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Sample records for early intergalactic medium

  1. The physics and early history of the intergalactic medium

    NASA Astrophysics Data System (ADS)

    Barkana, Rennan; Loeb, Abraham

    2007-04-01

    The intergalactic medium—the cosmic gas that fills the great spaces between the galaxies—is affected by processes ranging from quantum fluctuations in the very early Universe to radiative emission from newly formed stars. This gives the intergalactic medium a dual role as a powerful probe both of fundamental physics and of astrophysics. The heading of fundamental physics includes conditions in the very early Universe and cosmological parameters that determine the age of the Universe and its matter content. The astrophysics refers to chapters of the long cosmic history of stars and galaxies that are being revealed through the effects of stellar feedback on the cosmic gas. This review describes the physics of the intergalactic medium, focusing on recent theoretical and observational developments in understanding early cosmic history. In particular, the earliest generation of stars is thought to have transformed the Universe from darkness to light and to have had an enormous impact on the intergalactic medium. Half a million years after the Big Bang the Universe was filled with atomic hydrogen. As gravity pulled gas clouds together, the first stars ignited and their radiation turned the surrounding atoms back into free electrons and ions. From the observed spectral absorption signatures of the gas between us and distant sources, we know that the process of reionization pervaded most of space a billion years after the Big Bang, so that only a small fraction of the primordial hydrogen atoms remained between galaxies. Knowing exactly when and how the reionization process happened is a primary goal of cosmologists, because this would tell us when the early stars and black holes formed and in what kinds of galaxies. The distribution and clustering of these galaxies is particularly interesting since it is driven by primordial density fluctuations in the dark matter. Cosmic reionization is beginning to be understood with the help of theoretical models and computer

  2. A photoionization instability in the early intergalactic medium

    NASA Technical Reports Server (NTRS)

    Hogan, Craig J.

    1992-01-01

    It is argued that any fairly uniform source of ionizing photons can be the cause of an instability in the pregalactic medium on scales larger than a photon path length. Underdense regions receive more ionizing energy per atom and reach higher temperature and entropy, driving the density down still further. Fluctuations created by this instability can lead to the formation of structures resembling protogalaxies and intergalactic clouds, obviating the need for gas clouds or density perturbations of earlier cosmological provenance, as is usually assumed in theories of galaxy and structure formation. Characteristic masses for clouds produced by the instability, with log mass in solar units plotted against log radius in kpc, are illustrated.

  3. The Evolution of the Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    McQuinn, Matthew

    2016-09-01

    The bulk of cosmic matter resides in a dilute reservoir that fills the space between galaxies, the intergalactic medium (IGM). The history of this reservoir is intimately tied to the cosmic histories of structure formation, star formation, and supermassive black hole accretion. Our models for the IGM at intermediate redshifts (2≲z≲5) are a tremendous success, quantitatively explaining the statistics of Lyα absorption of intergalactic hydrogen. However, at both lower and higher redshifts (and around galaxies) much is still unknown about the IGM. We review the theoretical models and measurements that form the basis for the modern understanding of the IGM, and we discuss unsolved puzzles (ranging from the largely unconstrained process of reionization at high z to the missing baryon problem at low z), highlighting the efforts that have the potential to solve them.

  4. The Ionization History of The Intergalactic Medium:

    NASA Technical Reports Server (NTRS)

    Madau, Piero

    2003-01-01

    The funded project seeked a unified description of the ionization, physical structure, and evolution of the intergalactic medium (IGM) and quasar intervening absorption systems. We proposed to conduct theoretical studies of the IGM and QSO absorbers in the context of current theories of galaxy formation, developing and using numerical and analytical techniques aimed at a detailed modeling of cosmological radiative transfer, gas dynamics, and thermal and ionization evolution. The ionization history of the IGM has important implications for the metagalactic UV background, intergalactic helium absorption 21-cm tomography, metal absorption systems, fluctuations in the microwave background, and the cosmic rate of structure and star formation. All the original objectives of our program have been achieved, and the results widely used and quoted by the community. Indeed, they remain relevant as the level and complexity of research in this area has increased substantially since our proposal was submitted, due to new discoveries on galaxy formation and evolution, a flood of high-quality data on the distant universe, new theoretical ideas and direct numerical simulations of structure formation in hierarchical clustering theories.

  5. The Warm-Hot Intergalactic Medium

    NASA Technical Reports Server (NTRS)

    Hayes, Jeffrey (Technical Monitor)

    2005-01-01

    This grant is associated to a 5-year LTSA grant, on "Studying the Largest Reservoir of Baryons in the Universe: The Warm-Hot Intergalactic Medium". The first year of work within this program has been very rich, and has already produced several important results, as detailed in this paper. Table 2 of our original proposal justification, listed the planned year-by-year program, divided into two sub-fields: (A) the study of the z=0 (or Local Group WHIM) system, and (B) the study of the z greater than 0 (i.e- intervening WHIM) systems. For each of the two sub-fields we had planned to analyze, in the first year, a number of archival (Chandra, XMM and FUSE) and new (if observed) sightlines. Moreover, the plan for the z=0 system included the search for new interesting sightlines. We have accomplished all these tasks.

  6. From Galaxies to the Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Peeples, Molly S.

    2010-07-01

    Deep in dark matter halos, galaxies are large factories that convert gas into stars. Gas is accreted from the expansive intergalactic medium (IGM); stars process this gas by fusing lighter elements into heavier ones. In this Dissertation, I combine both observations and theories from a variety of subfields of astrophysics with analytic and numerical models in an aim for a comprehensive understanding of the underlying physics of star formation feedback, galaxy chemical evolution, and the IGM. The mass-metallicity relation is an observed tight correlation between the stellar masses and gas-phase oxygen abundances of star-forming galaxies. I show that while the intrinsic scatter in this relation is small, extreme outliers do exist; I argue that these outliers have unusual metallicities for their masses because they have unusual gas fractions for their masses. The low-mass high-metallicity galaxies appear to be nearing the end of their star formation, and thus should have abnormally small gas reservoirs with which to dilute their metals. On the other hand, the high-mass low-metallicity galaxies appear to be undergoing gas-rich galaxy mergers, implying that they have larger-than-normal amounts of gas diluting their metals. I then show through analytic arguments that while gas fractions can have a large impact on observed metallicities, the low-redshift mass-metallicity relation is dominated by outflow properties because typical galaxies have relatively small gas fractions. Specifically, the mass-metallicity relation implies that the efficiency with which galaxies expel metals should scale steeply with galaxy mass. Combining this model with reasonable models for star formation feedback, I show that the outflow metallicity should likewise vary with galaxy mass; future measurements of wind metallicity can therefore inform models of the physics underlying galaxy winds. The high-redshift IGM is primarily observed through the Lyman-alpha absorption of neutral hydrogen along

  7. Galaxy formation in an intergalactic medium dominated by explosions

    NASA Technical Reports Server (NTRS)

    Ostriker, J. P.; Cowie, L. L.

    1981-01-01

    The evolution of galaxies in an intergalactic medium dominated by explosions of star systems is considered analogously to star formation by nonlinearly interacting processes in the interstellar medium. Conditions for the existence of a hydrodynamic instability by which galaxy formation leads to more galaxy formation due to the propagation of the energy released at the death of massive stars are examined, and it is shown that such an explosive amplification is possible at redshifts less than about 5 and stellar system masses between 10 to the 8th and 10 to the 12th solar masses. Explosions before a redshift of about 5 are found to lead primarily to the formation of massive stars rather than galaxies, while those at a redshift close to 5 will result in objects of normal galactic scale. The model also predicts a dusty interstellar medium preventing the detection of objects of redshift greater than 3, numbers and luminosities of protogalaxies comparable to present observations, unvirialized groups of galaxies lying on two-dimensional surfaces, and a significant number of black holes in the mass range 1000-10,000 solar masses.

  8. The igmspec database of public spectra probing the intergalactic medium

    NASA Astrophysics Data System (ADS)

    Prochaska, J. X.

    2017-04-01

    We describe v02 of igmspec, a database of publicly available ultraviolet, optical, and near-infrared spectra that probe the intergalactic medium (IGM). This database, a child of the specdb repository in the specdb github organization, comprises 403 277 unique sources and 434 686 spectra obtained with the world's greatest observatories. All of these data are distributed in a single ≈ 25GB HDF5 file maintained at the University of California Observatories and the University of California, Santa Cruz. The specdb software package includes Python scripts and modules for searching the source catalog and spectral datasets, and software links to the linetools package for spectral analysis. The repository also includes software to generate private spectral datasets that are compliant with International Virtual Observatory Alliance (IVOA) protocols and a Python-based interface for IVOA Simple Spectral Access queries. Future versions of igmspec will ingest other sources (e.g. gamma-ray burst afterglows) and other surveys as they become publicly available. The overall goal is to include every spectrum that effectively probes the IGM. Future databases of specdb may include publicly available galaxy spectra (exgalspec) and published supernovae spectra (snspec). The community is encouraged to join the effort on github: https://github.com/specdb.

  9. Simulating the interaction of galaxies and the intergalactic medium

    NASA Astrophysics Data System (ADS)

    Carin, Robert A.

    2008-11-01

    The co-evolution of galaxies and the intergalactic medium as a function of environment is studied using hydrodynamic simulations of the ΛCDM cosmogony. It is demonstrated with non-radiative calculations that, in the absence of non-gravitational mechanisms, dark matter haloes accrete a near-universal fraction (˜ 0.9Ω_{b}/&Omega_;{m}) of baryons. The absence of a mass or redshift dependence of this fraction augurs well for parameter tests that use X-ray clusters as cosmological probes. Moreover, this result indicates that non-gravitational processes must efficiently regulate the formation of stars in dark matter haloes if the halo mass function is to be reconciled with the observed galaxy luminosity function. Simulations featuring stellar evolution and non-gravitational feedback mechanisms (photo-heating by the ultraviolet background, and thermal and kinetic supernovae feedback) are used to follow the evolution of star formation, and the thermo- and chemo-dynamical evolution of baryons. The observed star formation history of the Universe is reproduced, except at low redshift where it is overestimated by a factor of a few, possibly indicating the need for feedback from active galactic nuclei to quench cooling flows around massive galaxies. The simulations more accurately reproduce the observed abundance of galaxies with late-type morphologies than has been reported elsewhere. The unique initial conditions of these simulations, based on the Millennium Simulation, allow an unprecedented study of the role of large-scale environment to be conducted. The cosmic star formation rate density is found to vary by an order of magnitude across the extremes of environment expected in the local Universe. The mass fraction of baryons in the observationally elusive warm-hot intergalactic medium (WHIM), and the volume filling factor that this gas occupies, is also shown to vary by a factor of a few across such environments. This variation is attributed to differences in the halo

  10. Cosmic ray heating of intergalactic medium: patchy or uniform?

    NASA Astrophysics Data System (ADS)

    Jana, Ranita; Nath, Biman B.

    2018-06-01

    We study the heating of the intergalactic medium (IGM) surrounding high redshift star forming galaxies due to cosmic rays (CR). We take into account the diffusion of low energy cosmic rays and study the patchiness of the resulting heating. We discuss the case of IGM heating around a high redshift minihalo (z ˜ 10-20, M˜105-107 M⊙),and put an upper limit on the diffusion coefficient D ≤ 1 × 1026 cm2 s-1 for the heating to be inhomogeneous at z ˜ 10 and D ≤ 5-6 × 1026 cm2 s-1 at z ˜ 20. For typical values of D, our results suggest uniform heating by CR at high redshift, although there are uncertainties in magnetic field and other CR parameters. We also discuss two cases with continuous star formation, one in which the star formation rate (SFR) of a galaxy is high enough to make the IGM in the vicinity photoionized, and another in which the SFR is low enough to keep it neutral but high enough to cause significant heating by cosmic ray protons. In the neutral case (low SFR), we find that the resulting heating can make the gas hotter than the cosmic microwave background (CMB) radiation for D < 1030 cm2 s-1, within a few kpc of the galaxy, and unlikely to be probed by near future radio observations. In the case of photoionized IGM (high SFR), the resulting heating of the gas in the vicinity of high redshift (z ˜ 4) galaxies of mass ≥1012 M⊙ can suppress gas infall into the galaxy. At lower redshifts (z ˜ 0), an SFR of ˜1 M⊙ yr-1 can suppress the infall into galaxies of mass ≤1010 M⊙.

  11. X-ray ionization of the intergalactic medium by quasars

    NASA Astrophysics Data System (ADS)

    Graziani, Luca; Ciardi, B.; Glatzle, M.

    2018-06-01

    We investigate the impact of quasars on the ionization of the surrounding intergalactic medium (IGM) with the radiative transfer code CRASH4, now accounting for X-rays and secondary electrons. After comparing with analytic solutions, we post-process a cosmic volume (≈1.5 × 104 Mpc3h-3) containing a ULAS J1120+0641-like quasar (QSO) hosted by a 5 × 1011M⊙h-1 dark matter (DM) halo. We find that: (i) the average HII region (R ˜ 3.2 pMpc in a lifetime tf = 107 yrs) is mainly set by UV flux, in agreement with semi-analytic scaling relations; (ii) a largely neutral (xHII < 0.001), warm (T ˜ 103 K) tail extends up to few Mpc beyond the ionization front, as a result of the X-ray flux; (iii) LyC-opaque inhomogeneities induce a line of sight (LOS) scatter in R as high as few physical Mpc, consistent with the DLA scenario proposed to explain the anomalous size of the ULAS J1120+0641 ionized region. On the other hand, with an ionization rate \\dot{N}_{γ ,0} ˜ 10^{57} s-1, the assumed DLA clustering and gas opacity, only one LOS shows an HII region compatible with the observed one. We deduce that either the ionization rate of the QSO is at least one order of magnitude lower or the ULAS J1120+0641 bright phase is shorter than 107 yrs.

  12. On modeling and measuring the temperature of the z ∼ 5 intergalactic medium

    SciTech Connect

    Lidz, Adam; Malloy, Matthew, E-mail: alidz@sas.upenn.edu

    2014-06-20

    The temperature of the low-density intergalactic medium (IGM) at high redshift is sensitive to the timing and nature of hydrogen and He II reionization, and can be measured from Lyman-alpha (Lyα) forest absorption spectra. Since the memory of intergalactic gas to heating during reionization gradually fades, measurements as close as possible to reionization are desirable. In addition, measuring the IGM temperature at sufficiently high redshifts should help to isolate the effects of hydrogen reionization since He II reionization starts later, at lower redshift. Motivated by this, we model the IGM temperature at z ≳ 5 using semi-numeric models of patchymore » reionization. We construct mock Lyα forest spectra from these models and consider their observable implications. We find that the small-scale structure in the Lyα forest is sensitive to the temperature of the IGM even at redshifts where the average absorption in the forest is as high as 90%. We forecast the accuracy at which the z ≳ 5 IGM temperature can be measured using existing samples of high resolution quasar spectra, and find that interesting constraints are possible. For example, an early reionization model in which reionization ends at z ∼ 10 should be distinguishable—at high statistical significance—from a lower redshift model where reionization completes at z ∼ 6. We discuss improvements to our modeling that may be required to robustly interpret future measurements.« less

  13. Hydrodynamic Simulations and Tomographic Reconstructions of the Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Stark, Casey William

    The Intergalactic Medium (IGM) is the dominant reservoir of matter in the Universe from which the cosmic web and galaxies form. The structure and physical state of the IGM provides insight into the cosmological model of the Universe, the origin and timeline of the reionization of the Universe, as well as being an essential ingredient in our understanding of galaxy formation and evolution. Our primary handle on this information is a signal known as the Lyman-alpha forest (or Ly-alpha forest) -- the collection of absorption features in high-redshift sources due to intervening neutral hydrogen, which scatters HI Ly-alpha photons out of the line of sight. The Ly-alpha forest flux traces density fluctuations at high redshift and at moderate overdensities, making it an excellent tool for mapping large-scale structure and constraining cosmological parameters. Although the computational methodology for simulating the Ly-alpha forest has existed for over a decade, we are just now approaching the scale of computing power required to simultaneously capture large cosmological scales and the scales of the smallest absorption systems. My thesis focuses on using simulations at the edge of modern computing to produce precise predictions of the statistics of the Ly-alpha forest and to better understand the structure of the IGM. In the first part of my thesis, I review the state of hydrodynamic simulations of the IGM, including pitfalls of the existing under-resolved simulations. Our group developed a new cosmological hydrodynamics code to tackle the computational challenge, and I developed a distributed analysis framework to compute flux statistics from our simulations. I present flux statistics derived from a suite of our large hydrodynamic simulations and demonstrate convergence to the per cent level. I also compare flux statistics derived from simulations using different discretizations and hydrodynamic schemes (Eulerian finite volume vs. smoothed particle hydrodynamics) and

  14. Evolution of Structure in the Intergalactic Medium and the Nature of the LY-Alpha Forest

    NASA Technical Reports Server (NTRS)

    Bi, Hongguang; Davidsen, Arthur F.

    1997-01-01

    We have performed a detailed statistical study of the evolution of structure in a photoionized intergalactic medium (IGM) using analytical simulations to extend the calculation into the mildly nonlinear density regime found to prevail at z = 3. Our work is based on a simple fundamental conjecture: that the probability distribution function of the density of baryonic diffuse matter in the universe is described by a lognormal (LN) random field. The LN distribution has several attractive features and follows plausibly from the assumption of initial linear Gaussian density and velocity fluctuations at arbitrarily early times. Starting with a suitably normalized power spectrum of primordial fluctuations in a universe dominated by cold dark matter (CDM), we compute the behavior of the baryonic matter, which moves slowly toward minima in the dark matter potential on scales larger than the Jeans length. We have computed two models that succeed in matching observations. One is a nonstandard CDM model with OMEGA = 1, h = 0.5, and GAMMA = 0.3, and the other is a low-density flat model with a cosmological constant (LCDM), with OMEGA = 0.4, OMEGA(sub LAMBDA) = 0.6, and h = 0.65. In both models, the variance of the density distribution function grows with time, reaching unity at about z = 4, where the simulation yields spectra that closely resemble the Ly-alpha forest absorption seen in the spectra of high-z quasars. The calculations also successfully predict the observed properties of the Ly-alpha forest clouds and their evolution from z = 4 down to at least z = 2, assuming a constant intensity for the metagalactic UV background over this redshift range. However, in our model the forest is not due to discrete clouds, but rather to fluctuations in a continuous intergalactic medium. At z = 3; typical clouds with measured neutral hydrogen column densities N(sub H I) = 10(exp 13.3), 10(exp 13.5), and 10(exp 11.5) /sq cm correspond to fluctuations with mean total densities

  15. The Warm-Hot Intergalactic Medium Explorer (WHIMex) Mission Concept

    NASA Astrophysics Data System (ADS)

    Lillie, Charles F.; Cash, W. C.; McEntaffer, R. L.; Zhang, W.; O'Dell, S.; Bautz, M.; Elvis, M.

    2011-05-01

    WHIMEx is a low-cost, highly capable, single instrument X-ray observatory proposed as a NASA Explorer 2011 mission. WHIMEx will use high resolution X-ray spectroscopy (R ≥ 4000) to probe the hot, tenuous gas that populates the great stretches between the galaxies - the place where most of the baryons in the Universe reside. The bulk of this gas is so hot that it can only be studied in the soft X-ray region where the atomic diagnostics for highly ionized species reside. And this gas is so tenuous that it can only be observed in absorption. To detect the absorption lines of O VII and O VIII along the line of sight to distant AGN requires an order of magnitude improvement in both spectral resolution and collecting area over the current best X-ray spectrographs on Chandra and XMM-Newton. WHIMEx achieves this goal in a compact and affordable package through the application of technologies that were developed over the last decade for the International X-ray Observatory. WHIMex uses ultra-thin, light, densely nested parabolic-hyperbolic mirror pairs to create a telescope with a high collecting area and 15 arcsecond resolution. The X-ray beam is dispersed in wavelength by an array of radial gratings in the extreme off-plane mount. Spectral resolving power of 4000 (λ/δλ) is expected in the 0.15 to 2keV band to bring weak absorption lines out of the noise. A collecting area up to 360 cm2 will enable spectral observations of high red shift AGNs.If selected WHIMEx could be launched in mid- 2017 on a Taurus or Athena II from Vandenberg AFB into its 540 km, 70° inclination low earth orbit. In flight, it would open up a new field of exploration with high resolution observations of AGN outflows, the IGM, interstellar medium, mass transfer binaries, stellar coronae and much more

  16. The Warm-Hot Intergalactic Medium Explorer (WHIMex)

    NASA Astrophysics Data System (ADS)

    Lillie, Charles F.; Cash, W. C.; Science, WHIMex; Instrument Teams

    2011-09-01

    WHIMex is a low-cost, highly capable, single instrument X-ray observatory proposed as a NASA Explorer 2011 mission. WHIMex will use high resolution X-ray spectroscopy (R ≥ 4000) to probe the hot, tenuous gas that populates the great stretches between the galaxies - the place where most of the baryons in the Universe reside. The bulk of this gas is so hot that it can only be studied in the soft X-ray region where the atomic diagnostics for highly ionized species reside. And this gas is so tenuous that it can only be observed in absorption. To detect the absorption lines of O VII and O VIII along the line of sight to distant AGN requires an order of magnitude improvement in both spectral resolution and collecting area over the current best X-ray spectrographs on Chandra and XMM-Newton. WHIMex achieves this goal in a compact and affordable package through the application of technologies that were developed over the last decade for the International X-ray Observatory. WHIMex uses ultra-thin, light, densely nested parabolic-hyperbolic mirror pairs to create a telescope with a high collecting area and <15 arcsecond resolution. The X-ray s are dispersed in wavelength by an array of radial gratings in the extreme off-plane mount. Spectral resolving power of 4000 (λ/δλ) is expected in the 0.3 to 0.8 keV band to bring weak absorption lines out of the noise. A collecting area up to 360 cm2 will enable spectral observations of high red shift AGNs. If selected WHIMex could be launched in mid- 2017 on a Taurus or Athena II from Vandenberg AFB into a 540 km, 70° inclination low earth orbit. In flight, it would open a new field of exploration with high resolution observations of AGN outflows, the IGM, Interstellar Medium, mass transfer binaries, stellar coronae and much more.

  17. Galactic wind X-ray heating of the intergalactic medium during the Epoch of Reionization

    NASA Astrophysics Data System (ADS)

    Meiksin, Avery; Khochfar, Sadegh; Paardekooper, Jan-Pieter; Dalla Vecchia, Claudio; Kohn, Saul

    2017-11-01

    The diffuse soft X-ray emissivity from galactic winds is computed during the Epoch of Reionization (EoR). We consider two analytic models, a pressure-driven wind and a superbubble model, and a 3D cosmological simulation including gas dynamics from the First Billion Years (FiBY) project. The analytic models are normalized to match the diffuse X-ray emissivity of star-forming galaxies in the nearby Universe. The cosmological simulation uses physically motivated star formation and wind prescriptions, and includes radiative transfer corrections. The models and the simulation all are found to produce sufficient heating of the intergalactic medium to be detectable by current and planned radio facilities through 21 cm measurements during the EoR. While the analytic models predict a 21 cm emission signal relative to the cosmic microwave backgroundsets in by ztrans ≃ 8-10, the predicted signal in the FiBY simulation remains in absorption until reionization completes. The 21 cm absorption differential brightness temperature reaches a minimum of ΔT ≃ -130 to -200 mK, depending on model. Allowing for additional heat from high-mass X-ray binaries pushes the transition to emission to ztrans ≃ 10-12, with shallower absorption signatures having a minimum of ΔT ≃ -110 to -140 mK. The 21 cm signal may be a means of distinguishing between the wind models, with the superbubble model favouring earlier reheating. While an early transition to emission may indicate X-ray binaries dominate the reheating, a transition to emission as early as ztrans > 12 would suggest the presence of additional heat sources.

  18. Does Light from Steady Sources Bear Any Observable Imprint of the Dispersive Intergalactic Medium?

    NASA Astrophysics Data System (ADS)

    Lieu, Richard; Duan, Lingze

    2018-02-01

    There has recently been some interest in the prospect of detecting ionized intergalactic baryons by examining the properties of incoherent light from background cosmological sources, namely quasars. Although the paper by Lieu et al. proposed a way forward, it was refuted by the later theoretical work of Hirata & McQuinn and the observational study of Hales et al. In this paper we investigate in detail the manner in which incoherent radiation passes through a dispersive medium both from the frameworks of classical and quantum electrodynamics, leading us to conclude that the premise of Lieu et al. would only work if the pulses involved are genuinely classical ones containing many photons per pulse; unfortunately, each photon must not be treated as a pulse that is susceptible to dispersive broadening. We are nevertheless able to change the tone of the paper at this juncture by pointing out that because current technology allows one to measure the phase of individual modes of radio waves from a distant source, the most reliable way of obtaining irrefutable evidence of dispersion, namely via the detection of its unique signature of a quadratic spectral phase, may well be already accessible. We demonstrate how this technique is only applied to measure the column density of the ionized intergalactic medium.

  19. Observations of the missing baryons in the warm-hot intergalactic medium.

    PubMed

    Nicastro, F; Kaastra, J; Krongold, Y; Borgani, S; Branchini, E; Cen, R; Dadina, M; Danforth, C W; Elvis, M; Fiore, F; Gupta, A; Mathur, S; Mayya, D; Paerels, F; Piro, L; Rosa-Gonzalez, D; Schaye, J; Shull, J M; Torres-Zafra, J; Wijers, N; Zappacosta, L

    2018-06-01

    It has been known for decades that the observed number of baryons in the local Universe falls about 30-40 per cent short 1,2 of the total number of baryons predicted 3 by Big Bang nucleosynthesis, as inferred 4,5 from density fluctuations of the cosmic microwave background and seen during the first 2-3 billion years of the Universe in the so-called 'Lyman α forest' 6,7 (a dense series of intervening H I Lyman α absorption lines in the optical spectra of background quasars). A theoretical solution to this paradox locates the missing baryons in the hot and tenuous filamentary gas between galaxies, known as the warm-hot intergalactic medium. However, it is difficult to detect them there because the largest by far constituent of this gas-hydrogen-is mostly ionized and therefore almost invisible in far-ultraviolet spectra with typical signal-to-noise ratios 8,9 . Indeed, despite large observational efforts, only a few marginal claims of detection have been made so far 2,10 . Here we report observations of two absorbers of highly ionized oxygen (O VII) in the high-signal-to-noise-ratio X-ray spectrum of a quasar at a redshift higher than 0.4. These absorbers show no variability over a two-year timescale and have no associated cold absorption, making the assumption that they originate from the quasar's intrinsic outflow or the host galaxy's interstellar medium implausible. The O VII systems lie in regions characterized by large (four times larger than average 11 ) galaxy overdensities and their number (down to the sensitivity threshold of our data) agrees well with numerical simulation predictions for the long-sought warm-hot intergalactic medium. We conclude that the missing baryons have been found.

  20. Measurement of the small-scale structure of the intergalactic medium using close quasar pairs.

    PubMed

    Rorai, Alberto; Hennawi, Joseph F; Oñorbe, Jose; White, Martin; Prochaska, J Xavier; Kulkarni, Girish; Walther, Michael; Lukić, Zarija; Lee, Khee-Gan

    2017-04-28

    The distribution of diffuse gas in the intergalactic medium (IGM) imprints a series of hydrogen absorption lines on the spectra of distant background quasars known as the Lyman-α forest. Cosmological hydrodynamical simulations predict that IGM density fluctuations are suppressed below a characteristic scale where thermal pressure balances gravity. We measured this pressure-smoothing scale by quantifying absorption correlations in a sample of close quasar pairs. We compared our measurements to hydrodynamical simulations, where pressure smoothing is determined by the integrated thermal history of the IGM. Our findings are consistent with standard models for photoionization heating by the ultraviolet radiation backgrounds that reionized the universe. Copyright © 2017, American Association for the Advancement of Science.

  1. Quasi-stellar objects in the intergalactic medium: Source for the cosmic X-ray background

    SciTech Connect

    Sherman, R.D.

    1980-06-15

    QSOs are regarded as sources of both electromagnetic radiation and ejected matter that heat and ionize a dense intergalactic medium (IGM). Using current estimates of QSO luminosity, number density, evolution, and spectral index, we study three viable models: the diffuse cosmic X-ray background is (1) due entirely to thermal Bremsstrahlung of the IGM, (2) completely supplied by QSO X-radiation, (3) or a combination of both. The upper limits on an IGM fractional density with respect to closure are ..cap omega..=0.26, 0.24, and 0.21 for pure collisional, photo/collisional mixture, and pure photoionization, respectively. These calculations give emission spectra, Compton distortion ofmore » the cosmic microwave background, and optical depths to distant OSOs for comparison with relevant data.« less

  2. Measurement of the small-scale structure of the intergalactic medium using close quasar pairs

    DOE PAGES

    Rorai, Alberto; Hennawi, Joseph F.; Oñorbe, Jose; ...

    2017-04-28

    The distribution of diffuse gas in the intergalactic medium (IGM) imprints a series of hydrogen absorption lines on the spectra of distant background quasars known as the Lyman-α forest. Cosmological hydrodynamical simulations predict that IGM density fluctuations are suppressed below a characteristic scale where thermal pressure balances gravity. We measured this pressure-smoothing scale by quantifying absorption correlations in a sample of close quasar pairs. We compared our measurements to hydrodynamical simulations, where pressure smoothing is determined by the integrated thermal history of the IGM. Lastly, our findings are consistent with standard models for photoionization heating by the ultraviolet radiation backgroundsmore » that reionized the universe.« less

  3. The evolution of the intergalactic medium and the origin of the galaxy luminosity function

    NASA Technical Reports Server (NTRS)

    Valls-Gabaud, David; Blanchard, Alain; Mamon, Gary

    1993-01-01

    The coupling of the Press and Schechter prescription with the CDM scenario and the Hoyle-Rees-Ostriker cooling criterion leads to a galaxy formation scenario in which galaxies are overproduced by a large factor. Although star formation might be suppressed in the smaller halos, a large amount of energy per galactic mass is needed to account for the present number density of galaxies. The evolution of the intergalactic medium (IGM) provides a simple criterion to prevent galaxy formation without requiring feedback, since halos with small virial temperatures are not able to retain the infalling hot gas of the IGM. If the ionizing background has decreased since z is approximately 1 - 2, then this criterion explains the slope of the luminosity function at the faint end. In addition, this scenario predicts two populations of dwarf galaxies, well differentiated in age, gas content, stellar populations, and clustering properties, which can be identified with dE and dIm galaxies.

  4. The effect of feedback on the emission properties of the warm-hot intergalactic medium

    NASA Astrophysics Data System (ADS)

    Roncarelli, M.; Cappelluti, N.; Borgani, S.; Branchini, E.; Moscardini, L.

    2012-08-01

    At present, 30-40 per cent of the baryons in the local Universe is still undetected. According to theoretical predictions, this gas should reside in filaments filling the large-scale structure (LSS) in the form of a warm-hot intergalactic medium (WHIM), at temperatures 105-107 K, thus emitting in the soft X-ray energies via free-free interaction and line emission from heavy elements. In this work, we characterize the properties of the X-ray emission of the WHIM, and the LSS in general, focusing on the influence of different physical mechanisms, namely galactic winds (GWs), black hole feedback and star formation, and providing estimates of possible observational constraints. To this purpose, we use a set of cosmological hydrodynamical simulations that include a self-consistent treatment of star formation and chemical enrichment of the intergalactic medium, which allows us to follow the evolution of different metal species. We construct a set of simulated light cones to make predictions of the emission in the 0.3-10 keV energy range. We obtain that GWs increase the emission of both galaxy clusters and WHIM by a factor of 2. The amount of oxygen at average temperature and, consequently, the amount of expected bright O VII and O VIII lines are increased by a factor of 3 due to GWs and by 20 per cent when assuming a top-heavy initial mass function. We compare our results with current observational constraints and find that the emission from faint groups and WHIM should account for half to all of the unresolved X-ray background in the 1-2 keV band.

  5. Probing the Intergalactic Medium with Ly α and 21 cm Fluctuations

    SciTech Connect

    Heneka, Caroline; Cooray, Asantha; Feng, Chang

    2017-10-10

    We study 21 cm and Ly α fluctuations, as well as H α , while distinguishing between Ly α emission of galactic, diffuse, and scattered intergalactic medium (IGM) origin. Cross-correlation information about the state of the IGM is obtained, testing neutral versus ionized medium cases with different tracers in a seminumerical simulation setup. In order to pave the way toward constraints on reionization history and modeling beyond power spectrum information, we explore parameter dependencies of the cross-power signal between 21 cm and Ly α , which displays a characteristic morphology and a turnover from negative to positive correlation at scalesmore » of a couple Mpc{sup −1}. In a proof of concept for the extraction of further information on the state of the IGM using different tracers, we demonstrate the use of the 21 cm and H α cross-correlation signal to determine the relative strength of galactic and IGM emission in Ly α . We conclude by showing the detectability of the 21 cm and Ly α cross-correlation signal over more than one decade in scale at high signal-to-noise ratio for upcoming probes like SKA and the proposed all-sky intensity mapping satellites SPHEREx and CDIM, while also including the Ly α damping tail and 21 cm foreground avoidance in the modeling.« less

  6. X-RAY ABSORPTION BY THE WARM-HOT INTERGALACTIC MEDIUM IN THE HERCULES SUPERCLUSTER

    SciTech Connect

    Ren, Bin; Fang, Taotao; Buote, David A., E-mail: fangt@xmu.edu.cn

    2014-02-10

    ''Missing baryons'', in the form of warm-hot intergalactic medium (WHIM), are expected to reside in cosmic filamentary structures that can be traced by signposts such as large-scale galaxy superstructures. The clear detection of an X-ray absorption line in the Sculptor Wall demonstrated the success of using galaxy superstructures as a signpost to search for the WHIM. Here we present an XMM -Newton Reflection Grating Spectrometer observation of the blazar Mkn 501, located in the Hercules Supercluster. We detected an O VII Kα absorption line at the 98.7% level (2.5σ) at the redshift of the foreground Hercules Supercluster. The derived properties of themore » absorber are consistent with theoretical expectations of the WHIM. We discuss the implication of our detection for the search for the ''missing baryons''. While this detection shows again that using signposts is a very effective strategy to search for the WHIM, follow-up observations are crucial both to strengthen the statistical significance of the detection and to rule out other interpretations. A local, z ∼ 0 O VII Kα absorption line was also clearly detected at the 4σ level, and we discuss its implications for our understanding of the hot gas content of our Galaxy.« less

  7. X-ray optics for WHIMex: the Warm Hot Intergalactic Medium Explorer

    NASA Astrophysics Data System (ADS)

    Cash, W.; McEntaffer, R.; Zhang, W.; Casement, S.; Lillie, C.; Schattenburg, M.; Bautz, M.; Holland, A.; Tsunemi, H.; O'Dell, S.

    2011-09-01

    The x-ray astronomy community has never flown a celestial source spectrograph that can resolve natural line widths in absorption the way the ultraviolet community did with OAO-3 Copernicus back in 1972. Yet there is important science to be mined there, and right now, the large flagship missions like the International X-ray Observatory are not progressing toward launch. WHIMEx is an Explorer concept proposed earlier this year to open up that science regime in the next few years. The concept features a modified off-plane grating spectrograph design that will support high resolution (λ/δλ ~ 4000) in the soft x-ray band with a high packing density that will enable a modest cost space mission. We discuss the design and capabilities for the WHIMEx mission. Its prime science goal is detecting high temperature oxygen in the Intergalactic Medium, but it has a broad range of science potential cutting across all of x-ray astronomy and should give us a new window on the Universe.

  8. 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.

  9. PATCHY BLAZAR HEATING: DIVERSIFYING THE THERMAL HISTORY OF THE INTERGALACTIC MEDIUM

    SciTech Connect

    Lamberts, Astrid; Chang, Philip; Pfrommer, Christoph

    TeV-blazars potentially heat the intergalactic medium (IGM) as their gamma rays interact with photons of the extragalactic background light to produce electron–positron pairs, which lose their kinetic energy to the surrounding medium through plasma instabilities. This results in a heating mechanism that is only weakly sensitive to the local density, and therefore approximately spatially uniform, naturally producing an inverted temperature–density relation in underdense regions. In this paper we go beyond the approximation of uniform heating and quantify the heating rate fluctuations due to the clustered distribution of blazars and how this impacts the thermal history of the IGM. We analyticallymore » compute a filtering function that relates the heating rate fluctuations to the underlying dark matter density field. We implement it in the cosmological code GADGET-3 and perform large-scale simulations to determine the impact of inhomogeneous heating. We show that because of blazar clustering, blazar heating is inhomogeneous for z ≳ 2. At high redshift, the temperature–density relation shows an important scatter and presents a low temperature envelope of unheated regions, in particular at low densities and within voids. However, the median temperature of the IGM is close to that in the uniform case, albeit slightly lower at low redshift. We find that blazar heating is more complex than initially assumed and that the temperature–density relation is not unique. Our analytic model for the heating rate fluctuations couples well with large-scale simulations and provides a cost-effective alternative to subgrid models.« less

  10. Probing the nature of dark matter through the metal enrichment of the intergalactic medium

    NASA Astrophysics Data System (ADS)

    Bremer, Jonas; Dayal, Pratika; Ryan-Weber, Emma V.

    2018-06-01

    We focus on exploring the metal enrichment of the intergalactic medium (IGM) in cold and warm (1.5 and 3 keV) dark matter (DM) cosmologies, and the constraints this yields on the DM particle mass, using a semi-analytic model, DELPHI, that jointly tracks the DM and baryonic assembly of galaxies at z ≃ 4-20 including both supernova (SN) and (a range of) reionization feedback (models). We find that while M_{UV}≳ -15 galaxies contribute half of all IGM metals in the cold dark matter (CDM) model by z ≃ 4.5, given the suppression of low-mass haloes, larger haloes with M_{UV}≲ -15 provide about 80 per cent of the IGM metal budget in 1.5 keV warm dark matter (WDM) models using two different models for the metallicity of the interstellar medium. Our results also show that the only models compatible with two different high-redshift data sets, provided by the evolving ultraviolet luminosity function (UV LF) at z ≃ 6-10 and IGM metal density, are standard CDM and 3 keV WDM that do not include any reionization feedback; a combination of the UV LF and the Díaz et al. point provides a weaker constraint, allowing CDM and 3 and 1.5 keV WDM models with SN feedback only, as well as CDM with complete gas suppression of all haloes with v_{circ} ≲ 30 km s^{-1}. Tightening the error bars on the IGM metal enrichment, future observations, at z ≳ 5.5, could therefore represent an alternative way of shedding light on the nature of DM.

  11. The scattering of Lyα radiation in the intergalactic medium: numerical methods and solutions

    NASA Astrophysics Data System (ADS)

    Higgins, Jonathan; Meiksin, Avery

    2012-11-01

    Two methods are developed for solving the steady-state spherically symmetric radiative transfer equation for resonance line radiation emitted by a point source in the intergalactic medium, in the context of the Wouthuysen-Field mechanism for coupling the hyperfine structure spin temperature of hydrogen to the gas temperature. One method is based on solving the ray and moment equations using finite differences. The second uses a Monte Carlo approach incorporating methods that greatly improve the accuracy compared with previous approaches in this context. Several applications are presented serving as test problems for both a static medium and an expanding medium, including inhomogeneities in the density and velocity fields. Solutions are obtained in the coherent scattering limit and for Doppler RII redistribution with and without recoils. We find generally that the radiation intensity is linear in the cosine of the azimuthal angle with respect to radius to high accuracy over a broad frequency region across the line centre for both linear and perturbed velocity fields, yielding the Eddington factors fν ≃ 1/3 and gν ≃ 3/5. The radiation field produced by a point source divides into three spatial regimes for a uniformly expanding homogeneous medium. The regimes are governed by the fraction of the distance r from the source in terms of the distance r* required for a photon to redshift from line centre to the frequency needed to escape from the expanding gas. For a standard cosmology, before the Universe was reionized r* takes on the universal value independent of redshift of 1.1 Mpc, depending only on the ratio of the baryon to dark matter density. At r/r* < 1, the radiation field is accurately described in the diffusion approximation, with the scattering rate declining with the distance from the source as r-7/3, except at r/r* ≪ 1 where frequency redistribution nearly doubles the mean intensity around line centre. At r/r* > 1, the diffusion approximation breaks

  12. X-Ray Constraints on the Warm-Hot Intergalactic Medium

    NASA Technical Reports Server (NTRS)

    Kuntz, K. D.; Snowden, S. I.; Mushotzky, R. F.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    Three observational constraints can be placed on a warm-hot intergalactic medium (WHIM) using ROSAT Position Sensitive Proportional Counter (PSPC) pointed and survey data, the emission strength, the energy spectrum, and the fluctuation spectrum. The upper limit to the emission strength of the WHIM is 7.5 +/- 1.0 keV/(s*sq cm*sr*keV) in the 3/4 keV band, an unknown portion of which value may be due to our own Galactic halo. The spectral stape of the WHIM emission can be described as thermal emission with logT = 6.42, although the true spectrum is more likely to come from a range of temperatures. The values of emission strength and spectral shape are in reasonable agreement with hydrodynamical cosmological models. The autocorrelation function in the 0.44 keV < E < 1.21 keV band range, w(theta), for the extragalactic soft X-ray background (SXRB) which includes both the WHIM and contributions due to point sources, is approx. < 0.002 for 10 min < 0 < 20 min in the 3/4 keV band. This value is lower than the Croft et al. (2000) cosmological model by a factor of approx. 5, but is still not inconsistent with cosmological models. It is also found that the normalization of the extragalactic power law component of the soft X-ray background spectrum must be 9.5 +/- 0.9 keV/(s*sq cm*sr*keV) to be consistent with the ROSAT All-Sky Survey.

  13. The Temperature-Density Relation in the Intergalactic Medium at Redshift langzrang = 2.4

    NASA Astrophysics Data System (ADS)

    Rudie, Gwen C.; Steidel, Charles C.; Pettini, Max

    2012-10-01

    We present new measurements of the temperature-density (T-ρ) relation for neutral hydrogen in the 2.0 < z < 2.8 intergalactic medium (IGM) using a sample of ~6000 individual H I absorbers fitted with Voigt profiles constrained in all cases by multiple Lyman series transitions. We find model-independent evidence for a positive correlation between the column density of H I (N H I ) and the minimum observed velocity width of absorbers (b min). With minimal interpretation, this implies that the T-ρ relation in the IGM is not "inverted," contrary to many recent studies. Fitting b min as a function of N H I results in line-width-column-density dependence of the form b min = b 0(N H I /N H I,0)Γ-1 with a minimum line width at mean density (\\rho /\\bar{\\rho }= 1, N_H\\,\\mathsc{i, 0} = 10^{13.6} cm-2) of b 0 = 17.9 ± 0.2 km s-1 and a power-law index of (Γ - 1) = 0.15 ± 0.02. Using analytic arguments, these measurements imply an "equation of state" for the IGM at langzrang = 2.4 of the form T=T_0 \\left(\\rho /\\bar{\\rho }\\right)^{\\gamma -1} with a temperature at mean density of T 0 = [1.94 ± 0.05] × 104 K and a power-law index (γ - 1) = 0.46 ± 0.05. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W. M. Keck Foundation.

  14. Thermal Sunyaev-Zel'dovich effect in the intergalactic medium with primordial magnetic fields

    NASA Astrophysics Data System (ADS)

    Minoda, Teppei; Hasegawa, Kenji; Tashiro, Hiroyuki; Ichiki, Kiyotomo; Sugiyama, Naoshi

    2017-12-01

    The presence of ubiquitous magnetic fields in the universe is suggested from observations of radiation and cosmic ray from galaxies or the intergalactic medium (IGM). One possible origin of cosmic magnetic fields is the magnetogenesis in the primordial universe. Such magnetic fields are called primordial magnetic fields (PMFs), and are considered to affect the evolution of matter density fluctuations and the thermal history of the IGM gas. Hence the information of PMFs is expected to be imprinted on the anisotropies of the cosmic microwave background (CMB) through the thermal Sunyaev-Zel'dovich (tSZ) effect in the IGM. In this study, given an initial power spectrum of PMFs as P (k )∝B1Mpc 2knB , we calculate dynamical and thermal evolutions of the IGM under the influence of PMFs, and compute the resultant angular power spectrum of the Compton y -parameter on the sky. As a result, we find that two physical processes driven by PMFs dominantly determine the power spectrum of the Compton y -parameter; (i) the heating due to the ambipolar diffusion effectively works to increase the temperature and the ionization fraction, and (ii) the Lorentz force drastically enhances the density contrast on small scale just after the recombination epoch. These facts result in making the anisotropies of the CMB temperature on small scales, and we find that the signal goes up to 10 μ K2 around ℓ˜106 with B1 Mpc=0.1 nG and nB=0.0 . Therefore, CMB measurements on such small scales may provide a hint for the existence of the PMFs.

  15. PAPER-64 Constraints On Reionization. II. The Temperature of the z =8.4 Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Pober, Jonathan C.; Ali, Zaki S.; Parsons, Aaron R.; McQuinn, Matthew; Aguirre, James E.; Bernardi, Gianni; Bradley, Richard F.; Carilli, Chris L.; Cheng, Carina; DeBoer, David R.; Dexter, Matthew R.; Furlanetto, Steven R.; Grobbelaar, Jasper; Horrell, Jasper; Jacobs, Daniel C.; Klima, Patricia J.; Kohn, Saul A.; Liu, Adrian; MacMahon, David H. E.; Maree, Matthys; Mesinger, Andrei; Moore, David F.; Razavi-Ghods, Nima; Stefan, Irina I.; Walbrugh, William P.; Walker, Andre; Zheng, Haoxuan

    2015-08-01

    We present constraints on both the kinetic temperature of the intergalactic medium (IGM) at z = 8.4, and on models for heating the IGM at high-redshift with X-ray emission from the first collapsed objects. These constraints are derived using a semi-analytic method to explore the new measurements of the 21 cm power spectrum from the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER), which were presented in a companion paper, Ali et al. Twenty-one cm power spectra with amplitudes of hundreds of mK2 can be generically produced if the kinetic temperature of the IGM is significantly below the temperature of the cosmic microwave background (CMB); as such, the new results from PAPER place lower limits on the IGM temperature at z = 8.4. Allowing for the unknown ionization state of the IGM, our measurements find the IGM temperature to be above ≈5 K for neutral fractions between 10% and 85%, above ≈7 K for neutral fractions between 15% and 80%, or above ≈10 K for neutral fractions between 30% and 70%. We also calculate the heating of the IGM that would be provided by the observed high redshift galaxy population, and find that for most models, these galaxies are sufficient to bring the IGM temperature above our lower limits. However, there are significant ranges of parameter space that could produce a signal ruled out by the PAPER measurements; models with a steep drop-off in the star formation rate density at high redshifts or with relatively low values for the X-ray to star formation rate efficiency of high redshift galaxies are generally disfavored. The PAPER measurements are consistent with (but do not constrain) a hydrogen spin temperature above the CMB temperature, a situation which we find to be generally predicted if galaxies fainter than the current detection limits of optical/NIR surveys are included in calculations of X-ray heating.

