matter in the Galaxy and making some general assumptions regarding the phase-space distribution of the dark matter. In this study, the visible components of the Galaxy have been comprehensively reviewed to create an axisymmetric model of the Galaxy that is consistent with the available observations, and the dark matter phase-space distribution is assumed to follow a lowered-isothermal form. Poisson's equations are then solved self-consistently to construct models of the spatial and velocity distribution of Galactic dark matter. The total gravitational potential from normal and dark matter are calculated and compared to the current observations of the rotation curve and to the radial velocity distributions of blue horizontal-branch and blue straggler stars. It is found that this analysis allows for a wide range of parameters for the dark matter. The implications for direct and indirect detection of dark matter are discussed in detail. In the appendices, two additional projects are presented. In Appendix A, the recent observations of the positron fraction and the total electron spectrum in cosmic rays are addressed by considering a nested leaky-box model for the propagation of cosmic rays in the Galaxy. This is found to obviate the need for exotic processes such as the annihilation or decay of dark matter to explain the recent observations. In Appendix B, we discuss a novel dark matter detector involving triggered cavitation in acoustic fields. The theory behind the detector is presented in detail, and we discuss the work than has been done to create a prototype

  8. [Dominant Thalamus and Aphasia].

    PubMed

    Nakano, Akiko; Shimomura, Tatsuo

    2015-12-01

    Many studies have shown that lesions of the dominant thalamus precipitate language disorders in a similar manner to transcortical aphasias, in a phenomenon known as "thalamic aphasia." In some cases, however, aphasia may not occur or may appear transiently following thalamic lesions. Furthermore, dominant thalamic lesions can produce changes in character, as observed in patients with amnesic disorder. Previous work has explored the utility of thalamic aphasia as a discriminative feature for classification of aphasia. Although the thalamus may be involved in the function of the brainstem reticular activating system and play a role in attentional network and in memory of Papez circuit or Yakovlev circuit, the mechanism by which thalamic lesion leads to the emergence of aphasic disorders is unclear. In this review, we we survey historical and recent literature on thalamic aphasia in an attempt to understand the neural processes affected by thalamic lesions.

  9. Solar system tests for realistic f( T) models with non-minimal torsion-matter coupling

    NASA Astrophysics Data System (ADS)

    Lin, Rui-Hui; Zhai, Xiang-Hua; Li, Xin-Zhou

    2017-08-01

    In the previous paper, we have constructed two f( T) models with non-minimal torsion-matter coupling extension, which are successful in describing the evolution history of the Universe including the radiation-dominated era, the matter-dominated era, and the present accelerating expansion. Meantime, the significant advantage of these models is that they could avoid the cosmological constant problem of Λ CDM. However, the non-minimal coupling between matter and torsion will affect the tests of the Solar system. In this paper, we study the effects of the Solar system in these models, including the gravitation redshift, geodetic effect and perihelion precession. We find that Model I can pass all three of the Solar system tests. For Model II, the parameter is constrained by the uncertainties of the planets' estimated perihelion precessions.

  10. Thermal dark matter from a highly decoupled sector

    DOE PAGES

    Berlin, Asher; Hooper, Dan; Krnjaic, Gordan

    2016-11-17

    It has recently been shown that if the dark matter is in thermal equilibrium with a sector that is highly decoupled from the Standard Model, it can freeze out with an acceptable relic abundance, even if the dark matter is as heavy as ~1–100 PeV. In such scenarios, both the dark and visible sectors are populated after inflation, but with independent temperatures. The lightest particle in the dark sector will be generically long-lived and can come to dominate the energy density of the Universe. Upon decaying, these particles can significantly reheat the visible sector, diluting the abundance of dark mattermore » and thus allowing for dark matter particles that are much heavier than conventional WIMPs. In this study, we present a systematic and pedagogical treatment of the cosmological history in this class of models, emphasizing the simplest scenarios in which a dark matter candidate annihilates into hidden sector particles which then decay into visible matter through the vector, Higgs, or lepton portals. In each case, we find ample parameter space in which very heavy dark matter particles can provide an acceptable thermal relic abundance. We also discuss possible extensions of models featuring these dynamics.« less

  11. Antiproton constraints on dark matter annihilations from internal electroweak bremsstrahlung

    SciTech Connect

    Garny, Mathias; Ibarra, Alejandro; Vogl, Stefan E-mail: alejandro.ibarra@ph.tum.de