  16. PAPER-64 CONSTRAINTS ON REIONIZATION. II. THE TEMPERATURE OF THE z = 8.4 INTERGALACTIC MEDIUM

    SciTech Connect

    Pober, Jonathan C.; Ali, Zaki S.; Parsons, Aaron R.

    We present constraints on both the kinetic temperature of the intergalactic medium (IGM) at z = 8.4, and on models for heating the IGM at high-redshift with X-ray emission from the first collapsed objects. These constraints are derived using a semi-analytic method to explore the new measurements of the 21 cm power spectrum from the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER), which were presented in a companion paper, Ali et al. Twenty-one cm power spectra with amplitudes of hundreds of mK{sup 2} can be generically produced if the kinetic temperature of the IGM ismore » significantly below the temperature of the cosmic microwave background (CMB); as such, the new results from PAPER place lower limits on the IGM temperature at z = 8.4. Allowing for the unknown ionization state of the IGM, our measurements find the IGM temperature to be above ≈5 K for neutral fractions between 10% and 85%, above ≈7 K for neutral fractions between 15% and 80%, or above ≈10 K for neutral fractions between 30% and 70%. We also calculate the heating of the IGM that would be provided by the observed high redshift galaxy population, and find that for most models, these galaxies are sufficient to bring the IGM temperature above our lower limits. However, there are significant ranges of parameter space that could produce a signal ruled out by the PAPER measurements; models with a steep drop-off in the star formation rate density at high redshifts or with relatively low values for the X-ray to star formation rate efficiency of high redshift galaxies are generally disfavored. The PAPER measurements are consistent with (but do not constrain) a hydrogen spin temperature above the CMB temperature, a situation which we find to be generally predicted if galaxies fainter than the current detection limits of optical/NIR surveys are included in calculations of X-ray heating.« less

  17. Tracing the Cosmic Metal Evolution in the Low-redshift Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Shull, J. Michael; Danforth, Charles W.; Tilton, Evan M.

    2014-11-01

    Using the Cosmic Origins Spectrograph aboard the Hubble Space Telescope, we measured the abundances of six ions (C III, C IV, Si III, Si IV, N V, and O VI) in the low-redshift (z <= 0.4) intergalactic medium (IGM). Both C IV and Si IV have increased in abundance by a factor of ~10 from z ≈ 5.5 to the present. We derive ion mass densities, ρion ≡ Ωionρcr, with Ωion expressed relative to the closure density. Our models of mass-abundance ratios, (Si III/Si IV) = 0.67+0.35-0.19, (C III/C IV) = 0.70+0.43-0.20, and (Ω C \\scriptsize{III} + Ω C \\scriptsize{IV}) / (Ω _Si \\scriptsize{III} + Ω _Si \\scriptsize{IV}) = 4.9+2.2-1.1, are consistent with the photoionization parameter log U = -1.5 ± 0.4, hydrogen photoionization rate ΓH = (8 ± 2) × 10-14 s-1 at z < 0.4, and specific intensity I 0 = (3 ± 1) × 10-23 erg cm-2 s-1 Hz-1 sr-1 at the Lyman limit. Consistent ionization corrections for C and Si are scaled to an ionizing photon flux Φ0 = 104 cm-2 s-1, baryon overdensity Δ b ≈ 200 ± 50, and "alpha-enhancement" (Si/C enhanced to three times its solar ratio). We compare these metal abundances to the expected IGM enrichment and abundances in higher photoionized states of carbon (C V) and silicon (Si V, Si VI, and Si VII). Our ionization modeling infers IGM metal densities of (5.4 ± 0.5) × 105 M ⊙ Mpc-3 in the photoionized Lyα forest traced by the C and Si ions and (9.1 ± 0.6) × 105 M ⊙ Mpc-3 in hotter gas traced by O VI. Combining both phases, the heavy elements in the IGM have mass density ρ Z = (1.5 ± 0.8) × 106 M ⊙ Mpc-3 or Ω Z ≈ 10-5. This represents 10% ± 5% of the metals produced by (6 ± 2) × 108 M ⊙ Mpc-3 of integrated star formation with yield ym = 0.025 ± 0.010. The missing metals at low redshift may reside within galaxies and in undetected ionized gas in galactic halos and circumgalactic medium. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope

  18. 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

  19. Probing the chemical composition of the Z < 1 intergalactic medium with observations and simulations

    NASA Astrophysics Data System (ADS)

    Cooksey, Kathy L.

    2009-09-01

    Metals are produced in the stars in the galaxies, and a variety of feedback processes move metals from the sites of production into the intergalactic medium (IGM), enriching the material for future generations of stars. The signature of this process is etched in the recycled gas: its metallicity, elemental abundances, density, distribution, etc. The study of the low- redshift, z <, IGM is the study of the last eight-billion years of cosmic chemical evolution and all prior enrichment. In this thesis, I characterize the cosmic enrichment cycle with the use of observations and simulations. The gas is observed through quasar absorption- line spectroscopy. As the light of a distant quasar travels to us, intervening clouds of gas absorb the light at wavelengths characteristic, albeit redshifted, of the elements in the clouds. By identifying and modeling the elements associated with the absorption systems, I learn the ionic composition and density of the cosmic web (voids, filaments, and/or groups) along the line of sight. >From a detailed study of a single sightline, I observe a multi-phase IGM, with kinematically-distinct, hot and warm components ( T [approximate] 10 5.5 K and 10 4 K, respectively). By correlating the absorption systems with a complementary galaxy survey of the field around the background quasar, I find that the IGM systems arise in a variety of galactic environments. The metal- lines systems all have L > 0.1 L [low *] galaxies within a few hundred kiloparsecs, which suggests this is the distance to which galactic feedback processes typically disperse metals. I conduct a large, blind survey for triply-ionized carbon (C IV) absorption at z < 1 in the spectra of 49 low-redshift quasars and compare their propertie with those detected at z > 1. The mass density in C IV doublets with 13 < = log N (C +3 ) <= 15 at z < 1 has increased by a factor of 2.8 ± 0.7 over the error- weighted mean of the 1.5 < z < 5 measurements, where the mass density has not evolved

  20. Probing the Metal Enrichment of the Intergalactic Medium at z = 5-6 Using the Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Cai, Zheng; Fan, Xiaohui; Dave, Romeel; Finlator, Kristian; Oppenheimer, Ben

    2017-11-01

    We test the galactic outflow model by probing associated galaxies of four strong intergalactic C IV absorbers at z = 5-6 using the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) ramp narrowband filters. The four strong C IV absorbers reside at z = 5.74, 5.52, 4.95, and 4.87, with column densities ranging from N C IV = 1013.8 to 1014.8 cm-2. At z = 5.74, we detect an I-dropout Lyα emitter (LAE) candidate with a projected impact parameter of 42 physical kpc from the C IV absorber. This LAE candidate has a Lyα-based star formation rate (SFRLyα ) of 2 M ⊙ yr-1 and a UV-based SFR of 4 M ⊙ yr-1. Although we cannot completely rule out that this I-dropout emitter may be an [O II] interloper, its measured properties are consistent with the C IV powered galaxy at z = 5.74. For C IV absorbers at z = 4.95 and z = 4.87, although we detect two LAE candidates with impact parameters of 160 and 200 kpc, such distances are larger than that predicted from the simulations. Therefore, we treat them as nondetections. For the system at z = 5.52, we do not detect LAE candidates, placing a 3σ upper limit of SFRLyα ≈ 1.5 M ⊙ yr-1. In summary, in these four cases, we only detect one plausible C IV source at z = 5.74. Combining the modest SFR of the one detection and the three nondetections, our HST observations strongly support that smaller galaxies (SFRLyα ≲ 2 M ⊙ yr-1) are main sources of intergalactic C IV absorbers, and such small galaxies play a major role in the metal enrichment of the intergalactic medium at z ≳ 5.

  1. A census of Hα emitters in the intergalactic medium of the NGC 2865 system

    NASA Astrophysics Data System (ADS)

    Urrutia-Viscarra, F.; Arnaboldi, M.; Mendes de Oliveira, C.; Gerhard, O.; Torres-Flores, S.; Carrasco, E. R.; de Mello, D.

    2014-09-01

    Tidal debris, which are rich in HI gas and formed in interacting and merging systems, are suitable laboratories to study star formation outside galaxies. Recently, several such systems were observed, which contained many young star forming regions outside the galaxies. In previous works, we have studied young star forming regions outside galaxies in different systems with optical and/or gaseous tidal debris, in order to understand how often they occur and in which type of environments. In this paper, we searched for star forming regions around the galaxy NGC 2865, a shell galaxy that is circled by a ring of HI with a total mass of 1.2 × 109 M⊙. Using the multi-slit imaging spectroscopy technique with the Gemini telescope, we detected all Hα emitting sources in the surroundings of the galaxy NGC 2865, down to a flux limit of 10-18 erg cm-2 s-1 Å-1. With the spectra information and the near and far-ultraviolet flux, we characterize the star formation rates, masses, ages, and metallicities for these HII regions. In total, we found 26 emission-line sources in a 60 × 60 Kpc field centered over the southeastern tail of the HI gas present around the galaxy NGC 2865. Out of the 26 Hα emitters, 19 are in the satellite galaxy FGCE 0745, and seven are intergalactic HII regions scattered over the south tail of the HI gas around NGC 2865. We found that the intergalactic HII regions are young (<200 Myr) with stellar masses in the range 4 × 103 M⊙ to 17 × 106 M⊙. These are found in a region of low HI gas density, where the probability of forming stars is expected to be low. For one of the intergalactic HII regions, we estimated a solar oxygen abundance of 12 + log(O/H) ~ 8.7. We also were able to estimate the metallicity for the satellite galaxy FGCE 0745 to be 12 + log(O/H) ~ 8.0. Given these physical parameters, the intergalactic HII regions are consistent with young star forming regions (or clusters), which are born in situ outside the NGC 2865 galaxy from a pre

  2. The Spread of Metals into the Low-redshift Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Pratt, Cameron T.; Stocke, John T.; Keeney, Brian A.; Danforth, Charles W.

    2018-03-01

    We investigate the association between galaxies and metal-enriched and metal-deficient absorbers in the local universe (z < 0.16) using a large compilation of far-ultraviolet spectra of bright active galactic nuclei targets observed with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope. In this homogeneous sample of 18 O VI detections at {N}{{O}{{VI}}}≥slant 13.5 {cm}}-2 and 18 nondetections at {N}{{O}{{VI}}}< 13.5 {cm}}-2 using {Ly}α absorbers with {N}{{H}{{I}}}≥slant {10}14 {cm}}-2, the maximum distance O VI extends from galaxies of various luminosities is ∼0.6 Mpc, or ∼5 virial radii, confirming and refining earlier results. This is an important value that must be matched by numerical simulations, which input the strength of galactic winds at the sub-grid level. We present evidence that the primary contributors to the spread of metals into the circum- and intergalactic media are sub-L* galaxies (0.25{L}* < L< {L}* ). The maximum distances that metals are transported from these galaxies is comparable to, or less than, the size of a group of galaxies. These results suggest that, where groups are present, the metals produced by the group galaxies do not leave the group. Since many O VI nondetections in our sample occur at comparably close impact parameters as those of the metal-bearing absorbers, some more pristine intergalactic material appears to be accreting onto groups where it can mix with metal-bearing clouds.

  3. Probing the Metal Enrichment of the Intergalactic Medium at z = 5–6 Using the Hubble Space Telescope

    SciTech Connect

    Cai, Zheng; Fan, Xiaohui; Dave, Romeel

    We test the galactic outflow model by probing associated galaxies of four strong intergalactic C iv absorbers at z = 5–6 using the Hubble Space Telescope ( HST ) Advanced Camera for Surveys (ACS) ramp narrowband filters. The four strong C iv absorbers reside at z = 5.74, 5.52, 4.95, and 4.87, with column densities ranging from N {sub Civ} = 10{sup 13.8} to 10{sup 14.8} cm{sup −2}. At z = 5.74, we detect an i-dropout Ly α emitter (LAE) candidate with a projected impact parameter of 42 physical kpc from the C iv absorber. This LAE candidate has amore » Ly α -based star formation rate (SFR{sub Lyα} ) of 2 M {sub ⊙} yr{sup −1} and a UV-based SFR of 4 M {sub ⊙} yr{sup −1}. Although we cannot completely rule out that this i-dropout emitter may be an [O ii] interloper, its measured properties are consistent with the C iv powered galaxy at z = 5.74. For C iv absorbers at z = 4.95 and z = 4.87, although we detect two LAE candidates with impact parameters of 160 and 200 kpc, such distances are larger than that predicted from the simulations. Therefore, we treat them as nondetections. For the system at z = 5.52, we do not detect LAE candidates, placing a 3 σ upper limit of SFR{sub Lyα} ≈ 1.5 M {sub ⊙} yr{sup −1}. In summary, in these four cases, we only detect one plausible C iv source at z = 5.74. Combining the modest SFR of the one detection and the three nondetections, our HST observations strongly support that smaller galaxies (SFR{sub Lyα} ≲ 2 M {sub ⊙} yr{sup −1}) are main sources of intergalactic C iv absorbers, and such small galaxies play a major role in the metal enrichment of the intergalactic medium at z ≳ 5.« less

  4. Enrichment of intergalactic matter.

    NASA Technical Reports Server (NTRS)

    Silk, J.; Siluk, R. S.

    1972-01-01

    The primordial gas out of which the Galaxy condensed may have been significantly enriched in heavy elements. A specific mechanism of enrichment is described, in which quasi-stellar sources eject enriched matter into the intergalactic medium. This matter is recycled through successive generations of these sources, and is progressively enriched. The enriched intergalactic matter is accreted by the protogalaxy and we find, for rates of mass ejection by quasi-stellar sources equal to about one solar mass per year in heavy elements, that this mechanism can account for the heavy-element abundances in the oldest Population II stars. Expressions are given for the degree of enrichment of the intergalactic gas as a function of redshift, and we show that our hypothesis implies that the present density of intergalactic gas must be at least a factor 3 larger than the mean density in galaxies at the present epoch.

  5. Characterization of the warm-hot intergalactic medium near the Coma cluster through high-resolution spectroscopy of X Comae

    NASA Astrophysics Data System (ADS)

    Bonamente, M.; Ahoranta, J.; Tilton, E.; Tempel, E.; Morandi, A.

    2017-08-01

    We have analysed all available archival XMM-Newton observations of X Comae, a bright X-ray quasar behind the Coma cluster, to study the properties of the warm-hot intergalactic medium (WHIM) in the vicinity of the nearest massive galaxy cluster. The reflection grating spectrometer observations confirm the possible presence of a Ne ix K α absorption line at the redshift of Coma, although with a limited statistical significance. This analysis is therefore in line with the earlier analysis by Takei et al. based on a sub-set of these data. Its large column density and optical depth, however, point to implausible conditions for the absorbing medium, thereby casting serious doubts to its reality. Chandra has never observed X Comae and therefore cannot provide additional information on this source. We combine upper limits to the presence of other X-ray absorption lines (notably from O vii and O viii) at the redshift of Coma with positive measurements of the soft excess emission from Coma measured by ROSAT (Bonamente et al.). The combination of emission from warm-hot gas at kT ˜ 1/4 keV and upper limits from absorption lines provide useful constraints on the density and the sightline length of the putative WHIM towards Coma. We conclude that the putative warm-hot medium towards Coma is consistent with expected properties, with a baryon overdensity δb ≥ 10 and a sightline extent of order of tens of Mpc.

  6. 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.

  7. X-Ray Scattering Echoes and Ghost Halos from the Intergalactic Medium: Relation to the Nature of AGN Variability

    NASA Astrophysics Data System (ADS)

    Corrales, Lia

    2015-05-01

    X-ray bright quasars might be used to trace dust in the circumgalactic and intergalactic medium through the phenomenon of X-ray scattering, which is observed around Galactic objects whose light passes through a sufficient column of interstellar gas and dust. Of particular interest is the abundance of gray dust larger than 0.1 μ m, which is difficult to detect at other wavelengths. To calculate X-ray scattering from large grains, one must abandon the traditional Rayleigh-Gans approximation. The Mie solution for the X-ray scattering optical depth of the universe is ∼ 1%. This presents a great difficulty for distinguishing dust scattered photons from the point source image of Chandra, which is currently unsurpassed in imaging resolution. The variable nature of AGNs offers a solution to this problem, as scattered light takes a longer path and thus experiences a time delay with respect to non-scattered light. If an AGN dims significantly (≳ 3 dex) due to a major feedback event, the Chandra point source image will be suppressed relative to the scattering halo, and an X-ray echo or ghost halo may become visible. I estimate the total number of scattering echoes visible by Chandra over the entire sky: {{N}ech}∼ {{10}3}({{ν }fb}/y{{r}-1}), where {{ν }fb} is the characteristic frequency of feedback events capable of dimming an AGN quickly.

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

    NASA Astrophysics Data System (ADS)

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

    1988-11-01

    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 omega0 = 1 and h = 0.5 was considered (here h = H0 bar 100/kms/Mpc and H0 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.

  9. On the deuterium abundance and the importance of stellar mass loss in the interstellar and intergalactic medium

    NASA Astrophysics Data System (ADS)

    van de Voort, Freeke; Quataert, Eliot; Faucher-Giguère, Claude-André; Kereš, Dušan; Hopkins, Philip F.; Chan, T. K.; Feldmann, Robert; Hafen, Zachary

    2018-06-01

    We quantify the gas-phase abundance of deuterium and fractional contribution of stellar mass loss to the gas in cosmological zoom-in simulations from the Feedback In Realistic Environments project. At low metallicity, our simulations confirm that the deuterium abundance is very close to the primordial value. The chemical evolution of the deuterium abundance that we derive here agrees quantitatively with analytical chemical evolution models. We furthermore find that the relation between the deuterium and oxygen abundance exhibits very little scatter. We compare our simulations to existing high-redshift observations in order to determine a primordial deuterium fraction of (2.549 ± 0.033) × 10-5 and stress that future observations at higher metallicity can also be used to constrain this value. At fixed metallicity, the deuterium fraction decreases slightly with decreasing redshift, due to the increased importance of mass-loss from intermediate-mass stars. We find that the evolution of the average deuterium fraction in a galaxy correlates with its star formation history. Our simulations are consistent with observations of the Milky Way's interstellar medium (ISM): the deuterium fraction at the solar circle is 85-92 per cent of the primordial deuterium fraction. We use our simulations to make predictions for future observations. In particular, the deuterium abundance is lower at smaller galactocentric radii and in higher mass galaxies, showing that stellar mass loss is more important for fuelling star formation in these regimes (and can even dominate). Gas accreting on to galaxies has a deuterium fraction above that of the galaxies' ISM, but below the primordial fraction, because it is a mix of gas accreting from the intergalactic medium and gas previously ejected or stripped from galaxies.

  10. The Dispersion of Fast Radio Bursts from a Structured Intergalactic Medium at Redshifts z < 1.5

    NASA Astrophysics Data System (ADS)

    Shull, J. Michael; Danforth, Charles W.

    2018-01-01

    We analyze the sources of free electrons that produce the large dispersion measures, {DM}≈ 300{--}1600 (in units of cm‑3 pc), observed toward fast radio bursts (FRBs). Individual galaxies typically produce {DM}∼ 25{--}60 {{cm}}-3 {pc} from ionized gas in their disk, disk-halo interface, and circumgalactic medium. Toward an FRB source at redshift z, a homogeneous intergalactic medium (IGM) containing a fraction {f}{IGM} of cosmological baryons will produce {DM}=(935 {{cm}}-3 {pc}){f}{IGM} {h}70-1I(z), where I{(z)=(2/3{{{Ω }}}m)[\\{{{{Ω }}}m(1+z)}3+{{{Ω }}}{{Λ }}\\}{}1/2-1]. A structured IGM of photoionized Lyα absorbers in the cosmic web produces similar dispersion, modeled from the observed distribution, {f}b(N,z), of H I (Lyα-forest) absorbers in column density and redshift with ionization corrections and scaling relations from cosmological simulations. An analytic formula for DM(z) applied to observed FRB dispersions suggests that {z}{FRB}≈ 0.2{--}1.5 for an IGM containing a significant baryon fraction, {f}{IGM}=0.6+/- 0.1. Future surveys of the statistical distribution, DM(z), of FRBs identified with specific galaxies and redshifts can be used to calibrate the IGM baryon fraction and distribution of Lyα absorbers. Fluctuations in DM at the level ±10 cm‑3 pc will arise from filaments and voids in the cosmic web.

  11. The evolution of cooling flows. I - Self-similar cluster flows. [of gas in intergalactic medium

    NASA Technical Reports Server (NTRS)

    Chevalier, Roger A.

    1987-01-01

    The evolution of a cooling flow from an initial state of hydrostatic equilibrium in a cluster of galaxies is investigated. After gas mass and energy are injected into the cluster at an early phase, the gas approaches hydrostatic equilibrium over most of the cluster and cooling becomes important in the dense central regions. As time passes, cooling strongly affects an increasing amount of gas. The effects of mass removal from the flow, the inclusion of magnetic or cosmic-ray pressure, and heat conduction are considered individually.

  12. The faint intergalactic-medium red-shifted emission balloon: future UV observations with EMCCDs

    NASA Astrophysics Data System (ADS)

    Kyne, Gillian; Hamden, Erika T.; Lingner, Nicole; Morrissey, Patrick; Nikzad, Shouleh; Martin, D. Christopher

    2016-08-01

    We present the latest developments in our joint NASA/CNES suborbital project. This project is a balloon-borne UV multi-object spectrograph, which has been designed to detect faint emission from the circumgalactic medium (CGM) around low redshift galaxies. One major change from FIREBall-1 has been the use of a delta-doped Electron Multiplying CCD (EMCCD). EMCCDs can be used in photon-counting (PC) mode to achieve extremely low readout noise (¡ 1e-). Our testing initially focused on reducing clock-induced-charge (CIC) through wave shaping and well depth optimisation with the CCD Controller for Counting Photons (CCCP) from Nüvü. This optimisation also includes methods for reducing dark current, via cooling and substrate voltage adjustment. We present result of laboratory noise measurements including dark current. Furthermore, we will briefly present some initial results from our first set of on-sky observations using a delta-doped EMCCD on the 200 inch telescope at Palomar using the Palomar Cosmic Web Imager (PCWI).

  13. Constraints on the Sunyaev-Zel'dovich signal from the warm-hot intergalactic medium from WMAP and SPT data

    NASA Astrophysics Data System (ADS)

    Génova-Santos, Ricardo; Suárez-Velásquez, I.; Atrio-Barandela, F.; Mücket, J. P.

    2013-07-01

    The fraction of ionized gas in the warm-hot intergalactic medium induces temperature anisotropies on the cosmic microwave background similar to those of clusters of galaxies. The Sunyaev-Zel'dovich (SZ) anisotropies due to these low-density, weakly non-linear, baryon filaments cannot be distinguished from that of clusters using frequency information, but they can be separated since their angular scales are very different. To determine the relative contribution of the WHIM SZ signal to the radiation power spectrum of temperature anisotropies, we explore the parameter space of the concordance Λ cold dark matter model using Monte Carlo Markov chains and the Wilkinson Microwave Anisotropy Probe 7 yr and South Pole Telescope data. We find marginal evidence of a contribution by diffuse gas, with amplitudes of AWHIM = 10-20 μK2, but the results are also compatible with a null contribution from the WHIM, allowing us to set an upper limit of AWHIM < 43 μK2 (95.4 per cent CL). The signal produced by galaxy clusters remains at ACL = 4.5 μK2, a value similar to what is obtained when no WHIM is included. From the measured WHIM amplitude, we constrain the temperature-density phase diagram of the diffuse gas, and find it to be compatible with numerical simulations. The corresponding baryon fraction in the WHIM varies from 0.43 to 0.47, depending on model parameters. The forthcoming Planck data could set tighter constraints on the temperature-density relation.

  14. The concerted impact of galaxies and QSOs on the ionization and thermal state of the intergalactic medium

    NASA Astrophysics Data System (ADS)

    Kakiichi, Koki; Graziani, Luca; Ciardi, Benedetta; Meiksin, Avery; Compostella, Michele; Eide, Marius B.; Zaroubi, Saleem

    2017-07-01

    We present a detailed analysis of the ionization and thermal structure of the intergalactic medium (IGM) around a high-redshift (z = 10) QSO, using a large suite of cosmological, multifrequency radiative transfer simulations, exploring the contribution from galaxies as well as the QSO, and the effect of X-rays and secondary ionization. We show that in high-z QSO environments both the central QSO and the surrounding galaxies concertedly control the reionization morphology of hydrogen and helium and have a non-linear impact on the thermal structure of the IGM. A QSO imprints a distinctive morphology on H II regions if its total ionizing photon budget exceeds that of the surrounding galaxies since the onset of hydrogen reionization; otherwise, the morphology shows little difference from that of H II regions produced only by galaxies. In addition, the spectral shape of the collective radiation field from galaxies and QSOs controls the thickness of the I-fronts. While a UV-obscured QSO can broaden the I-front, the contribution from other UV sources, either galaxies or unobscured QSOs, is sufficient to maintain a sharp I-front. X-ray photons from the QSO are responsible for a prominent extended tail of partial ionization ahead of the I-front. QSOs leave a unique imprint on the morphology of He II/He III regions. We suggest that, while the physical state of the IGM is modified by QSOs, the most direct test to understand the role of galaxies and QSOs during reionization is to perform galaxy surveys in a region of sky imaged by 21 cm tomography.

  15. Filling the Void: A Comprehensive Survey of the Intergalactic Medium at z 1 Using STIS/COS Archival Spectra

    NASA Astrophysics Data System (ADS)

    Khaire, Vikram

    2017-08-01

    There exists a large void in our understanding of the intergalactic medium (IGM) at z=0.5-1.5, spanning a significant cosmic time of 4 Gyr. This hole resulted from a paucity of near-UV QSO spectra, which were historically very expensive to obtain. However, with the advent of COS and the HST UV initiative, sufficient STIS/COS NUV spectra have finally become available, enabling the first statistical analyses. We propose a comprehensive study of the z 1 IGM using the Ly-alpha forest of 26 archival QSO spectra. This analysis will: (1) measure the distribution of HI absorbers to several percent precision down to log NHI < 13 to test our model of the IGM, and determine the extragalactic UV background (UVB) at that epoch; (2) measure the Ly-alpha forest power spectrum to 12%, providing another precision test of LCDM and our theory of the IGM; (3) measure the thermal state of the IGM, which reflects the balance of heating (photoheating, HI/HeII reionization) and cooling (Hubble expansion) of cosmic baryons, and directly verify the predicted cooldown of IGM gas after reionization for the first time; (4) generate high-quality reductions, coadds, and continuum fits that will be released to the public to enable other science cases. These results, along with our state-of-the-art hydrodynamical simulations, and theoretical models of the UVB, will fill the 4 Gyr hole in our understanding of the IGM. When combined with existing HST and ground-based data from lower and higher z, they will lead to a complete, empirical description of the IGM from HI reionization to the present, spanning more than 10 Gyr of cosmic history, adding substantially to Hubble's legacy of discovery on the IGM.

  16. An HST/COS Survey of the Low-redshift Intergalactic Medium. I. Survey, Methodology, and Overall Results

    NASA Astrophysics Data System (ADS)

    Danforth, Charles W.; Keeney, Brian A.; Tilton, Evan M.; Shull, J. Michael; Stocke, John T.; Stevans, Matthew; Pieri, Matthew M.; Savage, Blair D.; France, Kevin; Syphers, David; Smith, Britton D.; Green, James C.; Froning, Cynthia; Penton, Steven V.; Osterman, Steven N.

    2016-02-01

    We use high-quality, medium-resolution Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) observations of 82 UV-bright active galactic nuclei (AGNs) at redshifts zAGN < 0.85 to construct the largest survey of the low-redshift intergalactic medium (IGM) to date: 5138 individual extragalactic absorption lines in H I and 25 different metal-ion species grouped into 2611 distinct redshift systems at zabs < 0.75 covering total redshift pathlengths ΔzH I = 21.7 and ΔzO VI = 14.5. Our semi-automated line-finding and measurement technique renders the catalog as objectively defined as possible. The cumulative column density distribution of H I systems can be parametrized d{ N }(\\gt N)/{dz} = {C}14{(N/{10}14{{cm}}-2)}-(β -1), with C14 = 25 ± 1 and β = 1.65 ± 0.02. This distribution is seen to evolve both in amplitude, {C}14\\propto {(1+z)}2.3+/- 0.1, and slope β(z) = 1.75-0.31 z for z ≤ 0.47. We observe metal lines in 418 systems, and find that the fraction of IGM absorbers detected in metals is strongly dependent on {N}{{H}{{I}}}. The distribution of O VI absorbers appears to evolve in the same sense as the Lyα forest. We calculate contributions to Ωb from different components of the low-z IGM and determine the Lyα decrement as a function of redshift. IGM absorbers are analyzed via a two-point correlation function in velocity space. We find substantial clustering of H I absorbers on scales of Δv = 50-300 km s-1 with no significant clustering at Δv ≳ 1000 km s-1. Splitting the sample into strong and weak absorbers, we see that most of the clustering occurs in strong, NH I ≳ 1013.5 cm-2, metal-bearing IGM systems. The full catalog of absorption lines and fully reduced spectra is available via the Mikulski Archive for Space Telescopes (MAST) as a high-level science product at http://archive.stsci.edu/prepds/igm/. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science

  17. THE COLUMN DENSITY DISTRIBUTION AND CONTINUUM OPACITY OF THE INTERGALACTIC AND CIRCUMGALACTIC MEDIUM AT REDSHIFT (z) = 2.4

    SciTech Connect

    Rudie, Gwen C.; Steidel, Charles C.; Shapley, Alice E.

    2013-06-01

    We present new high-precision measurements of the opacity of the intergalactic and circumgalactic medium (IGM; CGM) at (z) = 2.4. Using Voigt profile fits to the full Ly{alpha} and Ly{beta} forests in 15 high-resolution high-S/N spectra of hyperluminous QSOs, we make the first statistically robust measurement of the frequency of absorbers with H I column densities 14{approx}< log (N{sub H{sub I}}/cm{sup -2}){approx}<17.2. We also present the first measurements of the frequency distribution of H I absorbers in the volume surrounding high-z galaxies (the CGM, 300 pkpc), finding that the incidence of absorbers in the CGM is much higher than inmore » the IGM. In agreement with Rudie et al., we find that there are fractionally more high-N{sub H{sub I}} absorbers than low-N{sub H{sub I}} absorbers in the CGM compared to the IGM, leading to a shallower power law fit to the CGM frequency distribution. We use these new measurements to calculate the total opacity of the IGM and CGM to hydrogen-ionizing photons, finding significantly higher opacity than most previous studies, especially from absorbers with log (N{sub H{sub I}}/cm{sup -2}) < 17.2. Reproducing the opacity measured in our data as well as the incidence of absorbers with log (N{sub H{sub I}}/cm{sup -2})>17.2 requires a broken power law parameterization of the frequency distribution with a break near N{sub H{sub I}} Almost-Equal-To 10{sup 15} cm{sup -2}. We compute new estimates of the mean free path ({lambda}{sub mfp}) to hydrogen-ionizing photons at z{sub em} = 2.4, finding {lambda}{sub mfp} = 147 {+-} 15 Mpc when considering only IGM opacity. If instead, we consider photons emanating from a high-z star-forming galaxy and account for the local excess opacity due to the surrounding CGM of the galaxy itself, the mean free path is reduced to {lambda}{sub mfp} = 121 {+-} 15 Mpc. These {lambda}{sub mfp} measurements are smaller than recent estimates and should inform future studies of the metagalactic UV background

  18. The Cosmological Impact of Luminous TeV Blazars. II. Rewriting the Thermal History of the Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Chang, Philip; Broderick, Avery E.; Pfrommer, Christoph

    2012-06-01

    The universe is opaque to extragalactic very high energy gamma rays (VHEGRs, E > 100 GeV) because they annihilate and pair produce on the extragalactic background light. The resulting ultrarelativistic pairs are commonly assumed to lose energy primarily through inverse Compton scattering of cosmic microwave background (CMB) photons, reprocessing the original emission from TeV to GeV energies. In Broderick et al., we argued that this is not the case; powerful plasma instabilities driven by the highly anisotropic nature of the ultrarelativistic pair distribution provide a plausible way to dissipate the kinetic energy of the TeV-generated pairs locally, heating the intergalactic medium (IGM). Here, we explore the effect of this heating on the thermal history of the IGM. We collate the observed extragalactic VHEGR sources to determine a local VHEGR heating rate. Given the pointed nature of VHEGR observations, we estimate the correction for the various selection effects using Fermi observations of high- and intermediate-peaked BL Lac objects. As the extragalactic component of the local VHEGR flux is dominated by TeV blazars, we then estimate the evolution of the TeV blazar luminosity density by tying it to the well-observed quasar luminosity density and producing a VHEGR heating rate as a function of redshift. This heating is relatively homogeneous for z <~ 4, but there is greater spatial variation at higher redshift (order unity at z ~ 6) because of the reduced number of blazars that contribute to local heating. We show that this new heating process dominates photoheating in the low-redshift evolution of the IGM and calculate the effect of this heating in a one-zone model. As a consequence, the inclusion of TeV blazar heating qualitatively and quantitatively changes the structure and history of the IGM. Due to the homogeneous nature of the extragalactic background light, TeV blazars produce a uniform volumetric heating rate. This heating is sufficient to increase the

  19. The Column Density Distribution and Continuum Opacity of the Intergalactic and Circumgalactic Medium at Redshift langzrang = 2.4

    NASA Astrophysics Data System (ADS)

    Rudie, Gwen C.; Steidel, Charles C.; Shapley, Alice E.; Pettini, Max

    2013-06-01

    We present new high-precision measurements of the opacity of the intergalactic and circumgalactic medium (IGM; CGM) at langzrang = 2.4. Using Voigt profile fits to the full Lyα and Lyβ forests in 15 high-resolution high-S/N spectra of hyperluminous QSOs, we make the first statistically robust measurement of the frequency of absorbers with H I column densities 14 \\lesssim log (N_H\\,\\scriptsize{ I}/ {cm}^{-2}) \\lesssim 17.2. We also present the first measurements of the frequency distribution of H I absorbers in the volume surrounding high-z galaxies (the CGM, 300 pkpc), finding that the incidence of absorbers in the CGM is much higher than in the IGM. In agreement with Rudie et al., we find that there are fractionally more high-N H I absorbers than low-N H I absorbers in the CGM compared to the IGM, leading to a shallower power law fit to the CGM frequency distribution. We use these new measurements to calculate the total opacity of the IGM and CGM to hydrogen-ionizing photons, finding significantly higher opacity than most previous studies, especially from absorbers with log (N_H\\,\\scriptsize{ I}/ {cm}^{-2}) < 17.2. Reproducing the opacity measured in our data as well as the incidence of absorbers with log (N_H\\,\\scriptsize{ I}/ {cm}^{-2}) \\gt 17.2 requires a broken power law parameterization of the frequency distribution with a break near N H I ≈1015 cm-2. We compute new estimates of the mean free path (λmfp) to hydrogen-ionizing photons at z em = 2.4, finding λmfp = 147 ± 15 Mpc when considering only IGM opacity. If instead, we consider photons emanating from a high-z star-forming galaxy and account for the local excess opacity due to the surrounding CGM of the galaxy itself, the mean free path is reduced to λmfp = 121 ± 15 Mpc. These λmfp measurements are smaller than recent estimates and should inform future studies of the metagalactic UV background and of ionizing sources at z ≈ 2-3. Based on data obtained at the W. M. Keck Observatory

  20. 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.

  1. A New Method to Directly Measure the Jeans Scale of the Intergalactic Medium Using Close Quasar Pairs

    NASA Astrophysics Data System (ADS)

    Rorai, Alberto; Hennawi, Joseph F.; White, Martin

    2013-10-01

    Although the baryons in the intergalactic medium (IGM) trace dark matter fluctuations on megaparsec scales, on smaller scales ~100 kpc, fluctuations are suppressed because the finite temperature gas is pressure supported against gravity, analogous to the classical Jeans argument. This Jeans filtering scale, which quantifies the small-scale structure of the IGM, has fundamental cosmological implications. First, it provides a thermal record of heat injected by ultraviolet photons during cosmic reionization events, and thus constrains the thermal and reionization history of the universe. Second, the Jeans scale determines the clumpiness of the IGM, a critical ingredient in models of cosmic reionization. Third, it sets the minimum mass scale for gravitational collapse from the IGM, and hence plays a pivotal role in galaxy formation. Unfortunately, it is extremely challenging to measure the Jeans scale via the standard technique of analyzing purely longitudinal Lyα forest spectra, because the thermal Doppler broadening of absorption lines along the line-of-sight, is highly degenerate with Jeans smoothing. In this work, we show that the Jeans filtering scale can be directly measured by characterizing the coherence of correlated Lyα forest absorption in close quasar pairs, with separations small enough ~100 kpc to resolve it. We present a novel technique for this purpose, based on the probability density function (PDF) of phase angle differences of homologous longitudinal Fourier modes in close quasar pair spectra. A Bayesian formalism is introduced based on the phase angle PDF, and Markov Chain Monte Carlo techniques are used to characterize the precision of a hypothetical Jeans scale measurement, and explore degeneracies with other thermal parameters governing the IGM. A semi-analytical model of the Lyα forest is used to generate a large grid (500) of thermal models from a dark matter only simulation. Our full parameter study indicates that a realistic sample of only

  2. A NEW METHOD TO DIRECTLY MEASURE THE JEANS SCALE OF THE INTERGALACTIC MEDIUM USING CLOSE QUASAR PAIRS

    SciTech Connect

    Rorai, Alberto; Hennawi, Joseph F.; White, Martin

    2013-10-01

    Although the baryons in the intergalactic medium (IGM) trace dark matter fluctuations on megaparsec scales, on smaller scales ∼100 kpc, fluctuations are suppressed because the finite temperature gas is pressure supported against gravity, analogous to the classical Jeans argument. This Jeans filtering scale, which quantifies the small-scale structure of the IGM, has fundamental cosmological implications. First, it provides a thermal record of heat injected by ultraviolet photons during cosmic reionization events, and thus constrains the thermal and reionization history of the universe. Second, the Jeans scale determines the clumpiness of the IGM, a critical ingredient in models of cosmic reionization.more » Third, it sets the minimum mass scale for gravitational collapse from the IGM, and hence plays a pivotal role in galaxy formation. Unfortunately, it is extremely challenging to measure the Jeans scale via the standard technique of analyzing purely longitudinal Lyα forest spectra, because the thermal Doppler broadening of absorption lines along the line-of-sight, is highly degenerate with Jeans smoothing. In this work, we show that the Jeans filtering scale can be directly measured by characterizing the coherence of correlated Lyα forest absorption in close quasar pairs, with separations small enough ∼100 kpc to resolve it. We present a novel technique for this purpose, based on the probability density function (PDF) of phase angle differences of homologous longitudinal Fourier modes in close quasar pair spectra. A Bayesian formalism is introduced based on the phase angle PDF, and Markov Chain Monte Carlo techniques are used to characterize the precision of a hypothetical Jeans scale measurement, and explore degeneracies with other thermal parameters governing the IGM. A semi-analytical model of the Lyα forest is used to generate a large grid (500) of thermal models from a dark matter only simulation. Our full parameter study indicates that a realistic

  3. High Resolution Spectroscopy of X-ray Quasars: Searching for the X-ray Absorption from the Warm-Hot Intergalactic Medium

    NASA Technical Reports Server (NTRS)

    Fang, Taotao; Canizares, Claude R.; Marshall, Herman L.

    2004-01-01

    We present a survey of six low to moderate redshift quasars with Chandra and XMM-Newton. The primary goal is to search for the narrow X-ray absorption lines produced by highly ionized metals in the Warm-Hot Intergalactic Medium. All the X-ray spectra can be well fitted by a power law with neutral hydrogen absorption. Only one feature is detected at above 3-sigma level in all the spectra, which is consistent with statistic fluctuation. We discuss the implications in our understanding of the baryon content of the universe. We also discuss the implication of the non-detection of the local (z approx. 0) X-ray absorption.

  4. Coincidences between O VI and O VII Lines: Insights from High-resolution Simulations of the Warm-hot Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Cen, Renyue

    2012-07-01

    With high-resolution (0.46 h -1 kpc), large-scale, adaptive mesh-refinement Eulerian cosmological hydrodynamic simulations we compute properties of O VI and O VII absorbers from the warm-hot intergalactic medium (WHIM) at z = 0. Our new simulations are in broad agreement with previous simulations with ~40% of the intergalactic medium being in the WHIM. Our simulations are in agreement with observed properties of O VI absorbers with respect to the line incidence rate and Doppler-width-column-density relation. It is found that the amount of gas in the WHIM below and above 106 K is roughly equal. Strong O VI absorbers are found to be predominantly collisionally ionized. It is found that (61%, 57%, 39%) of O VI absorbers of log N(O VI) cm2 = (12.5-13, 13-14, > 14) have T < 105 K. Cross correlations between galaxies and strong [N(O VI) > 1014 cm-2] O VI absorbers on ~100-300 kpc scales are suggested as a potential differentiator between collisional ionization and photoionization models. Quantitative prediction is made for the presence of broad and shallow O VI lines that are largely missed by current observations but will be detectable by Cosmic Origins Spectrograph observations. The reported 3σ upper limit on the mean column density of coincidental O VII lines at the location of detected O VI lines by Yao et al. is above our predicted value by a factor of 2.5-4. The claimed observational detection of O VII lines by Nicastro et al., if true, is 2σ above what our simulations predict.

  5. Development of a hot intergalactic medium in spiral-rich galaxy groups: the example of HCG 16

    NASA Astrophysics Data System (ADS)

    Vrtilek, Jan M.; O'Sullivan, Ewan; David, Laurence P.; Giacintucci, Simona; Zezas, Andreas; Mamon, Gary; Ponman, Trevor J; Raychaudhury, Somak

    2014-08-01

    Galaxy groups provide the environment in which the majority of galaxies evolve, with low velocity dispersions and small galaxy separations that are conducive to tidal interactions and mergers between group members. X-ray observations reveal the frequent presence of hot gas in groups, with larger quantities linked to early-type galaxies, whereas cold gas is common in spiral-dominated groups. Clarification of the origin and role of the hot medium is central to the understanding of the evolution of the galaxy population and of all phases of the IGM.We here report on the nuclear activity, star formation and the high luminosity X-ray binary populations of the spiral-dominated, likely not yet virialized, group HCG 16, as well as on its intra-group medium, based principally on deep (150 ks) Chandra X-ray observations of the group, as well as new Giant Metrewave Radio Telescope (GMRT) 610 MHz radio data. We confirm the presence of obscured active nuclei in NGC 833 and NGC 835, and identify what may be a previously unrecognized nuclear source in NGC 838; all are variable. NGC 838 and NGC 839 are both starburst-dominated systems, with galactic superwinds that show X-ray and radio evidence of IGM interaction, but only weak nuclear activity; NGC 848 is also dominated by emission from its starburst.We confirm the existence of a faint, extended low-temperature (0.3 keV) intra-group medium, a subject of some uncertainty in earlier studies. The diffuse emission is strongest in a ridge linking the four principal galaxies, and is at least partly coincident with a large-scale HI tidal filament, indicating that the IGM in the inner part of the group is highly multi-phase. We conclude that starburst winds and shock-heating of stripped HI may play an important role in the early stages of IGM formation, with galactic winds contributing 20-40% of the observed hot gas in the system.

  6. A galaxy overdensity at z = 0.401 associated with an X-ray emitting structure of warm-hot intergalactic medium

    NASA Astrophysics Data System (ADS)

    Mannucci, F.; Bonnoli, G.; Zappacosta, L.; Maiolino, R.; Pedani, M.

    2007-06-01

    We present the results of spectroscopic observations of galaxies associated with the diffuse X-ray emitting structure discovered by Zappacosta et al. (2002, A&A, 394, 7). After measuring the redshifts of 161 galaxies, we confirm an overdensity of galaxies with projected dimensions of at least 2 Mpc, determine its spectroscopic redshift in z = 0.401 ± 0.002, and show that it is spatially coincident with the diffuse X-ray emission. This confirms the original claim that this X-ray emission has an extragalactic nature and is due to the warm-hot intergalactic medium (WHIM). We used this value of the redshift to compute the temperature of the emitting gas. The resulting value depends on the metallicity that is assumed for the IGM, and is constrained to be between 0.3 and 0.6 keV for metallicities between 0.05 and 0.3 solar, in good agreement with the expectations from the WHIM. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG), operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica), and with the William Hershel Telescope (WHT), operated by the ING, both at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/468/807

  7. The Faint End of the Quasar Luminosity Function at z ~ 4: Implications for Ionization of the Intergalactic Medium and Cosmic Downsizing

    NASA Astrophysics Data System (ADS)

    Glikman, Eilat; Djorgovski, S. G.; Stern, Daniel; Dey, Arjun; Jannuzi, Buell T.; Lee, Kyoung-Soo

    2011-02-01

    We present an updated determination of the z ~ 4 QSO luminosity function (QLF), improving the quality of the determination of the faint end of the QLF presented by Glikman et al. (2010). We have observed an additional 43 candidates from our survey sample, yielding one additional QSO at z = 4.23 and increasing the completeness of our spectroscopic follow-up to 48% for candidates brighter than R = 24 over our survey area of 3.76 deg2. We study the effect of using K-corrections to compute the rest-frame absolute magnitude at 1450 Å compared with measuring M 1450 directly from the object spectra. We find a luminosity-dependent bias: template-based K-corrections overestimate the luminosity of low-luminosity QSOs, likely due to their reliance on templates derived from higher luminosity QSOs. Combining our sample with bright quasars from the Sloan Digital Sky Survey and using spectrum-based M 1450 for all the quasars, we fit a double power law to the binned QLF. Our best fit has a bright-end slope, α = 3.3 ± 0.2, and faint-end slope, β = 1.6+0.8 -0.6. Our new data revise the faint-end slope of the QLF down to flatter values similar to those measured at z ~ 3. The break luminosity, though poorly constrained, is at M* = -24.1+0.7 -1.9, approximately 1-1.5 mag fainter than at z ~ 3. This QLF implies that QSOs account for about half the radiation needed to ionize the intergalactic medium at these redshifts. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  8. Intergalactic medium emission observations with the cosmic web imager. II. Discovery of extended, kinematically linked emission around SSA22 Lyα BLOB 2

    SciTech Connect

    Christopher Martin, D.; Chang, Daphne; Matuszewski, Matt

    The intergalactic medium (IGM) is the dominant reservoir of baryons, delineates the large-scale structure of the universe at low to moderate overdensities, and provides gas from which galaxies form and evolve. Simulations of a cold-dark-matter- (CDM-) dominated universe predict that the IGM is distributed in a cosmic web of filaments and that galaxies should form along and at the intersections of these filaments. While observations of QSO absorption lines and the large-scale distribution of galaxies have confirmed the CDM paradigm, the cosmic web of IGM has never been confirmed by direct imaging. Here we report our observation of the Lyαmore » blob 2 (LAB2) in SSA22 with the Cosmic Web Imager (CWI). This is an integral field spectrograph optimized for low surface brightness, extended emission. With 22 hr of total on- and off-source exposure, CWI has revealed that LAB2 has extended Lyα emission that is organized into azimuthal zones consistent with filaments. We perform numerous tests with simulations and the data to secure the robustness of this result, which relies on data with modest signal-to-noise ratios. We have developed a smoothing algorithm that permits visualization of data cube slices along image or spectral image planes. With both raw and smoothed data cubes we demonstrate that the filaments are kinematically associated with LAB2 and display double-peaked profiles characteristic of optically thick Lyα emission. The flux is 10-20 times brighter than expected for the average emission from the IGM but is consistent with boosted fluorescence from a buried QSO or gravitation cooling radiation. Using simple emission models, we infer a baryon mass in the filaments of at least 1-4 × 10{sup 11} M {sub ☉}, and the dark halo mass is at least 2 × 10{sup 12} M {sub ☉}. The spatial-kinematic morphology is more consistent with inflow from the cosmic web than outflow from LAB2, although an outflow feature maybe present at one azimuth. LAB2 and the surrounding

  9. Intergalactic Travel Bureau

    NASA Astrophysics Data System (ADS)

    Koski, Olivia; Rosin, Mark; Guerilla Science Team

    2014-03-01

    The Intergalactic Travel Bureau is an interactive theater outreach experience that engages the public in the incredible possibilities of space tourism. The Bureau is staffed by professional actors, who play the role of space travel agents, and professional astrophysicists, who play the role of resident scientists. Members of the public of all ages were invited to visit with bureau staff to plan the vacation of their dreams-to space. We describe the project's successful nine day run in New York in August 2013. Funded by the American Physical Society Public Outreach and Informing the Public Grants.

  10. Virgo Intergalactic Globulars from the Sloan Survey

    NASA Astrophysics Data System (ADS)

    Gregg, Michael; West, Michael

    2017-07-01

    We have identified a new sample of Virgo intergalactic globular clusters (IGCs) and ultra compact dwarfs (UCDs) which have been serendipitously observed to date in Sloan Survey spectroscopy. There are 23 new objects with secure redshifts, all relatively red point sources with reliable velocities placing them at Virgo distances. They are spread widely across Virgo, significantly extending the spatial distribution of Virgo IGCs and UCDs to regions outside the well-studied M87 core region. The new sample are generally fainter, bluer, and probably more metal poor on average than the more centrally located, previously known objects. This systematic change carries information about the formation and continued evolution by accretion of the Virgo cluster, indicating a transition to less massive and less luminous objects being tidally disrupted in the outskirts now and in the recent past, compared to conditions in the inner cluster at early epochs.

  11. Observing Interstellar and Intergalactic Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Han, J. L.

    2017-08-01

    Observational results of interstellar and intergalactic magnetic fields are reviewed, including the fields in supernova remnants and loops, interstellar filaments and clouds, Hii regions and bubbles, the Milky Way and nearby galaxies, galaxy clusters, and the cosmic web. A variety of approaches are used to investigate these fields. The orientations of magnetic fields in interstellar filaments and molecular clouds are traced by polarized thermal dust emission and starlight polarization. The field strengths and directions along the line of sight in dense clouds and cores are measured by Zeeman splitting of emission or absorption lines. The large-scale magnetic fields in the Milky Way have been best probed by Faraday rotation measures of a large number of pulsars and extragalactic radio sources. The coherent Galactic magnetic fields are found to follow the spiral arms and have their direction reversals in arms and interarm regions in the disk. The azimuthal fields in the halo reverse their directions below and above the Galactic plane. The orientations of organized magnetic fields in nearby galaxies have been observed through polarized synchrotron emission. Magnetic fields in the intracluster medium have been indicated by diffuse radio halos, polarized radio relics, and Faraday rotations of embedded radio galaxies and background sources. Sparse evidence for very weak magnetic fields in the cosmic web is the detection of the faint radio bridge between the Coma cluster and A1367. Future observations should aim at the 3D tomography of the large-scale coherent magnetic fields in our Galaxy and nearby galaxies, a better description of intracluster field properties, and firm detections of intergalactic magnetic fields in the cosmic web.

  12. Intergalactic HI in the NGC5018 group

    NASA Technical Reports Server (NTRS)

    Guhathakurta, P.; Knapp, G. R.; Vangorkom, Jacqueline H.; Kim, D.-W.

    1990-01-01

    The cold interstellar and intergalactic medium is in the small group of galaxies whose brightest member is the elliptical galaxy NGC5018. Researchers' attention was first drawn to this galaxy as possibly containing cold interstellar gas by the detection by the Infrared Astronomy Satellite (IRAS) of emission at lambda 60 microns and lambda 100 microns at an intensity of about 1 Jy (Knapp et al. 1989), which is relatively strong for an elliptical (Jura et al. 1987). These data showed that the temperature of the infrared emission is less than 30K and that its likely source is therefore interstellar dust. A preliminary search for neutral hydrogen (HI) emission from this galaxy using the Very Large Array (VLA) showed that there appears to be HI flowing between NGC5018 and the nearby Sc galaxy NGC5022 (Kim et al. 1988). Since NGC5018 has a well-developed system of optical shells (cf. Malin and Carter 1983; Schweizer 1987) this observation suggests that NGC5018 may be in the process of forming its shell system by the merger of a cold stellar system with the elliptical, as suggested by Quinn (1984). Researchers describe follow-up HI observations of improved sensitivity and spatial resolution, and confirm that HI is flowing between NCG5022 and NGC5018, and around NGC5018. The data show, however, that the HI bridge actually connects NGC5022 and another spiral in the group, MCG03-34-013, both spatially and in radial velocity, and that in doing so it flows through and around NGC5018, which lies between the spiral galaxies. This is shown by the total HI map, with the optical positions of the above three galaxies labelled.

  13. Ionization in the local interstellar and intergalactic media

    SciTech Connect

    Cheng, K.

    1990-01-01

    Detailed photoionization calculations for the local interstellar medium (LISM) and the intergalactic medium (IGM) are presented. Constraints in the LISM are imposed by H I column density derived from IUE and Copernicus data toward nearby B stars and hot white dwarfs. The EUV radiation field is modeled including contributions from discrete stellar sources and from a thermal bremsstrahlung-radiative recombination spectrum emitted from the surrounding 10(exp 6) K coronal substrate. Lower limits to the fractional ionization of hydrogen and helium of 0.17 and 0.30 respectively are established. The derived limits have important implications for the interpretation of the H I andmore » He I backscattering results. The high He ionization fraction results primarily from very strong line emission below 500 A originating in the surrounding coronal substrate while the H ionization is dominated by the EUV radiation from the discrete stellar sources. The dual effects of thermal conduction and the EUV spectrum of the 10(exp 6) K plasma on ionization in the cloud skin are explored. The EUV radiation field and Auger ionization have insignificant effects on the resulting ionic column densities of Si IV, C IV, N V and O VI through the cloud skin. Calculations show that the abundances of these species are dominated by collisional ionization in the thermal conduction front. Because of a low charge exchange rate with hydrogen, the ionic column density ratios of N(C III)/N(C II) and N(N II)/N(N I) are dominated by the EUV radiation field in the local interstellar medium. These ratios should be important diagnostics for the EUV radiation field and serve as surrogate indicators of the interstellar He and H ionization fraction respectively. The same photoionization model is applied to the intergalactic medium.« less

  14. Galactic and Intergalactic Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Klein, U.; Fletcher, A.

    This course-tested textbook conveys the fundamentals of magnetic fields and relativistic plasma in diffuse cosmic media, with a primary focus on phenomena that have been observed at different wavelengths. Theoretical concepts are addressed wherever necessary, with derivations presented in sufficient detail to be generally accessible. In the first few chapters the authors present an introduction to various astrophysical phenomena related to cosmic magnetism, with scales ranging from molecular clouds in star-forming regions and supernova remnants in the Milky Way, to clusters of galaxies. Later chapters address the role of magnetic fields in the evolution of the interstellar medium, galaxies and galaxy clusters. The book is intended for advanced undergraduate and postgraduate students in astronomy and physics and will serve as an entry point for those starting their first research projects in the field.

  15. Quasar Absorption in the UV: Probing the Intergalactic Medium

    NASA Technical Reports Server (NTRS)

    Weinberg, David; Katz, Neal

    1998-01-01

    The purpose of this project is to model the low-redshift Lyman-alpha forest and exploration of the relation between Lyman-alpha absorbers and galaxies. This paper shows that the simulation models that are so successful at explaining properties of the high-redshift forest also account for the most important results of observational studies of the low-redshift forest, from HST (especially the Quasar Absorption Line Key Project) and ground-based follow-up.

  16. The Environmental Impact of Intra-Cluster Medium on the Interstellar Medium in Early Type Galaxies

    NASA Technical Reports Server (NTRS)

    Trinchieri, Ginevra

    1993-01-01

    Draft versions of three articles submitted for publication are presented. The first two articles address high resolution X-ray images of early type galaxies observed with the ROSAT HRI and PSPC. Data for NGC 1553 and NGC 5846 indicate that the emission is highly irregular, with interesting features at different scales. The gas temperatures also vary both with the galactocentric radius and in correspondence to regions of higher emission and denser material. Strikingly similar features are observed in the X-ray and H-alpha morphologies of NGC 1553 and NGC 5846, while smooth, regular isophotes are observed in NGC 4649 at both wavelengths. The third article addresses ROSAT PSPC observations of 5 X-ray bright early type galaxies.

  17. The Influence of Plasma Effects of Pair Beams on the Intergalactic Cascade Emission of Blazars

    NASA Astrophysics Data System (ADS)

    Menzler, Ulf; Schlickeiser, Reinhard

    2014-03-01

    The attenuation of TeV γ-rays from distant blazars by the extragalactic background light (EBL) produces relativistic electron-positron pair beams. It has been shown by Broderick et. al. (2012) and Schlickeiser et. al (2012) that a pair beam traversing the intergalactic medium is unstable to linear two-stream instabilities of both electrostatic and electromagnetic nature. While for strong blazars all free pair energy is dissipated in heating the intergalactic medium and a potential electromagnetic cascade via inverse-Compton scattering with the cosmic microwave background is suppressed, we investigate the case of weak blazars where the back reaction of generated electrostatic turbulence leads to a plateauing of the electron energy spectrum. In the ultra-relativistic Thomson limit we analytically calculate the inverse-Compton spectral energy distribution for both an unplateaued and a plateaued beam scenario, showing a peak reduction factor of Rpeak ≈ 0.345. This is consistent with the FERMI non-measurements of a GeV excess in the spectrum of EBL attenuated TeV blazars. Claims on the lower bound of the intergalactic magnetic field strengths, made by several authors neglecting plasma effects, are thus put into question.

  18. The Environmental Impact of Intra-Cluster Medium on the Interstellar Medium in Early Type Galaxies

    NASA Technical Reports Server (NTRS)

    Trinchieri, Ginevra

    1997-01-01

    High resolution X-ray images of three early type galaxies observed with the ROSAT HRI are presented. Data for NGC 1553 and NGC 5846 indicate that the emission is highly irregular, with interesting features on scales from a few arcsec to a few arcmin. The gas temperatures also vary both with the galactocentric radius and in correspondence to regions of higher emission and denser material. Strikingly similar features are observed in the X-ray and H(alpha) morphologies of NGC 1553 and NGC 5846, while smoother, more regular isophotes are observed in NGC 4649 at both wavelengths. A connection between these two kinds of emission therefore seems likely. In the light of our observations we discuss possible scenarios that can and account for the connection between X-ray and H(alpha) emissions.

  19. Constraints on dark matter from intergalactic radiation

    NASA Technical Reports Server (NTRS)

    Overduin, J. M.; Wesson, P. S.

    1992-01-01

    Several of the dark matter candidates that have been proposed are believed to be unstable to decay, which would contribute photons to the radiation field between galaxies. The main candidates of this type are light neutrinos and axions, primordial mini-black holes, and a nonzero 'vacuum' energy. All of these can be constrained in nature by observational data on the extragalactic background light and the microwave background radiation. Black holes and the vacuum can be ruled out as significant contributors to the 'missing mass'. Light axions are also unlikely candidates; however, those with extremely small rest energies (the so-called 'invisible' axions) remain feasible. Light neutrinos, like those proposed by Sciama, are marginally viable. In general, we believe that the intergalactic radiation field is an important way of constraining all types of dark matter.

  20. Intergalactic stellar populations in intermediate redshift clusters

    NASA Astrophysics Data System (ADS)

    Melnick, J.; Giraud, E.; Toledo, I.; Selman, F.; Quintana, H.

    2012-11-01

    A substantial fraction of the total stellar mass in rich clusters of galaxies resides in a diffuse intergalactic component usually referred to as the intracluster light (ICL). Theoretical models indicate that these intergalactic stars originate mostly from the tidal interaction of the cluster galaxies during the assembly history of the cluster, and that a significant fraction of these stars could have formed in situ from the late infall of cold metal-poor gas clouds on to the cluster. However, these models also overpredict the fraction of stellar mass in the ICL by a substantial margin, something that is still not well understood. The models also make predictions about the age distribution of the ICL stars, which may provide additional observational constraints. Here we present population synthesis models for the ICL of an intermediate redshift (z = 0.29) X-ray cluster that we have extensively studied in previous papers. The advantage of observing intermediate redshift clusters rather than nearby ones is that the former fit the field of view of multi-object spectrographs in 8-m telescopes and therefore permit us to encompass most of the ICL with only a few well-placed slits. In this paper we show that by stacking spectra at different locations within the ICL it is possible to reach sufficiently high signal-to-noise ratios to fit population synthesis models and derive meaningful results. The models provide ages and metallicities for the dominant populations at several different locations within the ICL and the brightest cluster galaxies (BCG) halo, as well as measures of the kinematics of the stars as a function of distance from the BCG. We thus find that the ICL in our cluster is dominated by old metal-rich stars, at odds with what has been found in nearby clusters where the stars that dominate the ICL are old and metal poor. While we see weak evidence of a young, metal-poor component, if real, these young stars would amount to less than 1 per cent of the total ICL

  1. Learning through English Language in Early Childhood Education: A Case of English Medium Schools in China

    ERIC Educational Resources Information Center

    Mwalongo, Leopard Jacob

    2016-01-01

    In China the English medium schools are now mushrooming and many parents send their children at very early age. These schools enroll children of pre-school to school age to learn through English as foreign language regardless of their proficiency in the first language. Therefore the study aims at examining the learning English language as a…

  2. Early Childhood: Language and Bullying in an English-Medium School in China

    ERIC Educational Resources Information Center

    Lehman, Clayton Wayne

    2017-01-01

    The purpose of this small-scale study was to examine whether language is a factor in the reporting of bullying behavior by young English language learners enrolled in an early childhood program of an English-medium school in China. Further investigated was whether an English-only language policy affects the reporting of bullying behavior.…

  3. Impacts of Early Childhood Education on Medium- and Long-Term Educational Outcomes

    ERIC Educational Resources Information Center

    McCoy, Dana Charles; Yoshikawa, Hirokazu; Ziol-Guest, Kathleen M.; Duncan, Greg J.; Schindler, Holly S.; Magnuson, Katherine; Yang, Rui; Koepp, Andrew; Shonkoff, Jack P.

    2017-01-01

    Despite calls to expand early childhood education (ECE) in the United States, questions remain regarding its medium- and long-term impacts on educational outcomes. We use meta-analysis of 22 high-quality experimental and quasi-experimental studies conducted between 1960 and 2016 to find that on average, participation in ECE leads to statistically…

  4. New photoionization models of intergalactic clouds

    NASA Technical Reports Server (NTRS)

    Donahue, Megan; Shull, J. M.

    1991-01-01

    New photoionization models of optically thin low-density intergalactic gas at constant pressure, photoionized by QSOs, are presented. All ion stages of H, He, C, N, O, Si, and Fe, plus H2 are modeled, and the column density ratios of clouds at specified values of the ionization parameter of n sub gamma/n sub H and cloud metallicity are predicted. If Ly-alpha clouds are much cooler than the previously assumed value, 30,000 K, the ionization parameter must be very low, even with the cooling contribution of a trace component of molecules. If the clouds cool below 6000 K, their final equilibrium must be below 3000 K, owing to the lack of a stable phase between 6000 and 3000 K. If it is assumed that the clouds are being irradiated by an EUV power-law continuum typical of WSOs, with J0 = 10 exp -21 ergs/s sq cm Hz, typical cloud thicknesses along the line of sight that are much smaller than would be expected from shocks, thermal instabilities, or gravitational collapse are derived.

  5. INTERGALACTIC 'PIPELINE' FUNNELS MATTER BETWEEN COLLIDING GALAXIES

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This visible-light picture, taken by NASA's Hubble Space Telescope, reveals an intergalactic 'pipeline' of material flowing between two battered galaxies that bumped into each other about 100 million years ago. The pipeline [the dark string of matter] begins in NGC 1410 [the galaxy at left], crosses over 20,000 light-years of intergalactic space, and wraps around NGC 1409 [the companion galaxy at right] like a ribbon around a package. Although astronomers have taken many stunning pictures of galaxies slamming into each other, this image represents the clearest view of how some interacting galaxies dump material onto their companions. These results are being presented today at the 197th meeting of the American Astronomical Society in San Diego, CA. Astronomers used the Space Telescope Imaging Spectrograph to confirm that the pipeline is a continuous string of material linking both galaxies. Scientists believe that the tussle between these compact galaxies somehow created the pipeline, but they're not certain why NGC 1409 was the one to begin gravitationally siphoning material from its partner. And they don't know where the pipeline begins in NGC 1410. More perplexing to astronomers is that NGC 1409 is seemingly unaware that it is gobbling up a steady flow of material. A stream of matter funneling into the galaxy should have fueled a spate of star birth. But astronomers don't see it. They speculate that the gas flowing into NGC 1409 is too hot to gravitationally collapse and form stars. Astronomers also believe that the pipeline itself may contribute to the star-forming draught. The pipeline, a pencil-thin, 500 light-year-wide string of material, is moving a mere 0.02 solar masses of matter a year. Astronomers estimate that NGC 1409 has consumed only about a million solar masses of gas and dust, which is not enough material to spawn some of the star-forming regions seen in our Milky Way. The low amount means that there may not be enough material to ignite star birth

  6. Giant Intergalactic Gas Stream Longer Than Thought

    NASA Astrophysics Data System (ADS)

    2010-01-01

    A giant stream of gas flowing from neighbor galaxies around our own Milky Way is much longer and older than previously thought, astronomers have discovered. The new revelations provide a fresh insight on what started the gaseous intergalactic streamer. The astronomers used the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) to fill important gaps in the picture of gas streaming outward from the Magellanic Clouds. The first evidence of such a flow, named the Magellanic Stream, was discovered more than 30 years ago, and subsequent observations added tantalizing suggestions that there was more. However, the earlier picture showed gaps that left unanswered whether this other gas was part of the same system. "We now have answered that question. The stream is continuous," said David Nidever, of the University of Virginia. "We now have a much more complete map of the Magellanic Stream," he added. The astronomers presented their findings to the American Astronomical Society's meeting in Washington, DC. The Magellanic Clouds are the Milky Way's two nearest neighbor galaxies, about 150,000 to 200,000 light-years distant from the Milky Way. Visible in the Southern Hemisphere, they are much smaller than our Galaxy and may have been distorted by its gravity. Nidever and his colleagues observed the Magellanic Stream for more than 100 hours with the GBT. They then combined their GBT data with that from earlier studies with other radio telescopes, including the Arecibo telescope in Puerto Rico, the Parkes telescope in Australia, and the Westerbork telescope in the Netherlands. The result shows that the stream is more than 40 percent longer than previously known with certainty. One consequence of the added length of the gas stream is that it must be older, the astronomers say. They now estimate the age of the stream at 2.5 billion years. The revised size and age of the Magellanic Stream also provides a new potential explanation for how the flow got started

  7. Intergalactic Helium Absorption toward High-Redshift Quasars

    NASA Technical Reports Server (NTRS)

    Giroux, Mark L.; Fardal, Mark A.; Shull, J. Michael

    1995-01-01

    The recent Hubble Space Telescope (HST) observations of the z(q) = 3.286 quasar Q0302-003 (Jakobsen et at. 1994) and the z(q) = 3.185 quasar Q1935-67 by Tytler (1995) show absorption edges at the redshifted wavelength of He II 304 A. A key goal is to distinguish between contributions from discrete Ly-alpha forest clouds and a smoothly distributed intergalactic medium (IGM). We model the contributions from each of these sources of He II absorption, including the distribution of line Doppler widths and column densities, the 'He II proximity effect' from the quasar, and a self-consistent derivation of the He II opacity of the universe as a function of the spectrum of ionizing sources, with the assumption that both the clouds and the IGM are photoionized. The He II edge can be fully accounted for by He II line blanketing for reasonable distributions of line widths and column densities in the Ly-alpha forest, provided that the ionizing sources have spectral index alpha(s) greater than 1.5, and any He II proximity effect is neglected. Even with some contribution from a diffuse IGM, it is difficult to account for the edge observed by Jakobsen et al. (1994) with a 'hard' source spectrum (alpha(s) less than 1.3). The proximity effect modifies the relative contributions of the clouds and IGM to tau(He II) near the quasar (z approx. less than z(q)) and markedly increases the amount of He II absorption required. This implies, for example, that to account for the He II edge with line blanketing alone, the minimum spectral index alpha(s) must be increased from 1.5 to 1.9. We demonstrate the need for higher resolution observations that characterize the change in transmission as z approaches z(q) and resolve line-free gaps in the continuum. We set limits on the density of the diffuse IGM and suggest that the IGM and Ly-alpha clouds are likely to be a significant repository for dark baryons.

  8. Density Bounded H II Regions: Ionization of the Diffuse Interstellar and Intergalactic Media

    NASA Astrophysics Data System (ADS)

    Zurita, A.; Rozas, M.; Beckman, J. E.

    2000-05-01

    We present a study of the diffuse ionized gas (DIG) for a sample of nearby spiral galaxies using Hα images, after constructing their H II region catalogues. The integrated Hα emission of the DIG accounts for between 25% to 60% of the total Hα of the galaxy and a high ionizing photon flux is necessary to keep this gas ionized. We suggest that Lyman photons leaking from the most luminous H II regions are the prime source of the ionization of the DIG; they are more than enough to ionize the measured DIG in the model in which H II regions with luminosity in Hα greater than LStr=1038.6 erg sme are density bounded. We go on to show that this model can quantify the ionization observed in the skins of the high velocity clouds well above the plane of our Galaxy and predicts the ionization of the intergalactic medium.

  9. UNDERSTANDING THE STRUCTURE OF THE HOT INTERSTELLAR MEDIUM IN NORMAL EARLY-TYPE GALAXIES.

    NASA Astrophysics Data System (ADS)

    Traynor, Liam; Kim, Dong-Woo; Chandra Galaxy Atlas

    2018-01-01

    The hot interstellar medium (ISM) of early-type galaxies (ETG's) provides crucial insight into the understanding of their formation and evolution. Mechanisms such as type Ia supernovae heating, AGN feedback, deepening potential depth through dark matter assembly and ramp-pressure stripping are known to affect the structure of the ISM. By using temperature maps and radial temperature profiles of the hot ISM from ~70 ETG's with archival Chandra data, it is possible to classify the galaxy's ISM into common structural types. This is extended by using 3D fitting of the radial temperature profile in order to provide models that further constrain the structural types. Five structural types are present, negative (temperature decreases with radii), positive (temperature increases with radii), hybrid-dip (temperature decreases at small radii and increases at large radii), hybrid-bump (inverse of hybrid-dip) and quasi-isothermal (temperature is constant at all radii). This work will be continued by 1) determining which mechanisms are present in which galaxies and 2) analysing the model parameters between galaxies within each structural type to determine whether each type can be described by a single set of model parameters, indicating that the same physical processes are responsible for creating that structural type.

  10. Intergalactic Extinction of High Energy Gamma-Rays

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1998-01-01

    We discuss the determination of the intergalactic pair-production absorption coefficient as derived by Stecker and De Jager by making use of a new empirically based calculation of the spectral energy distribution of the intergalactic infrared radiation field as given by Malkan and Stecker. We show that the results of the Malkan and Stecker calculation agree well with recent data on the infrared background. We then show that Whipple observations of the flaring gamma-ray spectrum of Mrk 421 hint at extragalactic absorption and that the HEGRA observations of the flaring spectrum of Mrk 501 appear to strongly indicate extragalactic absorption. We also discuss the determination of the y-ray opacity at higher redshifts, following the treatment of Salamon and Stecker. We give a predicted spectrum, with absorption included for PKS 2155-304. This XBL lies at a redshift of 0.12, the highest redshift source yet observed at an energy above 0.3 TeV. This source should have its spectrum steepened by approx. 1 in its spectral index between approx. 0.3 and approx. 3 TeV and should show an absorption cutoff above approx. 6 TeV.

  11. Active galactic nuclei feedback, quiescence and circumgalactic medium metal enrichment in early-type galaxies

    NASA Astrophysics Data System (ADS)

    Eisenreich, Maximilian; Naab, Thorsten; Choi, Ena; Ostriker, Jeremiah P.; Emsellem, Eric

    2017-06-01

    We present three-dimensional hydrodynamical simulations showing the effect of kinetic and radiative active galactic nuclei (AGN) feedback on a model galaxy representing a massive quiescent low-redshift early-type galaxy of M* = 8.41 × 1010 M⊙, harbouring an MBH = 4 × 108 M⊙ black hole surrounded by a cooling gaseous halo. We show that, for a total baryon fraction of ˜20 per cent of the cosmological value, feedback from the AGN can keep the galaxy quiescent for about 4.35 Gyr and with properties consistent with black hole mass and X-ray luminosity scaling relations. However, this can only be achieved if the AGN feedback model includes both kinetic and radiative feedback modes. The simulation with only kinetic feedback fails to keep the model galaxy fully quiescent, while one with only radiative feedback leads to excessive black hole growth. For higher baryon fractions (e.g. 50 per cent of the cosmological value), the X-ray luminosities exceed observed values by at least one order of magnitude, and rapid cooling results in a star-forming galaxy. The AGN plays a major role in keeping the circumgalactic gas at observed metallicities of Z/Z⊙ ≳ 0.3 within the central ˜30 kpc by venting nuclear gas enriched with metals from residual star formation activity. As indicated by previous cosmological simulations, our results are consistent with a model for which the black hole mass and the total baryon fraction are set at higher redshifts z > 1 and the AGN alone can keep the model galaxy on observed scaling relations. Models without AGN feedback violate both the quiescence criterion as well as circumgalactic medium metallicity constraints.

  12. Atomic Data Revisions for Transitions Relevant to Observations of Interstellar, Circumgalactic, and Intergalactic Matter

    SciTech Connect

    Cashman, Frances H.; Kulkarni, Varsha P.; Kisielius, Romas

    2017-05-01

    Measurements of element abundances in galaxies from astrophysical spectroscopy depend sensitively on the atomic data used. With the goal of making the latest atomic data accessible to the community, we present a compilation of selected atomic data for resonant absorption lines at wavelengths longward of 911.753 Å (the H i Lyman limit), for key heavy elements (heavier than atomic number 5) of astrophysical interest. In particular, we focus on the transitions of those ions that have been observed in the Milky Way interstellar medium (ISM), the circumgalactic medium (CGM) of the Milky Way and/or other galaxies, and the intergalactic mediummore » (IGM). We provide wavelengths, oscillator strengths, associated accuracy grades, and references to the oscillator strength determinations. We also attempt to compare and assess the recent oscillator strength determinations. For about 22% of the lines that have updated oscillator strength values, the differences between the former values and the updated ones are ≳0.1 dex. Our compilation will be a useful resource for absorption line studies of the ISM, as well as studies of the CGM and IGM traced by sight lines to quasars and gamma-ray bursts. Studies (including those enabled by future generations of extremely large telescopes) of absorption by galaxies against the light of background galaxies will also benefit from our compilation.« less

  13. Observational Search for Negative Matter in Intergalactic Voids

    NASA Technical Reports Server (NTRS)

    Forward, Robert L.

    1999-01-01

    Negative matter is a hypothetical form of matter with negative rest mass, inertial mass, and gravitational mass. It is not antimatter. If negative matter could be collected in macroscopic amounts, its negative inertial property could be used to make an continuously operating propulsion system which requires neither energy nor reaction mass, yet still violates no laws of physics. Negative matter has never been observed, but its existence is not forbidden by the laws of physics. We propose that NASA support an extension to an ongoing astrophysical observational effort by da Costa, et al. (1996) which could possibly determine whether or not negative matter exists in the well-documented but little-understood intergalactic voids.

  14. IVF culture medium affects human intrauterine growth as early as the second trimester of pregnancy.

    PubMed

    Nelissen, Ewka C M; Van Montfoort, Aafke P A; Smits, Luc J M; Menheere, Paul P C A; Evers, Johannes L H; Coonen, Edith; Derhaag, Josien G; Peeters, Louis L; Coumans, Audrey B; Dumoulin, John C M

    2013-08-01

    When does a difference in human intrauterine growth of singletons conceived after IVF and embryo culture in two different culture media appear? Differences in fetal development after culture of embryos in one of two IVF media were apparent as early as the second trimester of pregnancy. Abnormal fetal growth patterns are a major risk factor for the development of chronic diseases in adult life. Previously, we have shown that the medium used for culturing embryos during the first few days after fertilization significantly affects the birthweight of the resulting human singletons. The exact onset of this growth difference was unknown. In this retrospective cohort study, all 294 singleton live births after fresh embryo transfer in the period July 2003 to December 2006 were included. These embryos originated from IVF treatments that were part of a previously described clinical trial. Embryos were allocated to culture in either Vitrolife or Cook commercially available sequential culture media. We analysed ultrasound examinations at 8 (n = 290), 12 (n = 83) and 20 weeks' (n = 206) gestation and used first-trimester serum markers [pregnancy-associated plasma protein-A (PAPP-A) and free β-hCG]. Differences between study groups were tested by the Student's t-test, χ(2) test or Fisher's exact test, and linear multivariable regression analysis to adjust for possible confounders (for example, parity, gestational age at the time of ultrasound and fetal gender). A total of 294 singleton pregnancies (Vitrolife group nVL = 168, Cook group: nC = 126) from 294 couples were included. At 8 weeks' gestation, there was no difference between crown-rump length-based and ovum retrieval-based gestational age (ΔGA) (nVL = 163, nC = 122, adjusted mean difference, -0.04 days, P = 0.84). A total of 83 women underwent first-trimester screening at 12 weeks' gestation (nVL = 45, nC = 38). ΔGA, nuchal translucency (multiples of median, MoM) and PAPP-A (MoM) did not differ between the study

  15. The cosmic transparency measured with Type Ia supernovae: implications for intergalactic dust

    NASA Astrophysics Data System (ADS)

    Goobar, Ariel; Dhawan, Suhail; Scolnic, Daniel

    2018-04-01

    Observations of high-redshift Type Ia supernovae (SNe Ia) are used to study the cosmic transparency at optical wavelengths. Assuming a flat ΛCDM cosmological model based on BAO and CMB results, redshift dependent deviations of SN Ia distances are used to constrain mechanisms that would dim light. The analysis is based on the most recent Pantheon SN compilation, for which there is a 0.03± 0.01 {(stat)} mag discrepancy in the distant supernova distance moduli relative to the ΛCDM model anchored by supernovae at z < 0.05. While there are known systematic uncertainties that combined could explain the observed offset, here we entertain the possibility that the discrepancy may instead be explained by scattering of supernova light in the intergalactic medium (IGM). We focus on two effects: Compton scattering by free electrons and extinction by dust in the IGM. We find that if the discrepancy is due entirely to dimming by dust, the measurements can be modeled with a cosmic dust density Ω _IGM^dust = 8 \\cdot 10^{-5} (1+z)^{-1}, corresponding to an average attenuation of 2 . 10-5 mag Mpc-1 in V-band. Forthcoming SN Ia studies may provide a definitive measurement of the IGM dust properties, while still providing an unbiased estimate of cosmological parameters by introducing additional parameters in the global fits to the observations.

  16. The cosmic transparency measured with Type Ia supernovae: implications for intergalactic dust

    NASA Astrophysics Data System (ADS)

    Goobar, Ariel; Dhawan, Suhail; Scolnic, Daniel

    2018-06-01

    Observations of high-redshift Type Ia supernovae (SNe Ia) are used to study the cosmic transparency at optical wavelengths. Assuming a flat Λ cold dark matter (ΛCDM) cosmological model based on baryon acoustic oscillations and cosmic microwave background measurements, redshift dependent deviations of SN Ia distances are used to constrain mechanisms that would dim light. The analysis is based on the most recent Pantheon SN compilation, for which there is a 0.03 ± 0.01 {({stat})} mag discrepancy in the distant supernova distance moduli relative to the ΛCDM model anchored by supernovae at z < 0.05. While there are known systematic uncertainties that combined could explain the observed offset, here we entertain the possibility that the discrepancy may instead be explained by scattering of supernova light in the intergalactic medium (IGM). We focus on two effects: Compton scattering by free electrons and extinction by dust in the IGM. We find that if the discrepancy is entirely due to dimming by dust, the measurements can be modelled with a cosmic dust density Ω _IGM^dust = 8 × 10^{-5} (1+z)^{-1}, corresponding to an average attenuation of 2 × 10-5 mag Mpc-1 in V band. Forthcoming SN Ia studies may provide a definitive measurement of the IGM dust properties, while still providing an unbiased estimate of cosmological parameters by introducing additional parameters in the global fits to the observations.

  17. Properties of the Intergalactic Magnetic Field Constrained by Gamma-Ray Observations of Gamma-Ray Bursts

    SciTech Connect

    Veres, P.; Dermer, C. D.; Dhuga, K. S.

    The magnetic field in intergalactic space gives important information about magnetogenesis in the early universe. The properties of this field can be probed by searching for radiation of secondary e {sup +} e {sup −} pairs created by TeV photons that produce GeV range radiation by Compton-scattering cosmic microwave background photons. The arrival times of the GeV “echo” photons depend strongly on the magnetic field strength and coherence length. A Monte Carlo code that accurately treats pair creation is developed to simulate the spectrum and time-dependence of the echo radiation. The extrapolation of the spectrum of powerful gamma-ray bursts (GRBs)more » like GRB 130427A to TeV energies is used to demonstrate how the intergalactic magnetic field can be constrained if it falls in the 10{sup −21}–10{sup −17} G range for a 1 Mpc coherence length.« less

  18. Fluctuations of the intergalactic ionization field at redshift z ~ 2

    NASA Astrophysics Data System (ADS)

    Agafonova, I. I.; Levshakov, S. A.; Reimers, D.; Hagen, H.-J.; Tytler, D.

    2013-04-01

    Aims: To probe the spectral energy distribution (SED) of the ionizing background radiation at z ≲ 2 and to specify the sources contributing to the intergalactic radiation field. Methods: The spectrum of a bright quasar HS 1103+6416 (zem = 2.19) contains five successive metal-line absorption systems at zabs = 1.1923, 1.7193, 1.8873, 1.8916, and 1.9410. The systems are optically thin and reveal multiple lines of different metal ions with the ionization potentials lying in the extreme ultraviolet (EUV) range (~1 Ryd to ~0.2 keV). For each system, the EUV SED of the underlying ionization field is reconstructed by means of a special technique developed for solving the inverse problem in spectroscopy. For the zabs = 1.8916 system, the analysis also involves the He I resonance lines of the Lyman series and the He iλ504 Å continuum, which are seen for the first time in any cosmic object except the Sun. Results: From one system to another, the SED of the ionizing continuum changes significantly, indicating that the intergalactic ionization field at z ≲ 2 fluctuates at the scale of at least Δz ~ 0.004. This is consistent with Δz ≲ 0.01 estimated from He II and H I Lyman-α forest measurements between the redshifts 2 and 3. A radiation intensity break by approximately an order of magnitude at E = 4 Ryd in SEDs restored for the zabs = 1.1923, 1.8873, 1.8916, and 1.9410 systems points to quasars as the main sources of the ionizing radiation. The SED variability is mostly caused by a small number of objects contributing at any given redshift to the ionizing background; at scales Δz ≳ 0.05, the influence of local radiation sources becomes significant. A remarkable SED restored for the zabs = 1.7193 system, with a sharp break shifted to E ~ 3.5 Ryd and a subsequent intensity decrease by ~1.5 dex, indicates a source with comparable inputs of both hard (active galactic nuclei, AGN) and soft (stellar) radiation components. Such a continuum can be emitted by (ultra

  19. Mountain Gem Russet: A medium to late season potato variety with high early and full season yield potential and excellent fresh market characteristics

    USDA-ARS?s Scientific Manuscript database

    Mountain Gem Russet is a medium to late maturing variety with both high early and full season yields of oblong-long, medium-russeted tubers having higher protein content than those of standard potato varieties. Mountain Gem Russet has greater resistance to tuber late blight, tuber malformations and ...

  20. Probing the interstellar medium in early-type galaxies with Infrared Space Oberservatory observations

    NASA Technical Reports Server (NTRS)

    Malhotra, S.; Hollenbach, D.; Helou, D.; Silbermann, N.; Valjavec, E.; Rubin, R.; Dale, D.; Hunter, D.; Lu, N.; Lord, S.; hide

    2000-01-01

    Four IRAS-detected early-type galaxies were observed with the Infrared Space Observatory (ISO). With the exception of the 15 mu m image of NGC 1052, the mid-IR images of NGC 1052, NGC 1155, NGC 5866, and NGC 6958 at 4.5, 7, and 15 mu m show extended emission.

  1. The warm-hot intergalactic medium at z ~ 2.2: Metal enrichment and ionization source

    NASA Astrophysics Data System (ADS)

    Bergeron, J.; Aracil, B.; Petitjean, P.; Pichon, C.

    2002-12-01

    Results are presented for our search for warm-hot gas towards the quasar Q 0329-385. We identify ten O VI systems of which two are within 5000 km s-1 of zem and a third one should be of intrinsic origin. The seven remaining systems have H I column densities 1013.7<=N (H I)<=1015.6 cm-2. At least ~ 1/3 of the individual O VI sub-systems have temperatures T < 1 x 105 K and cannot originate in collisionally ionized gas. Photoionization by a hard UV background field reproduces well the ionic ratios for metallicities in the range 10-2.5-10-0.5 solar, with possibly sub-solar N/C relative abundance. For [O/C]=0, the sizes inferred for the O VI clouds are in some cases larger than the maximum extent implied by the Hubble flow. This constraint is fulfilled assuming a moderate overabundance of oxygen relative to carbon. For a soft UV ionizing spectrum, an overabundance of O/C is required, [O/C]~ 0.0-1.3. For a hard(soft) U spectrum and [O/C]=0(1), the O VI regions have overdensities rho //lineρ ~ 10-40. Based on observations made at the European Southern Observatory (ESO), under prog. ID No. 166.A-0106(A), with the UVES spectrograph at the VLT, Paranal, Chile.

  2. A Snapshot Survey of AGNS/QSOS for Intergalactic Medium Studies

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Technical Monitor); Sembach, George

    2005-01-01

    This spectroscopic program with the Far Ultraviolet Spectroscopic Explorer (FUSE) program was designed to identify ultraviolet-bright active galactic nuclei (AGNs) and quasi-stellar objects (QSOs) for follow-up spectroscopy with FUSE and the Hubble Space Telescope (HST). All of the FUSE spectra obtained for this snapshot program (FUSE identifier D808) have been examined for data quality and flux levels. As expected, only a small number of objects observed (4/19) have flux levels suitable for follow-up spectroscopy. A portion of our effort in this program was devoted to comparing the spectra obtained in these snapshot exposures to others to determine if the spectra could be used for detailed scientific analyses. The resulting effort demonstrated that some of the brighter sources are relatively stable (non- variable), as determined through comparisons of the spectra at multiple epochs. For these brighter sources, the exposure times are simply too short to perform meaningful detailed analyses. Comparisons of the absorption lines in these spectra with those of higher signal-to-noise spectra, like those of PG1116+215 and H1821+643, showed that many of the lines of interest could not be characterized adequately at the S/N levels reached in the short snapshot exposures. As a result, the FUSE D808 observations are suitable only for their original purpose - flux determination. Several bright objects identified as part of this program include: HE0153-4520, flux >2x10E-14 erg cm^-2s^-1 at 1000 Angstroms IRASF04250-5718, flux >4x10E-14 erg cm^-2s^-1 A^-1 at 1000 Angstroms RXJ2154.1-4414, flux > 1.6x10E-14 erg cm^-2s^-1 A^-1 at 1000 Angstroms S50716+714, flux >2.5x10E-14 erg cm^-2s^-1 A^-1 at 1000 Angstroms. All of these objects have been incorporated into the primary target lists for the HST Cosmic Origins Spectrograph. Identifying such objects for follow-up observations with HST/COS was the primary goal of this program, so the program wa successful. In addition, some of the objects were included in proposed target lists for future FUSE observations. Given that the state of the FUSE observatory is uncertain at this time, it is unknown whether anyjof htese objects will be re-observed with FUSE. The results of this program have been communicated to the astronomical community via email and by word of mouth since the resuts in and of themselves do not warrant publication in an astronomical journal. However, these lists will be maintained for future observers. The data are archived in the Multi-Mission Archive at the Space Telescioe Science INstitute.

  3. WEAVE-QSO: A Massive Intergalactic Medium Survey for the William Herschel Telescope

    NASA Astrophysics Data System (ADS)

    Pieri, M. M.; Bonoli, S.; Chaves-Montero, J.; Pâris, I.; Fumagalli, M.; Bolton, J. S.; Viel, M.; Noterdaeme, P.; Miralda-Escudé, J.; Busca, N. G.; Rahmani, H.; Peroux, C.; Font-Ribera, A.; Trager, S. C.

    2016-12-01

    In these proceedings we describe the WEAVE-QSO survey, which will observe around 400,000 high redshift quasars starting in 2018. This survey is part of a broader WEAVE survey to be conducted at the 4.2m William Herschel Telescope. We will focus on chiefly on the science goals, but will also briefly summarise the target selection methods anticipated and the expected survey plan. Understanding the apparent acceleration in the expansion of the Universe is one of the key scientific challenges of our time. Many experiments have been proposed to study this expansion, using a variety of techniques. Here we describe a survey that can measure this acceleration and therefore help elucidate the nature of dark energy: a survey of the Lyα forest (and quasar absorption in general) in spectra towards z>2 quasars (QSOs). Further constraints on neutrino masses and warm dark matter are also anticipated. The same data will also shed light on galaxy formation via study of the properties of inflowing/outflowing gas associated with nearby galaxies and in a cosmic web context. Gas properties are sensitive to density, temperature, UV radiation, metallicity and abundance pattern, and so constraint galaxy formation in a variety of ways. WEAVE-QSO will study absorbers with a dynamic range spanning more than 8 orders of magnitude in column density, their thermal broadening, and a host of elements and ionization species. A core principal of the WEAVE-QSO survey is the targeting of QSOs with near 100% efficiency principally through use of the J-PAS (r < 23.2) and Gaia (r ≲ 20) data.

  4. Cosmic Carbon Chemistry: From the Interstellar Medium to the Early Earth

    PubMed Central

    Ehrenfreund, Pascale; Cami, Jan

    2010-01-01

    Astronomical observations have shown that carbonaceous compounds in the gas and solid state, refractory and icy are ubiquitous in our and distant galaxies. Interstellar molecular clouds and circumstellar envelopes are factories of complex molecular synthesis. A surprisingly large number of molecules that are used in contemporary biochemistry on Earth are found in the interstellar medium, planetary atmospheres and surfaces, comets, asteroids and meteorites, and interplanetary dust particles. In this article we review the current knowledge of abundant organic material in different space environments and investigate the connection between presolar and solar system material, based on observations of interstellar dust and gas, cometary volatiles, simulation experiments, and the analysis of extraterrestrial matter. Current challenges in astrochemistry are discussed and future research directions are proposed. PMID:20554702

  5. The metallicity of the intracluster medium over cosmic time: further evidence for early enrichment

    NASA Astrophysics Data System (ADS)

    Mantz, Adam B.; Allen, Steven W.; Morris, R. Glenn; Simionescu, Aurora; Urban, Ondrej; Werner, Norbert; Zhuravleva, Irina

    2017-12-01

    We use Chandra X-ray data to measure the metallicity of the intracluster medium (ICM) in 245 massive galaxy clusters selected from X-ray and Sunyaev-Zel'dovich (SZ) effect surveys, spanning redshifts 0 < z < 1.2. Metallicities were measured in three different radial ranges, spanning cluster cores through their outskirts. We explore trends in these measurements as a function of cluster redshift, temperature and surface brightness 'peakiness' (a proxy for gas cooling efficiency in cluster centres). The data at large radii (0.5-1 r500) are consistent with a constant metallicity, while at intermediate radii (0.1-0.5 r500) we see a late-time increase in enrichment, consistent with the expected production and mixing of metals in cluster cores. In cluster centres, there are strong trends of metallicity with temperature and peakiness, reflecting enhanced metal production in the lowest entropy gas. Within the cool-core/sharply peaked cluster population, there is a large intrinsic scatter in central metallicity and no overall evolution, indicating significant astrophysical variations in the efficiency of enrichment. The central metallicity in clusters with flat surface brightness profiles is lower, with a smaller intrinsic scatter, but increases towards lower redshifts. Our results are consistent with other recent measurements of ICM metallicity as a function of redshift. They reinforce the picture implied by observations of uniform metal distributions in the outskirts of nearby clusters, in which most of the enrichment of the ICM takes place before cluster formation, with significant later enrichment taking place only in cluster centres, as the stellar populations of the central galaxies evolve.