    2011-07-01

    If the dark matter particle is a Majorana fermion, annihilations into two fermions and one gauge boson could have, for some choices of the parameters of the model, a non-negligible cross-section. Using a toy model of leptophilic dark matter, we calculate the constraints on the annihilation cross-section into two electrons and one weak gauge boson from the PAMELA measurements of the cosmic antiproton-to-proton flux ratio. Furthermore, we calculate the maximal astrophysical boost factor allowed in the Milky Way under the assumption that the leptophilic dark matter particle is the dominant component of dark matter in our Universe. These constraints constitute very conservative estimates on the boost factor for more realistic models where the dark matter particle also couples to quarks and weak gauge bosons, such as the lightest neutralino which we also analyze for some concrete benchmark points. The limits on the astrophysical boost factors presented here could be used to evaluate the prospects to detect a gamma-ray signal from dark matter annihilations at currently operating IACTs as well as in the projected CTA.

  12. Condensate dark matter stars

    SciTech Connect

    Li, X.Y.; Harko, T.; Cheng, K.S. E-mail: harko@hkucc.hku.hk

    2012-06-01

    We investigate the structure and stability properties of compact astrophysical objects that may be formed from the Bose-Einstein condensation of dark matter. Once the critical temperature of a boson gas is less than the critical temperature, a Bose-Einstein Condensation process can always take place during the cosmic history of the universe. Therefore we model the dark matter inside the star as a Bose-Einstein condensate. In the condensate dark matter star model, the dark matter equation of state can be described by a polytropic equation of state, with polytropic index equal to one. We derive the basic general relativistic equations describing the equilibrium structure of the condensate dark matter star with spherically symmetric static geometry. The structure equations of the condensate dark matter stars are studied numerically. The critical mass and radius of the dark matter star are given by M{sub crit} ≈ 2(l{sub a}/1fm){sup 1/2}(m{sub χ}/1 GeV){sup −3/2}M{sub s}un and R{sub crit} ≈ 1.1 × 10{sup 6}(l{sub a}/1 fm){sup 1/2}(m{sub χ}/1 GeV){sup −3/2} cm respectively, where l{sub a} and m{sub χ} are the scattering length and the mass of dark matter particle, respectively.

  13. Detection of weak gravitational lensing distortions of distant galaxies by cosmic dark matter at large scales

    PubMed

    Wittman; Tyson; Kirkman; Dell'Antonio; Bernstein

    2000-05-11

    Most of the matter in the Universe is not luminous, and can be observed only through its gravitational influence on the appearance of luminous matter. Weak gravitational lensing is a technique that uses the distortions of the images of distant galaxies as a tracer of dark matter: such distortions are induced as the light passes through large-scale distributions of dark matter in the foreground. The patterns of the induced distortions reflect the density of mass along the line of sight and its distribution, and the resulting 'cosmic shear' can be used to distinguish between alternative cosmologies. But previous attempts to measure this effect have been inconclusive. Here we report the detection of cosmic shear on angular scales of up to half a degree using 145,000 galaxies and along three separate lines of sight. We find that the dark matter is distributed in a manner consistent with either an open universe, or a flat universe that is dominated by a cosmological constant. Our results are inconsistent with the standard cold-dark-matter model.

  14. Nonlinear electrodynamics and modification of initial singularities, and dark matter and dark energy affecting structure formation in the early and later universe

    NASA Astrophysics Data System (ADS)

    Beckwith, A. W.

    2015-07-01

    We find that having the scale factor close to zero due to a given magnetic field value in an early universe magnetic field affects how we would interpret Mukhanov's chapter on “self reproduction” of the universe in in his reference. The stronger an early-universe magnetic field is, the greater the likelihood of production of about 20 new domains of size 1/H, with H the early-universe Hubble constant, per Planck time interval in evolution. We form DM from considerations as to a minimum time step, and then generate DM via axions. Through Ng's quantum infinite statistics, we compare a DM count, giving entropy. The remainder of the document is in terms of DE as well as comparing entropy in galaxies versus entropy in the universe, through a lens of Mistra's quantum theory of the big bang.