  6. The metallicity of the intracluster medium over cosmic time: further evidence for early enrichment

    DOE PAGES

    Mantz, Adam B.; Allen, Steven W.; Morris, R. Glenn; ...

    2017-08-26

    Here, we use Chandra X-ray data to measure the metallicity of the intracluster medium (ICM) in 245 massive galaxy clusters selected from X-ray and Sunyaev–Zel'dovich (SZ) effect surveys, spanning redshifts 0 < z < 1.2. Metallicities were measured in three different radial ranges, spanning cluster cores through their outskirts. We explore trends in these measurements as a function of cluster redshift, temperature and surface brightness ‘peakiness’ (a proxy for gas cooling efficiency in cluster centres). The data at large radii (0.5–1 r500) are consistent with a constant metallicity, while at intermediate radii (0.1–0.5 r500) we see a late-time increase inmore » enrichment, consistent with the expected production and mixing of metals in cluster cores. In cluster centres, there are strong trends of metallicity with temperature and peakiness, reflecting enhanced metal production in the lowest entropy gas. Within the cool-core/sharply peaked cluster population, there is a large intrinsic scatter in central metallicity and no overall evolution, indicating significant astrophysical variations in the efficiency of enrichment. The central metallicity in clusters with flat surface brightness profiles is lower, with a smaller intrinsic scatter, but increases towards lower redshifts. Our results are consistent with other recent measurements of ICM metallicity as a function of redshift. They reinforce the picture implied by observations of uniform metal distributions in the outskirts of nearby clusters, in which most of the enrichment of the ICM takes place before cluster formation, with significant later enrichment taking place only in cluster centres, as the stellar populations of the central galaxies evolve.« less

  7. Statistical techniques for detecting the intergalactic magnetic field from large samples of extragalactic Faraday rotation data

    SciTech Connect

    Akahori, Takuya; Gaensler, B. M.; Ryu, Dongsu, E-mail: akahori@physics.usyd.edu.au, E-mail: bryan.gaensler@sydney.edu.au, E-mail: ryu@sirius.unist.ac.kr

    2014-08-01

    Rotation measure (RM) grids of extragalactic radio sources have been widely used for studying cosmic magnetism. However, their potential for exploring the intergalactic magnetic field (IGMF) in filaments of galaxies is unclear, since other Faraday-rotation media such as the radio source itself, intervening galaxies, and the interstellar medium of our Galaxy are all significant contributors. We study statistical techniques for discriminating the Faraday rotation of filaments from other sources of Faraday rotation in future large-scale surveys of radio polarization. We consider a 30° × 30° field of view toward the south Galactic pole, while varying the number of sources detectedmore » in both present and future observations. We select sources located at high redshifts and toward which depolarization and optical absorption systems are not observed so as to reduce the RM contributions from the sources and intervening galaxies. It is found that a high-pass filter can satisfactorily reduce the RM contribution from the Galaxy since the angular scale of this component toward high Galactic latitudes would be much larger than that expected for the IGMF. Present observations do not yet provide a sufficient source density to be able to estimate the RM of filaments. However, from the proposed approach with forthcoming surveys, we predict significant residuals of RM that should be ascribable to filaments. The predicted structure of the IGMF down to scales of 0.°1 should be observable with data from the Square Kilometre Array, if we achieve selections of sources toward which sightlines do not contain intervening galaxies and RM errors are less than a few rad m{sup –2}.« less

  8. A new measurement of the intergalactic temperature at z ˜ 2.55-2.95

    NASA Astrophysics Data System (ADS)

    Rorai, Alberto; Carswell, Robert F.; Haehnelt, Martin G.; Becker, George D.; Bolton, James S.; Murphy, Michael T.

    2018-03-01

    We present two measurements of the temperature-density relationship (TDR) of the intergalactic medium (IGM) in the redshift range 2.55 < z < 2.95 using a sample of 13 high-quality quasar spectra and high resolution numerical simulations of the IGM. Our approach is based on fitting the neutral hydrogen column density N_{H I} and the Doppler parameter b of the absorption lines in the Lyα forest. The first measurement is obtained using a novel Bayesian scheme that takes into account the statistical correlations between the parameters characterizing the lower cut-off of the b-N_{H I} distribution and the power-law parameters T0 and γ describing the TDR. This approach yields T0/103 K = 15.6 ± 4.4 and γ = 1.45 ± 0.17 independent of the assumed pressure smoothing of the small-scale density field. In order to explore the information contained in the overall b-N_{H I} distribution rather than only the lower cut-off, we obtain a second measurement based on a similar Bayesian analysis of the median Doppler parameter for separate column-density ranges of the absorbers. In this case, we obtain T0/103 K = 14.6 ± 3.7 and γ = 1.37 ± 0.17 in good agreement with the first measurement. Our Bayesian analysis reveals strong anticorrelations between the inferred T0 and γ for both methods as well as an anticorrelation of the inferred T0 and the pressure smoothing length for the second method, suggesting that the measurement accuracy can in the latter case be substantially increased if independent constraints on the smoothing are obtained. Our results are in good agreement with other recent measurements of the thermal state of the IGM probing similar (over-)density ranges.

  9. Multifrequency survey of the intergalactic cloud in the M96 group

    NASA Technical Reports Server (NTRS)

    Schneider, Stephen E.; Skrutskie, M. F.; Hacking, Perry B.; Young, Judith S.; Dickman, Robert L.

    1989-01-01

    The intergalactic cloud of neutral hydrogen in the M96 group are examined for signs of emission over a wide range of frequencies, from radio waves to X rays. Past or present stellar activity in the gas might have been expected to produce detectable visual infrared, CO, OH, or radio recombination-line emission. None was detected. The limits are used to study physical conditions in the intergalactic gas. In particular, B and V band limits on starlight and IRAS limits on the presence of dust strongly constrain the presence of stars or stellar by-products. However, given the uncertainties about physical conditions in the intergalactic environment, it is difficult to rule out entirely the presence of stellar-processed materials. Results of neutral hydrogen mapping from a large-scale survey of the intergalactic cloud and surrounding region are also presented. These observations confirm that the gas is confined to a large ringlike structure. The simplest interpretation remains that the intergalactic gas in Leo is primordial.

  10. Planck early results. XXIV. Dust in the diffuse interstellar medium and the Galactic halo

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Abergel, A.; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Blagrave, K.; Bock, J. J.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Cabella, P.; Cantalupo, C. M.; Cardoso, J.-F.; Catalano, A.; Cayón, L.; Challinor, A.; Chamballu, A.; Chiang, L.-Y.; Chiang, C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Couchot, F.; Coulais, A.; Crill, B. P.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Gasperis, G.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dickinson, C.; Donzelli, S.; Doré, O.; Dörl, U.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hovest, W.; Hoyland, R. J.; Huffenberger, K. M.; Jaffe, A. H.; Joncas, G.; Jones, A.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knox, L.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Leach, S.; Leonardi, R.; Leroy, C.; Linden-Vørnle, M.; Lockman, F. J.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; MacTavish, C. J.; Maffei, B.; Maino, D.; Mandolesi, N.; Mann, R.; Maris, M.; Marshall, D. J.; Martin, P.; Martínez-González, E.; Masi, S.; Matarrese, S.; Matthai, F.; Mazzotta, P.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; O'Dwyer, I. J.; Osborne, S.; Pajot, F.; Paladini, R.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pinheiro Gonçalves, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Poutanen, T.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Reinecke, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, P.; Smoot, G. F.; Starck, J.-L.; Stivoli, F.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Torre, J.-P.; Tristram, M.; Tuovinen, J.; Umana, G.; Valenziano, L.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Wilkinson, A.; Yvon, D.; Zacchei, A.; Zonca, A.

    2011-12-01

    This paper presents the first results from a comparison of Planck dust maps at 353, 545 and 857GHz, along with IRAS data at 3000 (100 μm) and 5000GHz (60 μm), with Green Bank Telescope 21-cm observations of Hi in 14 fields covering more than 800 deg2 at high Galactic latitude. The main goal of this study is to estimate the far-infrared to sub-millimeter (submm) emissivity of dust in the diffuse local interstellar medium (ISM) and in the intermediate-velocity (IVC) and high-velocity clouds (HVC) of the Galactic halo. Galactic dust emission for fields with average Hi column density lower than 2 × 1020 cm-2 is well correlated with 21-cm emission because in such diffuse areas the hydrogen is predominantly in the neutral atomic phase. The residual emission in these fields, once the Hi-correlated emission is removed, is consistent with the expected statistical properties of the cosmic infrared background fluctuations. The brighter fields in our sample, with an average Hi column density greater than 2 × 1020 cm-2, show significant excess dust emission compared to the Hi column density. Regions of excess lie in organized structures that suggest the presence of hydrogen in molecular form, though they are not always correlated with CO emission. In the higher Hi column density fields the excess emission at 857 GHz is about 40% of that coming from the Hi, but over all the high latitude fields surveyed the molecular mass faction is about 10%. Dust emission from IVCs is detected with high significance by this correlation analysis. Its spectral properties are consistent with, compared to the local ISM values, significantly hotter dust (T ~ 20K), lower submm dust opacity normalized per H-atom, and a relative abundance of very small grains to large grains about four times higher. These results are compatible with expectations for clouds that are part of the Galactic fountain in which there is dust shattering and fragmentation. Correlated dust emission in HVCs is not detected

  11. Influences on Early and Medium-Term Survival Following Surgical Repair of the Aortic Arch

    PubMed Central

    Bashir, Mohamad; Field, Mark; Shaw, Matthew; Fok, Matthew; Harrington, Deborah; Kuduvalli, Manoj; Oo, Aung

    2014-01-01

    .3% versus 4.9%, P > 0.99), and prolonged ventilation (8.6% versus 16.1%, P = 0.09). Overall mortality was 20.9% at 5 years, while it was 15.7% in the elective hemiarch and 25.9% in the total arch group (P = 0.065). Process control charts demonstrated stability of annualized mortality outcomes over the study period. Survival curve was flat and parallel compared to age- and sex-matched controls beyond 2 years. Multivariate analysis demonstrated the following independent factors associated with survival: renal dysfunction [hazard ratio (HR) = 3.11; 95% confidence interval (CI) = 1.44-6.73], New York Heart Association (NYHA) class ≥ III (HR = 2.25; 95% CI = 1.38-3.67), circulatory arrest time > 100 minutes (HR = 2.92; 95% CI = 1.57-5.43), peripheral vascular disease (HR = 2.44; 95% CI = 1.25-4.74), and concomitant coronary artery bypass graft operation (HR = 2.14; 95% CI = 1.20-3.80). Conclusions: Morbidity, mortality, and medium-term survival were not statistically different for patients undergoing elective hemi-aortic arch and total aortic arch surgery. The survival curve in this group of patients is flat and parallel to sex- and age-matched controls beyond 2 years. Multivariate analysis identified independent influences on survival as renal dysfunction, NYHA class ≥ III, circulatory arrest time (> 100 min), peripheral vascular disease, and concomitant coronary artery bypass grafting. Focus on preoperative optimization of some of these variables may positively influence long-term survival. PMID:26798716

  12. Far Ultraviolet Spectroscopy of the Intergalactic and Interstellar Absorption Toward 3C 273

    NASA Technical Reports Server (NTRS)

    Sembach, Kenneth R.; Howk, J. Christopher; Savage, Blair D.; Shull, J. Michael; Oegerle, William R.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We present Far Ultraviolet Spectroscopic Explorer observations of the molecular, neutral atomic, weakly ionized, and highly ionized components of the interstellar and intergalactic material toward the quasar 3C273. We identify Ly-beta absorption in eight of the known intergalactic Ly-alpha absorbers along the sight line with the rest-frame equivalent widths W(sub r)(Ly-alpha) > 50 micro-angstroms. Refined estimates of the H(I) column densities and Doppler parameters (b) of the clouds are presented. We find a range of b = 16-46 km/s. We detect multiple H(I) lines (Ly-beta - Ly-theta) in the 1590 km/s Virgo absorber and estimate logN(H(I)) = 15.85 +/- 0.10, ten times more H(I) than all of the other absorbers along the sight line combined. The Doppler width of this absorber, b = 16 km/s, implies T < 15,000 K. We detect O(VI) absorption at 1015 km/s at the 2-3(sigma) level that may be associated with hot, X-ray emitting gas in the Virgo Cluster. We detect weak C(III) and O(VI) absorption in the IGM at z=0.12007; this absorber is predominantly ionized and has N(H+)/N(H(I)) > 4000/Z, where Z is the metallicity. Strong Galactic interstellar O(VI) is present between -100 and +100 km/s with an additional high-velocity wing containing about 13% of the total O(VI) between +100 and +240 km/s. The Galactic O(VI), N(V), and C(IV) lines have similar shapes, with roughly constant ratios across the -100 to +100 km/s velocity range. The high velocity O(VI) wing is not detected in other species. Much of the interstellar high ion absorption probably occurs within a highly fragmented medium within the Loop IV remnant or in the outer cavity walls of the remnant. Multiple hot gas production mechanisms are required. The broad O(VI) absorption wing likely traces the expulsion of hot gas out of the Galactic disk into the halo. A flux limit of 5.4 x 10(epx -16) erg/sq cm/s on the amount of diffuse O(VI) emission present = 3.5' off the 3C273 sight line combined with the observed O(VI) column

  13. Conditioned Medium from Early-Outgrowth Bone Marrow Cells Is Retinal Protective in Experimental Model of Diabetes

    PubMed Central

    Duarte, Diego A.; Papadimitriou, Alexandros; Gilbert, Richard E.; Thai, Kerri; Zhang, Yanling; Rosales, Mariana A. B.; Lopes de Faria, José B.; Lopes de Faria, Jacqueline M.

    2016-01-01

    Bone marrow-derived cells were demonstrated to improve organ function, but the lack of cell retention within injured organs suggests that the protective effects are due to factors released by the cells. Herein, we tested cell therapy using early outgrowth cells (EOCs) or their conditioned media (CM) to protect the retina of diabetic animal models (type 1 and type 2) and assessed the mechanisms by in vitro study. Control and diabetic (db/db) mice (8 weeks of age) were randomized to receive a unique intravenous injection of 5×105EOCs or 0.25 ml thrice weekly tail-vein injections of 10x concentrated CM and Wystar Kyoto rats rendered diabetic were randomized to receive 0.50 ml thrice weekly tail-vein injections of 10x concentrated CM. Four weeks later, the animals were euthanized and the eyes were enucleated. Rat retinal Müller cells (rMCs) were exposed for 24 h to high glucose (HG), combined or not with EOC-conditioned medium (EOC-CM) from db/m EOC cultures. Diabetic animals showed increase in diabetic retinopathy (DR) and oxidative damage markers; the treatment with EOCs or CM infusions significantly reduced this damage and re-established the retinal function. In rMCs exposed to diabetic milieu conditions (HG), the presence of EOC-CM reduced reactive oxygen species production by modulating the NADPH-oxidase 4 system, thus upregulating SIRT1 activity and deacetylating Lys-310-p65-NFκB, decreasing GFAP and VEGF expressions. The antioxidant capacity of EOC-CM led to the prevention of carbonylation and nitrosylation posttranslational modifications on the SIRT1 molecule, preserving its activity. The pivotal role of SIRT1 on the mode of action of EOCs or their CM was also demonstrated on diabetic retina. These findings suggest that EOCs are effective as a form of systemic delivery for preventing the early molecular markers of DR and its conditioned medium is equally protective revealing a novel possibility for cell-free therapy for the treatment of DR. PMID:26836609

  14. Elastic light scattering for clinical pathogens identification: application to early screening of Staphylococcus aureus on specific medium

    NASA Astrophysics Data System (ADS)

    Schultz, E.; Genuer, V.; Marcoux, P.; Gal, O.; Belafdil, C.; Decq, D.; Maurin, Max; Morales, S.

    2018-02-01

    Elastic Light Scattering (ELS) is an innovative technique to identify bacterial pathogens directly on culture plates. Compelling results have already been reported for agri-food applications. Here, we have developed ELS for clinical diagnosis, starting with Staphylococcus aureus early screening. Our goal is to bring a result (positive/negative) after only 6 h of growth to fight surgical-site infections. The method starts with the acquisition of the scattering pattern arising from the interaction between a laser beam and a single bacterial colony growing on a culture medium. Then, the resulting image, considered as the bacterial species signature, is analyzed using statistical learning techniques. We present a custom optical setup able to target bacterial colonies with various sizes (30-500 microns). This system was used to collect a reference dataset of 38 strains of S. aureus and other Staphyloccocus species (5459 images) on ChromIDSAID/ MRSA bi-plates. A validation set from 20 patients has then been acquired and clinically-validated according to chromogenic enzymatic tests. The best correct-identification rate between S. aureus and S. non-aureus (94.7%) has been obtained using a support vector machine classifier trained on a combination of Fourier-Bessel moments and Local- Binary-Patterns extracted features. This statistical model applied to the validation set provided a sensitivity and a specificity of 90.0% and 56.9%, or alternatively, a positive predictive value of 47% and a negative predictive value of 93%. From a clinical point of view, the results head in the right direction and pave the way toward the WHO's requirements for rapid, low-cost, and automated diagnosis tools.

  15. Angular Distribution of Ly(alpha) Resonant Photons Emergent from Optically Thick Medium

    DTIC Science & Technology

    2012-02-26

    cosmology : theory - intergalactic medium - radiation transfer - scattering 1Division of Applied Mathematics, Brown University, Providence, RI 02912, USA...It definitely cannot be described by the Eddington approximation. The evolution of the angular distribution of resonant photons is not trivial. We

  16. Mid-Infrared Observations of Possible Intergalactic Star Forming Regions in the Leo Ring

    NASA Astrophysics Data System (ADS)

    Giroux, Mark; Smith, B.; Struck, C.

    2011-05-01

    Within the Leo group of galaxies lies a gigantic loop of intergalactic gas known as the Leo Ring. Not clearly associated with any particular galaxy, its origin remains uncertain. It may be a primordial intergalactic cloud alternatively, it may be a collision ring, or have a tidal origin. Combining archival Spitzer images of this structure with published UV and optical data, we investigate the mid-infrared properties of possible knots of star formation in the ring. These sources are very faint in the mid-infrared compared to star forming regions in the tidal features of interacting galaxies. This suggests they are either deficient in dust, or they may not be associated with the ring.

  17. The Growth of Early Galaxies and Reionization of Hydrogen

    NASA Astrophysics Data System (ADS)

    Chary, Ranga Ram

    2012-07-01

    The reionization of the intergalactic medium about a billion years after the Big Bang was an important event which occurred due to the release of ionizing photons from the growth of stellar mass and black holes in the early Universe. By leveraging the benefits of field galaxy surveys, I will present some recent breakthroughs in our understanding of how the earliest galaxies in the Universe evolved. I will present evidence that unlike in the local Universe where galaxy growth occurs through intermittent cannibalism, star-formation in the distant Universe is a more continuous if violent process with an overabundance of massive stars. Implications for the reionization history of the Universe will also be discussed.

  18. Bilingual Children as Policy Agents: Language Policy and Education Policy in Minority Language Medium Early Childhood Education and Care

    ERIC Educational Resources Information Center

    Bergroth, Mari; Palviainen, Åsa

    2017-01-01

    The current study examines bilingual children as language policy agents in the interplay between official language policy and education policy at three Swedish-medium preschools in Finland. For this purpose we monitored nine Finnish-Swedish bilingual children aged 3 to 5 years for 18 months. The preschools were located in three different parts of…

  19. Morphological evolution of the southwestern Black Sea coast of Turkey since the early 2000s: medium- vs. short-term changes

    NASA Astrophysics Data System (ADS)

    LiBassi, Nick; Özener, Haluk; Otay, Emre; Doğru, Aslı

    2018-06-01

    Coastal zones are in a state of continual flux worldwide, due in part to seasonal factors and in part to influences operating over longer periods of time. Discerning changes on different timescales remains a challenge. This study compares shoreline position and nearshore bathymetry over a time interval of 16 years in order to determine the extent of medium-term changes in comparison with short-term changes along the southwestern Black Sea coast of Turkey near Kilyos. For this purpose the results of surveys completed in 2001 and 2002 are compared with data collected in December 2015, September 2016, and March 2017 at the same location using a differential global positioning system (DGPS) in real-time kinematic (RTK) configuration combined with echo-sounder profiling. Average shoreline recession over the 16-year period (medium term) has been estimated at 3-4 cm/year as opposed to an average of 9.5 m in the 12-month period from June 2001 to June 2002 (short term). The medium-term nearshore sediment loss has been approx. 100-125 m3/m shoreline since the early 2000s. Over the same period a prominent offshore bar has moved seaward at a maximum rate of 1 m/year since 2002. Considering the large discrepancy in the shoreline recession rates recorded in the short and medium term, this aspect must be taken into account in any integrated coastal zone management strategy.

  20. Morphological evolution of the southwestern Black Sea coast of Turkey since the early 2000s: medium- vs. short-term changes

    NASA Astrophysics Data System (ADS)

    LiBassi, Nick; Özener, Haluk; Otay, Emre; Doğru, Aslı

    2017-12-01

    Coastal zones are in a state of continual flux worldwide, due in part to seasonal factors and in part to influences operating over longer periods of time. Discerning changes on different timescales remains a challenge. This study compares shoreline position and nearshore bathymetry over a time interval of 16 years in order to determine the extent of medium-term changes in comparison with short-term changes along the southwestern Black Sea coast of Turkey near Kilyos. For this purpose the results of surveys completed in 2001 and 2002 are compared with data collected in December 2015, September 2016, and March 2017 at the same location using a differential global positioning system (DGPS) in real-time kinematic (RTK) configuration combined with echo-sounder profiling. Average shoreline recession over the 16-year period (medium term) has been estimated at 3-4 cm/year as opposed to an average of 9.5 m in the 12-month period from June 2001 to June 2002 (short term). The medium-term nearshore sediment loss has been approx. 100-125 m3/m shoreline since the early 2000s. Over the same period a prominent offshore bar has moved seaward at a maximum rate of 1 m/year since 2002. Considering the large discrepancy in the shoreline recession rates recorded in the short and medium term, this aspect must be taken into account in any integrated coastal zone management strategy.

  1. Fluctuations in microwave background radiation due to secondary ionization of the intergalactic gas in the universe

    NASA Technical Reports Server (NTRS)

    Sunyayev, R. A.

    1979-01-01

    Secondary heating and ionization of the intergalactic gas at redshifts z approximately 10-30 could lead to the large optical depth of the Universe for Thomson scattering and could smooth the primordial fluctuations formed at z approximately 1500. It is shown that the gas motions connected with the large scale density perturbations at z approximately 10-15 must lead to the generation of secondary fluctuations of microwave background. The contribution of the rich clusters of galaxies and young galaxies to the fluctuations of microwave background is also estimated.

  2. An Increased Dietary Supply of Medium-Chain Fatty Acids during Early Weaning in Rodents Prevents Excessive Fat Accumulation in Adulthood

    PubMed Central

    van de Heijning, Bert J. M.; Oosting, Annemarie; Kegler, Diane; van der Beek, Eline M.

    2017-01-01

    Medium-chain fatty acids (MCFA) are a directly and readily absorbed source of energy. Exposure early-in-life to increased MCFA levels might affect development and impact (lipid) metabolism later in life. We tested whether an increased MCFA intake early-in-life positively affects adult body composition and metabolic status when challenged by a western-style diet (WSD). Male offspring of C57Bl/6j mice and Wistar rats were fed a control diet (CTRL; 10 w% fat, 14% MCFA) or a medium-chain triglycerides (MCT) diet with 20% MCFA until postnatal (PN) day 42, whereupon animals were fed a WSD (10 w% fat) until PN day 98. Body composition was monitored by Dual Energy X-ray Absorptiometry (DEXA). In rats, glucose homeostasis was assessed by glucose tolerance test (GTT) and insulin tolerance test (ITT); in mice, the HOmeostasis Model Assessment of Insulin Resistance (HOMA-IR) was calculated. At autopsy on PN day 98, plasma lipid profiles, glucose, insulin, and adipokines were measured; organs and fat pads were collected and the adipocyte size distribution was analysed. Milk analysis in mice showed that the maternal MCT diet was not translated into milk, and pups were thus only exposed to high MCT levels from early weaning onward: PN day 16 until 42. Mice exposed to MCT showed 28% less fat accumulation vs. CTRL during WSD. The average adipocyte cell size, fasting plasma triglycerides (TG), and leptin levels were reduced in MCT mice. In rats, no effects were found on the adult body composition, but the adipocyte cell size distribution shifted towards smaller adipocytes. Particularly mice showed positive effects on glucose homeostasis and insulin sensitivity. Increased MCFA intake early-in-life protected against the detrimental effects of an obesogenic diet in adulthood. PMID:28632178

  3. Evaluation of medium-term consequences of implementing commercial computerized physician order entry and clinical decision support prescribing systems in two ‘early adopter’ hospitals

    PubMed Central

    Cresswell, Kathrin M; Bates, David W; Williams, Robin; Morrison, Zoe; Slee, Ann; Coleman, Jamie; Robertson, Ann; Sheikh, Aziz

    2014-01-01

    Objective To understand the medium-term consequences of implementing commercially procured computerized physician order entry (CPOE) and clinical decision support (CDS) systems in ‘early adopter’ hospitals. Materials and methods In-depth, qualitative case study in two hospitals using a CPOE or a CDS system for at least 2 years. Both hospitals had implemented commercially available systems. Hospital A had implemented a CPOE system (with basic decision support), whereas hospital B invested additional resources in a CDS system that facilitated order entry but which was integrated with electronic health records and offered more advanced CDS. We used a combination of documentary analysis of the implementation plans, audiorecorded semistructured interviews with system users, and observations of strategic meetings and systems usage. Results We collected 11 documents, conducted 43 interviews, and conducted a total of 21.5 h of observations. We identified three major themes: (1) impacts on individual users, including greater legibility of prescriptions, but also some accounts of increased workloads; (2) the introduction of perceived new safety risks related to accessibility and usability of hardware and software, with users expressing concerns that some problems such as duplicate prescribing were more likely to occur; and (3) realizing organizational benefits through secondary uses of data. Conclusions We identified little difference in the medium-term consequences of a CPOE and a CDS system. It is important that future studies investigate the medium- and longer-term consequences of CPOE and CDS systems in a wider range of hospitals. PMID:24431334

  4. Must is a Four Letter Word: The Role of Plasma Instabilities in the Intergalactic Magnetic Field Story

    NASA Astrophysics Data System (ADS)

    Broderick, Avery

    2014-06-01

    The detection of inverse Compton halos from cosmological TeV sources provide a direct means to constrain the putative intergalactic magnetic field. However, the converse may not be the case! The fate of the pairs generated by TeV gamma rays annihilating on the extragalactic background light is presently unclear, clouded by the possibility that cosmological scale plasma instabilities may dominate their energetic evolution. I will briefly motivate these plasma instabilities theoretically, summarize some empirical evidence that they may be occurring in practice, and assess their potential impact upon studies of intergalactic magnetic fields.

  5. Ultraviolet studies of the intergalactic medium, active galactic nuclei, and the low-z Ly-alpha forest

    NASA Astrophysics Data System (ADS)

    Penton, Steven Victor

    1999-05-01

    A database of all active galactic nuclei (AGN) observed with the International Ultraviolet Explorer (IUE, 1976-1995) was created to determine the brightest UV (1250 Å) extragalactic sources. Combined spectra, and continuum lightcurves are available for ~700 AGN. Fifteen targets were selected from this database for observation of the low-z Lyα forest with the Hubble Space Telescope. These observations were taken with the Goddard High Resolution spectrograph and the G160M grating (1991-1997). 111 significance level >3σ Lyα absorbers were detected in the redshift range, 0.002 < z < 0.069. This Thesis evaluates the physical properties of these Lyα absorbers and compares them to their high-z counterparts. In addition, we use large galaxy catalogs (i.e. the CfA Redshift Survey) to compare the relationship between known galaxies and the low-z Lyα forest. We find that the low-z absorbers are similar in physical characteristic and density to those detected at high- z. Some of these clouds appear to be primordial matter, owing to the lack of detected metallicity. A comparison to the known galaxy distribution indicates that the low-z Lyα forest clusters less than galaxies, but more than random. This suggests that at least a fraction of the absorbers are associated with the gas in galaxy associations (i.e. filaments), while a second population is distributed more uniformly. Over equal pathlengths (cΔz ~60,000 km s -1 each) of galaxy-rich and galaxy-poor environments (voids), we determine that 80% of Lyα absorbers are near large-scale galactic structures (i.e. filaments), while 20% are in galaxy voids.

  6. Resolving the Structure of Ionized Helium in the Intergalactic Medium with the Far Ultraviolet Spectroscopic Explorer. 2.3

    NASA Technical Reports Server (NTRS)

    Kriss, G. A.; Shull, J. M.; Oegerle, W.; Zheng, W.; Davidsen, A. F.; Songaila, A.; Tumlinson, J.; Cowie, L. L.; Dehavreng, J.-M.; Friedman, S. D.

    2001-01-01

    The neutral hydrogen and the ionized helium absorption in the spectra of high-redshift quasi-stellar objects (QSOs) are unique probes of structure in the universe at epochs intermediate between the earliest density fluctuations seen in the cosmic background radiation and the distribution of galaxies visible today. We present Far-Ultraviolet Spectroscopic Explorer (FUSE) observations of the line of sight to the QSO HE2347-4342 in the 1000-1187 angstrom band at a resolving power of 15,000. Above redshift z = 2.7, the IGM is largely opaque in He II Ly-alpha (304 angstroms). At lower redshifts, the optical depth gradually decreases to a mean value tau = 1 at z = 2.4. We resolve the He II Ly-alpha absorption as a discrete forest of absorption lines in the z = 2.3 - 2.7 redshift range. Approximately 50% of these spectral features have H I counterparts with column densities N(sub HI) > 10(exp 12.3)/sq cm visible in a Keck spectrum. These account for most of the observed opacity in He II Ly-alpha. The remainder have N(sub HI) < 10(exp 12.3)/sq cm, below the threshold for current observations. A short extrapolation of the power-law distribution of H I column densities to lower values can account for these new absorbers. The He II to H I column density ratio eta averages approximately 80, consistent with photoionization of the IGM by a hard ionizing spectrum resulting from the integrated light of quasars at high redshift, but there is considerable scatter. Values of eta > 100 in many locations indicate that there may be localized contributions from starbursts or heavily filtered QSO radiation.

  7. Search for early gamma-ray production in supernovae located in a dense circumstellar medium with the Fermi Lat

    DOE PAGES

    Ackermann, M.; Arcavi, I.; Baldini, L.; ...

    2015-07-09

    Supernovae (SNe) exploding in a dense circumstellar medium (CSM) are hypothesized to accelerate cosmic rays in collisionless shocks and emit GeV γ-rays and TeV neutrinos on a timescale of several months. We perform the first systematic search for γ-ray emission in Fermi Large Area Telescope data in the energy range frommore » $$100\\;\\mathrm{MeV}$$ to $$300\\;\\mathrm{GeV}$$ from the ensemble of 147 SNe Type IIn exploding in a dense CSM. Here, we search for a γ-ray excess at each SNe location in a one-year time window. In order to enhance a possible weak signal, we simultaneously study the closest and optically brightest sources of our sample in a joint-likelihood analysis in three different time windows (1 year, 6 months, and 3 months). For the most promising source of the sample, SN 2010jl (PTF 10aaxf), we repeat the analysis with an extended time window lasting 4.5 years. We do not find a significant excess in γ-rays for any individual source nor for the combined sources and provide model-independent flux upper limits for both cases. Additionally, we derive limits on the γ-ray luminosity and the ratio of γ-ray-to-optical luminosity ratio as a function of the index of the proton injection spectrum assuming a generic γ-ray production model. Furthermore, we present detailed flux predictions based on multi-wavelength observations and the corresponding flux upper limit at a 95% confidence level (CL) for the source SN 2010jl (PTF 10aaxf).« less

  8. Medium-range predictability of early summer sea ice thickness distribution in the East Siberian Sea based on the TOPAZ4 ice-ocean data assimilation system

    NASA Astrophysics Data System (ADS)

    Nakanowatari, Takuya; Inoue, Jun; Sato, Kazutoshi; Bertino, Laurent; Xie, Jiping; Matsueda, Mio; Yamagami, Akio; Sugimura, Takeshi; Yabuki, Hironori; Otsuka, Natsuhiko

    2018-06-01

    Accelerated retreat of Arctic Ocean summertime sea ice has focused attention on the potential use of the Northern Sea Route (NSR), for which sea ice thickness (SIT) information is crucial for safe maritime navigation. This study evaluated the medium-range (lead time below 10 days) forecast of SIT distribution in the East Siberian Sea (ESS) in early summer (June-July) based on the TOPAZ4 ice-ocean data assimilation system. A comparison of the operational model SIT data with reliable SIT estimates (hindcast, satellite and in situ data) showed that the TOPAZ4 reanalysis qualitatively reproduces the tongue-like distribution of SIT in ESS in early summer and the seasonal variations. Pattern correlation analysis of the SIT forecast data over 3 years (2014-2016) reveals that the early summer SIT distribution is accurately predicted for a lead time of up to 3 days, but that the prediction accuracy drops abruptly after the fourth day, which is related to a dynamical process controlled by synoptic-scale atmospheric fluctuations. For longer lead times ( > 4 days), the thermodynamic melting process takes over, which contributes to most of the remaining prediction accuracy. In July 2014, during which an ice-blocking incident occurred, relatively thick SIT ( ˜ 150 cm) was simulated over the ESS, which is consistent with the reduction in vessel speed. These results suggest that TOPAZ4 sea ice information has great potential for practical applications in summertime maritime navigation via the NSR.

  9. Probing stochastic inter-galactic magnetic fields using blazar-induced gamma ray halo morphology

    NASA Astrophysics Data System (ADS)

    Duplessis, Francis; Vachaspati, Tanmay

    2017-05-01

    Inter-galactic magnetic fields can imprint their structure on the morphology of blazar-induced gamma ray halos. We show that the halo morphology arises through the interplay of the source's jet and a two-dimensional surface dictated by the magnetic field. Through extensive numerical simulations, we generate mock halos created by stochastic magnetic fields with and without helicity, and study the dependence of the halo features on the properties of the magnetic field. We propose a sharper version of the Q-statistics and demonstrate its sensitivity to the magnetic field strength, the coherence scale, and the handedness of the helicity. We also identify and explain a new feature of the Q-statistics that can further enhance its power.

  10. Probing the Intergalactic Magnetic Field with the Anisotropy of the Extragalactic Gamma-ray Background

    NASA Technical Reports Server (NTRS)

    Venters, T. M.; Pavlidou, V.

    2013-01-01

    The intergalactic magnetic field (IGMF) may leave an imprint on the angular anisotropy of the extragalactic gamma-ray background through its effect on electromagnetic cascades triggered by interactions between very high energy photons and the extragalactic background light. A strong IGMF will deflect secondary particles produced in these cascades and will thus tend to isotropize lower energy cascade photons, thereby inducing a modulation in the anisotropy energy spectrum of the gamma-ray background. Here we present a simple, proof-of-concept calculation of the magnitude of this effect and demonstrate that current Fermi data already seem to prefer nonnegligible IGMF values. The anisotropy energy spectrum of the Fermi gamma-ray background could thus be used as a probe of the IGMF strength.

  11. Probing the Intergalactic Magnetic Field with the Anisotropy of the Extragalactic Gamma-Ray Background

    NASA Technical Reports Server (NTRS)

    Venters, T. M.; Pavlidou, V.

    2012-01-01

    The intergalactic magnetic field (IGMF) may leave an imprint on the anisotropy properties of the extragalactic gamma-ray background, through its effect on electromagnetic cascades triggered by interactions between very high energy photons and the extragalactic background light. A strong IGMF will deflect secondary particles produced in these cascades and will thus tend to isotropize lower energy cascade photons, thus inducing a modulation in the anisotropy energy spectrum of the gamma-ray background. Here we present a simple, proof-of-concept calculation of the magnitude of this effect and demonstrate that the two extreme cases (zero IGMF and IGMF strong enough to completely isotropize cascade photons) would be separable by ten years of Fermi observations and reasonable model parameters for the gamma-ray background. The anisotropy energy spectrum of the Fermi gamma-ray background could thus be used as a probe of the IGMF strength.

  12. Probing stochastic inter-galactic magnetic fields using blazar-induced gamma ray halo morphology

    SciTech Connect

    Duplessis, Francis; Vachaspati, Tanmay, E-mail: fdupless@asu.edu, E-mail: tvachasp@asu.edu

    Inter-galactic magnetic fields can imprint their structure on the morphology of blazar-induced gamma ray halos. We show that the halo morphology arises through the interplay of the source's jet and a two-dimensional surface dictated by the magnetic field. Through extensive numerical simulations, we generate mock halos created by stochastic magnetic fields with and without helicity, and study the dependence of the halo features on the properties of the magnetic field. We propose a sharper version of the Q-statistics and demonstrate its sensitivity to the magnetic field strength, the coherence scale, and the handedness of the helicity. We also identify andmore » explain a new feature of the Q-statistics that can further enhance its power.« less

  13. Elevated Medium-Chain Acylcarnitines Are Associated With Gestational Diabetes Mellitus and Early Progression to Type 2 Diabetes and Induce Pancreatic β-Cell Dysfunction.

    PubMed

    Batchuluun, Battsetseg; Al Rijjal, Dana; Prentice, Kacey J; Eversley, Judith A; Burdett, Elena; Mohan, Haneesha; Bhattacharjee, Alpana; Gunderson, Erica P; Liu, Ying; Wheeler, Michael B

    2018-05-01

    Specific circulating metabolites have emerged as important risk factors for the development of diabetes. The acylcarnitines (acylCs) are a family of metabolites known to be elevated in type 2 diabetes (T2D) and linked to peripheral insulin resistance. However, the effect of acylCs on pancreatic β-cell function is not well understood. Here, we profiled circulating acylCs in two diabetes cohorts: 1 ) women with gestational diabetes mellitus (GDM) and 2 ) women with recent GDM who later developed impaired glucose tolerance (IGT), new-onset T2D, or returned to normoglycemia within a 2-year follow-up period. We observed a specific elevation in serum medium-chain (M)-acylCs, particularly hexanoyl- and octanoylcarnitine, among women with GDM and individuals with T2D without alteration in long-chain acylCs. Mice treated with M-acylCs exhibited glucose intolerance, attributed to impaired insulin secretion. Murine and human islets exposed to elevated levels of M-acylCs developed defects in glucose-stimulated insulin secretion and this was directly linked to reduced mitochondrial respiratory capacity and subsequent ability to couple glucose metabolism to insulin secretion. In conclusion, our study reveals that an elevation in circulating M-acylCs is associated with GDM and early stages of T2D onset and that this elevation directly impairs β-cell function. © 2018 by the American Diabetes Association.

  14. No sign (yet) of intergalactic globular clusters in the Local Group

    NASA Astrophysics Data System (ADS)

    Mackey, A. D.; Beasley, M. A.; Leaman, R.

    2016-07-01

    We present Gemini Multi-Object Spectrograph (GMOS) imaging of 12 candidate intergalactic globular clusters (IGCs) in the Local Group, identified in a recent survey of the Sloan Digital Sky Survey (SDSS) footprint by di Tullio Zinn & Zinn. Our image quality is sufficiently high, at ˜0.4-0.7 arcsec, that we are able to unambiguously classify all 12 targets as distant galaxies. To reinforce this conclusion we use GMOS images of globular clusters in the M31 halo, taken under very similar conditions, to show that any genuine clusters in the putative IGC sample would be straightforward to distinguish. Based on the stated sensitivity of the di Tullio Zinn & Zinn search algorithm, we conclude that there cannot be a significant number of IGCs with MV ≤ -6 lying unseen in the SDSS area if their properties mirror those of globular clusters in the outskirts of M31 - even a population of 4 would have only a ≈1 per cent chance of non-detection.

  15. Constraints on the Intergalactic Magnetic Field with Gamma-Ray Observations of Blazars

    NASA Astrophysics Data System (ADS)

    Finke, Justin D.; Reyes, Luis C.; Georganopoulos, Markos; Reynolds, Kaeleigh; Ajello, Marco; Fegan, Stephen J.; McCann, Kevin

    2015-11-01

    Distant BL Lacertae objects emit γ-rays that interact with the extragalactic background light (EBL), creating electron-positron pairs, and reducing the flux measured by ground-based imaging atmospheric Cherenkov telescopes (IACTs) at very-high energies (VHE). These pairs can Compton-scatter the cosmic microwave background, creating a γ-ray signature at slightly lower energies that is observable by the Fermi Large Area Telescope (LAT). This signal is strongly dependent on the intergalactic magnetic field (IGMF) strength (B) and its coherence length (LB). We use IACT spectra taken from the literature for 5 VHE-detected BL Lac objects and combine them with LAT spectra for these sources to constrain these IGMF parameters. Low B values can be ruled out by the constraint that the cascade flux cannot exceed that observed by the LAT. High values of B can be ruled out from the constraint that the EBL-deabsorbed IACT spectrum cannot be greater than the LAT spectrum extrapolated into the VHE band, unless the cascade spectrum contributes a sizable fraction of the LAT flux. We rule out low B values (B ≲ 10-19 G for LB ≥ 1 Mpc) at >5σ in all trials with different EBL models and data selection, except when using >1 GeV spectra and the lowest EBL models. We were not able to constrain high values of B.

  16. Morphology of blazar-induced gamma ray halos due to a helical intergalactic magnetic field

    SciTech Connect

    Long, Andrew J.; Vachaspati, Tanmay, E-mail: andrewjlong@asu.edu, E-mail: tvachasp@asu.edu

    We study the characteristic size and shape of idealized blazar-induced cascade halos in the 1–100,GeV energy range assuming various non-helical and helical configurations for the intergalactic magnetic field (IGMF). While the magnetic field creates an extended halo, the helicity provides the halo with a twist. Under simplifying assumptions, we assess the parameter regimes for which it is possible to measure the size and shape of the halo from a single source and then to deduce properties of the IGMF. We find that blazar halo measurements with an experiment similar to Fermi-LAT are best suited to probe a helical magnetic fieldmore » with strength and coherence length today in the ranges 10{sup −17} ∼< B{sub 0} / Gauss ∼< 10{sup −13} and 10 Mpc ∼< λ ∼< 10 Gpc where H ∼ B{sub 0}{sup 2} / λ is the magnetic helicity density. Stronger magnetic fields or smaller coherence scales can still potentially be investigated, but the connection between the halo morphology and the magnetic field properties is more involved. Weaker magnetic fields or longer coherence scales require high photon statistics or superior angular resolution.« less

  17. Sensitivity of the Cherenkov Telescope Array to the Detection of Intergalactic Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Meyer, Manuel; Conrad, Jan; Dickinson, Hugh

    2016-08-01

    Very high energy (VHE; energy E ≳ 100 GeV) γ-rays originating from extragalactic sources undergo pair production with low-energy photons of background radiation fields. These pairs can inverse-Compton-scatter background photons, initiating an electromagnetic cascade. The spatial and temporal structure of this secondary γ-ray signal is altered as the {e}+{e}- pairs are deflected in an intergalactic magnetic field (IGMF). We investigate how VHE observations with the future Cherenkov Telescope Array, with its high angular resolution and broad energy range, can potentially probe the IGMF. We identify promising sources and simulate γ-ray spectra over a wide range of values of the IGMF strength and coherence length using the publicly available ELMAG Monte Carlo code. Combining simulated observations in a joint likelihood approach, we find that current limits on the IGMF can be significantly improved. The projected sensitivity depends strongly on the time a source has been γ-ray active and on the emitted maximum γ-ray energy.

  18. A model for intergalactic filaments and galaxy formation during the first gigayear

    NASA Astrophysics Data System (ADS)

    Harford, A. Gayler; Hamilton, Andrew J. S.

    2017-11-01

    We propose a physically based, analytic model for intergalactic filaments during the first gigayear of the universe. The structure of a filament is based upon a gravitationally bound, isothermal cylinder of gas. The model successfully predicts for a cosmological simulation the total mass per unit length of a filament (dark matter plus gas) based solely upon the sound speed of the gas component, contrary to the expectation for collisionless dark matter aggregation. In the model, the gas, through its hydrodynamic properties, plays a key role in filament structure rather than being a passive passenger in a preformed dark matter potential. The dark matter of a galaxy follows the classic equation of collapse of a spherically symmetric overdensity in an expanding universe. In contrast, the gas usually collapses more slowly. The relative rates of collapse of these two components for individual galaxies can explain the varying baryon deficits of the galaxies under the assumption that matter moves along a single filament passing through the galaxy centre, rather than by spherical accretion. The difference in behaviour of the dark matter and gas can be simply and plausibly related to the model. The range of galaxies studied includes that of the so-called too big to fail galaxies, which are thought to be problematic for the standard Λ cold dark matter model of the universe. The isothermal-cylinder model suggests a simple explanation for why these galaxies are, unaccountably, missing from the night sky.

  19. CONSTRAINTS ON THE INTERGALACTIC MAGNETIC FIELD WITH GAMMA-RAY OBSERVATIONS OF BLAZARS

    DOE PAGES

    Finke, Justin D.; Reyes, Luis C.; Georganopoulos, Markos; ...

    2015-11-12

    Distant BL Lacertae objects emit γ rays which interact with the extragalactic background light (EBL), creating electron-positron pairs, and reducing the flux measured by ground-based imaging atmospheric Cherenkov telescopes (IACTs) at very-high energies (VHE). These pairs can Comptonscatter the cosmic microwave background, creating a γ-ray signature at slightly lower energies observable by the Fermi Large Area Telescope (LAT). This signal is strongly dependent on the intergalactic magnetic field (IGMF) strength (B) and its coherence length (LB). We use IACT spectra taken from the literature for 5 VHE-detected BL Lac objects, and combine it with LAT spectra for these sources tomore » constrain these IGMF parameters. Low B values can be ruled out by the constraint that the cascade flux cannot exceed that observed by the LAT. High values of B can be ruled out from the constraint that the EBL-deabsorbed IACT spectrum cannot be greater than the LAT spectrum extrapolated into the VHE band, unless the cascade spectrum contributes a sizable fraction of the LAT flux. We rule out low B values (B . 10 -19 G for LB ≥ 1 Mpc) at > 5σ in all trials with different EBL models and data selection, except when« less

  20. In vitro culture of early secondary preantral follicles in hanging drop of ovarian cell-conditioned medium to obtain MII oocytes from outbred deer mice.

    PubMed

    Choi, Jung Kyu; Agarwal, Pranay; He, Xiaoming

    2013-12-01

    The ovarian follicle (each contains a single oocyte) is the fundamental functional tissue unit of mammalian ovaries. In humans, it has been long held true that females are born with a maximum number of follicles (or oocytes) that are not only nonrenewable, but also undergoing degeneration with time with a sharply decreased oocyte quality after the age of ∼35. Therefore, it is of importance to isolate and bank ovarian follicles for in vitro culture to obtain fertilizable oocytes later, to preserve the fertility of professional women who may want to delay childbearing, young and unmarried women who may lose gonadal function because of exposure to environmental/occupational hazards or aggressive medical treatments, such as radiation and chemotherapy, and even endangered species and breeds. Although they contributed significantly to the understanding of follicle science and biology, most studies reported to date on this topic were done using the man-made, unnatural inbred animal species. It was found in this study that the conventional two-dimensional microliter drop and three-dimensional hanging drop (HD) methods, reported to be effective for in vitro culture of preantral follicles from inbred mice, are not directly transferrable to outbred deer mice. Therefore, a modified HD method was developed in this study to achieve a much higher (>5 times compared to the best conventional methods) percentage of developing early secondary preantral follicles from the outbred mice to the antral stage, for which, the use of an ovarian cell-conditioned medium and multiple follicles per HD were identified to be crucial. It was further found that the method for in vitro maturation of oocytes in antral follicles obtained by in vitro culture of preantral follicles could be very different from that for oocytes in antral follicles obtained by hormone stimulation in vivo. Therefore, this study should provide important guidance for establishing effective protocols of in vitro follicle

  1. In Vitro Culture of Early Secondary Preantral Follicles in Hanging Drop of Ovarian Cell-Conditioned Medium to Obtain MII Oocytes from Outbred Deer Mice

    PubMed Central

    Choi, Jung Kyu; Agarwal, Pranay

    2013-01-01

    The ovarian follicle (each contains a single oocyte) is the fundamental functional tissue unit of mammalian ovaries. In humans, it has been long held true that females are born with a maximum number of follicles (or oocytes) that are not only nonrenewable, but also undergoing degeneration with time with a sharply decreased oocyte quality after the age of ∼35. Therefore, it is of importance to isolate and bank ovarian follicles for in vitro culture to obtain fertilizable oocytes later, to preserve the fertility of professional women who may want to delay childbearing, young and unmarried women who may lose gonadal function because of exposure to environmental/occupational hazards or aggressive medical treatments, such as radiation and chemotherapy, and even endangered species and breeds. Although they contributed significantly to the understanding of follicle science and biology, most studies reported to date on this topic were done using the man-made, unnatural inbred animal species. It was found in this study that the conventional two-dimensional microliter drop and three-dimensional hanging drop (HD) methods, reported to be effective for in vitro culture of preantral follicles from inbred mice, are not directly transferrable to outbred deer mice. Therefore, a modified HD method was developed in this study to achieve a much higher (>5 times compared to the best conventional methods) percentage of developing early secondary preantral follicles from the outbred mice to the antral stage, for which, the use of an ovarian cell-conditioned medium and multiple follicles per HD were identified to be crucial. It was further found that the method for in vitro maturation of oocytes in antral follicles obtained by in vitro culture of preantral follicles could be very different from that for oocytes in antral follicles obtained by hormone stimulation in vivo. Therefore, this study should provide important guidance for establishing effective protocols of in vitro follicle

  2. Insights into early stage of antibiotic development in small- and medium-sized enterprises: a survey of targets, costs, and durations.

    PubMed

    Årdal, Christine; Baraldi, Enrico; Theuretzbacher, Ursula; Outterson, Kevin; Plahte, Jens; Ciabuschi, Francesco; Røttingen, John-Arne

    2018-01-01

    Antibiotic innovation has dwindled to dangerously low levels in the past 30 years. Since resistance continues to evolve, this innovation deficit can have perilous consequences on patients. A number of new incentives have been suggested to stimulate greater antibacterial drug innovation. To design effective solutions, a greater understanding is needed of actual antibiotic discovery and development costs and timelines. Small and medium-sized enterprises (SMEs) undertake most discovery and early phase development for antibiotics and other drugs. This paper attempts to gather a better understanding of SMEs' targets, costs, and durations related to discovery and early phase development of antibacterial therapies. DRIVE-AB, a project focused on developing new economic incentives to stimulate antibacterial innovation, held a European stakeholder meeting in February 2015. All SMEs invited to this meeting ( n  = 44) were subsequently sent a survey to gather more data regarding their areas of activity, completed and expected development costs and timelines, and business models. Twenty-five companies responded to the survey. Respondents were primarily small companies each focusing on developing 1 to 3 new antibiotics, focused on pathogens of public health importance. Most have not yet completed any clinical trials. They have reported ranges of discovery and development out-of-pocket costs that appear to be less expensive than other studies of general pharmaceutical research and development (R&D) costs. The duration ranges reported for completing each phase of R&D are highly variable when compared to previously published general pharmaceutical innovation average durations. However, our sample population is small and may not be fully representative of all relevant antibiotic SMEs. The data collected by this study provide important insights and estimates about R&D in European SMEs focusing on antibiotics, which can be combined with other data to design incentives to

  3. Agnostic stacking of intergalactic doublet absorption: measuring the Ne VIII population

    NASA Astrophysics Data System (ADS)

    Frank, Stephan; Pieri, Matthew M.; Mathur, Smita; Danforth, Charles W.; Shull, J. Michael

    2018-05-01

    We present a blind search for doublet intergalactic metal absorption with a method dubbed `agnostic stacking'. Using a forward-modelling framework, we combine this with direct detections in the literature to measure the overall metal population. We apply this novel approach to the search for Ne VIII absorption in a set of 26 high-quality COS spectra. We probe to an unprecedented low limit of log N>12.3 at 0.47≤z ≤1.34 over a path-length Δz = 7.36. This method selects apparent absorption without requiring knowledge of its source. Stacking this mixed population dilutes doublet features in composite spectra in a deterministic manner, allowing us to measure the proportion corresponding to Ne VIII absorption. We stack potential Ne VIII absorption in two regimes: absorption too weak to be significant in direct line studies (12.3 < log N < 13.7), and strong absorbers (log N > 13.7). We do not detect Ne VIII absorption in either regime. Combining our measurements with direct detections, we find that the Ne VIII population is reproduced with a power-law column density distribution function with slope β = -1.86 ^{+0.18 }_{ -0.26} and normalization log f_{13.7} = -13.99 ^{+0.20 }_{ -0.23}, leading to an incidence rate of strong Ne VIII absorbers dn/dz =1.38 ^{+0.97 }_{ -0.82}. We infer a cosmic mass density for Ne VIII gas with 12.3 < log N < 15.0 of Ω _{{{Ne {VIII}}}} = 2.2 ^{+1.6 }_{ _-1.2} × 10^{-8}, a value significantly lower that than predicted by recent simulations. We translate this density into an estimate of the baryon density Ωb ≈ 1.8 × 10-3, constituting 4 per cent of the total baryonic mass.

  4. Intergalactic Hydrogen Clouds at Low Redshift: Connections to Voids and Dwarf Galaxies

    NASA Technical Reports Server (NTRS)

    Shull, J. Michael; Stocke, John T.; Penton, Steve

    1996-01-01

    We provide new post-COSTAR data on one sightline (Mrk 421) and updated data from another (I Zw 1) from our Hubble Space Telescope (HST) survey of intergalactic Ly(alpha) clouds located along sightlines to four bright quasars passing through well-mapped galaxy voids (16000 km/s pathlength) and superclusters (18000 km/s). We report two more definite detections of low-redshift Ly(alpha) clouds in voids: one at 3047 km/s (heliocentric) toward Mrk 421 and a second just beyond the Local Supercluster at 2861 km/s toward I Zw 1, confirming our earlier discovery of Ly(alpha) absorption clouds in voids (Stocke et al., ApJ, 451, 24). We have now identified ten definite and one probable low-redshift neutral hydrogen absorption clouds toward four targets, a frequency of approximately one absorber every 3400 km/s above 10(exp 12.7/sq cm column density. Of these ten absorption systems, three lie within voids; the probable absorber also lies in a void. Thus, the tendency of Ly(alpha) absorbers to 'avoid the voids' is not as clear as we found previously. If the Ly(alpha) clouds are approximated as homogeneous spheres of 100 kpc radius, their masses are approximately 10(exp 9)solar mass (about 0.01 times that of bright L* galaxies) and they are 40 times more numerous, comparable to the density of dwarf galaxies and of low-mass halos in numerical CDM simulations. The Ly(alpha) clouds contribute a fraction Omega(sub cl)approximately equals 0.003/h(sub 75) to the closure density of the universe, comparable to that of luminous matter. These clouds probably require a substantial amount of nonbaryonic dark matter for gravitational binding. They may represent extended haloes of low-mass protogalaxies which have not experienced significant star formation or low-mass dwarf galaxies whose star formation ceased long ago, but blew out significant gaseous material.

  5. Constraining the Intergalactic and Circumgalactic Media with Lyman-Alpha Absorption

    NASA Astrophysics Data System (ADS)

    Sorini, Daniele; Onorbe, Jose; Hennawi, Joseph F.; Lukic, Zarija

    2018-01-01

    Lyman-alpha (Ly-a) absorption features detected in quasar spectra in the redshift range 0intergalactic and circumgalactic media (IGM/CGM) and, consequently, to constrain models of galaxy formation and cosmology. In the first part of my thesis, I overcome numerical challenges posed by cosmological hydrodynamic simulations by developing a novel semi-analytic technique to predict various statistics of Ly-a absorption in the IGM with large N-body cosmological simulations. The technique developed is more accurate than previous attempts in the literature, and can be applied to Gpc-scale N-body simulations, allowing an accurate investigation of the Ly-a absorption on unprecedentedly large scales. In the second part of my thesis, I compare predictions of state-of-the-art hydrodynamic cosmological simulations with observations of the mean Ly-a absorption around foreground quasars, damped Ly-a absorbers, and Lyman-break galaxies, at different transverse distances (~20kpc-20Mpc) from background quasars. Far from galaxies >2Mpc, the simulations asymptotically match the observations, because the ΛCDM model successfully describes the ambient IGM. This represents a critical advantage of studying the mean absorption profile. However, significant differences between the simulations, and between simulations and observations are present on scales 20kpc-2Mpc, illustrating the challenges of accurately modeling and resolving galaxy formation physics. It is noteworthy that these differences are observed as far out as ~2Mpc, indicating that the `sphere-of-influence' of galaxies could extend to approximately ~20 times the halo virial radius (~100kpc). Current observations are very precise on these scales and can thus strongly discriminate between different galaxy formation models. I demonstrate that the Ly-a absorption profile is primarily sensitive to the underlying temperature-density relationship of diffuse gas around galaxies, and argue that it

  6. A Longitudinal Study of Early Reading Development in Two Languages: Comparing Literacy Outcomes in Irish Immersion, English Medium and Gaeltacht Schools

    ERIC Educational Resources Information Center

    Parsons, Christine E.; Lyddy, Fiona

    2016-01-01

    Schools in Ireland vary in how they introduce reading in the two official languages, Irish and English. There is particular variability within immersion (Irish medium) schools. Some introduce Irish reading first (IRF) and others English reading first (ERF). This study compared the development of Irish and English skills in children attending…

  7. Growth problems of stellar black holes in early galaxies

    NASA Astrophysics Data System (ADS)

    Orofino, M. C.; Ferrara, A.; Gallerani, S.

    2018-06-01

    The nature of the seeds of the observed high-z super-massive black holes (SMBH) is unknown. Although different options have been proposed, involving e.g. intermediate mass direct collapse black holes, BH remnants of massive stars remain the most natural explanation. To identify the most favorable conditions (if any) for their rapid growth, we study the accretion rate of a M• = 100M⊙ BH formed in a typical z = 10 galaxy under different conditions (e.g. galaxy structure, BH initial position and velocity). We model the galaxy baryonic content and follow the BH orbit and accretion history for 300 Myr (the time span in 10 > z > 7), assuming the radiation-regulated accretion model by Park & Ricotti (2013). We find that, within the limits of our model, BH seeds cannot grow by more than 30%, suggesting that accretion on light-seed models are inadequate to explain high-z SMBH. We also compute the X-ray emission from such accreting stellar BH population in the [0.5 - 8] keV band and find it comparable to the one produced by high-mass X-ray binaries. This study suggests that early BHs, by X-ray pre-heating of the intergalactic medium at cosmic dawn, might leave a specific signature on the HI 21 cm line power spectrum potentially detectable with SKA.

  8. Enriching the hot circumgalactic medium

    NASA Astrophysics Data System (ADS)

    Crain, Robert A.; McCarthy, Ian G.; Schaye, Joop; Theuns, Tom; Frenk, Carlos S.

    2013-07-01

    Simple models of galaxy formation in a cold dark matter universe predict that massive galaxies are surrounded by a hot, quasi-hydrostatic circumgalactic corona of slowly cooling gas, predominantly accreted from the intergalactic medium (IGM). This prediction is borne out by the recent cosmological hydrodynamical simulations of Crain et al., which reproduce observed scaling relations between the X-ray and optical properties of nearby disc galaxies. Such coronae are metal poor, but observations of the X-ray emitting circumgalactic medium (CGM) of local galaxies typically indicate enrichment to near-solar iron abundance, potentially signalling a shortcoming in current models of galaxy formation. We show here that, while the hot CGM of galaxies formed in the simulations is typically metal poor in a mass-weighted sense, its X-ray luminosity-weighted metallicity is often close to solar. This bias arises because the soft X-ray emissivity of a typical ˜0.1 keV corona is dominated by collisionally excited metal ions that are synthesized in stars and recycled into the hot CGM. We find that these metals are ejected primarily by stars that form in situ to the main progenitor of the galaxy, rather than in satellites or external galaxies. The enrichment of the hot CGM therefore proceeds in an `inside-out' fashion throughout the assembly of the galaxy: metals are transported from the central galaxy by supernova-driven winds and convection over several Gyr, establishing a strong negative radial metallicity gradient. Whilst metal ions synthesized by stars are necessary to produce the X-ray emissivity that enables the hot CGM of isolated galaxies to be detected with current instrumentation, the electrons that collisionally excite them are equally important. Since our simulations indicate that the electron density of hot coronae is dominated by the metal-poor gas accreted from the IGM, we infer that the hot CGM observed via X-ray emission is the outcome of both hierarchical

  9. TeV gamma rays from 3C 279 - A possible probe of origin and intergalactic infrared radiation fields

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; De Jager, O. C.; Salamon, M. H.

    1992-01-01

    The gamma-ray spectrum of 3C 279 during 1991 June exhibited a near-perfect power law between 50 MeV and over 5 GeV with a differential spectral index of -(2.02 +/- 0.07). If extrapolated, the gamma-ray spectrum of 3C 279 should be easily detectable with first-generation air Cerenkov detectors operating above about 0.3 TeV provided there is no intergalactic absorption. However, by using model-dependent lower and upper limits for the extragalactic infrared background radiation field, a sharp cutoff of the 3C 279 spectrum is predicted at between about 0.1 and about 1 TeV. The sensitivity of present air Cerenkov detectors is good enough to measure such a cutoff, which would provide the first opportunity to obtain a measurement of the extragalactic background infrared radiation field.

  10. The Origin of Dwarf Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Toloba, Elisa

    2012-10-01

    Abridge. We have conducted a spectrophotometric study of dwarf early-type galaxies (dEs) in the Virgo cluster and in regions of lower density. We have found that these galaxies show many properties in common with late-type galaxies but not with more massive early-types (E/S0). The properties of the dEs in Virgo show gradients within the cluster. dEs in the outer parts of the Virgo cluster are kinematically supported by rotation, while those in the center are supported by the random motions of their stars (i.e. pressure supported). The rotationally supported dEs have disky isophotes and faint underlying spiral/irregular substructures, they also show younger ages than those pressure supported, which have boxy isophotes and are smooth and regular, without any substructure. We compare the position of these dEs with massive early-type galaxies in the Faber-Jackson and Fundamental Plane relations, and we find that, although there is no difference between the position of rotationally and pressure supported dEs, both deviate from the relations of massive early-type galaxies in the direction of dwarf spheroidal systems (dSphs). We have used their offset with respect to the Fundamental Plane of E/S0 galaxies to estimate their dark matter fraction. All the properties studied in this work agree with a ram pressure stripping scenario, where late-type galaxies infall into the cluster, their interaction with the intergalactic medium blows away their gas and, as a result, they are quenched in a small amount of time. However, those dEs in the center of the cluster seem to have been fully transformed leaving no trace of their possible spiral origin, thus, if that is the case, they must have experienced a more violent mechanism in combination with ram pressure stripping.

  11. Vaccine Pipeline Has Grown During The Past Two Decades With More Early-Stage Trials From Small And Medium-Size Companies.

    PubMed

    Hwang, Thomas J; Kesselheim, Aaron S

    2016-02-01

    Many serious diseases lack safe and effective vaccines. Using a large commercial database, we examined trends in global vaccine research and development and found that the proportion of new vaccine candidates entering all stages of clinical development increased by 3-5 percentage points over the past two decades. Small and medium-size companies accounted for nearly twice as many new Phase I vaccine trials compared to large companies, but late-stage (Phase III) vaccine trials were dominated by large companies. There were no significant differences between vaccines and drugs in the probability of success in clinical trials or in profitability. Small and medium-size companies, including spin-outs from academic research centers, play an important role in innovative research and discovery. Our findings suggest that policy making targeted at smaller companies, such as prizes or opportunities for public-private partnerships, could support the development of new vaccines, particularly those targeting unmet medical needs and emerging public health threats. Project HOPE—The People-to-People Health Foundation, Inc.

  12. The ATLAS3D project - XXVII. Cold gas and the colours and ages of early-type galaxies

    NASA Astrophysics Data System (ADS)

    Young, Lisa M.; Scott, Nicholas; Serra, Paolo; Alatalo, Katherine; Bayet, Estelle; Blitz, Leo; Bois, Maxime; Bournaud, Frédéric; Bureau, Martin; Crocker, Alison F.; Cappellari, Michele; Davies, Roger L.; Davis, Timothy A.; de Zeeuw, P. T.; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnović, Davor; Kuntschner, Harald; McDermid, Richard M.; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Weijmans, Anne-Marie

    2014-11-01

    We present a study of the cold gas contents of the ATLAS3D early-type galaxies, in the context of their optical colours, near-ultraviolet colours and Hβ absorption line strengths. Early-type (elliptical and lenticular) galaxies are not as gas poor as previously thought, and at least 40 per cent of local early-type galaxies are now known to contain molecular and/or atomic gas. This cold gas offers the opportunity to study recent galaxy evolution through the processes of cold gas acquisition, consumption (star formation) and removal. Molecular and atomic gas detection rates range from 10 to 34 per cent in red sequence early-type galaxies, depending on how the red sequence is defined, and from 50 to 70 per cent in blue early-type galaxies. Notably, massive red sequence early-type galaxies (stellar masses >5 × 1010 M⊙, derived from dynamical models) are found to have H I masses up to M(H I)/M* ˜ 0.06 and H2 masses up to M(H2)/M* ˜ 0.01. Some 20 per cent of all massive early-type galaxies may have retained atomic and/or molecular gas through their transition to the red sequence. However, kinematic and metallicity signatures of external gas accretion (either from satellite galaxies or the intergalactic medium) are also common, particularly at stellar masses ≤5 × 1010 M⊙, where such signatures are found in ˜50 per cent of H2-rich early-type galaxies. Our data are thus consistent with a scenario in which fast rotator early-type galaxies are quenched former spiral galaxies which have undergone some bulge growth processes, and in addition, some of them also experience cold gas accretion which can initiate a period of modest star formation activity. We discuss implications for the interpretation of colour-magnitude diagrams.

  13. THE INTRAGROUP VERSUS THE INTRACLUSTER MEDIUM

    SciTech Connect

    Cavaliere, A.; Fusco-Femiano, R.; Lapi, A., E-mail: roberto.fuscofemiano@iaps.inaf.it

    2016-06-20

    Galaxy groups differ from clusters primarily by way of their lower masses, M ∼ 10{sup 14} M {sub ⊙} versus M ∼ 10{sup 15} M {sub ⊙}. We discuss how mass affects the thermal state of the intracluster or the intragroup medium, specifically as to their entropy levels and radial profiles. We show that entropy is produced in both cases by the continuing inflow of intergalactic gas across the system boundary into the gravitational potential well. The inflow is highly supersonic in clusters, but weakly so in groups. The former condition implies strong accretion shocks with substantial conversion of amore » large bulk kinetic into thermal energy, whereas the latter condition implies less effective conversion of lower energies. These features produce a conspicuous difference in entropy deposition at the current boundary. Thereafter, adiabatic compression of the hot gas into the potential well converts such time histories into radial profiles throughout a cluster or a group. In addition, in both cases, a location of the system at low z in the accelerating universe or in a poor environment will starve out the inflow and the entropy production and produce flattening or even bending down of the outer profile. We analyze, in detail, the sharp evidence provided by the two groups ESO 3060170 and RXJ1159+5531 that have been recently observed in X-rays out to their virial radii and find a close and detailed match with our expectations.« less

  14. The effects of starter microbiota and the early life feeding of medium chain triglycerides on the gastric transcriptome profile of 2- or 3-week-old cesarean delivered piglets.

    PubMed

    Trevisi, Paolo; Priori, Davide; Motta, Vincenzo; Luise, Diana; Jansman, Alfons J M; Koopmans, Sietse-Jan; Bosi, Paolo

    2017-01-01

    The stomach is an underestimated key interface between the ingesta and the digestive system, affecting the digestion and playing an important role in several endocrine functions. The quality of starter microbiota and the early life feeding of medium chain triglycerides may affect porcine gastric maturation. Two trials (T1, T2) were carried out on 12 and 24 cesarean-delivered piglets (birth, d0), divided over two microbiota treatments, but slaughtered and sampled at two or three weeks of age, respectively. All piglets were fed orally: sow serum (T1) or pasteurized sow colostrum (T2) on d0; simple starter microbiota ( Lactobacillus amylovorus , Clostridium glycolicum and Parabacteroides spp.) (d1-d3); complex microbiota inoculum (sow diluted feces, CA) or a placebo (simple association, SA) (d3-d4) and milk replacer ad libitum (d0-d4). The The T1 piglets and half of the T2 piglets were then fed a moist diet (CTRL); the remaining half of the T2 piglets were fed the CTRL diet fortified with medium chain triglycerides and 7% coconut oil (MCT). Total mRNA from the oxyntic mucosa was analyzed using Affymetrix©Porcine Gene array strips. Exploratory functional analysis of the resulting values was carried out using Gene Set Enrichment Analysis. Complex microbiota upregulated 11 gene sets in piglets of each age group vs. SA. Of these sets, 6 were upregulated at both ages, including the set of gene markers of oxyntic mucosa. In comparison with the piglets receiving SA, the CA enriched the genes in the sets related to interferon response when the CTRL diet was given while the same sets were impoverished by CA with the MCT diet. Early colonization with a complex starter microbiota promoted the functional maturation of the oxyntic mucosa in an age-dependent manner. The dietary fatty acid source may have affected the recruitment and the maturation of the immune cells, particularly when the piglets were early associated with a simplified starter microbiota.

  15. A multiparametric analysis of the Einstein sample of early-type galaxies. 2: Galaxy formation history and properties of the interstellar medium

    NASA Technical Reports Server (NTRS)

    Eskridge, Paul B.; Fabbiano, Giuseppina; Kim, Dong-Woo

    1995-01-01

    We have conducted bivariate and multivariate statistical analysis of data measuring the integrated luminosity, shape, and potential depth of the Einstein sample of early-type galaxies (presented by Fabbiano et al. 1992). We find significant correlations between the X-ray properties and the axial ratios (a/b) of our sample, such that the roundest systems tend to have the highest L(sub x) and L(sub x)/L(sub B). The most radio-loud objects are also the roundest. We confirm the assertion of Bender et al. (1989) that galaxies with high L(sub x) are boxy (have negative a(sub 4)). Both a/b and a(sub 4) are correlated with L(sub B), but not with IRAS 12 um and 100 um luminosities. There are strong correlations between L(sub x), Mg(sub 2), and sigma(sub nu) in the sense that those systems with the deepest potential wells have the highest L(sub x) and Mg(sub 2). Thus the depth of the potential well appears to govern both the ability to reatin an ISM at the present epoch and to retain the enriched ejecta of early star formation bursts. Both L(sub x)/L(sub B) and L(sub 6) (the 6 cm radio luminosity) show threshold effects with sigma(sub nu) exhibiting sharp increases at log sigma(sub nu) approximately = 2.2. Finally, there is clearly an interrelationship between the various stellar and structural parameters: The scatter in the bivariate relationships between the shape parameters (a/b and a(sub 4)) and the depth parameter sigma(sub nu) is a function of abundance in the sense that, for a given a(sub 4) or a/b, the systems with the highest sigma(sub nu) also have the highest Mg(sub 2). Furthermore, for a constant sigma(sun nu), disky galaxies tend to have higher Mg(sub 2) than boxy ones. Alternatively, for a given abundance, boxy ellipticals tend to be more massive than disky ellipticals. One possibility is that early-type galaxies of a given mass, originating from mergers (boxy ellipticals), have lower abundances than 'primordial' (disky) early-type galaxies. Another is that

  16. Erratum: ``FUSE and STIS Observations of the Warm-hot Intergalactic Medium toward PG 1259+593'' (ApJS, 153, 165 [2004])

    NASA Astrophysics Data System (ADS)

    Richter, Philipp; Savage, Blair D.; Tripp, Todd M.; Sembach, Kenneth R.

    2004-12-01

    There was a minor error in the form of equation (4) in the original paper; the first bracketed term on the right-hand side is missing a -1. The correct equation is: ΔX=0.5[(1+zmax)2-1]-[(1+zmin)2-1]. (4) Another error also occurred in the calculation of Ωb(BL) in the last paragraph of § 3.5 (p. 198). The correct limit is Ωb(BL)<=0.0035h-175 [instead of Ωb(BL)<=0.0031h-175]. Note the wrong value is cited a second time in list item 5 of the Summary (§ 5; p. 204).

  17. Time delay of cascade radiation for TeV blazars and the measurement of the intergalactic magnetic field

    DOE PAGES

    Dermer, Charles D.; Cavadini, Massimo; Razzaque, Soebur; ...

    2011-05-06

    Here, recent claims that the strength B IGMF of the intergalactic magnetic field (IGMF) is ≳10 –15 G are based on upper limits to the expected cascade flux in the GeV band produced by blazar TeV photons absorbed by the extragalactic background light. This limit depends on an assumption that the mean blazar TeV flux remains constant on timescales ≳2(B IGMF/10 –18G) 2/(E/10 GeV) 2 yr for an IGMF coherence length ≈1 Mpc, where E is the measured photon energy. Restricting TeV activity of 1ES 0229+200 to ≈3-4 years during which the source has been observed leads to a moremore » robust lower limit of B IGMF ≳10 –18 G, which can be larger by an order of magnitude if the intrinsic source flux above ≈5-10 TeV from 1ES 0229+200 is strong.« less

  18. Effect of early addition of bone morphogenetic protein 5 (BMP5) to embryo culture medium on in vitro development and expression of developmentally important genes in bovine preimplantation embryos.

    PubMed

    García, Elina V; Miceli, Dora C; Rizo, Gabriela; Valdecantos, Pablo A; Barrera, Antonio D

    2015-09-01

    Previous studies have reported that bone morphogenetic protein 5 (BMP5) is differentially expressed in the isthmus of bovine oviducts and it is present in the oviductal fluid. However, the specific action of this factor is unknown. To evaluate whether BMP5 exerts some effect during early bovine embryo development, gene expression of BMP5, BMP receptors, and the effect of exogenous BMP5 on in vitro development and expression of developmentally important genes were assessed. In experiment 1, pools of embryos at two-cell, four-cell, eight-cell, and blastocyst stages, derived from in vitro fertilization, were collected for analysis of BMP5 and BMP receptors (BMPR1A, BMPR1B, and BMPR2) messenger RNA (mRNA) expression. On the basis of previous results, in experiment 2, presumptive zygotes were cultured for the first 48 hours after insemination in CR1aa medium assaying three different treatments: (1) control (CR1aa); (2) vehicle control (CR1aa + 0.04 mM HCl), and (3) BMP5 treatment (CR1aa + 100 ng/mL of BMP5). The cleavage rate was evaluated 48 hours after insemination (Day 2), and then, embryos were transferred to CR1aa + 10% fetal bovine serum. The blastocyst rate was determined on Day 7. In experiment 3, pools of embryos at two-cell, four-cell, eight-cell, and blastocyst stages, derived from control and BMP5-treated groups, were collected for analysis of ID2 (BMP target gene), OCT4, NANOG, and SOX2 (pluripotency genes) mRNA expression. BMP5 transcripts were not detectable in any of the embryonic stages examined, whereas the relative mRNA abundance of the three BMP receptors analyzed was greater in early embryo development stages before maternal-embryonic transition, raising the possibility of a direct effect of exogenous BMPs on the embryo during the first developmental period. Although early addition of 100 ng/mL of BMP5 to the embryo culture medium had no effect on the cleavage rate, a significantly higher proportion of cleaved embryos developed to the

  19. Residual fluctuations in the matter and radiation distribution after the decoupling epoch. [of early universe

    NASA Technical Reports Server (NTRS)

    Silk, J.; Wilson, M. L.

    1980-01-01

    The residual spectra of matter and radiation fluctuations in the early universe are investigated, and the evolution of primordial adiabatic and isothermal fluctuations through the decoupling epoch is studied. Amplification of adiabatic density fluctuations during decoupling, or velocity 'overshoot', is largely suppressed by Compton drag. Consequently, the amplitude of density fluctuations entering the horizon prior to decoupling is larger than hitherto assumed in the adiabatic theory. Damping of primordial adiabatic density fluctuations by an order of magnitude occurs on mass-scales of 3 x 10 to the 13th solar masses (Omega = 1) or 10 to the 14th solar masses (Omega = 0.2). Comparison of the residual radiation fluctuations with observational limits indicates that the adiabatic theory is only acceptable if re-ionization of the intergalactic medium results in additional scattering of the radiation after decoupling. Primordial isothermal fluctuations are found to yield radiation fluctuations which are insensitive to the assumed spectrum and lie a factor of about 5 below current limits

  20. The Transient High Energy Sky and Early Universe Surveyor

    NASA Astrophysics Data System (ADS)

    O'Brien, P. T.

    2016-04-01

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

  1. Ten More New Sightlines for the Study of Intergalactic Helium, and Hundreds of Far-Ultraviolet-Bright Quasars, from the Sloan Digital Sky Survey, Galaxy Evolution Explorer, and Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Syphers, David; Anderson, Scott F.; Zheng, Wei; Haggard, Daryl; Meiksin, Avery; Schneider, Donald P.; York, Donald G.

    2009-11-01

    Absorption along quasar sightlines remains among the most sensitive direct measures of He II reionization in much of the intergalactic medium (IGM). Until recently, fewer than a half-dozen unobscured quasar sightlines suitable for the He II Gunn-Peterson test were known; although these handful demonstrated great promise, the small sample size limited confidence in cosmological inferences. We have recently added nine more such clean He II quasars, exploiting Sloan Digital Sky Survey (SDSS) quasar samples, broadband ultraviolet (UV) imaging from Galaxy Evolution Explorer (GALEX), and high-yield UV spectroscopic confirmations from Hubble Space Telescope (HST). Here we markedly expand this approach by cross-correlating SDSS DR7 and GALEX GR4+5 to catalog 428 SDSS and 165 other quasars with z > 2.78 having likely (~70%) GALEX detections, suggesting they are bright into the far-UV. Reconnaissance HST Cycle 16 Supplemental prism data for 29 of these new quasar-GALEX matches spectroscopically confirm 17 as indeed far-UV bright. At least 10 of these confirmations have clean sightlines all the way down to He II Lyα, substantially expanding the number of known clean He II quasars, and reaffirming the order of magnitude enhanced efficiency of our selection technique. Combined confirmations from this and our past programs yield more than 20 He II quasars, quintupling the sample. These provide substantial progress toward a sample of He II quasar sightlines large enough, and spanning a sufficient redshift range, to enable statistical IGM studies that may avoid individual object peculiarity and sightline variance. Our expanded catalog of hundreds of high-likelihood far-UV-bright QSOs additionally will be useful for understanding the extreme-UV properties of the quasars themselves. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc

  2. A Determination of the Intergalactic Redshift Dependent UV-Optical-NIR Photon Density Using Deep Galaxy Survey Data and the Gamma-Ray Opacity of the Universe

    NASA Technical Reports Server (NTRS)

    Stecker, Floyd W.

    2012-01-01

    We calculate the intensity and photon spectrum of the intergalactic background light (IBL) as a function of red shift using an approach based on observational data obtained at in different wavelength bands from local to deep galaxy surveys. Our empirically based approach allows us, for the firs.t time, to obtain a completely model independent determination of the IBL and to quantify its uncertainties. Using our results on the IBL, we then place upper and lower limits on the opacity of the universe to gamma-rays, independent of previous constraints.

  3. FIREBall-2: Trailblazing observations of the space UV circumgalactic medium

    NASA Astrophysics Data System (ADS)

    Martin, Christopher

    The Faint Intergalactic-medium Redshifted Emission Balloon (FIREBall-2) is designed to discover and map faint emission from the circumgalactic medium of low redshift galaxies (0.3intergalactic and circumgalactic (IGM, CGM) emission available from any instrument at the time. FIREBall-2 has been significantly upgraded compared to FB-1, and is in the final stages of integration for a September 2016 flight from Ft. Sumner, New Mexico. The spectrograph has been redesigned with a wider field of view and greater efficiency. An upgraded detector system including a groundbreaking high QE, low-noise, UV optimized CCD detector is under final dark current and noise testing and will improve instrument performance by more than an order of magnitude. CNES is providing the spectrograph, gondola, and gondola flight support team, with construction of all components complete and final alignment and testing ongoing. We propose three additional years of funding to support the FIREBall-2 team in one additional flight in 2018 to fully utilize the upgraded spectrograph. This second flight, along with the funded 2016 flight, will conduct an initial blind CGM survey of dense fields at z 0.7, conduct a targeted search of circumquasar (CQM) media for selected targets, and conduct follow up on likely tar-gets selected via GALEX and a pilot survey conducted by our group. We will also conduct a statistical search for the faint IGM via statistical stacking of our data. The FIREBall-2 team includes two female graduate students in key roles (both of whom are finishing their PhDs in 2016) and is overseen by a female Postdoctoral scholar (supported by NSF AAPF and Caltech Millikan Fellowships, in addition to a recent Roman Technology Fellowship award). Additional funding is necessary to keep this

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

    SciTech Connect

    Falceta-Gonçalves, D.; Kowal, G.

    2015-07-20

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

  5. Supplementing goat kids with coconut medium chain fatty acids in early life influences growth and rumen papillae development until 4 months after supplementation but effects on in vitro methane emissions and the rumen microbiota are transient.

    PubMed

    Debruyne, Sieglinde; Ruiz-González, Alexis; Artiles-Ortega, Einar; Ampe, Bart; Van Den Broeck, Wim; De Keyser, Ellen; Vandaele, Leen; Goossens, Karen; Fievez, Veerle

    2018-05-04

    The aim of this study was to investigate the methane (CH4) reducing potential of a combination of prenatal and/or postnatal treatment with coconut oil medium chain fatty acids (CO MCFA) in goat kids. The hypothesis is that influencing rumen function during early life has more chances for success than in the adult life, related to the resilience of the mature rumen microbiota. Forty-eight pregnant does were split into two experimental groups: treated does (D+) received 40 g/d of CO MCFA in a test compound feed, while control does (D-) received a control compound feed, during the last 3 wk of gestation. Twin kids from 10 does of each group were split up into a treated (K+) and nontreated (K-) group, resulting in four experimental groups: D+K+, D+K-, D-K+, and D-K-. The K+ kids received 1.8 mL/d of CO MCFA from birth until 2-wk postweaning (11 wk). Irrespective of treatment, the experimental rearing conditions resulted in absence of rumen protozoa at all sampling times, assessed by quantitative PCR (qPCR). In vitro incubations with rumen fluid at 4 wk old showed 82% lower CH4 production of inoculum from D+K+ kids compared to D-K- kids (P = 0.01). However, this was accompanied by lower total volatile fatty acids (tVFA) production (P = 0.006) and higher hydrogen accumulation (P = 0.008). QPCR targeting the mcrA and rrs genes confirmed a lower abundance of total methanogens (P < 0.02) and total eubacteria (P = 0.02) in D+K+ kids at 4 wk old. Methanogenic activity, as assessed by mcrA expression by RT-qPCR, was also lower in these kids. However, activity did not always reflect methanogen abundance. At 11 and 28 wk old, prenatal and postnatal effects on in vitro fermentation and rumen microbiota disappeared. Nevertheless, lower milk replacer intake in the first 4 wk resulted in reduced BW in K+ kids, persisting until 28 wk of age. Additionally, differences assigned to postnatal treatment were found in papillae density, width, and length in different areas of the rumen

  6. The origin of dwarf early-type galaxies

    NASA Astrophysics Data System (ADS)

    Toloba, E.

    2013-05-01

    We have conducted a spectrophotometric study of dwarf early-type galaxies (dEs) in the Virgo cluster and in regions of lower density. We have found that these galaxies show many properties in common with late-type galaxies but not with more massive early-types (E/S0). The properties of the dEs in Virgo show gradients within the cluster. dEs in the outer parts of the Virgo cluster are kinematically supported by rotation, while those in the center are supported by the random motions of their stars (i.e. pressure supported). The rotationally supported dEs have disky isophotes and faint underlying spiral/irregular substructures, they also show younger ages than those pressure supported, which have boxy isophotes and are smooth and regular, without any substructure. We compare the position of these dEs with massive early-type galaxies in the Faber-Jackson and Fundamental Plane relations, and we find that, although there is no difference between the position of rotationally and pressure supported dEs, both deviate from the relations of massive early-type galaxies in the direction of dwarf spheroidal systems (dSphs). We have used their offset with respect to the Fundamental Plane of E/S0 galaxies to estimate their dark matter fraction. All the properties studied in this work agree with a ram pressure stripping scenario, where late-type galaxies infall into the cluster, their interaction with the intergalactic medium blows away their gas and, as a result, they are quenched in a small amount of time. However, those dEs in the center of the cluster seem to have been fully transformed leaving no trace of their possible spiral origin, thus, if that is the case, they must have experienced a more violent mechanism in combination with ram pressure stripping, the open problem is that even galaxy harassment does not fully explain the observed properties for the pressure supported dEs in the center of the Virgo cluster.

  7. Building the Hot Intra-Group Medium in Spiral-Rich Compact Groups

    NASA Astrophysics Data System (ADS)

    O'Sullivan, Ewan

    2014-11-01

    Galaxy groups provide a natural laboratory for investigating the formation of the hot intergalactic medium (IGM). While galaxy clusters gain most of their hot gas through accretion and gravitational shocks, in groups the processes of galaxy evolution (stripping, collisions, star formation) play an important role in the initial build up of the hot halo. We present Chandra and XMM-Newton observations of groups still in the process of forming their IGM, including the well known compact groups HCG 16 and Stephan's Quintet (HCG 92). We show that starburst winds and shock-heating of stripped HI provide important contributions of gas and metals to the IGM, and discuss the impact of gas stripping, enhanced star formation and nuclear activity in the group member galaxies.

  8. CBI: Systems or Medium?

    ERIC Educational Resources Information Center

    Higginbotham-Wheat, Nancy L.

    This paper addresses one area of conflict in decisionmaking in computer-based instruction (CBI) research: the relationship between the researcher's definition of CBI either as a medium or as an integrated system and the design of meaningful research questions. (A medium is defined here as a device for the delivery of instruction, while an…

  9. A Determination of the Intergalactic Redshift Dependent UV-Optical-NIR Photon Density Using Deep Galaxy Survey Data and the Gamma-ray Opacity of the Universe

    NASA Technical Reports Server (NTRS)

    Stecker, Floyd W.; Malkan, Matthew A.; Scully, Sean T.

    2012-01-01

    We calculate the intensity and photon spectrum of the intergalactic background light (IBL) as a function of redshift using an approach based on observational data obtained in many different wavelength bands from local to deep galaxy surveys. This allows us to obtain an empirical determination of the IBL and to quantify its observationally based uncertainties. Using our results on the IBL, we then place 68% confidence upper and lower limits on the opacity of the universe to gamma-rays, free of the theoretical assumptions that were needed for past calculations. We compare our results with measurements of the extragalactic background light and upper limits obtained from observations made by the Fermi Gamma-ray Space Telescope.

  10. A DETERMINATION OF THE INTERGALACTIC REDSHIFT-DEPENDENT ULTRAVIOLET-OPTICAL-NIR PHOTON DENSITY USING DEEP GALAXY SURVEY DATA AND THE GAMMA-RAY OPACITY OF THE UNIVERSE

    SciTech Connect

    Stecker, Floyd W.; Malkan, Matthew A.; Scully, Sean T., E-mail: Floyd.W.Stecker@nasa.gov, E-mail: malkan@astro.ucla.edu, E-mail: scullyst@jmu.edu

    2012-12-20

    We calculate the intensity and photon spectrum of the intergalactic background light (IBL) as a function of redshift using an approach based on observational data obtained in many different wavelength bands from local to deep galaxy surveys. This allows us to obtain an empirical determination of the IBL and to quantify its observationally based uncertainties. Using our results on the IBL, we then place 68% confidence upper and lower limits on the opacity of the universe to {gamma}-rays, free of the theoretical assumptions that were needed for past calculations. We compare our results with measurements of the extragalactic background lightmore » and upper limits obtained from observations made by the Fermi Gamma-ray Space Telescope.« less

  11. Synthetic laser medium

    DOEpatents

    Stokowski, S.E.

    1987-10-20

    A laser medium is particularly useful in high average power solid state lasers. The laser medium includes a chromium dopant and preferably neodymium ions as codopant, and is primarily a gadolinium scandium gallium garnet, or an analog thereof. Divalent cations inhibit spiral morphology as large boules from which the laser medium is derived are grown, and a source of ions convertible between a trivalent state and a tetravalent state at a low ionization energy are in the laser medium to reduce an absorption coefficient at about one micron wavelength otherwise caused by the divalent cations. These divalent cations and convertible ions are dispersed in the laser medium. Preferred convertible ions are provided from titanium or cerium sources.

  12. Synthetic laser medium

    DOEpatents

    Stokowski, Stanley E.

    1989-01-01

    A laser medium is particularly useful in high average power solid state lasers. The laser medium includes a chormium dopant and preferably neodymium ions as codopant, and is primarily a gadolinium scandium gallium garnet, or an analog thereof. Divalent cations inhibit spiral morphology as large boules from which the laser medium is derived are grown, and a source of ions convertible between a trivalent state and a tetravalent state at a low ionization energy are in the laser medium to reduce an absorption coefficient at about one micron wavelength otherwise caused by the divalent cations. These divalent cations and convertible ions are dispersed in the laser medium. Preferred convertible ions are provided from titanium or cerium sources.

  13. X-Ray Background from Early Binaries

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-11-01

    What impact did X-rays from the first binary star systems have on the universe around them? A new study suggests this radiation may have played an important role during the reionization of our universe.Ionizing the UniverseDuring the period of reionization, the universe reverted from being neutral (as it was during recombination, the previous period)to once again being ionized plasma a state it has remained in since then. This transition, which occurred between 150 million and one billion years after the Big Bang (redshift of 6 z 20), was caused by the formation of the first objects energetic enough to reionize the universes neutral hydrogen.ROSAT image of the soft X-ray background throughout the universe. The different colors represent different energy bands: 0.25 keV (red), 0.75 keV (green), 1.5 keV (blue). [NASA/ROSAT Project]Understanding this time period in particular, determining what sources caused the reionization, and what the properties were of the gas strewn throughout the universe during this time is necessary for us to be able to correctly interpret cosmological observations.Conveniently, the universe has provided us with an interesting clue: the large-scale, diffuse X-ray background we observe all around us. What produced these X-rays, and what impact did this radiation have on the intergalactic medium long ago?The First BinariesA team of scientists led by Hao Xu (UC San Diego) has suggested that the very first generation of stars might be an important contributor to these X-rays.This hypothetical first generation, Population III stars, are thought to have formed before and during reionization from large clouds of gas containing virtually no metals. Studies suggest that a large fraction of Pop III stars formed in binaries and when those stars ended their lives as black holes, ensuing accretion from their companions could produceX-ray radiation.The evolution with redshift of the mean X-ray background intensities. Each curve represents a different

  14. The Digital Medium Meets the Advertising Message.

    ERIC Educational Resources Information Center

    Nisenholtz, Martin

    1994-01-01

    Discusses the likelihood that companies will use online services as an advertising medium. Topics addressed include the art of interactive marketing; advertising in the digital age; early experiments with interactive marketing, including the use of videotex and videodisc; and recent trends that set the stage for interactive marketing to personal…

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  16. The violent interstellar medium

    NASA Technical Reports Server (NTRS)

    Mccray, R.; Snow, T. P., Jr.

    1979-01-01

    Observational evidence for high-velocity and high-temperature interstellar gas is reviewed. The physical processes that characterize this gas are described, including the ionization and emissivity of coronal gas, the behavior and appearance of high-velocity shocks, and interfaces between coronal gas and cooler interstellar gas. Hydrodynamical models for the action of supernova explosions and stellar winds on the interstellar medium are examined, and recent attempts to synthesize all the processes considered into a global model for the interstellar medium are discussed.

  17. Hypermedia as medium

    NASA Technical Reports Server (NTRS)

    Dede, Christopher J.

    1990-01-01

    Claims and rebuttals that hypermedia (the associative, nonlinear interconnection of multimedia materials) is a fundamentally innovative means of thinking and communicating are described. This representational architecture has many advantages that make it a major advance over other media; however, it also has several intrinsic problems that severly limits its effectiveness as a medium. These advantages and limits in applications are discussed.