  15. Exothermic dark matter

    SciTech Connect

    Graham, Peter W.; Saraswat, Prashant; Harnik, Roni; Rajendran, Surjeet

    2010-09-15

    We propose a novel mechanism for dark matter to explain the observed annual modulation signal at DAMA/LIBRA which avoids existing constraints from every other dark matter direct detection experiment including CRESST, CDMS, and XENON10. The dark matter consists of at least two light states with mass {approx}few GeV and splittings {approx}5 keV. It is natural for the heavier states to be cosmologically long-lived and to make up an O(1) fraction of the dark matter. Direct detection rates are dominated by the exothermic reactions in which an excited dark matter state downscatters off of a nucleus, becoming a lower energy state. In contrast to (endothermic) inelastic dark matter, the most sensitive experiments for exothermic dark matter are those with light nuclei and low threshold energies. Interestingly, this model can also naturally account for the observed low-energy events at CoGeNT. The only significant constraint on the model arises from the DAMA/LIBRA unmodulated spectrum but it can be tested in the near future by a low-threshold analysis of CDMS-Si and possibly other experiments including CRESST, COUPP, and XENON100.

  16. [Autosomal dominant polycystic kidney].

    PubMed

    Jorge Adad, S; Estevão Barbosa, M; Fácio Luíz, J M; Furlan Rodrigues, M C; Iwamoto, S

    1996-01-01

    A 48-year-old male had autosomic dominant polycystic kidneys with dimensions, to the best of our knowledge, never previously reported; the right kidney weighed 15,100 g and measured 53 x 33 x 9cm and the left one 10.200 g and 46 x 21 x 7cm, with cysts measuring up to 14cm in diameter. Nephrectomy was done to control persistent hematuria and to relief disconfort caused by the large kidneys. The renal function is stable four years after transplantation.

  17. The Mysterious Universe - Exploring Our World with Particle Accelerators

    SciTech Connect

    Brau, James E

    2010-11-23

    The universe is dark and mysterious, more so than even Einstein imagined. While modern science has established deep understanding of ordinary matter, unidentified elements ("Dark Matter" and "Dark Energy") dominate the structure of the universe, its behavior and its destiny. What are these curious elements? We are now working on answers to these and other challenging questions posed by the universe with experiments at particle accelerators on Earth. Results of this research may revolutionize our view of nature as dramatically as the advances of Einstein and other quantum pioneers one hundred years ago. Professor Brau will explain for the general audience the mysteries, introduce facilities which explore them experimentally and discuss our current understanding of the underlying science. The presentation is at an introductory level, appropriate for anyone interested in physics and astronomy.

  18. The Mysterious Universe - Exploring Our World with Particle Accelerators

    ScienceCinema

    Brau, James E [University of Oregon

    2016-07-12

    The universe is dark and mysterious, more so than even Einstein imagined. While modern science has established deep understanding of ordinary matter, unidentified elements ("Dark Matter" and "Dark Energy") dominate the structure of the universe, its behavior and its destiny. What are these curious elements? We are now working on answers to these and other challenging questions posed by the universe with experiments at particle accelerators on Earth. Results of this research may revolutionize our view of nature as dramatically as the advances of Einstein and other quantum pioneers one hundred years ago. Professor Brau will explain for the general audience the mysteries, introduce facilities which explore them experimentally and discuss our current understanding of the underlying science. The presentation is at an introductory level, appropriate for anyone interested in physics and astronomy.

  19. A universe without weak interactions

    NASA Astrophysics Data System (ADS)

    Harnik, Roni; Kribs, Graham D.; Perez, Gilad

    2006-08-01

    A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical “weakless universe” is matched to our Universe by simultaneously adjusting standard model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the weakless universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multiparameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe.

  20. Small-scale cosmic microwave background anisotropies as probe of the geometry of the universe

    NASA Technical Reports Server (NTRS)

    Kamionkowski, Marc; Spergel, David N.; Sugiyama, Naoshi

    1994-01-01

    We perform detailed calculations of cosmic microwave background (CMB) anisotropies in a cold dark matter (CDM)-dominated open universe with primordial adiabatic density perturbations for a variety of reionization histories. The CMB anisotropies depend primarily on the geometry of the universe, which in a matter-dominated universe is determined by Omega and the optical depth to the surface of last scattering. In particular, the location on the primary Doppler peak depends primarily on Omega and is fairly insensitive to the other unknown parameters, such as Omega(sub b), h, Lambda, and the shape of the power spectrum. Therefore, if the primordial density perturbations are adiabatic, measurements of CMB anisotropies on small scales may be used to determine Omega.