  18. Holographic recording medium

    NASA Technical Reports Server (NTRS)

    Gange, Robert Allen (Inventor)

    1977-01-01

    A holographic recording medium comprising a conductive substrate, a photoconductive layer and an electrically alterable layer of a linear, low molecular weight hydrocarbon polymer has improved fatigue resistance. An acrylic barrier layer can be interposed between the photoconductive and electrically alterable layers.

  19. An Empirical Determination of the Intergalactic Background Light from UV to FIR Wavelengths Using FIR Deep Galaxy Surveys and the Gamma-Ray Opacity of the Universe

    NASA Astrophysics Data System (ADS)

    Stecker, Floyd W.; Scully, Sean T.; Malkan, Matthew A.

    2016-08-01

    We have previously calculated the intergalactic background light (IBL) as a function of redshift from the Lyman limit in the far-ultraviolet to a wavelength of 5 μm in the near-infrared range, based purely on data from deep galaxy surveys. Here, we use similar methods to determine the mid- and far-infrared IBL from 5 to 850 μm. Our approach enables us to constrain the range of photon densities by determining the uncertainties in observationally determined luminosity densities and spectral gradients. By also including the effect of the 2.7 K cosmic background photons, we determine upper and lower limits on the opacity of the universe to γ-rays up to PeV energies within a 68% confidence band. Our direct results on the IBL are consistent with those from complimentary γ-ray analyses using observations from the Fermi γ-ray space telescope and the H.E.S.S. air Čerenkov telescope. Thus, we find no evidence of previously suggested processes for the modification of γ-ray spectra other than that of absorption by pair production alone.

  20. AN EMPIRICAL DETERMINATION OF THE INTERGALACTIC BACKGROUND LIGHT FROM UV TO FIR WAVELENGTHS USING FIR DEEP GALAXY SURVEYS AND THE GAMMA-RAY OPACITY OF THE UNIVERSE

    SciTech Connect

    Stecker, Floyd W.; Scully, Sean T.; Malkan, Matthew A., E-mail: Floyd.W.Stecker@nasa.gov, E-mail: scullyst@jmu.edu, E-mail: malkan@astro.ucla.edu

    We have previously calculated the intergalactic background light (IBL) as a function of redshift from the Lyman limit in the far-ultraviolet to a wavelength of 5 μ m in the near-infrared range, based purely on data from deep galaxy surveys. Here, we use similar methods to determine the mid- and far-infrared IBL from 5 to 850 μ m. Our approach enables us to constrain the range of photon densities by determining the uncertainties in observationally determined luminosity densities and spectral gradients. By also including the effect of the 2.7 K cosmic background photons, we determine upper and lower limits onmore » the opacity of the universe to γ -rays up to PeV energies within a 68% confidence band. Our direct results on the IBL are consistent with those from complimentary γ -ray analyses using observations from the Fermi γ -ray space telescope and the H.E.S.S. air Čerenkov telescope. Thus, we find no evidence of previously suggested processes for the modification of γ -ray spectra other than that of absorption by pair production alone.« less

  1. Liquid chromatographic extraction medium

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1994-09-13

    A method and apparatus are disclosed for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water. 1 fig.

  2. Liquid chromatographic extraction medium

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1994-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  3. First Look at a Major Transition Period in the Early Universe

    NASA Astrophysics Data System (ADS)

    1997-08-01

    than 10 15 times more luminous than the Sun, or 10,000 times brighter than the entire Milky Way galaxy in which we live. Caption to ESO PR Photo 22b/97 [GIF, 22k] Follow-up observations with the now decommissioned ESA/NASA International Ultraviolet Explorer satellite observatory showed that the light from this quasar travels the long way to us without being significantly absorbed in the ultraviolet spectral region. This is demonstrated in ESO PR Photo 22b/97 which shows its overall spectrum. Note in particular the intensity increase towards the ultraviolet part (to the left in the diagram) due to the unusually `clear view' in this direction. New observations of HE 2347-4342 have now provided important information, not only about the quasar itself, but especially about the conditions in the surrounding intergalactic medium at this early time. Early evolution of the Universe There is general agreement among most scientists that the Universe emanated from a hot and extremely dense initial state in the so-called Big Bang . Just three minutes later, the production of enormous quantities of hydrogen and helium nuclei of protons and neutrons came to an end. Lots of free electrons were moving around and the numerous photons were scattered from these and the `naked' atomic nuclei. After some 100,000 years, the Universe had cooled down to a few thousand degrees and the nuclei and electrons combined to form atoms. The photons were then no longer scattered and the Universe became transparent. Cosmologists refer to this moment as the recombination epoch . The microwave background radiation we now observe from all directions gives a picture of the state of great homogeneity in the Universe at that epoch. In the next phase the primeval atoms, more than 99% of which were of hydrogen and helium, moved together and began to form huge clouds from which galaxies and stars later emerged. When the first generation of stars and, somewhat later, of quasars, had formed, their intensive

  4. SPATIALLY EXTENDED 21 cm SIGNAL FROM STRONGLY CLUSTERED UV AND X-RAY SOURCES IN THE EARLY UNIVERSE

    SciTech Connect

    Ahn, Kyungjin; Xu, Hao; Norman, Michael L.

    2015-03-20

    We present our prediction for the local 21 cm differential brightness temperature (δT{sub b}) from a set of strongly clustered sources of Population III (Pop III) and II (Pop II) objects in the early universe, by a numerical simulation of their formation and radiative feedback. These objects are located inside a highly biased environment, which is a rare, high-density peak (“Rarepeak”) extending to ∼7 comoving Mpc. We study the impact of ultraviolet and X-ray photons on the intergalactic medium (IGM) and the resulting δT{sub b}, when Pop III stars are assumed to emit X-ray photons by forming X-ray binaries verymore » efficiently. We parameterize the rest-frame spectral energy distribution of X-ray photons, which regulates X-ray photon-trapping, IGM-heating, secondary Lyα pumping and the resulting morphology of δT{sub b}. A combination of emission (δT{sub b} > 0) and absorption (δT{sub b} < 0) regions appears in varying amplitudes and angular scales. The boost of the signal by the high-density environment (δ ∼ 0.64) and on a relatively large scale combines to make Rarepeak a discernible, spatially extended (θ ∼ 10′) object for 21 cm observation at 13 ≲ z ≲ 17, which is found to be detectable as a single object by SKA with integration time of ∼1000 hr. Power spectrum analysis by some of the SKA precursors (Low Frequency Array, Murchison Widefield Array, Precision Array for Probing the Epoch of Reionization) of such rare peaks is found to be difficult due to the rarity of these peaks, and the contribution only by these rare peaks to the total power spectrum remains subdominant compared to that by all astrophysical sources.« less

  5. The Interstellar Medium

    NASA Technical Reports Server (NTRS)

    Tielens, Alexander G. G. M.

    1995-01-01

    The Interstellar Medium (ISM) forms an integral part of the lifecycle of stars and the galaxy. Stars are formed by gravitational contraction of interstellar clouds. Over their life, stars return much of their mass to the ISM through winds and supernova explosions, resulting in a slow enrichment in heavy elements. Understanding the origin and evolution of the ISM is a key problem within astrophysics. The KAO has made many important contributions to studies of the interstellar medium both on the macro and on the micro scale. In this overview, I will concentrate on two breakthroughs in the last decade in which KAO observations have played a major role: (1) the importance of large Polycyclic Aromatic Hydrocarbon (PAH) molecules for the ISM (section 3) and (2) the study of Photodissociation Regions (PDRs) as an analog for the diffuse ISM at large (section 4). Appropriately, the micro and macro problem are intricately interwoven in these problems. Finally, section 5 reviews the origin of the (CII) emission observed by COBE.

  6. The diffuse interstellar medium

    NASA Technical Reports Server (NTRS)

    Cox, Donald P.

    1990-01-01

    The last 20 years of the efforts to understand the diffuse ISM are reviewed, with recent changes of fundamental aspects being highlighted. Attention is given to the interstellar pressure and its components, the weight of the ISM, the midplane pressure contributions, and pressure contributions at 1 kpc. What velocity dispersions, cosmic ray pressure, and magnetic field pressure that can be expected for a gas in a high magnetic field environment is addressed. The intercloud medium is described, with reference to the work of Cox and Slavin (1989). Various caveats are discussed and a number of areas for future investigation are identified. Steps that could be taken toward a successful phase segregation model are discussed.

  7. FIREBall-2: Trailblazing observations of the space UV circumgalactic medium (Columbia University, Co-I Proposal)

    NASA Astrophysics Data System (ADS)

    Schiminovich, David

    Columbia University is a Co-I institution in a collaborative research program with Caltech, the Lead Institution (PI: Christopher Martin). The Faint Intergalactic-medium Redshifted Emission Balloon (FIREBall-2) is designed to discover and map faint emission from the circumgalactic medium of low redshift galaxies (0.3intergalactic and circumgalactic (IGM, CGM) emission available from any instrument at the time. FIREBall-2 has been significantly upgraded compared to FB-1, and is in the final stages of integration for a September 2016 flight from Ft. Sumner, New Mexico. The spectrograph has been redesigned with a wider field of view and greater efficiency. An upgraded detector system including a groundbreaking high QE, low-noise, UV optimized CCD detector is under final dark current and noise testing and will improve instrument performance by more than an order of magnitude. CNES is providing the spectrograph, gondola, and gondola flight support team, with construction of all components complete and final alignment and testing ongoing. We propose three additional years of funding to support the FIREBall-2 team in one additional flight in 2018 to fully utilize the upgraded spectrograph. This second flight, along with the funded 2016 flight, will conduct an initial blind CGM survey of dense fields at z 0.7, conduct a targeted search of circumquasar (CQM) media for selected targets, and conduct follow up on likely tar-gets selected via GALEX and a pilot survey conducted by our group. We will also conduct a statistical search for the faint IGM via statistical stacking of our data. The FIREBall-2 team includes two female graduate students in key roles (both of whom are finishing their PhDs in 2016) and is overseen by a female Postdoctoral scholar (supported by NSF AAPF

  8. The Circumgalactic Medium of Andromeda

    NASA Astrophysics Data System (ADS)

    Lehner, Nicolas; Project AMIGA Team

    2017-03-01

    Our view of galaxies has been transformed in recent years with diffuse halo gas surrounding galaxies that contains at least as many metals and baryons as their disks. While single sight lines through galaxy halos seen in absorption have provided key new constraints, they provide only average properties. Our massive neighbor, the Andromeda (M31) galaxy, provides an unique way to study its circumgalactic medium whereby we can study it using not one or two, but ~36 sightlines thanks to its proximity. With our Large HST program - Project AMIGA (Absorption Maps In the Gas of Andromeda), our goals are to determine the spatial distribution of the halo properties of a L* galaxy using 36 background targets at different radii and azimuths. In this brief paper, I discuss briefly the scientific rationale of Project AMIGA and some early science results. In particular, for the first time we have demonstrated that M31 has a gaseous halo that extends to R vir with as much as metal and baryonic masses than in its disk and has substantial change in its ionization properties with more highly ionized gas found at R ~ R vir than cooler gas found near the disk.

  9. SciTech Connect

    Imara, Nia; Loeb, Abraham, E-mail: nimara@cfa.harvard.edu

    Infrared emission from intergalactic dust might compromise the ability of future experiments to detect subtle spectral distortions in the Cosmic Microwave Background (CMB) from the early universe. We provide the first estimate of foreground contamination of the CMB signal due to diffuse dust emission in the intergalactic medium. We use models of the extragalactic background light to calculate the intensity of intergalactic dust emission and find that emission by intergalactic dust at z ≲ 0.5 exceeds the sensitivity of the planned Primordial Inflation Explorer to CMB spectral distortions by 1–3 orders of magnitude. In the frequency range ν = 150–2400more » GHz, we place an upper limit of 0.06% on the contribution to the far-infrared background from intergalactic dust emission.« less

  10. Early results from the Far Infrared Absolute Spectrophotometer (FIRAS)

    NASA Technical Reports Server (NTRS)

    Mather, J. C.; Cheng, E. S.; Shafer, R. A.; Eplee, R. E.; Isaacman, R. B.; Fixsen, D. J.; Read, S. M.; Meyer, S. S.; Weiss, R.; Wright, E. L.

    1991-01-01

    The Far Infrared Absolute Spectrophotometer (FIRAS) on the Cosmic Background Explorer (COBE) mapped 98 percent of the sky, 60 percent of it twice, before the liquid helium coolant was exhausted. The FIRAS covers the frequency region from 1 to 100/cm with a 7 deg angular resolution. The spectral resolution is 0.2/cm for frequencies less than 20/cm and 0.8/cm for higher frequencies. Preliminary results include: a limit on the deviations from a Planck curve of 1 percent of the peak brightness from 1 to 20/cm, a temperature of 2.735 +/- 0.06 K, a limit on the Comptonization parameter y of 0.001, on the chemical potential parameter mu of 0.01, a strong limit on the existence of a hot smooth intergalactic medium, and a confirmation that the dipole anisotropy spectrum is that of a Doppler shifted blackbody.

  11. First look at a major transition period in the early Universe

    NASA Astrophysics Data System (ADS)

    1997-08-01

    in ESO PR Photo 22b/97 which shows its overall spectrum. Note in particular the intensity increase towards the ultraviolet part (to the left in the diagram) due to the unusually `clear view' in this direction. New observations of HE 2347-4342 have now provided important information, not only about the quasar itself, but especially about the conditions in the surrounding intergalactic medium at this early time. Early evolution of the Universe There is general agreement among most scientists that the Universe emanated from a hot and extremely dense initial state in the so-called Big Bang. Just three minutes later, the production of enormous quantities of hydrogen and helium nuclei of protons and neutrons came to an end. Lots of free electrons were moving around and the numerous photons were scattered from these and the `naked' atomic nuclei. After some 100,000 years, the Universe had cooled down to a few thousand degrees and the nuclei and electrons combined to form atoms. The photons were then no longer scattered and the Universe became transparent. Cosmologists refer to this moment as the recombination epoch. The microwave background radiation we now observe from all directions gives a picture of the state of great homogeneity in the Universe at that epoch. In the next phase the primeval atoms, more than 99% of which were of hydrogen and helium, moved together and began to form huge clouds from which galaxies and stars later emerged. When the first generation of stars and, somewhat later, of quasars, had formed, their intensive ultraviolet radiation began to knock off electrons from the hydrogen and helium atoms. Now the intergalactic gas again became ionized [4] in steadily growing spheres around the ionizing sources. This is the so-called re-ionization epoch. Is it possible to observe the re-ionization epoch directly? It is believed that a sufficient number of energetic photons to cause re-ionization of most of the primeval hydrogen atoms in intergalactic space had

  12. The Infrared Medium-deep Survey. IV. The Low Eddington Ratio of A Faint Quasar at z ∼ 6: Not Every Supermassive Black Hole is Growing Fast in the Early Universe

    NASA Astrophysics Data System (ADS)

    Kim, Yongjung; Im, Myungshin; Jeon, Yiseul; Kim, Minjin; Hyun, Minhee; Kim, Dohyeong; Kim, Jae-Woo; Taak, Yoon Chan; Yoon, Yongmin; Choi, Changsu; Hong, Jueun; Jun, Hyunsung David; Karouzos, Marios; Kim, Duho; Kim, Ji Hoon; Lee, Seong-Kook; Pak, Soojong; Park, Won-Kee

    2018-03-01

    To date, most of the luminous quasars known at z ∼ 6 have been found to be in maximal accretion with the Eddington ratios, {λ }Edd}∼ 1, suggesting enhanced nuclear activities in the early universe. However, this may not be the whole picture of supermassive black hole (SMBH) growth, since previous studies have not reached faint quasars that are more likely to harbor SMBHs with low {λ }Edd}. To gain a better understanding of the accretion activities in quasars in the early universe, we obtained a deep near-infrared (NIR) spectrum of a quasar, IMS J220417.92+011144.8 (hereafter IMS J2204+0112), one of the faintest quasars that has been identified at z ∼ 6. From the redshifted C IV λ1549 emission line in the NIR spectrum, we find that IMS J2204+0112 harbors a SMBH with a solar mass of about a billion and {λ }Edd}∼ 0.1, but with a large uncertainty in both quantities (0.41 dex). IMS J2204+0112 has one of the lowest Eddington ratios among quasars at z ∼ 6, but a common value among quasars at z ∼ 2. Its low {λ }Edd} can be explained with two scenarios; the SMBH growth from a stellar-mass black hole through short-duration super-Eddington accretion events or from a massive black hole seed (∼ {10}5 {M}ȯ ) with Eddington-limited accretion. NIR spectra of more faint quasars are needed to better understand the accretion activities of SMBHs at z ∼ 6.

  13. Propagation of monochromatic light in a hot and dense medium

    NASA Astrophysics Data System (ADS)

    Masood, Samina S.

    2017-12-01

    Photons, as quanta of electromagnetic fields, determine the electromagnetic properties of an extremely hot and dense medium. Considering the properties of the photons in the interacting medium of charged particles, we explicitly calculate the electromagnetic properties such as the electric permittivity, magnetic permeability, refractive index and the propagation speed of electromagnetic signals in an extremely hot and dense background. Photons acquire a dynamically generated mass in such a medium. The screening mass of the photon, the Debye shielding length and the plasma frequency are calculated as functions of the statistical parameters of the medium. We study the properties of the propagating particles in astrophysical systems of distinct statistical conditions. The modifications in the properties of the medium lead to the equation of state of the system. We mainly calculate all these parameters for extremely high temperatures of the early universe.

  14. Quasars Probing Quasars. VII. The Pinnacle of the Cool Circumgalactic Medium Surrounds Massive z ~ 2 Galaxies

    NASA Astrophysics Data System (ADS)

    Prochaska, J. Xavier; Lau, Marie Wingyee; Hennawi, Joseph F.

    2014-12-01

    We survey the incidence and absorption strength of the metal-line transitions C II 1334 and C IV 1548 from the circumgalactic medium (CGM) surrounding z ~ 2 quasars, which act as signposts for massive dark matter halos M halo ≈ 1012.5 M ⊙. On scales of the virial radius (r vir ≈ 160 kpc), we measure a high covering fraction fC = 0.73 ± 0.10 to strong C II 1334 absorption (rest equivalent width W 1334 >= 0.2 Å), implying a massive reservoir of cool (T ~ 104 K) metal enriched gas. We conservatively estimate a metal mass exceeding 108 M ⊙. We propose that these metals trace enrichment of the incipient intragroup/intracluster medium that these halos eventually inhabit. This cool CGM around quasars is the pinnacle among galaxies observed at all epochs, as regards covering the fraction and average equivalent width of H I Lyα and low-ion metal absorption. We argue that the properties of this cool CGM primarily reflect the halo mass, and that other factors such as feedback, star-formation rate, and accretion from the intergalactic medium are secondary. We further estimate that the CGM of massive, z ~ 2 galaxies accounts for the majority of strong Mg II absorption along random quasar sightlines. Last, we detect an excess of strong C IV 1548 absorption (W 1548 >= 0.3 Å) over random incidence to the 1 Mpc physical impact parameter and measure the quasar-C IV cross-correlation function: ξ C \\scriptsize{IV-Q}(r) = (r/r_0)-γ with r0 = 7.5+2.8-1.4 h-1 Mpc and γ = 1.7+0.1-0.2. Consistent with previous work on larger scales, we infer that this highly ionized C IV gas traces massive (1012 M ⊙) halos.

  15. Medium Duty Electric Vehicle Demonstration Project

    SciTech Connect

    Mackie, Robin J. D.

    2015-05-31

    The Smith Electric Vehicle Demonstration Project (SDP) was integral to the Smith business plan to establish a manufacturing base in the United States (US) and produce a portfolio of All Electric Vehicles (AEV’s) for the medium duty commercial truck market. Smith focused on the commercial depot based logistics market, as it represented the market that was most ready for the early adoption of AEV technology. The SDP enabled Smith to accelerate its introduction of vehicles and increase the size of its US supply chain to support early market adoption of AEV’s that were cost competitive, fully met the needs ofmore » a diverse set of end users and were compliant with Federal safety and emissions requirements. The SDP accelerated the development and production of various electric drive vehicle systems to substantially reduce petroleum consumption, reduce vehicular emissions of greenhouse gases (GHG), and increase US jobs.« less

  16. Absorption systems at z ˜ 2 as a probe of the circum galactic medium: a probabilistic approach

    NASA Astrophysics Data System (ADS)

    Mongardi, C.; Viel, M.; D'Odorico, V.; Kim, T.-S.; Barai, P.; Murante, G.; Monaco, P.

    2018-05-01

    We characterize the properties of the intergalactic medium (IGM) around a sample of galaxies extracted from state-of-the-art hydrodynamical simulations of structure formation in a cosmological volume of 25 Mpc comoving at z ˜ 2. The simulations are based on two different sub-resolution schemes for star formation and supernova feedback: the MUlti-Phase Particle Integrator (MUPPI) scheme and the Effective Model. We develop a quantitative and probabilistic analysis based on the apparent optical depth method of the properties of the absorbers as a function of impact parameter from their nearby galaxies: in such a way we probe different environments from circumgalactic medium (CGM) to low density filaments. Absorbers' properties are then compared with a spectroscopic observational data set obtained from high resolution quasar spectra. Our main focus is on the NCIV - NHI relation around simulated galaxies: the results obtained with MUPPI and the Effective model are remarkably similar, with small differences only confined to regions at impact parameters b = [1 - 3] × rvir. Using {C IV} as a tracer of the metallicity, we obtain evidence that the observed metal absorption systems have the highest probability to be confined in a region of 150-400 kpc around galaxies. Near-filament environments have instead metallicities too low to be probed by present-day telescopes, but could be probed by future spectroscopical studies. Finally we compute {C IV} covering fractions which are in agreement with observational data.

  17. HERA: Illuminating Our Early Universe

    NASA Astrophysics Data System (ADS)

    DeBoer, David

    2014-06-01

    The Hydrogen Epoch of Reionization Arrays (HERA) roadmap is a staged plan for using the unique properties of the 21cm line from neutral hydrogen to probe our cosmic dawn, from the birth of the first stars and black holes, through the full reionization of the primordial intergalactic medium (IGM). HERA is a collaboration between the Precision Array Probing the Epoch of Reionization (PAPER), US-Murchison Widefield Array (MWA), and MIT Epoch of Reionization (MITEOR) teams.The first phase of the HERA roadmap entailed the operation of the PAPER and MWA telescopes to explore techniques and designs required to detect the primordial HI signal in the presence of radio continuum foreground emission some four orders of magnitude brighter. Studies with PAPER and the MWA have led to a new understanding of the interplay of foreground and instrumental systematics in the context of a three-dimensional cosmological intensity-mapping experiment. We are now able to remove foregrounds to the limits of our sensitivity with these instruments, culminating in the first physically meaningful upper limits on the power spectrum of 2 cm emission from reionization.Building on this understanding, the next stage of HERA entails a new 14m diameter antenna element that is optimized both for sensitivity and for minimizing foreground systematics. Arranging these elements in a compact hexagonal grid yields an array that facilitates calibration, leverages proven foreground removal techniques, and is scalable to large collecting areas. The HERA phase II will be located in the radio quiet environment of the SKA site in Karoo, South Africa, and have a sensitivity close to two orders of magnitude better than PAPER and the MWA, with broader frequency coverage, HERA can paint an uninterrupted picture through reionization, back to the end of the Dark Ages.This paper will present a summary of the current understanding of the signal characteristics and measurements and describe this planned HERA telescope to

  18. Teacher Beliefs regarding Bilingualism in an English Medium Reading Program

    ERIC Educational Resources Information Center

    Vaish, Viniti

    2012-01-01

    Reading classes in schools where English is the medium of instruction are increasingly servicing a linguistically diverse population; however, teacher-training for English teachers lacks a focus on bilingualism. Using the context of Singapore, this paper analyses beliefs on bilingualism of English teachers in an early intervention reading program.…

  19. An Empirical Determination of the Intergalactic Background Light Using Near-Infrared Deep Galaxy Survey Data Out to 5 Micrometers and the Gamma-Ray Opacity of the Universe

    NASA Technical Reports Server (NTRS)

    Scully, Sean T.; Malkan, Matthew A.; Stecker, Floyd W.

    2014-01-01

    We extend our previous model-independent determination of the intergalactic background light, based purely on galaxy survey data, out to a wavelength of 5 micrometers. Our approach enables us to constrain the range of photon densities, based on the uncertainties from observationally determined luminosity densities and colors. We further determine a 68% confidence upper and lower limit on the opacity of the universe to gamma-rays up to energies of 1.6/(1 + z) terraelectron volts. A comparison of our lower limit redshift-dependent opacity curves to the opacity limits derived from the results of both ground-based air Cerenkov telescope and Fermi-LAT observations of PKS 1424+240 allows us to place a new upper limit on the redshift of this source, independent of IBL modeling.

  20. An empirical determination of the intergalactic background light using near-infrared deep galaxy survey data out to 5 μm and the gamma-ray opacity of the universe

    SciTech Connect

    Scully, Sean T.; Malkan, Matthew A.; Stecker, Floyd W., E-mail: Floyd.W.Stecker@nasa.gov

    2014-04-01

    We extend our previous model-independent determination of the intergalactic background light, based purely on galaxy survey data, out to a wavelength of 5 μm. Our approach enables us to constrain the range of photon densities, based on the uncertainties from observationally determined luminosity densities and colors. We further determine a 68% confidence upper and lower limit on the opacity of the universe to γ-rays up to energies of 1.6/(1 + z) TeV. A comparison of our lower limit redshift-dependent opacity curves to the opacity limits derived from the results of both ground-based air Cerenkov telescope and Fermi-LAT observations of PKSmore » 1424+240 allows us to place a new upper limit on the redshift of this source, independent of IBL modeling.« less

  1. Nonlinear dynamo in the intracluster medium

    NASA Astrophysics Data System (ADS)

    Beresnyak, Andrey; Miniati, Francesco

    2018-05-01

    Hot plasma in galaxy clusters, the intracluster medium is observed to be magnetized with magnetic fields of around a μG and the correlation scales of tens of kiloparsecs, the largest scales of the magnetic field so far observed in the Universe. Can this magnetic field be used as a test of the primordial magnetic field in the early Universe? In this paper, we argue that if the cluster field was created by the nonlinear dynamo, the process would be insensitive to the value of the initial field. Our model combines state of the art hydrodynamic simulations of galaxy cluster formation in a fully cosmological context with nonlinear dynamo theory. Initial field is not a parameter in this model, yet it predicts magnetic scale and strength compatible with observations.

  2. Optical imaging of objects in turbid medium with ultrashort pulses

    NASA Astrophysics Data System (ADS)

    Wang, Chih-Yu; Sun, Chia-Wei; Yang, Chih Chung; Kiang, Yean-Woei; Lin, Chii-Wann

    2000-07-01

    Photons are seriously scattered when entering turbid medium; this the images of objects hidden in turbid medium can not be obtained by just collecting the transmitted photons. Early-arriving photons, which are also called ballistic or snake protons, are much less scattered when passing through turbid medium, and contains more image information than the late-arriving ones. Therefore, objects embedded in turbid medium can be imaged by gathering the ballistic and snake photons. In the present research we try to recover images of objects in turbid medium by simultaneously time-gate and polarization-gate to obtain the snake photons. An Argon-pumped Ti-Sapphire laser with 100fs pulses was employed as a light source. A streak camera with a 2ps temporal resolution was used to extract the ballistic and snake photons. Two pieces of lean swine meat, measured 4mmX3mm and 5xxX4mm, respectively, were placed in a 10cmX10cmX3cm acrylic tank, which was full of diluted milk. A pair of polarizer and an analyzer was used to extract the light that keeps polarization unchanged. The combination of time gating and polarization gating resulted in good images of objects hidden in turbid medium.

  3. Heating the warm ionized medium

    NASA Technical Reports Server (NTRS)

    Reynolds, R. J.; Cox, D. P.

    1992-01-01

    If photoelectric heating by grains within the diffuse ionized component of the interstellar medium is 10 exp -25 ergs/s per H atom, the average value within diffuse H I regions, then grain heating equals or exceeds photoionization heating of the ionized gas. This supplemental heat source would obviate the need for energetic ionizing photons to balance the observed forbidden-line cooling and could be responsible in part for enhanced intensities of some of the forbidden lines.

  4. The Dual-channel Extreme Ultraviolet Continuum Experiment: Sounding Rocket EUV Observations of Local B Stars to Determine Their Potential for Supplying Intergalactic Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Erickson, Nicholas; Green, James C.; France, Kevin; Stocke, John T.; Nell, Nicholas

    2018-06-01

    We describe the scientific motivation and technical development of the Dual-channel Extreme Ultraviolet Continuum Experiment (DEUCE). DEUCE is a sounding rocket payload designed to obtain the first flux-calibrated spectra of two nearby B stars in the EUV 650-1150Å bandpass. This measurement will help in understanding the ionizing flux output of hot B stars, calibrating stellar models and commenting on the potential contribution of such stars to reionization. DEUCE consists of a grazing incidence Wolter II telescope, a normal incidence holographic grating, and the largest (8” x 8”) microchannel plate detector ever flown in space, covering the 650-1150Å band in medium and low resolution channels. DEUCE will launch on December 1, 2018 as NASA/CU sounding rocket mission 36.331 UG, observing Epsilon Canis Majoris, a B2 II star.

  5. THE STRUCTURE OF THE CIRCUMGALACTIC MEDIUM OF GALAXIES: COOL ACCRETION INFLOW AROUND NGC 1097

    SciTech Connect

    Bowen, David V.; Jenkins, Edward B.; Chelouche, Doron

    We present Hubble Space Telescope far-UV spectra of four QSOs whose sightlines pass through the halo of NGC 1097 at impact parameters of ρ = 48–165 kpc. NGC 1097 is a nearby spiral galaxy that has undergone at least two minor merger events, but no apparent major mergers, and is relatively isolated with respect to other nearby bright galaxies. This makes NGC 1097 a good case study for exploring baryons in a paradigmatic bright-galaxy halo. Ly α absorption is detected along all sightlines and Si iii λ 1206 is found along the three sightlines with the smallest ρ ; metalmore » lines of C ii, Si ii, and Si iv are only found with certainty toward the innermost sightline. The kinematics of the absorption lines are best replicated by a model with a disk-like distribution of gas approximately planar to the observed 21 cm H i disk, which is rotating more slowly than the inner disk, and into which gas is infalling from the intergalactic medium. Some part of the absorption toward the innermost sightline may arise either from a small-scale outflow or from tidal debris associated with the minor merger that gives rise to the well known “dog-leg” stellar stream that projects from NGC 1097. When compared to other studies, NGC 1097 appears to be a “typical” absorber, although the large dispersion in absorption line column density and equivalent width in a single halo goes perhaps some way toward explaining the wide range of these values seen in higher- z studies.« less

  6. Atomic and molecular_diagnostics of the interstellar medium

    NASA Astrophysics Data System (ADS)

    Roueff, E.

    1987-08-01

    Ever since molecular species have been discovered in space in the 30's and early 40's by the optical identification of CH, CH+ and CN in absorption towards nearby hot stars, the question of molecule formation has accompanied the observational efforts. The purpose of this paper is to point out presently existing observational constraints and the limits they may cast on our knowledge of the interstellar medium. The need for reliable atomic and molecular data will be emphasized with some specific examples.

  7. How Does the Medium Affect the Message?

    ERIC Educational Resources Information Center

    Dommermuth, William P.

    1974-01-01

    This experimental comparison of the advertising effectiveness of television, movies, radio, and print finds no support for McLuhan's idea that television is a "cool" medium and movies are a "hot" medium. (RB)

  8. Patchy intergalactic He II absorption in HE 2347-4342. II. The possible discovery of the epoch of He-reionization

    NASA Astrophysics Data System (ADS)

    Reimers, D.; Kohler, S.; Wisotzki, L.; Groote, D.; Rodriguez-Pascual, P.; Wamsteker, W.

    1997-11-01

    We report on observations of redshifted Heii303.8 Angstroms absorption in the high-redshift QSO HE2347-4342 (z=2.885, V=16.1) with the Goddard High Resolution Spectrograph on board HST in its low resolution mode (bigtriangleup lambda = 0.7 Angstroms). With f_λ=3.6\\ 10(-15) ergcm(-2) s(-1) Angstroms(-1) at the expected position of Heii304 Angstroms absorption it is the most UV-bright high redshift QSO discovered so far. We show that the Heii opacity as a function of redshift is patchy showing spectral regions with low Heii opacity (``voids'') and regions with high Heii opacity (blacked-out ``troughs'') and no detectable flux. Combination with high-resolution optical spectra of the Lyalpha forest using CASPEC at the 3.6m telescope shows that the voids can be explained either exclusively by Lyalpha forest cloud absorption with a moderate N_{subs {He{sc ii}}}/N_{subs {H{sc i}}} ratio eta <=100 and turbulent line broadening or by a combination of Lyalpha forest with eta = 45 and thermal broadening plus a diffuse medium with tau_ {subs {GP}}({subs {He{sc ) ii}}} ~ 0.3. Since the latter is a minimum assumption for the Lyalpha forest, a strict upper limit to a diffuse medium is Omega_ {subs {diff}}<0.02 h50(-1.5) at z=2.8. In the troughs in addition to the Lyalpha forest opacity a continuous Heii 304 Angstroms opacity tau = 4.8(+infty }_{-2) is required. In case of photoionization, the troughs would require a diffuse component with a density close to Omega =~ 0.077(eta /45)(-0.5) h50(-1.5) , i.e. all baryons in the universe, which is inconsistent, however, with the observed absence of such a component in the voids. A tentative interpretation is that we observe the epoch of partial Heii reionization of the universe with patches not yet reionized. In that case a diffuse component with Omega_ {subs {diff}}>= 1.3\\ 10(-4) h(-1}_{50) would be sufficient to explain the ``trough'' opacity. The size of the 1163--1172 Angstroms trough is ~ 6 h50(-1) Mpc or ~ 2300 kms(-1

  9. A comparison of the original Rappaport medium (R medium) and the Rappaport-Vassiliadis medium (RV medium) in the isolation of salmonellae from meat products.

    PubMed Central

    Vassiliadis, P.; Kalapothaki, V.; Mavrommati, C.; Trichopoulos, D.

    1984-01-01

    The Rappaport-Vassiliadis enrichment medium (RV medium) in 10 ml quantities (RV/43 degrees C, 10 ml) inoculated with 0.1 ml of pre-enrichment medium (P medium) was found more efficient in the isolation of salmonellae from 409 pre-enriched samples (mainly meat products), than the original Rappaport medium incubated at 43 degrees C (R/43 degrees C) and the RV medium in 5 ml quantities (RV/43 degrees C, 5 ml) inoculated with 0.01 ml of P medium (P less than 0.001, in both instances). Therefore, the inoculum from pre-enriched foods should not be less than 0.1 ml in 10 ml of RV medium. The RV/43 degrees, 10 ml was also better (P less than 0.01) in detecting samples containing salmonellas than the original Rappaport medium incubated at 37 degrees C (R/37 degrees C, 10 ml) and the modification R25 of R medium incubated at 37 degrees C. The R25 modification was used in 10 ml quantities (R25/37 degrees C, 10 ml) inoculated with 0.1 ml of P medium and in 5 ml quantities (R25/37 degrees, 5 ml) inoculated with 0.01 ml of P medium. The last two R25 procedures were of the same efficiency in isolating salmonellas from meat products. PMID:6747286

  10. 49 CFR 195.306 - Test medium.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Test medium. 195.306 Section 195.306... PIPELINE Pressure Testing § 195.306 Test medium. (a) Except as provided in paragraphs (b), (c), and (d) of this section, water must be used as the test medium. (b) Except for offshore pipelines, liquid...

  11. 49 CFR 195.306 - Test medium.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Test medium. 195.306 Section 195.306... PIPELINE Pressure Testing § 195.306 Test medium. (a) Except as provided in paragraphs (b), (c), and (d) of this section, water must be used as the test medium. (b) Except for offshore pipelines, liquid...

  12. 27 CFR 19.914 - Medium plants.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Medium plants. 19.914... OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Distilled Spirits For Fuel Use Permits § 19.914 Medium plants. Any person wishing to establish a medium plant shall make application for and obtain in...

  13. Theory of interstellar medium diagnostics

    NASA Technical Reports Server (NTRS)

    Fahr, H. J.

    1983-01-01

    The theoretical interpretation of observed interplanetary resonance luminescence patterns is used as one of the must promising methods to determine the state of the local interstellar medium (LISM). However, these methods lead to discrepant results that would be hard to understand in the framework of any physical LISM scenario. Assuming that the observational data are reliable, two possibilities which could help to resolve these discrepancies are discussed: (1) the current modeling of resonance luminescence patterns is unsatisfactory and has to be improved, and (2) the extrapolated interstellar parameters are not indicative of the unperturbed LISM state, but rather designate an intermediate state attained in the outer regions of the solar system. It is shown that a quantitative treatment of the neutral gas-plasma interaction effects in the interface between the heliospheric and the interstellar plasmas is of major importance for the correct understanding of the whole complex.

  14. Sintered composite medium and filter

    DOEpatents

    Bergman, Werner

    1987-01-01

    A particulate filter medium is formed of a sintered composite of 0.5 micron diameter quartz fibers and 2 micron diameter stainless steel fibers. A preferred composition is about 40 vol. % quartz and about 60 vol. % stainless steel fibers. The media is sintered at about 1100.degree. C. to bond the stainless steel fibers into a cage network which holds the quartz fibers. High filter efficiency and low flow resistance are provided by the smaller quartz fibers. High strength is provided by the stainless steel fibers. The resulting media has a high efficiency and low pressure drop similar to the standard HEPA media, with tensile strength at least four times greater, and a maximum operating temperature of about 550.degree. C. The invention also includes methods to form the composite media and a HEPA filter utilizing the composite media. The filter media can be used to filter particles in both liquids and gases.

  15. Interstellar Medium Absorption Profile Spectrograph (IMAPS)

    NASA Technical Reports Server (NTRS)

    Jenkins, E. B.

    1985-01-01

    The design and fabrication of an objective-grating echelle spectrograph to fly on sounding rockets and record spectra of stars from approximately 920 to 1120A with a resolving power lambda/delta lambda = 200,000 is discussed. The scientific purpose of the program is to observe, with ten times better velocity resolution than before, the plentiful absorption lines in this spectral region produced by atoms, ions and molecules in the interstellar medium. In addition, an important technical goal is to develop and flight-quality a new ultraviolet, photon-counting image sensor which has a windowless, opaque photocathode and a CCD bombarded directly by the accelerated photoelectrons. Except for some initial difficulties with the performance of CCDs, the development of the payload instrument is relatively straightforward and our overall design goals are satisfied. The first flight occurred in late 1984, but no data were obtained because of an inrush of air degraded the instrument's vacuum and caused the detector's high voltage to arc. A second flight in early 1985 was a complete success and obtained a spectrum of pi Sco. Data from this mission are currently being reduced; quick-look versions of the spectra indicate that excellent results will be obtained. Currently, the payload is being reconfigured to fly on a Spartan mission in 1988.

  16. Medium Range Flood Forecasting for Agriculture Damage Reduction

    NASA Astrophysics Data System (ADS)

    Fakhruddin, S. H. M.

    2014-12-01

    Early warning is a key element for disaster risk reduction. In recent decades, major advancements have been made in medium range and seasonal flood forecasting. This progress provides a great opportunity to reduce agriculture damage and improve advisories for early action and planning for flood hazards. This approach can facilitate proactive rather than reactive management of the adverse consequences of floods. In the agricultural sector, for instance, farmers can take a diversity of options such as changing cropping patterns, applying fertilizer, irrigating and changing planting timing. An experimental medium range (1-10 day) flood forecasting model has been developed for Bangladesh and Thailand. It provides 51 sets of discharge ensemble forecasts of 1-10 days with significant persistence and high certainty. This type of forecast could assist farmers and other stakeholders for differential preparedness activities. These ensembles probabilistic flood forecasts have been customized based on user-needs for community-level application focused on agriculture system. The vulnerabilities of agriculture system were calculated based on exposure, sensitivity and adaptive capacity. Indicators for risk and vulnerability assessment were conducted through community consultations. The forecast lead time requirement, user-needs, impacts and management options for crops were identified through focus group discussions, informal interviews and community surveys. This paper illustrates potential applications of such ensembles for probabilistic medium range flood forecasts in a way that is not commonly practiced globally today.

  17. Chandra Catches Early Phase of Cosmic Assembly

    NASA Astrophysics Data System (ADS)

    2004-08-01

    A NASA Chandra X-ray Observatory image has revealed a complex of several intergalactic hot gas clouds in the process of merging. The superb Chandra spatial resolution made it possible to distinguish individual galaxies from the massive clouds of hot gas. One of the clouds, which that envelops hundreds of galaxies, has an extraordinarily low concentration of iron atoms, indicating that it is in the very early stages of cluster evolution. "We may be seeing hot intergalactic gas in a relatively pristine state before it has been polluted by gas from galaxies," said Q. Daniel Wang of the University of Massachusetts in Amherst, and lead author on an upcoming Astrophysical Journal article describing the study. "This discovery should provide valuable insight into how the most massive structures in the universe are assembled." 3-Panel Image of Abell 2125, Its Core & Galaxy C153 3-Panel Image of Abell 2125, Its Core & Galaxy C153 The complex, known as Abell 2125,is about 3 billion light years from Earth, and is seen at a time about 11 billion years after the Big Bang, when many galaxy clusters are believed to have formed. The Chandra Abell 2125 image shows several huge elongated clouds of multimillion degree gas coming together from different directions. These hot gas clouds, each of which contains hundreds of galaxies, appear to be in the process of merging to form a single massive galaxy cluster. Chandra, Hubble Space Telescope, and Very Large Array radio telescope data show that several galaxies in the Abell 2125 core cluster are being stripped of their gas as they fall through surrounding high-pressure hot gas. This stripping process has enriched the core cluster's gas in heavy elements such as iron. Abell 2125's Core & Galaxy C153 Abell 2125's Core & Galaxy C153 The gas in the pristine cloud, which is still several million light years away from the core cluster, is conspicuous for its lack of iron atoms. This anemic cloud must be in a very early evolutionary stage. The

  18. Medium chain triglycerides and hepatic encephalopathy

    PubMed Central

    Morgan, M. Hilary; Bolton, C. H.; Morris, J. S.; Read, A. E.

    1974-01-01

    The oral administration of short (C6) and medium (C8 and (C10) chain triglycerides produced no clinical or electroencephalographic changes in patients with cirrhosis of the liver. Arterial ammonia levels were also monitored in these patients and showed no significant change after medium chain triglycerides. It was concluded that medium chain triglycerides, known to be of potential value in the treatment of malabsorption in patients with cirrhosis, are not clinically contraindicated, even in patients with evidence of hepatic encephalopathy. PMID:4841275

  19. Medium Range Ensembles Flood Forecasts for Community Level Applications

    NASA Astrophysics Data System (ADS)

    Fakhruddin, S.; Kawasaki, A.; Babel, M. S.; AIT

    2013-05-01

    Early warning is a key element for disaster risk reduction. In recent decades, there has been a major advancement in medium range and seasonal forecasting. These could provide a great opportunity to improve early warning systems and advisories for early action for strategic and long term planning. This could result in increasing emphasis on proactive rather than reactive management of adverse consequences of flood events. This can be also very helpful for the agricultural sector by providing a diversity of options to farmers (e.g. changing cropping pattern, planting timing, etc.). An experimental medium range (1-10 days) flood forecasting model has been developed for Bangladesh which provides 51 set of discharge ensembles forecasts of one to ten days with significant persistence and high certainty. This could help communities (i.e. farmer) for gain/lost estimation as well as crop savings. This paper describe the application of ensembles probabilistic flood forecast at the community level for differential decision making focused on agriculture. The framework allows users to interactively specify the objectives and criteria that are germane to a particular situation, and obtain the management options that are possible, and the exogenous influences that should be taken into account before planning and decision making. risk and vulnerability assessment was conducted through community consultation. The forecast lead time requirement, users' needs, impact and management options for crops, livestock and fisheries sectors were identified through focus group discussions, informal interviews and questionnaire survey.

  20. English-Medium Instruction in an English-French Bilingual Setting: Issues of Quality and Equity in Cameroon

    ERIC Educational Resources Information Center

    Kuchah, Kuchah

    2016-01-01

    Despite its multilingual nature Cameroon's educational system provides for full immersion into either French-medium or English-medium education from the first year schooling. Following political tensions in the early 1990s the country decided to reaffirm its commitment to promote bilingualism in the educational system with the outcome being the…

  1. Chemically defined medium and Caenorhabditis elegans

    NASA Technical Reports Server (NTRS)

    Szewczyk, Nathaniel J.; Kozak, Elena; Conley, Catharine A.

    2003-01-01

    BACKGROUND: C. elegans has been established as a powerful genetic system. Use of a chemically defined medium (C. elegans Maintenance Medium (CeMM)) now allows standardization and systematic manipulation of the nutrients that animals receive. Liquid cultivation allows automated culturing and experimentation and should be of use in large-scale growth and screening of animals. RESULTS: We find that CeMM is versatile and culturing is simple. CeMM can be used in a solid or liquid state, it can be stored unused for at least a year, unattended actively growing cultures may be maintained longer than with standard techniques, and standard C. elegans protocols work well with animals grown in defined medium. We also find that there are caveats to using defined medium. Animals in defined medium grow more slowly than on standard medium, appear to display adaptation to the defined medium, and display altered growth rates as they change the composition of the defined medium. CONCLUSIONS: As was suggested with the introduction of C. elegans as a potential genetic system, use of defined medium with C. elegans should prove a powerful tool.

  2. Early Intervention.

    ERIC Educational Resources Information Center

    Nathanson, Jeanne H., Ed.

    1992-01-01

    This theme issue focuses on early intervention. The four articles presented on this theme are: (1) "Deaf Infants, Hearing Mothers: A Research Report" (Kathryn P. Meadow-Orlans, and others), reporting findings on effects of auditory loss on early development; (2) "Maintaining Involvement of Inner City Families in Early Intervention Programs through…

  3. Selective medium for aerobic incubation of Campylobacter

    USDA-ARS?s Scientific Manuscript database

    Studies were conducted on the formulation of a selective medium that could be used to isolate Campylobacter from mixed bacterial cultures using aerobic incubation. A non-selective, basal broth medium was prepared and supplemented with Bolton, Cefex, or Skirrow antibiotic mixtures. The ability of pur...

  4. 49 CFR 236.811 - Speed, medium.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Speed, medium. 236.811 Section 236.811 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Speed, medium. A speed not exceeding 40 miles per hour. ...

  5. 49 CFR 236.811 - Speed, medium.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Speed, medium. 236.811 Section 236.811 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Speed, medium. A speed not exceeding 40 miles per hour. ...

  6. 49 CFR 236.811 - Speed, medium.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Speed, medium. 236.811 Section 236.811 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Speed, medium. A speed not exceeding 40 miles per hour. ...

  7. 49 CFR 236.811 - Speed, medium.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Speed, medium. 236.811 Section 236.811 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Speed, medium. A speed not exceeding 40 miles per hour. ...

  8. 49 CFR 236.811 - Speed, medium.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Speed, medium. 236.811 Section 236.811 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Speed, medium. A speed not exceeding 40 miles per hour. ...

  9. Improved chemically defined basal medium (CMRL-1969) for primary monkey kidney and human diploid cells.

    PubMed

    Healy, G M; Teleki, S; von Seefried, A; Walton, M J; Macmorine, H G

    1971-01-01

    An improved tissue culture basal medium, CMRL-1969, supplemented with serum, has been evaluated by measuring the growth responses of primary cultures of trypsin-dispersed monkey kidney cells (PMKC) and of an established culture of a human diploid cell strain (HDCS). Medium H597, an early modification of medium 199 which has been used successfully in the preparation of poliomyelitis vaccine for 15 years, was used for comparison. In addition, parallel testing was done with Basal Medium Eagle (BME) widely used for the growth of HDCS. The improvements in basal medium CMRL-1969 are attributed to changes in amino acid concentrations, in vitamin composition, and, in particular, to enhanced buffering capacity. The latter has been achieved by the use of free-base amino acids and by increasing the dibasic sodium phosphate. The new medium has already been used to advantage for the production of polioviruses in PMKC where equivalent titers were obtained from cultures initiated with 70% of the number of cells required with earlier media. The population-doubling time was reduced in this system. Also, with small inocula of HDCS, the time required to obtain maximum cell yield was shorter with CMRL-1969 than with BME. Both media were supplemented with 10% calf serum. Maximum cell yields after repeated subcultivation in the new basal medium were greatly increased and the stability of the strain, as shown by chromosomal analysis, was not affected. Basal medium CMRL-1969 can be prepared easily in liquid or powdered form.

  10. Improved Chemically Defined Basal Medium (CMRL-1969) for Primary Monkey Kidney and Human Diploid Cells 1

    PubMed Central

    Healy, G. M.; Teleki, S.; Seefried, A. V.; Walton, M. J.; Macmorine, H. G.

    1971-01-01

    An improved tissue culture basal medium, CMRL-1969, supplemented with serum, has been evaluated by measuring the growth responses of primary cultures of trypsin-dispersed monkey kidney cells (PMKC) and of an established culture of a human diploid cell strain (HDCS). Medium H597, an early modification of medium 199 which has been used successfully in the preparation of poliomyelitis vaccine for 15 years, was used for comparison. In addition, parallel testing was done with Basal Medium Eagle (BME) widely used for the growth of HDCS. The improvements in basal medium CMRL-1969 are attributed to changes in amino acid concentrations, in vitamin composition, and, in particular, to enhanced buffering capacity. The latter has been achieved by the use of free-base amino acids and by increasing the dibasic sodium phosphate. The new medium has already been used to advantage for the production of polioviruses in PMKC where equivalent titers were obtained from cultures initiated with 70% of the number of cells required with earlier media. The population-doubling time was reduced in this system. Also, with small inocula of HDCS, the time required to obtain maximum cell yield was shorter with CMRL-1969 than with BME. Both media were supplemented with 10% calf serum. Maximum cell yields after repeated subcultivation in the new basal medium were greatly increased and the stability of the strain, as shown by chromosomal analysis, was not affected. Basal medium CMRL-1969 can be prepared easily in liquid or powdered form. PMID:4322279

  11. Collaborative Manufacturing for Small-Medium Enterprises

    NASA Astrophysics Data System (ADS)

    Irianto, D.

    2016-02-01

    Manufacturing systems involve decisions concerning production processes, capacity, planning, and control. In a MTO manufacturing systems, strategic decisions concerning fulfilment of customer requirement, manufacturing cost, and due date of delivery are the most important. In order to accelerate the decision making process, research on decision making structure when receiving order and sequencing activities under limited capacity is required. An effective decision making process is typically required by small-medium components and tools maker as supporting industries to large industries. On one side, metal small-medium enterprises are expected to produce parts, components or tools (i.e. jigs, fixture, mold, and dies) with high precision, low cost, and exact delivery time. On the other side, a metal small- medium enterprise may have weak bargaining position due to aspects such as low production capacity, limited budget for material procurement, and limited high precision machine and equipment. Instead of receiving order exclusively, a small-medium enterprise can collaborate with other small-medium enterprise in order to fulfill requirements high quality, low manufacturing cost, and just in time delivery. Small-medium enterprises can share their best capabilities to form effective supporting industries. Independent body such as community service at university can take a role as a collaboration manager. The Laboratory of Production Systems at Bandung Institute of Technology has implemented shared manufacturing systems for small-medium enterprise collaboration.

  12. Method to prepare nanoparticles on porous mediums

    DOEpatents

    Vieth, Gabriel M [Knoxville, TN; Dudney, Nancy J [Oak Ridge, TN; Dai, Sheng [Knoxville, TN

    2010-08-10

    A method to prepare porous medium decorated with nanoparticles involves contacting a suspension of nanoparticles in an ionic liquid with a porous medium such that the particles diffuse into the pores of the medium followed by heating the resulting composition to a temperature equal to or greater than the thermal decomposition temperature of the ionic liquid resulting in the removal of the liquid portion of the suspension. The nanoparticles can be a metal, an alloy, or a metal compound. The resulting compositions can be used as catalysts, sensors, or separators.

  13. The epoch of cosmic heating by early sources of X-rays

    NASA Astrophysics Data System (ADS)

    Eide, Marius B.; Graziani, Luca; Ciardi, Benedetta; Feng, Yu; Kakiichi, Koki; Di Matteo, Tiziana

    2018-05-01

    Observations of the 21 cm line from neutral hydrogen indicate that an epoch of heating (EoH) might have preceded the later epoch of reionization. Here we study the effects on the ionization state and the thermal history of the intergalactic medium (IGM) during the EoH induced by different assumptions on ionizing sources in the high-redshift Universe: (i) stars; (ii) X-ray binaries (XRBs); (iii) thermal bremsstrahlung of the hot interstellar medium (ISM); and (iv) accreting nuclear black holes (BHs). To this aim, we post-process outputs from the (100 h-1 comoving Mpc)3 hydrodynamical simulation MassiveBlack-II with the cosmological 3D radiative transfer code CRASH, which follows the propagation of ultraviolet and X-ray photons, computing the thermal and ionization state of hydrogen and helium through the EoH. We find that stars determine the fully ionized morphology of the IGM, while the spectrally hard XRBs pave way for efficient subsequent heating and ionization by the spectrally softer ISM. With the seeding prescription in MassiveBlack-II, BHs do not contribute significantly to either ionization or heating. With only stars, most of the IGM remains in a cold state (with a median T = 11 K at z = 10), however, the presence of more energetic sources raises the temperature of regions around the brightest and more clustered sources above that of the cosmic microwave background, opening the possibility to observing the 21 cm signal in emission.

  14. Reionization of Hydrogen and Helium by Early Stars and Quasars

    NASA Astrophysics Data System (ADS)

    Wyithe, J. Stuart B.; Loeb, Abraham

    2003-04-01

    We compute the reionization histories of hydrogen and helium caused by the ionizing radiation fields produced by stars and quasars. For the quasars we use a model based on halo-merger rates that reproduces all known properties of the quasar luminosity function at high redshifts. The less constrained properties of the ionizing radiation produced by stars are modeled with two free parameters: (i) a transition redshift, ztran, above which the stellar population is dominated by massive, zero-metallicity stars and below which it is dominated by a Scalo mass function; and (ii) the product of the escape fraction of stellar ionizing photons from their host galaxies and the star formation efficiency, fescf*. We constrain the allowed range of these free parameters at high redshifts on the basis of the lack of the H I Gunn-Peterson trough at z<~6 and the upper limit on the total intergalactic optical depth for electron scattering, τes<0.18, from recent cosmic microwave background (CMB) experiments. We find that quasars ionize helium by a redshift z~4, but cannot reionize hydrogen by themselves before z~6. A major fraction of the allowed combinations of fescf* and ztran leads to an early peak in the ionized fraction because of the presence of metal-free stars at high redshifts. This sometimes results in two reionization epochs, namely, an early H II or He III overlap phase followed by recombination and a second overlap phase. Even if early overlap is not achieved, the peak in the visibility function for scattering of the CMB often coincides with the early ionization phase rather than with the actual reionization epoch. Consequently, τes does not correspond directly to the reionization redshift. We generically find values of τes>~7%, which should be detectable by the MAP satellite.

  15. Incompatibility of Contrast Medium and Trisodium Citrate

    SciTech Connect

    Delcour, Christian, E-mail: christian.delcour@chu-charleroi.be; Bruninx, Guy

    2013-02-15

    To test the compatibility of trisodium citrate, a catheter lock solution, with iodinated contrast medium. Iohexol, iobitridol, iodixanol, ioxaglate, ioxithalamate, iomeprol, and iopromide were tested. In all tests, 2 ml of contrast medium were mixed with 2 ml of trisodium citrate solution. Iodixanol and ioxaglate provoked a highly viscous gluelike precipitation when mixed with trisodium citrate. A brief transient precipitate was observed with iohexol, iomeprol, and ioxithalamate. Permanent precipitation occurred with iobitridol and iopromide. One must be aware of the potential for precipitation when contrast medium is mixed with trisodium citrate solution. Before trisodium citrate solution is injected, the cathetermore » should be thoroughly flushed with saline if a contrast medium has previously been injected through it.« less

  16. Small and medium power reactors 1987

    NASA Astrophysics Data System (ADS)

    1987-12-01

    This TECDOC follows the publication of TECDOC-347: Small and Medium Power Reactors (SMPR) Project Initiation Study, Phase 1, published in 1985 and TECDOC-376: Small and Medium Power Reactors 1985 published in 1986. It is mainly intended for decision makers in Developing Member States interested in embarking on a nuclear power program. It consists of two parts: (1) guidelines for the introduction of small and medium power reactors in developing countries. These Guidelines were established during the Advisory Group Meeting held in Vienna from 11 to 15 May 1987. Their purpose is to review key aspects relating to the introduction of small and medium power reactors in developing countries; (2) up-dated information on SMPR Concepts Contributed by Supplier Industries. According to the recommendations of the Second Technical Committee Meeting on SMPRs held in Vienna in March 1985, this part contains the up-dated information formerly published in Annex 1 of the above mentioned TECDOC-347.

  17. Generation of medium frequency electrotherapeutic signals

    NASA Astrophysics Data System (ADS)

    Płaza, Mirosław; Szcześniak, Zbigniew; Dudek, Jolanta

    2017-08-01

    In this paper, generation methods of sinusoidal medium frequency electrotherapeutic signals have been studied. Signals of this type are increasingly used in electrotherapy owing to the development of both physical medicine and engineering sciences. The article presents analysis and comparison of analogue and digital methods of generation therapeutic signals. Analysis presented in the paper attempts to answer the question which technique of medium frequency signal generation can be most broadly applied in electrotherapy methods.

  18. Early and Extended Helium Reionization over More Than 600 Million Years of Cosmic Time

    NASA Astrophysics Data System (ADS)

    Worseck, Gábor; Prochaska, J. Xavier; Hennawi, Joseph F.; McQuinn, Matthew

    2016-07-01

    We measure the effective optical depth of He II Lyα absorption {τ }{eff,{He}{{II}}} at 2.3\\lt z\\lt 3.5 in 17 UV-transmitting quasars observed with UV spectrographs on the Hubble Space Telescope. The median {τ }{eff,{He}{{II}}} values increase gradually from 1.95 at z=2.7 to 5.17 at z=3.4, but with a strong sightline-to-sightline variance. Many ≃ 35 comoving Mpc regions of the z\\gt 3 intergalactic medium (IGM) remain transmissive ({τ }{eff,{He}{{II}}}\\lt 4), and the gradual trend with redshift appears consistent with density evolution of a fully reionized IGM. These modest optical depths imply average He II fractions of {x}{He{{II}}}\\lt 0.01 and He II ionizing photon mean free paths of ≃ 50 comoving Mpc at z≃ 3.4, thus requiring that a substantial volume of the helium in the universe was already doubly ionized at early times; this stands in conflict with current models of He II reionization driven by luminous quasars. Along 10 sightlines we measure the coeval H I Lyα effective optical depths, allowing us to study the density dependence of {τ }{eff,{He}{{II}}} at z˜ 3. We establish that the dependence of {τ }{eff,{He}{{II}}} on increasing {τ }{eff,{{H}}{{I}}} is significantly shallower than expected from simple models of an IGM reionized in He II. This requires higher He II photoionization rates in overdense regions or underdense regions being not in photoionization equilibrium. Moreover, there are very large fluctuations in {τ }{eff,{He}{{II}}} at all {τ }{eff,{{H}}{{I}}} which greatly exceed the expectations from these simple models. These data present a distinct challenge to scenarios of He II reionization—an IGM where He II appears to be predominantly ionized at z≃ 3.4, and with a radiation field strength that may be correlated with the density field, but exhibits large fluctuations at all densities. Based on observations made with the NASA/ESA Hubble Space Telescope (HST), obtained at the Space Telescope Science Institute, which is

  19. Ethanol production using a soy hydrolysate-based medium or a yeast autolysate-based medium

    DOEpatents

    Ingram, Lonnie O.

    2000-01-01

    This invention presents a method for the production of ethanol that utilizes a soy hydrolysate-based nutrient medium or a yeast autolysate-based medium nutrient medium in conjunction with ethanologenic bacteria and a fermentable sugar for the cost-effective production of ethanol from lignocellulosic biomass. The invention offers several advantages over presently available media for use in ethanol production, including consistent quality, lack of toxins and wide availability.

  20. 'That proves my point': How mediums reconstrue disconfirmation in medium-sitter interactions.

    PubMed

    Enoksen, Anette Einan; Dickerson, Paul

    2018-04-01

    Previous research has examined how the talk of mediums attends to the epistemological status of their readings. Such work has identified that mediums frequently use question-framed propositions that are typically confirmed by the sitter, thereby conferring epistemological status on the medium. This study seeks to investigate what happens when the sitter disconfirms the propositions of the medium. The study focuses on the ways in which such disconfirmation can be responded to such that it is reconstrued as evidence of the psychic nature of the medium's reading. Televised demonstrations of psychic readings involving British and US mediums and their sitters are analysed. The results suggest that mediums rework disconfirmation as proof in several ways: first, by emphasizing the different access that sitter and medium have to knowledge (e.g., about the future); second, as evidence that the medium has access to the actual voice of the deceased (and may therefore mishear what the deceased has said to them); and third, as revealing an important truth that has hitherto been concealed from the sitter. The implications of these findings are considered for cases where speakers bring different and potentially competing, epistemological resources to an interaction. © 2018 The British Psychological Society.

  1. Early Rockets

    NASA Image and Video Library

    2004-04-15

    In addition to Dr. Robert Goddard's pioneering work, American experimentation in rocketry prior to World War II grew, primarily in technical societies. This is an early rocket motor designed and developed by the American Rocket Society in 1932.

  2. CHROMagar Orientation Medium Reduces Urine Culture Workload

    PubMed Central

    Manickam, Kanchana; Karlowsky, James A.; Adam, Heather; Lagacé-Wiens, Philippe R. S.; Rendina, Assunta; Pang, Paulette; Murray, Brenda-Lee

    2013-01-01

    Microbiology laboratories continually strive to streamline and improve their urine culture algorithms because of the high volumes of urine specimens they receive and the modest numbers of those specimens that are ultimately considered clinically significant. In the current study, we quantitatively measured the impact of the introduction of CHROMagar Orientation (CO) medium into routine use in two hospital laboratories and compared it to conventional culture on blood and MacConkey agars. Based on data extracted from our Laboratory Information System from 2006 to 2011, the use of CO medium resulted in a 28% reduction in workload for additional procedures such as Gram stains, subcultures, identification panels, agglutination tests, and biochemical tests. The average number of workload units (one workload unit equals 1 min of hands-on labor) per urine specimen was significantly reduced (P < 0.0001; 95% confidence interval [CI], 0.5326 to 1.047) from 2.67 in 2006 (preimplementation of CO medium) to 1.88 in 2011 (postimplementation of CO medium). We conclude that the use of CO medium streamlined the urine culture process and increased bench throughput by reducing both workload and turnaround time in our laboratories. PMID:23363839

  3. Design of Fully Austenitic Medium Manganese Steels

    NASA Astrophysics Data System (ADS)

    Luan, G.; Volkova, O.; Mola, J.

    2018-06-01

    Due to their higher ferrite potential compared to high Mn twinning-induced plasticity (TWIP) steels, medium Mn steels usually exhibit austenitic-ferritic microstructures, which makes them suitable for third-generation advanced high-strength steel applications. Nevertheless, the strain hardening characteristics of medium Mn steels are inferior to those of fully austenitic high Mn steels. The present work introduces alloy design strategies to obtain fully austenitic medium Mn steels capable of the TWIP effect. To achieve a fully austenitic microstructure, the martensite start temperature is reduced by raising the C concentration to above 1 mass-%, which in turn facilitates the formation of cementite. The formation of cementite during cooling from austenitization temperature is counteracted by alloying with Al. Microstructural examination of slowly-cooled Fe‑Mn‑Al‑C and Fe‑Mn‑C steels indicated that Al changes the morphology of intergranular cementite from plate-shaped to equiaxed.

  4. Solar collector having a solid transmission medium

    DOEpatents

    Schertz, William W.; Zwerdling, Solomon

    1977-06-14

    There is provided a radiant energy transmission device capable of operation in a concentrative mode in which energy incident on an entrance area is directed toward and concentrated on an exit area of smaller area than the entrance area. The device includes a solid radiant energy transmission medium having surfaces coincident with the entrance and exit areas and particularly contoured reflective side walls. The surface coinciding with the entrance area is coupled to a cover plate formed of a radiant energy transmissive material. An energy transducer is coupled to the surface of the medium coinciding with the exit area.

  5. Heavy quark energy loss in nuclear medium

    SciTech Connect

    Zhang, Benr-Wei; Wang, Enke; Wang, Xin-Nian

    2003-09-16

    Multiple scattering, modified fragmentation functions and radiative energy loss of a heavy quark propagating in a nuclear medium are investigated in perturbative QCD. Because of the quark mass dependence of the gluon formation time, the medium size dependence of heavy quark energy loss is found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss is also significantly suppressed relative to a light quark due to the suppression of collinear gluon emission by a heavy quark.

  6. Comparison of Mycobacterium tuberculosis culture using liquid culture medium and Lowenstein Jensen medium in abdominal tuberculosis.

    PubMed

    Shah, Sudeep R; Shenai, Shubhada; Desai, Devendra C; Joshi, Anand; Abraham, Philip; Rodrigues, Camilla

    2010-11-01

    Traditionally, the Lowenstein Jensen (LJ) medium has been used for culturing Mycobacterium tuberculosis. In abdominal tuberculosis (TB), the reported yield from tissue culture is between 20% and 60%. Liquid cultures are reported to give a higher yield but there is little data available in abdominal TB. To compare the yield of TB culture with BACTEC 460TB liquid medium and LJ medium for patients with suspected abdominal TB and determine cost effectiveness. This prospective study was done in consecutive cases with clinical, radiological, endoscopic/surgical, and histological suspicion of abdominal TB. Tissue biopsies obtained at colonoscopy or surgery were processed and plated on LJ medium as well as the BACTEC 460TB system. NAP (ρ-nitro-α-acetylamino-β-hydroxy-propiophenone) differentiation was carried out to determine species. The cost of each method and cost per yield were calculated. Of the 29 cases, 22 cases (76%) were positive on BACTEC 460TB culture while 14 (48%) were positive on LJ medium giving a 64% increment in yield. However, the culture of one patient grew on LJ medium, where the BACTEC 460TB was negative. The additional cost of BACTEC 460TB is Rs. 460 and LJ is Rs. 40. Samples from patients with abdominal TB should be processed on both liquid and LJ medium. For high yield, the use of a liquid culture medium system is essential.

  7. An amorphous alloy core medium frequency magnetic-link for medium voltage photovoltaic inverters

    NASA Astrophysics Data System (ADS)

    Rabiul Islam, Md.; Guo, Youguang; Wei Lin, Zhi; Zhu, Jianguo

    2014-05-01

    The advanced magnetic materials with high saturation flux density and low specific core loss have led to the development of an efficient, compact, and lightweight multiple-input multiple-output medium frequency magnetic-link. It offers a new route to eliminate some critical limitations of recently proposed medium voltage photovoltaic inverters. In this paper, a medium frequency magnetic-link is developed with Metglas amorphous alloy 2605S3A. The common magnetic-link generates isolated and balanced multiple DC supplies for all of the H-bridge inverter cells of the medium voltage inverter. The design and implementation of the prototype, test platform, and the experimental test results are analyzed and discussed. The medium frequency non-sinusoidal excitation electromagnetic characteristics of alloy 2605S3A are also compared with that of alloy 2605SA1. It is expected that the proposed new technology will have great potential for future renewable power generation systems and smart grid applications.

  8. Cable Television...the Medium for Hispanics?

    ERIC Educational Resources Information Center

    Guernica, Antonio Jose

    1977-01-01

    Cable represents the only avenue available for Hispanics to gain substantial control over a communications medium. It has the potential to provide Hispanics not only with ownership opportunities, but also with employment, quality programming, and long-term commitments and responsibilities to meet the programming needs of the Hispanics in this…

  9. Photonuclear activation of pure isotopic mediums.

    SciTech Connect

    Grohman, Mark A.; Lukosi, Eric Daniel

    2010-06-01

    This work simulated the response of idealized isotopic U-235, U-238, Th-232, and Pu-239 mediums to photonuclear activation with various photon energies. These simulations were conducted using MCNPX version 2.6.0. It was found that photon energies between 14-16 MeV produce the highest response with respect to neutron production rates from all photonuclear reactions. In all cases, Pu-239 responds the highest, followed by U-238. Th-232 produces more overall neutrons at lower photon energies then U-235 when material thickness is above 3.943 centimeters. The time it takes each isotopic material to reach stable neutron production rates in time is directly proportional to themore » material thickness and stopping power of the medium, where thicker mediums take longer to reach stable neutron production rates and thinner media display a neutron production plateau effect, due to the lack of significant attenuation of the activating photons in the isotopic mediums. At this time, no neutron sensor system has time resolutions capable of verifying these simulations, but various indirect methods are possible and should be explored for verification of these results.« less

  10. 49 CFR 195.306 - Test medium.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... this section, water must be used as the test medium. (b) Except for offshore pipelines, liquid... which produces a hoop stress of 50 percent of specified minimum yield strength; (3) The test section is... pressure is equal to or greater than a pressure that produces a hoop stress of 50 percent of specified...

  11. Medium-range fire weather forecasts

    Treesearch

    J.O. Roads; K. Ueyoshi; S.C. Chen; J. Alpert; F. Fujioka

    1991-01-01

    The forecast skill of theNational Meteorological Center's medium range forecast (MRF) numerical forecasts of fire weather variables is assessed for the period June 1,1988 to May 31,1990. Near-surface virtual temperature, relative humidity, wind speed and a derived fire weather index (FWI) are forecast well by the MRF model. However, forecast relative humidity has...

  12. Radiofrequency recombination lines from the interstellar medium

    NASA Technical Reports Server (NTRS)

    Dupree, A. K.

    1971-01-01

    Observations of recombination lines form normal H II regions, extended H II regions, nonthermal sources, and the H I medium are discussed. Detection of recombination lines from elements other than hydrogen may provide a means of identifying fossil Stromgren spheres at high temperature.

  13. Particle Diffusion in an Inhomogeneous Medium

    ERIC Educational Resources Information Center

    Bringuier, E.

    2011-01-01

    This paper is an elementary introduction to particle diffusion in a medium where the coefficient of diffusion varies with position. The introduction is aimed at third-year university courses. We start from a simple model of particles hopping on a discrete lattice, in one or more dimensions, and then take the continuous-space limit so as to obtain…

  14. A Dark Horse Medium in Basic Business

    ERIC Educational Resources Information Center

    Eckert, Sidney W.

    1974-01-01

    The Dark Horse (DH) board is described and discussed as one medium which may be utilized in the classroom. The DH Board holds fairly heavy three-dimensional display objects and consists of two components: a special material which serves as the display surface and an adhesive material which is fixed to objects displayed. (SC)

  15. Phase object retrieval through scattering medium

    NASA Astrophysics Data System (ADS)

    Zhao, Ming; Zhao, Meijing; Wu, Houde; Xu, Wenhai

    2018-05-01

    Optical imaging through a scattering medium has been an interesting and important research topic, especially in the field of biomedical imaging. However, it is still a challenging task due to strong scattering. This paper proposes to recover the phase object behind the scattering medium from one single-shot speckle intensity image using calibrated transmission matrices (TMs). We construct the forward model as a non-linear mapping, since the intensity image loses the phase information, and then a generalized phase retrieval algorithm is employed to recover the hidden object. Moreover, we show that a phase object can be reconstructed with a small portion of the speckle image captured by the camera. The simulation is performed to demonstrate our scheme and test its performance. Finally, a real experiment is set up, we measure the TMs from the scattering medium, and then use it to reconstruct the hidden object. We show that a phase object of size 32 × 32 is retrieved from 150 × 150 speckle grains, which is only 1/50 of the speckles area. We believe our proposed method can benefit the community of imaging through the scattering medium.

  16. Separation medium containing thermally exfoliated graphite oxide

    NASA Technical Reports Server (NTRS)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Herrera-Alonso, Margarita (Inventor)

    2012-01-01

    A separation medium, such as a chromatography filling or packing, containing a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 m.sup.2/g to 2600 m.sup.2/g, wherein the thermally exfoliated graphite oxide has a surface that has been at least partially functionalized.

  17. Effects of medium concentration on antibody production

    NASA Technical Reports Server (NTRS)

    Williams, J.

    1984-01-01

    Antibody production by two different cell lines was measured as the media were supplemented with varied amounts of glucose and fetal bovine serum. Both cell lines elaborated antidinitrophenyl hapten antibodies. Two basic media were used: RPMI 1640 and Dulbecco's modified Eagle's medium. The production of antibodies was followed from 0 to 180 h and was assayed by radioimmunoassay.

  18. Microprint as a medium for primary publication

    USGS Publications Warehouse

    Herman, C.M.; Luhn, H.P.

    1964-01-01

    Microprint has been demonstrated an acceptable medium for publication in an experiment conducted by the Wildlife Disease Association. With author composition costs slightly over seven cents per 3x5 inch card, up to 47 pages. Need is recognized for development of standards and improvement of accessory retrieval apparatus.

  19. Medium density fiberboard from mixed southern hardwoods

    Treesearch

    George E. Woodson

    1977-01-01

    Medium-density fiberboards of acceptable quality were made from a mixture of barky chips from 14 southern hardwoods. Boards made from fiber refined at three different plate clearances did not vary significantly in bending, internal bond (IB), or linear expansion. but, lack of replications and the fact that the refiner was not loaded to capacity caused these results to...

  20. Early Rockets

    NASA Image and Video Library

    2004-04-15

    During the 19th century, rocket enthusiasts and inventors began to appear in almost every country. Some people thought these early rocket pioneers were geniuses, and others thought they were crazy. Claude Ruggieri, an Italian living in Paris, apparently rocketed small animals into space as early as 1806. The payloads were recovered by parachute. As depicted here by artist Larry Toschik, French authorities were not always impressed with rocket research. They halted Ruggieri's plans to launch a small boy using a rocket cluster. (Reproduced from a drawing by Larry Toschik and presented here courtesy of the artist and Motorola Inc.)

  1. In-medium properties of mesons

    NASA Astrophysics Data System (ADS)

    Metag, Volker; Nanova, Mariana; Brinkmann, Kai-Thomas

    2017-01-01

    In the project B.4, the modification of meson properties (mass, width) in a nuclear medium has been studied in photoproduction of mesons off nuclear targets. This work has been motivated by theoretical expectations of in-medium modifications of hadrons based on the conjecture of a partial restoration of chiral symmetry in a strongly interacting medium. It has been shown that these in-medium changes can be discussed in a compact form in terms of an optical potential describing the meson-nucleus interaction. Experimental approaches to determine the real and imaginary part of the meson-nucleus potential have been developed. The experiments have been performed with the Crystal Barrel/TAPS detector at the electron accelerator ELSA (Bonn) and the Crystal Ball/TAPS detector at MAMI (Mainz). Measuring the excitation function and momentum distribution for photo production of ω and η' mesons, the real parts of the ω and η'-nucleus potential, given by the in-medium mass shift, have been determined. For the η' meson a lowering of the mass at normal nuclear matter density by -(39±7(stat)±15(syst)) MeV is observed, while for the ω meson a slightly smaller mass shift is found, however, with much larger uncertainties, not excluding a zero mass shift. The imaginary part of the potentials has been extracted from the measurement of the transparency ratio which compares the meson production cross section per nucleon within a nucleus to the production cross section off the free proton. For the η' meson the imaginary part of the potential is found to be smaller than the real part. In case of the ω meson the opposite is observed. This makes the η' meson a good candidate for the search for meson-nucleus bound states while no resolved ω mesic states can be expected. The results are compared with theoretical predictions. An outlook on future experiments is given.

  2. Suggestions for Early Motion Picture Research.

    ERIC Educational Resources Information Center

    Jowett, Garth S.

    Only by examining the motion picture as a mass medium, shaped and defined within a specific socio-cultural period in history, can we increase our understanding of the function and contribution of this entertainment form. This paper offers several suggestions for further research into early motion picture history. One glaring deficiency among…

  3. Early Rockets

    NASA Image and Video Library

    1950-01-01

    Test firing of a Redstone Missile at Redstone Test Stand in the early 1950's. The Redstone was a high-accuracy, liquid-propelled, surface-to-surface missile developed by the von Braun Team under the management of the U.S. Army. The Redstone was the first major rocket development program in the United States.

  4. Early Math.

    ERIC Educational Resources Information Center

    Van Nuys, Ute Elisabeth

    1986-01-01

    Presents reviews of the following mathematics software designed to teach young children counting, number recognition, visual discrimination, matching, addition, and subtraction skills; Stickybear Numbers, Learning with Leeper, Getting Ready to Read and Add, Counting Parade, Early Games for Young Children, Charlie Brown's 1,2,3's, Let's Go Fishing,…

  5. Early Childhood.

    ERIC Educational Resources Information Center

    Peters, Donald L.; Willis, Sherry L.

    This book summarizes theory and discusses major issues pertaining to child development in the early childhood years. Chapter I provides an introduction to the conceptual framework and major theories of child development. Chapter II deals with motor, sensory, and perceptual development. Chapter III focuses on the cognitive-developmental theory of…

  6. Early Rockets

    NASA Image and Video Library

    2004-04-15

    During the early introduction of rockets to Europe, they were used only as weapons. Enemy troops in India repulsed the British with rockets. Later, in Britain, Sir William Congreve developed a rocket that could fire to about 9,000 feet. The British fired Congreve rockets against the United States in the War of 1812.

  7. Early Rockets

    NASA Image and Video Library

    2004-04-15

    In the 19th Century, experiments in America, Europe, and elsewhere attempted to build postal rockets to deliver mail from one location to another. The idea was more novel than successful. Many stamps used in these early postal rockets have become collector's items.

  8. 30 CFR 75.703-2 - Approved grounding mediums.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Approved grounding mediums. 75.703-2 Section 75... mediums. For purposes of grounding offtrack direct-current machines, the following grounding mediums are... alternating current grounding medium where such machines are fed by an ungrounded direct-current power system...

  9. 30 CFR 75.703-2 - Approved grounding mediums.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Approved grounding mediums. 75.703-2 Section 75... mediums. For purposes of grounding offtrack direct-current machines, the following grounding mediums are... alternating current grounding medium where such machines are fed by an ungrounded direct-current power system...

  10. 30 CFR 75.703-2 - Approved grounding mediums.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Approved grounding mediums. 75.703-2 Section 75... mediums. For purposes of grounding offtrack direct-current machines, the following grounding mediums are... alternating current grounding medium where such machines are fed by an ungrounded direct-current power system...

  11. 30 CFR 75.703-2 - Approved grounding mediums.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Approved grounding mediums. 75.703-2 Section 75... mediums. For purposes of grounding offtrack direct-current machines, the following grounding mediums are... alternating current grounding medium where such machines are fed by an ungrounded direct-current power system...

  12. 30 CFR 75.703-2 - Approved grounding mediums.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Approved grounding mediums. 75.703-2 Section 75... mediums. For purposes of grounding offtrack direct-current machines, the following grounding mediums are... alternating current grounding medium where such machines are fed by an ungrounded direct-current power system...

  13. Deuterium Abundance in the Local Interstellar Medium

    NASA Technical Reports Server (NTRS)

    Ferlet, R.; Gry, C.; Vidal-Madjar, A.

    1984-01-01

    The present situation of deuterium abundance evaluation in interstellar space is discussed, and it is shown that it should be or = .00001 by studying in more detail lambda the Sco line of sight and by observing two NaI interstellar components toward that star, it can be shown that the D/H evaluation made toward lambda Sco is in fact related to the local interstellar medium (less than 10 pc from the Sun). Because this evaluation is also or = .00001 it is in striking contrast with the one made toward alpha Aur (D/H or = .000018 confirming the fact that the deuterium abundance in the local interstellar medium varies by at least a factor of two over few parsecs.

  14. Magnetized Neutron Stars in the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Toropina, O. D.; Romanova, M. M.; Lovelace, R. V. E.

    2014-09-01

    We investigate the propagation of magnetized, isolated old neutron stars through the interstellar medium. We performed axisymmetric, non-relativistic magnetohydrodynamic simulations of the supersonic motion of neutron star with dipole magnetic field aligned with its velocity through the interstellar medium (ISM). We consider two cases: (1) where the accretion radius is larger than Alfvén radius, i.e. Racc>>RA and gravitational focusing is important; and (2) where Racc<

  15. Microwave gain medium with negative refractive index.

    PubMed

    Ye, Dexin; Chang, Kihun; Ran, Lixin; Xin, Hao

    2014-12-19

    Artificial effective media are attractive because of the fantastic applications they may enable, such as super lensing and electromagnetic invisibility. However, the inevitable loss due to their strongly dispersive nature is one of the fundamental challenges preventing such applications from becoming a reality. In this study, we demonstrate an effective gain medium based on negative resistance, to overcompensate the loss of a conventional passive metamaterial, meanwhile keeping its original negative-index property. Energy conservation-based theory, full-wave simulation and experimental measurement show that a fabricated sample consisting of conventional sub-wavelength building blocks with embedded microwave tunnel diodes exhibits a band-limited Lorentzian dispersion simultaneously with a negative refractive index and a net gain. Our work provides experimental evidence to the assertion that a stable net gain in negative-index gain medium is achievable, proposing a potential solution for the critical challenge current metamateiral technology faces in practical applications.

  16. Contrast Medium-Induced Acute Kidney Injury

    PubMed Central

    Sadat, Umar; Usman, Ammara; Boyle, Jonathan R.; Hayes, Paul D.; Solomon, Richard J.

    2015-01-01

    Contrast medium-induced acute kidney injury (CI-AKI) is a predominant cause of hospital-acquired renal insufficiency. With an increasing number of contrast medium-enhanced radiological procedures being performed in a rapidly increasing ageing population in the Western world, it is imperative that more attention is given to understand the aetiology of CI-AKI to devise novel diagnostic methods and to formulate effective prophylactic and therapeutic regimens to reduce its incidence and its associated morbidity and mortality. This article presents high-yield information on the above-mentioned aspects of CI-AKI, primarily based on results of randomised controlled trials, meta-analyses, systematic reviews and international consensus guidelines. PMID:26195974

  17. Fluorescence lifetime measurements in heterogeneous scattering medium

    NASA Astrophysics Data System (ADS)

    Nishimura, Goro; Awasthi, Kamlesh; Furukawa, Daisuke

    2016-07-01

    Fluorescence lifetime in heterogeneous multiple light scattering systems is analyzed by an algorithm without solving the diffusion or radiative transfer equations. The algorithm assumes that the optical properties of medium are constant in the excitation and emission wavelength regions. If the assumption is correct and the fluorophore is a single species, the fluorescence lifetime can be determined by a set of measurements of temporal point-spread function of the excitation light and fluorescence at two different concentrations of the fluorophore. This method is not dependent on the heterogeneity of the optical properties of the medium as well as the geometry of the excitation-detection on an arbitrary shape of the sample. The algorithm was validated by an indocyanine green fluorescence in phantom measurements and demonstrated by an in vivo measurement.

  18. Air Bursting Munition ABM Medium Calibre Applications

    DTIC Science & Technology

    2001-04-18

    NDIA 45th Annual Fuze Conference - Long Beach, CA - April 16-18, 2001 Folie 1 P2 15548 BB, P-VP/FD/11, © 2001 Oerlikon Contraves AG, Zürich...Switzerland Air Bursting Munition ABM Medium Calibre Applications Allan Buckley & Pierre Freymond Oerlikon Contraves Pyrotec AG CH-8050 Zurich...Project Number Task Number Work Unit Number Performing Organization Name(s) and Address(es) Oerlikon Contraves Pyrotec AG CH-8050 Zurich / Switzerland

  19. Grafilm; An Approach to a New Medium.

    ERIC Educational Resources Information Center

    Bryne-Daniel, J.

    "Grafilm" is a new medium which combines a variety of graphic and illustrative techniques on film stock. For example, by drawing on film it is possible to create a new type of animation. The emphasis in this book is on a graphic/poetic approach to film-making rather than a photographic/prosaic one. The book consists of a series of projects which…

  20. Supplementation of CHROMagar Candida Medium with Pal's Medium for Rapid Identification of Candida dubliniensis

    PubMed Central

    Sahand, Ismail H.; Moragues, María D.; Eraso, Elena; Villar-Vidal, María; Quindós, Guillermo; Pontón, José

    2005-01-01

    CHROMagar Candida medium is used for the isolation and identification of Candida species, but it does not differentiate Candida albicans from Candida dubliniensis. This differentiation can be achieved by using Pal's agar, which cannot be used in primary isolation. We have combined both media to obtain a new medium that can be used for the isolation and identification of C. dubliniensis in primary cultures. PMID:16272515

  1. Early Risers

    ERIC Educational Resources Information Center

    Asquith, Chistina

    2002-01-01

    In this article, the author features Bard High School Early College, the first public school in the country to offer a free, full-time college curriculum--and all the credits that go with it--to high schoolers. In Bard's four-year program, students race through high school requirements in 9th and 10th grades, then take college courses in 11th and…

  2. Does culture medium influence offspring birth weight?

    PubMed

    Carrasco, Beatriz; Boada, Montserrat; Rodríguez, Ignacio; Coroleu, Buenaventura; Barri, Pedro N; Veiga, Anna

    2013-11-01

    To determine whether the type of medium used to culture human embryos in vitro influences neonatal birth weight after IVF/intracytoplasmic sperm injection (ICSI). A prospective study and a retrospective study. Private assisted reproduction center. The prospective study included 449 IVF/ICSI cycles from August to December 2008. The retrospective analysis was performed for 2,518 IVF/ICSI cycles from October 2006 to December 2010. In the prospective study, patients were randomized for embryo culture in Cook or Vitrolife medium. The retrospective study was performed with three different culture media (MediCult, Cook, and Vitrolife). Mean birth weight, adjusted for gestational age and gender (z score) of newborns. In the prospective study, the average z score was -0.19 ± 0.85 in Cook and 0.08 ± 1.40 in Vitrolife. In the retrospective study, the z scores obtained in each group were as follows: Cook, -0.14 ± 0.96; MediCult, 0.06 ± 1.13; and Vitrolife, 0.03 ± 1.05. No significant differences were observed regarding the birth weight of children born in the different groups in both studies. The results do not show any relationship between the medium used for in vitro culture and mean birth weight adjusted for gestational age and gender of singletons born after IVF/ICSI. Copyright © 2013 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  3. Present-day Galaxy Evolution through Baryon Flows in the Circumgalactic Medium of the Galactic-Magellanic System

    NASA Astrophysics Data System (ADS)

    Barger, Kathleen Ann

    Galaxy evolution is governed by an intricate ballet of gas flows. To sustain star formation over many billions of years, more gas must inflow than outflow. Although numerous gas clouds surround the Milky Way, their attributes, origins, destinations, and responses to their surroundings need thorough investigation on an individual basis to realize how the entire population affects Galactic evolution. This dissertation hones in on two circumgalactic gas structures near the Milky Way: Complex A and the Magellanic Bridge. Complex A is an elongated gas structure that is traversing the hot Halo of the Milky Way, plummeting towards the Galaxy's disk. The Magellanic Bridge is a bridge of gas and stars that connects the Magellanic Clouds, created by galaxy interactions. In this thesis, I present the results of the highest sensitivity and kinematically resolved Halpha emission-line survey of Complex A and Halpha, [S II], and [N II] surveys of the Magellanic Bridge using the Wisconsin Halpha Mapper to explore their properties, surroundings, origins, and fates to unravel how circumgalactic structures influence galaxy evolution. I find that the observational properties of Complex A closely match with radiative transfer model predictions of a cloud ionized by the Milky Way and extragalactic background, implying a 5% escape fraction of ionizing photons from the Galactic disk. The multiline observations and modeling place the cloud's metallicity below solar. These results combined with other studies suggests the cloud has an intergalactic medium origin. I find that the global distribution of the warm ionized gas traces the neutral gas in the Magellanic Bridge. These observations place the ionized gas mass between (0.7 -- 1.6) x 108 solar masses, implying an ionization fraction of 25 -- 33% and a 5% maximum escape fraction of ionizing photons from the Magellanic Clouds. The line ratios reveal that the physical state of the the SMC-Tail and the LMC-Bridge interface regions differ

  4. Genome-wide transcriptome analysis of Clavibacter michiganensis subsp. michiganensis grown in xylem mimicking medium.

    PubMed

    Hiery, Eva; Adam, Susanne; Reid, Stephen; Hofmann, Jörg; Sonnewald, Sophia; Burkovski, Andreas

    2013-12-01

    The interaction between Clavibacter michiganensis subsp. michiganensis with its host, the tomato plant (Solanum lycopersicum), is poorly understood and only few virulence factors are known. While studying of the bacteria in planta is time-consuming and difficult, the analysis in vitro would facilitate research. Therefore, a xylem mimicking medium (XMM) for C. michiganensis subsp. michiganensis was established in this study based on an apoplast medium for Xanthomonas campestris pv. vesicatoria. In contrast to the apoplast medium, XMM contains no sugars, but amino acids which serve as nitrogen and carbon source. As a result, growth in XMM induced transcriptional changes of genes encoding putative sugar, amino acid and iron uptake systems. In summary, mRNA levels of about 8% of all C. michiganensis subsp. michiganensis genes were changed when XMM-grown bacteria were compared to M9 minimal medium-grown cells. Almost no transcriptional changes of genes encoding hydrolytic enzymes were detected, leading to the idea that XMM reflects the situation in the beginning of infection and therefore allows the characterization of virulence factors in this early stage of infection. The addition of the plant wound substance acetosyringone to the XMM medium led to a change in transcript amount, including genes coding for proteins involved in protein transport, iron uptake and regulation processes. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Dusty Plasma Effects in the Interplanetary Medium?

    NASA Astrophysics Data System (ADS)

    Mann, Ingrid; Issautier, Karine; Meyer-Vernet, Nicole; Le Chat, Gaétan; Czechowski, Andrzej; Zaslavsky, Arnaud; Zouganelis, Yannis; Belheouane, Soraya

    Cosmic dust particles exist in a variety of compositions and sizes in the interplanetary medium. There is little direct information on the composition, but those interplanetary dust particles that are collected in the upper Earth’s atmosphere and can be studied in the laboratory typically have an irregular, sometimes porous structure on scales <100 nm. They contain magnesium-rich silicates and silicon carbide, iron-nickel and iron-sulfur compounds, calcium- and aluminum oxides, and chemical compounds that contain a large mass fraction of carbon (e.g. carbonaceous species). A fraction of the dust originates from comets, but because of their bulk material temperature of about 280 K near 1 AU, most icy compounds have disappeared. The dust particles are embedded in the solar wind, a hot plasma with at 1 AU kinetic temperatures around 100 000 K and flow direction nearly radial outward from the Sun at supersonic bulk velocities around 400 km/s. Since the dust particles carry an electric surface charge they are subject to electromagnetic forces and the nanodust particles are efficiently accelerated to velocities of order of solar wind speed. The acceleration of the nanodust is similar, but not identical to the formation of pick-up ions. The S/WAVES radio wave instrument on STEREO measured a flux of nanodust at 1 AU [1]. The nanodust probably forms in the region inward of 1 AU and is accelerated by the solar wind as discussed. We also discuss the different paths of dust - plasma interactions in the interplanetary medium and their observations with space experiments. Comparing these interactions we show that the interplanetary medium near 1 AU can in many cases be described as “dust in plasma" rather than "dusty plasma”. [1] S. Belheouane, N. Meyer-Vernet, K. Issautier, G. Le Chat, A. Zaslavsky, Y. Zouganelis, I. Mann, A. Czechowski: Dynamics of nanoparticles detected at 1 AU by S/WAVES onboard STEREO spacecraft, in this session.

  6. Psychotherapeutic management of a potential spirit medium.

    PubMed

    Woon, T H; Teoh, C L

    1976-03-01

    Psychotherapeutic management of a potential spirit medium (shaman) in a modern University Hospital setting in Malaysia is described. Magical thinking, projection and spirit possession (trance state) occur during management. Discussion of management was based on what Heinz Wolff described as the psychotherapist's functions of (1) psychodynamic understanding; (2) the therapeutic function; and (3) the developmental function. This patient did not conform to the general criteria of a suitable patient for psychotherapy. But her willingness to engage in therapy contributed to a satisfactory outcome. The therapist's growth in cross-cultural therapeutic encounter seems to be prominent.

  7. Electromagnetically Induced Transparency In Rydberg Atomic Medium

    NASA Astrophysics Data System (ADS)

    Deng, Li; Cong, Lu; Chen, Ai-Xi

    2018-03-01

    Due to possessing big principal quantum number, Rydberg atom has some unique properties, for example: its radiative lifetime is long, dipole moment is large, and interaction between atoms is strong and so on. These properties make one pay attention to Rydberg atoms. In this paper we investigate the effects of Rydberg dipole-dipole interactions on electromagnetically induced transparency (EIT) schemes and group velocity in three-level systems of ladder type, which provides theoretical foundation for exploring the linear and nonlinear characteristics of light in a Rydberg electromagnetically-induced-transparency medium.

  8. Polycyclic aromatic hydrocarbons in stellar medium

    NASA Astrophysics Data System (ADS)

    Rastogi, Shantanu

    2005-06-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are an important com- ponent of the Interstellar Medium (ISM). They are being used as probes for understanding of process and conditions of different astrophysical environments. The understanding of their IR spectra and its variations with PAH size and ionization state is useful in characterizing the ISM. Spectral features of model graphene sheets and also that of smaller PAH molecules are reported. The variation of intensity with charge state of the molecule shows that cations give a better correlation with observations. The relationship between changes in charge distribution with intensity changes upon ionization has been probed.

  9. Photodegradation of organophosphorus pesticides in honey medium.

    PubMed

    Yuan, Zhimin; Yao, Jun; Liu, Haijun; Han, Jun; Trebše, Polonca

    2014-10-01

    Honey can be polluted due to environmental pollution and misuse of beekeeping practices. In the present study, photodegradation experiments of organophosphorus pesticides (coumaphos, methyl parathion and fenitrothion) in honey medium were conducted using Atlas Suntest simulator CPS+ as a sunlight producer. Photodegradation experiments were conducted under three different intensities as 250W/m(2), 500W/m(2) and 750W/m(2) to evaluate the impact of sunlight intensity on removal of OPs in honey medium. Significant decreases of three OPs' concentrations were observed. Coumaphos showed the highest degradability, reaching a degradation percentage of 90 percent within 15min. After 1h irradiation, residual percentages of coumaphos were 6.62 percent for 250W/m(2), 3.48 percent for 500W/m(2) and 2.98 percent for 750W/m(2), respectively. Methyl parathion and fenitrothion also could be removed through photodegradation efficiently. After 1h irradiation, the residual percentages of methyl parathion and fenitrothion under 750W/m(2) sunlight irradiation were 26.89 percent and 16.70 percent, respectively. Intensity of sunlight showed a positive impact on removal of OPs in honey medium. The higher intensity, the lower residual percentage. Photodegradation of three OPs fitted well with pseudo-first order kinetics. Half-lives calculated from pseudo-first order kinetics were 17.61min (250W/m(2)), 16.67min (500W/m(2)) and 17.58min (750W/m(2)) for coumaphos, 57.62min (250W/m(2)), 34.13min (500W/m(2)) and 31.69min (750W/m(2)) for methyl parathion and 144.70min (250W/m(2)), 95.47min (500W/m(2)) and 22.57min (750W/m(2)) for fenitrothion, respectively. Most of the three OPs could dissipate in a short time under sunlight irradiation. Photodegradation could be accepted as an appropriate method for the removal of OPs in honey medium. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Degradation testing of Mg alloys in Dulbecco's modified eagle medium: Influence of medium sterilization.

    PubMed

    Marco, Iñigo; Feyerabend, Frank; Willumeit-Römer, Regine; Van der Biest, Omer

    2016-05-01

    This work studies the in vitro degradation of Mg alloys for bioabsorbable implant applications under near physiological conditions. For this purpose, the degradation behaviour of Mg alloys in Dulbecco's modified eagle medium (DMEM) which is a commonly used cell culture medium is analysed. Unfortunately, DMEM can be contaminated by microorganisms, acidifying the medium and accelerating the Mg degradation process by dissolution of protective degradation layers, such as (Mgx,Cay)(PO4)z. In this paper the influence of sterilization by applying UV-C radiation and antibiotics (penicillin/streptomycin) is analysed with two implant material candidates: Mg-Gd and Mg-Ag alloys; and pure magnesium as well as Mg-4Y-3RE as a reference. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Optomagnetic composite medium with conducting nanoelements

    NASA Astrophysics Data System (ADS)

    Panina, L. V.; Grigorenko, A. N.; Makhnovskiy, D. P.

    2002-10-01

    A type of metal-dielectric composites has been proposed that is characterized by a resonancelike behavior of the effective permeability μeff in the infrared and visible spectral ranges. This material can be referred to as an optomagnetic medium. It consists of conducting inclusions in the shape of nonclosed contours or pairs of parallel sticks with length of 50-100 nm embedded in a dielectric matrix. The analytical formalism developed is based on solving the scattering problem for considered inclusions with impedance boundary condition, which yields the current and charge distributions within the inclusions. The magnetic properties originated by induced currents are enhanced by localized plasmon modes, which make an inclusion resonate at a much lower frequency than that of the half-wavelength requirement at microwaves. It implies that microstructure can be made on a scale much less than the wavelength and the effective permeability is a valid concept. The presence of the effective magnetic permeability and its resonant properties lead to unusual optical effects and open interesting applications. In particular, the condition for Brewster's angle becomes different resulting in reflectionless normal incidence from air (vacuum) if the effective permeability and permittivity are the same. The resonant behavior of the effective permeability of the proposed optomagnetic medium could be used for creation of optical polarizes, filters, phase shifters, and selective lenses.

  12. Interface Instabilities in the Interstellar Medium

    NASA Technical Reports Server (NTRS)

    Hunter, J. H., Jr.; Siopis, C.; Whitaker, R. W.; Lovelace, R. V. E.

    1995-01-01

    In the present communication, we reexamine two limiting cases of star-forming mechanisms involving self-gravity, thermodynamics, and velocity fields, that we believe must be ubiquitous in the ISM -- the generally oblique collision of supersonic gas streams or turbulent eddies. The general case of oblique collisions has not yet been examined. However, two limiting cases have been studied in detail: (1) The head-on collision of two identical gas streams that form dense, cool accretion shocks that become unstable and may form Jeans mass clouds, which subsequently undergo collapse. (2) Linearly unstable tangential velocity discontinuities, which result in Kelvin-Helmholtz (K-H) instabilities and related phenomena. The compressible K-H instabilities exhibit rich and unexpected behaviors. Moreover a new thermal-dynamic (T-D) mode was discovered that arises from the coupling of the perturbed thermal behavior and the unperturbed flow. The T-D mode has the curious characteristic that it may be strongly unstable to interface modes when the global modes in either medium are absolutely thermally stable. In the present communication additional models of case 1 are described and discussed, and self-gravity is added in the linear theory of tangential discontinuities, case 2. We prove that self-gravity fundamentally changes the behavior of interfacial modes -- density discontinuities (or steps) are inherently unstable on roughly the free-fall timescale of the denser medium to perturbations of all wavelengths.

  13. Formation of benzene in the interstellar medium

    PubMed Central

    Jones, Brant M.; Zhang, Fangtong; Kaiser, Ralf I.; Jamal, Adeel; Mebel, Alexander M.; Cordiner, Martin A.; Charnley, Steven B.

    2011-01-01

    Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block—the aromatic benzene molecule—has remained elusive for decades. Here we demonstrate in crossed molecular beam experiments combined with electronic structure and statistical calculations that benzene (C6H6) can be synthesized via the barrierless, exoergic reaction of the ethynyl radical and 1,3-butadiene, C2H + H2CCHCHCH2 → C6H6 + H, under single collision conditions. This reaction portrays the simplest representative of a reaction class in which aromatic molecules with a benzene core can be formed from acyclic precursors via barrierless reactions of ethynyl radicals with substituted 1,3-butadiene molecules. Unique gas-grain astrochemical models imply that this low-temperature route controls the synthesis of the very first aromatic ring from acyclic precursors in cold molecular clouds, such as in the Taurus Molecular Cloud. Rapid, subsequent barrierless reactions of benzene with ethynyl radicals can lead to naphthalene-like structures thus effectively propagating the ethynyl-radical mediated formation of aromatic molecules in the interstellar medium. PMID:21187430

  14. Coal char oxidation kinetics in air medium

    NASA Astrophysics Data System (ADS)

    Slyusarskiy, K. V.; Jankovskiy, S. A.; Korotkikh, A. G.; Sorokin, I. V.

    2017-01-01

    Research on oxidation in air medium process of three different coal chars with various carbon content was presented. The anthracite, T-grade bituminous coal and 2B-grade lignite char powders with particle size less than 80 µm were studied. The coal char oxidation was studied by isothermal method using coupled TG-DSC analyzer Netzsch STA 449 Jupiter F3 in the temperature range 1000-1200 °C. Experiments were carried out at ambient pressure. Volumetric flow rate of oxidation medium into analyzer chamber was 250 ml/min and consisted of oxygen and argon with volumetric ratio 24:1. Based on experimental data, the average rate of carbon oxidation reaction values were defined at each temperature. Kinetic constants (frequency factor and activation energy) of reaction were defined as well via 1st order Arrhenius equation. Activation energy values are in good agreement with the data presented in the literature. Activation energy values for anthracite char are 1.6-1.7 times higher than those for bituminous coal and lignite chars, respectively.

  15. Formation of Benzene in the Interstellar Medium

    NASA Technical Reports Server (NTRS)

    Jones, Brant M.; Zhang, Fangtong; Kaiser, Ralf I.; Jamal, Adeel; Mebel, Alexander M.; Cordiner, Martin A.; Charnley, Steven B.; Crim, F. Fleming (Editor)

    2010-01-01

    Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block-the aromatic benzene molecule-has remained elusive for decades. Here we demonstrate in crossed molecular beam experiments combined with electronic structure and statistical calculations that benzene (C6H6) can be synthesized via the barrierless, exoergic reaction of the ethynyl radical and 1,3- butadiene, C2H + H2CCHCHCH2 --> C6H6, + H, under single collision conditions. This reaction portrays the simplest representative of a reaction class in which aromatic molecules with a benzene core can be formed from acyclic precursors via barrierless reactions of ethynyl radicals with substituted 1,3-butadlene molecules. Unique gas-grain astrochemical models imply that this low-temperature route controls the synthesis of the very first aromatic ring from acyclic precursors in cold molecular clouds, such as in the Taurus Molecular Cloud. Rapid, subsequent barrierless reactions of benzene with ethynyl radicals can lead to naphthalene-like structures thus effectively propagating the ethynyl-radical mediated formation of aromatic molecules in the interstellar medium.

  16. Early Rockets

    NASA Image and Video Library

    2004-04-15

    This photograph is of the engine for the Redstone rocket. The Redstone ballistic missile was a high-accuracy, liquid-propelled, surface-to-surface missile developed by the Army Ballistic Missile Agency, Redstone Arsenal, in Huntsville, Alabama, under the direction of Dr. von Braun. The Redstone engine was a modified and improved version of the Air Force's Navaho cruise missile engine of the late forties. The A-series, as this would be known, utilized a cylindrical combustion chamber as compared with the bulky, spherical V-2 chamber. By 1951, the Army was moving rapidly toward the design of the Redstone missile, and the production was begun in 1952. Redstone rockets became the "reliable workhorse" for America's early space program. As an example of its versatility, the Redstone was utilized in the booster for Explorer 1, the first American satellite, with no major changes to the engine or missile.

  17. Early Rockets

    NASA Image and Video Library

    2004-04-15

    The image depicts Redstone missile being erected. The Redstone ballistic missile was a high-accuracy, liquid-propelled, surface-to-surface missile developed by Army Ballistic Missile Agency, Redstone Arsenal, in Huntsville, Alabama, under the direction of Dr. von Braun. The Redstone engine was a modified and improved version of the Air Force's Navaho cruise missile engine of the late forties. The A-series, as this would be known, utilized a cylindrical combustion chamber as compared with the bulky, spherical V-2 chamber. By 1951, the Army was moving rapidly toward the design of the Redstone missile, and the production was begun in 1952. Redstone rockets became the "reliable workhorse" for America's early space program. As an example of the versatility, Redstone was utilized in the booster for Explorer 1, the first American satellite, with no major changes to the engine or missile

  18. Early Rockets

    NASA Image and Video Library

    1958-05-15

    Redstone missile No. 1002 on the launch pad at Cape Canaveral, Florida, on May 16, 1958. The Redstone ballistic missile was a high-accuracy, liquid-propelled, surface-to-surface missile developed by the Army Ballistic Missile Agency, Redstone Arsenal, in Huntsville, Alabama, under the direction of Dr. von Braun. The Redstone engine was a modified and improved version of the Air Force's Navaho cruise missile engine of the late forties. The A-series, as this would be known, utilized a cylindrical combustion chamber as compared with the bulky, spherical V-2 chamber. By 1951, the Army was moving rapidly toward the design of the Redstone missile, and production was begun in 1952. Redstone rockets became the "reliable workhorse" for America's early space program. As an example of the versatility, Redstone was utilized in the booster for Explorer 1, the first American satellite, with no major changes to the engine or missile

  19. New medium for detection of esterase and gelatinase activity.

    PubMed

    Pácová, Z; Kocur, M

    1984-10-01

    A new medium was developed for detecting esterase and gelatinase activities in aerobic and facultatively anaerobic bacteria. The new medium was tested with various strains of bacteria and the results showed agreement between the reactions in the new medium and those obtained by conventional techniques. The new medium is more economical and may be used for a rapid differentiation of Serratia, Aeromonas and Vibrio species from biochemically similar bacteria.

  20. METHOD OF REMOVING IODINE FROM GASES AND FILTER MEDIUM THEREFOR

    DOEpatents

    Silverman, L.

    1961-08-01

    A method for the removal of iodine from large gas volumes is described. The gaseous medium is heated to a temperature not exceeding 400 deg C. Water vapor is then added to the medium in approximate amounts of 1 lb/cu ft of the medium. The medium is then passed through a porous copper fibrous pad having deposited thereon a coating of silver, the silver coating being treated with hydrogen sulfide forming a layer of silver sulfide. (AEC)

  1. Short-, Medium-, and Long-Term Consequences of Poor Infant Health: An Analysis Using Siblings and Twins

    ERIC Educational Resources Information Center

    Oreopoulos, Philip; Stabile, Mark; Walld, Randy; Roos, Leslie L.

    2008-01-01

    We use administrative data on a sample of births between 1978 and 1985 to investigate the short-, medium-, and long-term consequences of poor infant health. Our findings offer several advances to the existing literature on the effects of early infant health on subsequent health, education, and labor force attachment. First, we use a large sample…

  2. 21 CFR 133.103 - Asiago medium cheese.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Asiago medium cheese. 133.103 Section 133.103 Food... HUMAN CONSUMPTION CHEESES AND RELATED CHEESE PRODUCTS Requirements for Specific Standardized Cheese and Related Products § 133.103 Asiago medium cheese. Asiago medium cheese conforms to the definition and...

  3. 21 CFR 133.103 - Asiago medium cheese.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Asiago medium cheese. 133.103 Section 133.103 Food... HUMAN CONSUMPTION CHEESES AND RELATED CHEESE PRODUCTS Requirements for Specific Standardized Cheese and Related Products § 133.103 Asiago medium cheese. Asiago medium cheese conforms to the definition and...

  4. Lime-amended growing medium causes seedling growth distortions

    Treesearch

    R. Kasten Dumroese; Gale Thompson; David L. Wenny

    1990-01-01

    Although a commercial growing medium with incorporated agricultural lime had been successfully used for years, it caused growth distortion of coniferous and deciduous seedlings during 1988. Seedlings grown in the amended medium were stunted and chlorotic, often with disfigured needles and multiple tops. Seedlings grown in the same medium without incorporated lime grew...

  5. 27 CFR 19.675 - Medium plant permit applications.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Medium plant permit... Obtaining A Permit § 19.675 Medium plant permit applications. (a) General. Any person wishing to establish a medium plant must file form TTB F 5110.74, Application and Permit for an Alcohol Fuel Producer Under 26 U...

  6. 27 CFR 19.675 - Medium plant permit applications.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Medium plant permit... Obtaining A Permit § 19.675 Medium plant permit applications. (a) General. Any person wishing to establish a medium plant must file form TTB F 5110.74, Application and Permit for an Alcohol Fuel Producer Under 26 U...

  7. 27 CFR 19.675 - Medium plant permit applications.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Medium plant permit... Obtaining A Permit § 19.675 Medium plant permit applications. (a) General. Any person wishing to establish a medium plant must file form TTB F 5110.74, Application and Permit for an Alcohol Fuel Producer Under 26 U...

  8. 27 CFR 19.675 - Medium plant permit applications.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Medium plant permit... Obtaining A Permit § 19.675 Medium plant permit applications. (a) General. Any person wishing to establish a medium plant must file form TTB F 5110.74, Application and Permit for an Alcohol Fuel Producer Under 26 U...

  9. 7 CFR 51.2751 - U.S. Medium Virginia.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false U.S. Medium Virginia. 51.2751 Section 51.2751 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... § 51.2751 U.S. Medium Virginia. “U.S. Medium Virginia” consists of shelled Virginia type peanut kernels...

  10. 21 CFR 864.8500 - Lymphocyte separation medium.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Lymphocyte separation medium. 864.8500 Section 864.8500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... medium. (a) Identification. A lymphocyte separation medium is a device used to isolate lymphocytes from...

  11. 7 CFR 51.2751 - U.S. Medium Virginia.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false U.S. Medium Virginia. 51.2751 Section 51.2751 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... § 51.2751 U.S. Medium Virginia. “U.S. Medium Virginia” consists of shelled Virginia type peanut kernels...

  12. 7 CFR 51.2751 - U.S. Medium Virginia.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false U.S. Medium Virginia. 51.2751 Section 51.2751... STANDARDS) United States Standards for Shelled Virginia Type Peanuts Grades § 51.2751 U.S. Medium Virginia. “U.S. Medium Virginia” consists of shelled Virginia type peanut kernels of similar varietal...

  13. 21 CFR 864.8500 - Lymphocyte separation medium.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Lymphocyte separation medium. 864.8500 Section 864.8500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... medium. (a) Identification. A lymphocyte separation medium is a device used to isolate lymphocytes from...

  14. 7 CFR 51.2751 - U.S. Medium Virginia.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false U.S. Medium Virginia. 51.2751 Section 51.2751... STANDARDS) United States Standards for Shelled Virginia Type Peanuts Grades § 51.2751 U.S. Medium Virginia. “U.S. Medium Virginia” consists of shelled Virginia type peanut kernels of similar varietal...

  15. 21 CFR 864.8500 - Lymphocyte separation medium.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Lymphocyte separation medium. 864.8500 Section 864.8500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... medium. (a) Identification. A lymphocyte separation medium is a device used to isolate lymphocytes from...

  16. 7 CFR 51.2751 - U.S. Medium Virginia.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false U.S. Medium Virginia. 51.2751 Section 51.2751... STANDARDS) United States Standards for Shelled Virginia Type Peanuts Grades § 51.2751 U.S. Medium Virginia. “U.S. Medium Virginia” consists of shelled Virginia type peanut kernels of similar varietal...

  17. 21 CFR 864.8500 - Lymphocyte separation medium.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Lymphocyte separation medium. 864.8500 Section 864.8500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... medium. (a) Identification. A lymphocyte separation medium is a device used to isolate lymphocytes from...

  18. 21 CFR 133.103 - Asiago medium cheese.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Asiago medium cheese. 133.103 Section 133.103 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Related Products § 133.103 Asiago medium cheese. Asiago medium cheese conforms to the definition and...

  19. 21 CFR 133.103 - Asiago medium cheese.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Asiago medium cheese. 133.103 Section 133.103 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Related Products § 133.103 Asiago medium cheese. Asiago medium cheese conforms to the definition and...

  20. 21 CFR 864.8500 - Lymphocyte separation medium.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Lymphocyte separation medium. 864.8500 Section 864.8500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... medium. (a) Identification. A lymphocyte separation medium is a device used to isolate lymphocytes from...

  1. 21 CFR 133.103 - Asiago medium cheese.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Asiago medium cheese. 133.103 Section 133.103 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Related Products § 133.103 Asiago medium cheese. Asiago medium cheese conforms to the definition and...

  2. Response learning stimulates dendritic spine growth on dorsal striatal medium spiny neurons.

    PubMed

    Briones, Brandy A; Tang, Vincent D; Haye, Amanda E; Gould, Elizabeth

    2018-06-23

    Increases in the number and/or the size of dendritic spines, sites of excitatory synapses, have been linked to different types of learning as well as synaptic plasticity in several brain regions, including the hippocampus, sensory cortex, motor cortex, and cerebellum. By contrast, a previous study reported that training on a maze task requiring the dorsal striatum has no effect on medium spiny neuron dendritic spines in this area. These findings might suggest brain region-specific differences in levels of plasticity as well as different cellular processes underlying different types of learning. No previous studies have investigated whether dendritic spine density changes may be localized to specific subpopulations of medium spiny neurons, nor have they examined dendritic spines in rats trained on a dorsolateral striatum-dependent maze task in comparison to rats exposed to the same type of maze in the absence of training. To address these questions further, we labeled medium spiny neurons with the lipophilic dye DiI and stained for the protein product of immediate early gene zif 268, an indirect marker of neuronal activation, in both trained and untrained groups. We found a small but significant increase in dendritic spine density on medium spiny neurons of the dorsolateral striatum after short-term intensive training, along with robust increases in the density of spines with mushroom morphology coincident with reductions in the density of spines with thin morphology. However, these results were not associated with zif 268 expression. Our findings suggest that short-term intensive training on a dorsolateral striatum-dependent maze task induces rapid increases in dendritic spine density and maturation on medium spiny neurons of the dorsolateral striatum, an effect which may contribute to early acquisition of the learned response in maze training. Copyright © 2018. Published by Elsevier Inc.

  3. Medium-Scale Production of Citrinin by Penicillium citrinum in a Semisynthetic Medium

    PubMed Central

    Davis, N. D.; Dalby, D. K.; Diener, U. L.; Sansing, G. A.

    1975-01-01

    A convenient method is described for the production of up to 1.75 g of citrinin per liter by Penicillium citrinum growing in stationary culture in a 5-gallon (18.925 liters) carboy containing 4 liters of 4% sucrose and 2% yeast extract medium. PMID:1089161

  4. Rayleigh convective instability in a cloud medium

    NASA Astrophysics Data System (ADS)

    Shmerlin, B. Ya.; Shmerlin, M. B.

    2017-09-01

    The problem of convective instability of an atmospheric layer containing a horizontally finite region filled with a cloud medium is considered. Solutions exponentially growing with time, i.e., solitary cloud rolls or spatially localized systems of cloud rolls, have been constructed. In the case of axial symmetry, their analogs are convective vortices with both ascending and descending motions on the axis and cloud clusters with ring-shaped convective structures. Depending on the anisotropy of turbulent exchange, the scale of vortices changes from the tornado scale to the scale of tropical cyclones. The solutions with descending motions on the axis can correspond to the formation of a tornado funnel or a hurricane eye in tropical cyclones.

  5. Development of novel Alicyclobacillus spp. isolation medium.

    PubMed

    Chang, S; Kang, D-H

    2005-01-01

    To develop a new isolation medium with higher recovery rates of Alicyclobacillus spp. SK agar was developed with optimized incubation temperature, pH, acidulant, Tween 80 concentration and divalent cation addition. Results indicate that detection of Alicyclobacillus spp. by SK agar was significantly higher (P > 0.05) than those obtained by K agar, orange serum agar, and potato dextrose agar. Current media used for Alicyclobacillus spp. isolation still resulted in high numbers of false negative products. The sensitivity of SK agar to Alicyclobacillus spp. allows detection of low numbers of Alicyclobacillus spp. and also provides a more higher isolation results compared with currently used media. SK agar will be useful to the fruit juice industry to obtain more accurate numbers of contaminant Alicyclobacillus spp. With this media, false negative samples can be reduced, and the likelihood of exported products being rejected can be greatly reduced.

  6. Interface crack in a nonhomogeneous elastic medium

    NASA Technical Reports Server (NTRS)

    Delale, F.; Erdogan, F.

    1988-01-01

    The linear elasticity problem for an interface crack between two bonded half planes is reconsidered. It is assumed that one of the half planes is homogeneous and the second is nonhomogeneous in such a way that the elastic properties are continuous throughout the plane and have discontinuous derivatives along the interface. The problem is formulated in terms of a system of integral equations and the asymptotic behavior of the stress state near the crack tip is determined. The results lead to the conclusion that the singular behavior of stresses in the nonhomogeneous medium is identical to that in a homogeneous material provided the spacial distribution of material properties is continuous near and at the crack tip. The problem is solved for various values of the nonhomogeneity parameter and for four different sets of crack surface tractions, and the corresponding stress intensity factors are tabulated.

  7. Medium wave exposure characterisation using exposure quotients.

    PubMed

    Paniagua, Jesús M; Rufo, Montaña; Jiménez, Antonio; Antolín, Alicia; Pinar, Iván

    2010-06-01

    One of the aspects considered in the International Commission on Non-Ionizing Radiation Protection guidelines is that, in situations of simultaneous exposure to fields of different frequencies, exposure quotients for thermal and electrical stimulation effects should be examined. The aim of the present work was to analyse the electromagnetic radiation levels and exposure quotients for exposure to multiple-frequency sources in the vicinity of medium wave radio broadcasting antennas. The measurements were made with a spectrum analyser and a monopole antenna. Kriging interpolation was used to prepare contour maps and to estimate the levels in the towns and villages of the zone. The results showed that the exposure quotient criterion based on electrical stimulation effects to be more stringent than those based on thermal effects or power density levels. Improvement of dosimetry evaluations requires the spectral components of the radiation to be quantified, followed by application of the criteria for exposure to multiple-frequency sources.

  8. Medium Altitude Endurance Unmanned Air Vehicle

    NASA Astrophysics Data System (ADS)

    Ernst, Larry L.

    1994-10-01

    The medium altitude endurance unmanned air vehicle (MAE UAV) program (formerly the tactical endurance TE UAV) is a new effort initiated by the Department of Defense to develop a ground launched UAV that can fly out 500 miles, remain on station for 24 hours, and return. It will transmit high resolution optical, infrared, and synthetic aperture radar (SAR) images of well-defended target areas through satellite links. It will provide near-real-time, releasable, low cost/low risk surveillance, targeting and damage assessment complementary to that of satellites and manned aircraft. The paper describes specific objectives of the MAE UAV program (deliverables and schedule) and the program's unique position as one of several programs to streamline the acquisition process under the cognizance of the newly established Airborne Reconnaissance Office. I discuss the system requirements and operational concept and describe the technical capabilities and characteristics of the major subsystems (airframe, propulsion, navigation, sensors, communication links, ground station, etc.) in some detail.

  9. Dynamics of osmosis in a porous medium.

    PubMed

    Cardoso, Silvana S S; Cartwright, Julyan H E

    2014-11-01

    We derive from kinetic theory, fluid mechanics and thermodynamics the minimal continuum-level equations governing the flow of a binary, non-electrolytic mixture in an isotropic porous medium with osmotic effects. For dilute mixtures, these equations are linear and in this limit provide a theoretical basis for the widely used semi-empirical relations of Kedem & Katchalsky (Kedem & Katchalsky 1958 Biochim. Biophys. Acta 27, 229-246 (doi:10.1016/0006-3002(58)90330-5), which have hitherto been validated experimentally but not theoretically. The above linearity between the fluxes and the driving forces breaks down for concentrated or non-ideal mixtures, for which our equations go beyond the Kedem-Katchalsky formulation. We show that the heretofore empirical solute permeability coefficient reflects the momentum transfer between the solute molecules that are rejected at a pore entrance and the solvent molecules entering the pore space; it can be related to the inefficiency of a Maxwellian demi-demon.

  10. Polarization of submillimetre lines from interstellar medium

    NASA Astrophysics Data System (ADS)

    Zhang, Heshou; Yan, Huirong

    2018-04-01

    Magnetic fields play important roles in many astrophysical processes. However, there is no universal diagnostic for the magnetic fields in the interstellar medium (ISM) and each magnetic tracer has its limitation. Any new detection method is thus valuable. Theoretical studies have shown that submillimetre fine-structure lines are polarized due to atomic alignment by ultraviolet photon-excitation, which opens up a new avenue to probe interstellar magnetic fields. We will, for the first time, perform synthetic observations on the simulated three-dimensional ISM to demonstrate the measurability of the polarization of submillimetre atomic lines. The maximum polarization for different absorption and emission lines expected from various sources, including star-forming regions are provided. Our results demonstrate that the polarization of submillimetre atomic lines is a powerful magnetic tracer and add great value to the observational studies of the submilimetre astronomy.

  11. Medium Fidelity Simulation of Oxygen Tank Venting

    NASA Technical Reports Server (NTRS)

    Sweet, Adam; Kurien, James; Lau, Sonie (Technical Monitor)

    2001-01-01

    The item to he cleared is a medium-fidelity software simulation model of a vented cryogenic tank. Such tanks are commonly used to transport cryogenic liquids such as liquid oxygen via truck, and have appeared on liquid-fueled rockets for decades. This simulation model works with the HCC simulation system that was developed by Xerox PARC and NASA Ames Research Center. HCC has been previously cleared for distribution. When used with the HCC software, the model generates simulated readings for the tank pressure and temperature as the simulated cryogenic liquid boils off and is vented. Failures (such as a broken vent valve) can be injected into the simulation to produce readings corresponding to the failure. Release of this simulation will allow researchers to test their software diagnosis systems by attempting to diagnose the simulated failure from the simulated readings. This model does not contain any encryption software nor can it perform any control tasks that might be export controlled.

  12. Wave propagation in a random medium

    NASA Technical Reports Server (NTRS)

    Lee, R. W.; Harp, J. C.

    1969-01-01

    A simple technique is used to derive statistical characterizations of the perturbations imposed upon a wave (plane, spherical or beamed) propagating through a random medium. The method is essentially physical rather than mathematical, and is probably equivalent to the Rytov method. The limitations of the method are discussed in some detail; in general they are restrictive only for optical paths longer than a few hundred meters, and for paths at the lower microwave frequencies. Situations treated include arbitrary path geometries, finite transmitting and receiving apertures, and anisotropic media. Results include, in addition to the usual statistical quantities, time-lagged functions, mixed functions involving amplitude and phase fluctuations, angle-of-arrival covariances, frequency covariances, and other higher-order quantities.

  13. Motion of kinesin in a viscoelastic medium

    NASA Astrophysics Data System (ADS)

    Knoops, Gert; Vanderzande, Carlo

    2018-05-01

    Kinesin is a molecular motor that transports cargo along microtubules. The results of many in vitro experiments on kinesin-1 are described by kinetic models in which one transition corresponds to the forward motion and subsequent binding of the tethered motor head. We argue that in a viscoelastic medium like the cytosol of a cell this step is not Markov and has to be described by a nonexponential waiting time distribution. We introduce a semi-Markov kinetic model for kinesin that takes this effect into account. We calculate, for arbitrary waiting time distributions, the moment generating function of the number of steps made, and determine from this the average velocity and the diffusion constant of the motor. We illustrate our results for the case of a waiting time distribution that is Weibull. We find that for realistic parameter values, viscoelasticity decreases the velocity and the diffusion constant, but increases the randomness (or Fano factor).

  14. Effective Medium Theories for Multicomponent Poroelastic Composites

    SciTech Connect

    Berryman, J G

    2005-02-08

    In Biot's theory of poroelasticity, elastic materials contain connected voids or pores and these pores may be filled with fluids under pressure. The fluid pressure then couples to the mechanical effects of stress or strain applied externally to the solid matrix. Eshelby's formula for the response of a single ellipsoidal elastic inclusion in an elastic whole space to a strain imposed at a distant boundary is a very well-known and important result in elasticity. Having a rigorous generalization of Eshelby's results valid for poroelasticity means that the hard part of Eshelby's work (in computing the elliptic integrals needed to evaluatemore » the fourth-rank tensors for inclusions shaped like spheres, oblate and prolate spheroids, needles and disks) can be carried over from elasticity to poroelasticity--and also thermoelasticity--with only relatively minor modifications. Effective medium theories for poroelastic composites such as rocks can then be formulated easily by analogy to well-established methods used for elastic composites. An identity analogous to Eshelby's classic result has been derived [Physical Review Letters 79:1142-1145 (1997)] for use in these more complex and more realistic problems in rock mechanics analysis. Descriptions of the application of this result as the starting point for new methods of estimation are presented, including generalizations of the coherent potential approximation (CPA), differential effective medium (DEM) theory, and two explicit schemes. Results are presented for estimating drained shear and bulk modulus, the Biot-Willis parameter, and Skempton's coefficient. Three of the methods considered appear to be quite reliable estimators, while one of the explicit schemes is found to have some undesirable characteristics.« less

  15. Magnetic Fields in the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Clark, Susan

    2017-01-01

    The Milky Way is magnetized. Invisible magnetic fields thread the Galaxy on all scales and play a vital but still poorly understood role in regulating flows of gas in the interstellar medium and the formation of stars. I will present highlights from my thesis work on magnetic fields in the diffuse interstellar gas and in accretion disks. At high Galactic latitudes, diffuse neutral hydrogen is organized into an intricate network of slender linear features. I will show that these neutral hydrogen “fibers” are extremely well aligned with the ambient magnetic field as traced by both starlight polarization (Clark et al. 2014) and Planck 353 GHz polarized dust emission (Clark et al. 2015). The structure of the neutral interstellar medium is more tightly coupled to the magnetic field than previously known. Because the orientation of neutral hydrogen is an independent predictor of the local dust polarization angle, our work provides a new tool in the search for inflationary gravitational wave B-mode polarization in the cosmic microwave background, which is currently limited by dust foreground contamination. Magnetic fields also drive accretion in astrophysical disks via the magnetorotational instability (MRI). I analytically derive the behavior of this instability in the weakly nonlinear regime and show that the saturated state of the instability depends on the geometry of the background magnetic field. The analytical model describes the behavior of the MRI in a Taylor-Couette flow, a set-up used by experimentalists in the ongoing quest to observe MRI in the laboratory (Clark & Oishi 2016a, 2016b).

  16. Flow regimes for fluid injection into a confined porous medium

    DOE PAGES

    Zheng, Zhong; Guo, Bo; Christov, Ivan C.; ...

    2015-02-24

    We report theoretical and numerical studies of the flow behaviour when a fluid is injected into a confined porous medium saturated with another fluid of different density and viscosity. For a two-dimensional configuration with point source injection, a nonlinear convection–diffusion equation is derived to describe the time evolution of the fluid–fluid interface. In the early time period, the fluid motion is mainly driven by the buoyancy force and the governing equation is reduced to a nonlinear diffusion equation with a well-known self-similar solution. In the late time period, the fluid flow is mainly driven by the injection, and the governingmore » equation is approximated by a nonlinear hyperbolic equation that determines the global spreading rate; a shock solution is obtained when the injected fluid is more viscous than the displaced fluid, whereas a rarefaction wave solution is found when the injected fluid is less viscous. In the late time period, we also obtain analytical solutions including the diffusive term associated with the buoyancy effects (for an injected fluid with a viscosity higher than or equal to that of the displaced fluid), which provide the structure of the moving front. Numerical simulations of the convection–diffusion equation are performed; the various analytical solutions are verified as appropriate asymptotic limits, and the transition processes between the individual limits are demonstrated.« less

  17. Does Embryo Culture Medium Influence the Health and Development of Children Born after In Vitro Fertilization?

    PubMed

    Bouillon, Céline; Léandri, Roger; Desch, Laurent; Ernst, Alexandra; Bruno, Céline; Cerf, Charline; Chiron, Alexandra; Souchay, Céline; Burguet, Antoine; Jimenez, Clément; Sagot, Paul; Fauque, Patricia

    2016-01-01

    In animal studies, extensive data revealed the influence of culture medium on embryonic development, foetal growth and the behaviour of offspring. However, this impact has never been investigated in humans. For the first time, we investigated in depth the effects of embryo culture media on health, growth and development of infants conceived by In Vitro Fertilization until the age of 5 years old. This single-centre cohort study was based on an earlier randomized study. During six months, in vitro fertilization attempts (No. 371) were randomized according to two media (Single Step Medium--SSM group) or Global medium (Global group). This randomized study was stopped prematurely as significantly lower pregnancy and implantation rates were observed in the SSM group. Singletons (No. 73) conceived in the randomized study were included (42 for Global and 31 for SSM). The medical data for gestational, neonatal and early childhood periods were extracted from medical records and parental interviews (256 variables recorded). The developmental profiles of the children in eight domains (social, self-help, gross motor, fine motor, expressive language, language comprehension, letter knowledge and number knowledge--270 items) were compared in relation to the culture medium. The delivery rate was significantly lower in the SSM group than in the Global group (p<0.05). The culture medium had no significant effect on birthweight, risk of malformation (minor and major), growth and the frequency of medical concerns. However, the children of the Global group were less likely than those of the SSM group to show developmental problems (p = 0.002), irrespective of the different domains. In conclusion, our findings showed that the embryo culture medium may have an impact on further development.

  18. Highly selective medium for isolation of Listeria monocytogenes from food.

    PubMed Central

    al-Zoreky, N; Sandine, W E

    1990-01-01

    A new selective medium (Al-Zoreky-Sandine listeria medium [ASLM]) was formulated to recover Listeria monocytogenes from food specimens; the medium completely inhibited common food microflora. Recognition of Listeria colonies is evident by black discoloration of the medium due to esculin hydrolysis without need for special illuminating equipment. The medium contains acriflavin, ceftazidime, and moxalactam as selective agents. Compared with Listeria Selective Agar, ASLM was equally effective in recovering L. monocytogenes. However, ASLM inhibited micrococci, enterococci, and gram-negative bacteria, especially a strain that mimicked L. monocytogenes on Listeria Selective Agar. The new medium was able to recover heat injured cells with only 15% less count than the nonselective medium. Images PMID:2126701

  19. Changes of MK medium during storage of human cornea.

    PubMed Central

    Hasany, S M; Basu, P K

    1987-01-01

    By comparing the composition of McCarey-Kaufman (MK) medium before and after corneal storage we attempted to identify specific physiological changes in the medium as predictors of tissue damage. We also tried to determine if hydrocortisone (a lysosomal membrane stabiliser) added to the medium could reduce tissue damage during storage. Corneas (human and rabbit) were stored in the MK medium with and without hydrocortisone for 4 days at 4 degrees C. The water and nitrogen contents of the stored cornea were compared with those of the fresh cornea. The medium was analysed before and after corneal storage to determine the concentrations of glucose, protein, and amino acids as well as pH and osmolarity. Scanning electron microscopy (SEM) was used to estimate the degree of the corneal endothelial cell damage. The nitrogen contents and dry weights of the steroid treated and untreated stored corneas were similar to those of the fresh unstored cornea. The steroid treated cornea contained a lesser amount of water than the untreated cornea. The cornea stored in medium without steroid took up a greater amount of glucose from the medium than the cornea stored in medium with steroid. As compared with their concentrations in the fresh unused medium the concentrations of leucine, lysine, and glycine were lower and that of glutamic acid was higher in both the media used for corneal storage. However, the steroid treated storage medium as compared with the untreated storage medium had a greater reduction in the lowering of leucine, lysine, and glycine, and a lesser reduction in the increase of glutamic acid. Steroid treated medium also had a lesser amount of protein released from the stored cornea. Changes in the pH and osmolarity of the media before and after corneal storage were not remarkable. SEM showed that the endothelial cells of the cornea stored in the medium containing steroid were less damaged than those of the cornea stored in the medium without steroid. Images PMID

  20. Application of Medium and Seasonal Flood Forecasts for Agriculture Damage Assessment

    NASA Astrophysics Data System (ADS)

    Fakhruddin, Shamsul; Ballio, Francesco; Menoni, Scira

    2015-04-01

    Early warning is a key element for disaster risk reduction. In recent decades, major advancements have been made in medium range and seasonal flood forecasting. This progress provides a great opportunity to reduce agriculture damage and improve advisories for early action and planning for flood hazards. This approach can facilitate proactive rather than reactive management of the adverse consequences of floods. In the agricultural sector, for instance, farmers can take a diversity of options such as changing cropping patterns, applying fertilizer, irrigating and changing planting timing. An experimental medium range (1-10 day) and seasonal (20-25 days) flood forecasting model has been developed for Thailand and Bangladesh. It provides 51 sets of discharge ensemble forecasts of 1-10 days with significant persistence and high certainty and qualitative outlooks for 20-25 days. This type of forecast could assist farmers and other stakeholders for differential preparedness activities. These ensembles probabilistic flood forecasts have been customized based on user-needs for community-level application focused on agriculture system. The vulnerabilities of agriculture system were calculated based on exposure, sensitivity and adaptive capacity. Indicators for risk and vulnerability assessment were conducted through community consultations. The forecast lead time requirement, user-needs, impacts and management options for crops were identified through focus group discussions, informal interviews and community surveys. This paper illustrates potential applications of such ensembles for probabilistic medium range and seasonal flood forecasts in a way that is not commonly practiced globally today.

  1. Gas-rich dwarfs and accretion phenomena in early-type galaxies

    NASA Technical Reports Server (NTRS)

    Silk, J.; Norman, C.

    1979-01-01

    An analysis is presented of the combined effects of cloud accretion and galactic winds and coronae. An accretion model is developed wherein gas-rich dwarf galaxies are accreted into galactic halos, which provides an adequate source of H I to account for observations of neutral gas in early-type galaxies. Accretion is found to fuel the wind, thereby regulating the accretion flow and yielding a time-dependent model for star formation, enrichment, and nuclear activity. The permissible parameter range for intergalactic gas clouds and galaxy groups is discussed, along with the frequency of gas-rich dwarfs and their large ratios of gas mass to luminosity. Also considered is the occurrence of gas stripping and the consequent formation of dwarf spheroidal systems that remain in the halo, and gas clouds that dissipate and suffer further infall. A cosmological implication of the model is that, because the characteristic time scale of a gas-rich dwarf galaxy to be accreted and lose its gas is comparable to a Hubble time, there may have been a far more extensive primordial distribution of such systems at earlier epochs.

  2. Contribution of Co2+ in increasing chlorophyll a concentration of Nannochloropsis salina in controlled Conwy medium

    NASA Astrophysics Data System (ADS)

    Hala, Y.; Taba, P.; Suryati, E.; Kasih, P.; Firman, N. F.

    2018-03-01

    A research in determining the contribution of Co2+ on the increase of chlorophyll a concentration of Nannochloropsis salina has been caried out. The cultivation of N. salina was conducted in the Conwy medium with a salinity of 5%o and 25%o and various Co2+ concentration (2, 4, and 8 ppm). In this research, Co2+ was exposed early in the cultivation of N. salina. The growth of N. salina was observed daily by counting the number of populations using a haemocytometer while the chlorophyll a concentration was determined by a Uv-Vis spectrophotometer. The results showed that the growth of N. salina in the control was higher than that in the medium containing Co2+. The optimum growth time was achieved on 15th days (5%) and 8th days (25%). In the cultivation medium with a salinity of 5%, Co2+ with a concentration of 2 ppm increased the chlorophyll a level while Co2+ with concentrations of 4 and 8 ppm decreased it. In the medium of cultivation with a salinity of 25%, the increase in chlorophyll a level was observed at Co2+ concentrations of 2 and 4 ppm whereas the decrease in chlorophyl a level was given at a concentration of 8 ppm. It can be concluded that at low concentrations, Co2+ increased the concentration of chlorophyll a in N. salina.

  3. Embryo density and medium volume effects on early murine embryo development.

    PubMed

    Canseco, R S; Sparks, A E; Pearson, R E; Gwazdauskas, F C

    1992-10-01

    One-cell mouse embryos were used to determine the effects of drop size and number of embryos per drop for optimum development in vitro. Embryos were collected from immature C57BL6 female mice superovulated with pregnant mare serum gonadotropin and human chorionic gonadotropin and mated by CD1 males. Groups of 1, 5, 10, or 20 embryos were cultured in 5-, 10-, 20-, or 40-microliters drops of CZB under silicon oil at 37.5 degrees C in a humidified atmosphere of 5% CO2 and 95% air. Development score for embryos cultured in 10 microliters was higher than that of embryos cultured in 20 or 40 microliters. Embryos cultured in groups of 5, 10, or 20 had higher development scores than embryos cultured singly. The highest development score was obtained by the combination of 5 embryos per 10-microliters drop. The percentage of live embryos in 20 or 40 microliters was lower than that of embryos cultured in 10 microliters. Additionally, the percentage of live embryos cultured singly was lower than that of embryos cultured in groups. Our results suggest that a stimulatory interaction occurs among embryos possibly exerted through the secretion of growth factors. This effect can be diluted if the embryos are cultured in large drops or singly.

  4. Commercial cinema: a medium for development communication.

    PubMed

    Riber, J; Smith, S

    1985-01-01

    concerns about family planning. Understanding audience expectations in a commercial cinema context is the key to successfully adapting this medium for social development messages. Although some foreign technical assistance was provided, the success of the 2 films described depended on how their themes were adapted to the traditional feature film format. To date, commercial cinema has been an underutilized medium for development messages. WIF's experiences demonstrate how effective, well-conceived social messages can be presented in a commercial cinema context. It is hoped this will encourage other to use this widely available channel of mass communication.

  5. Hard QCD processes in the nuclear medium

    NASA Astrophysics Data System (ADS)

    Freese, Adam

    The environment inside the atomic nucleus is one of the most fascinating arenas for the study of quantum chromodynamics (QCD). The strongly-interacting nature of the nuclear medium a?ects the nature of both QCD processes and the quark-gluon structure of hadrons, allowing several unique aspects of the strong nuclear force to be investigated in reactions involving nuclear targets. The research presented in this dissertation explores two aspects of nuclear QCD: firstly, the partonic structure of the nucleus itself; and secondly, the use of the nucleus as a micro-laboratory in which QCD processes can be studied. The partonic structure of the nucleus is calculated in this work by deriving and utilizing a convolution formula. The hadronic structure of the nucleus and the quark-gluon structure of its constituent nucleons are taken together to determine the nuclear partonic structure. Light cone descriptions of short range correlations, in terms of both hadronic and partonic structure, are derived and taken into account. Medium modifications of the bound nucleons are accounted for using the color screening model, and QCD evolution is used to connect nuclear partonic structure at vastly di?erent energy scales. The formalism developed for calculating nuclear partonic structure is applied to inclusive dijet production from proton-nucleus collisions at LHC kinematics, and novel predictions are calculated and presented for the dijet cross section. The nucleus is investigated as a micro-laboratory in vector meson photoproduction reactions. In particular, the deuteron is studied in the break-up reaction gammad → Vpn, for both the φ(1020) and J/v vector mesons. The generalized eikonal approximation is utilized, allowing unambiguous separation of the impulse approximation and final state interactions (FSIs). Two peaks or valleys are seen in the angular distribution of the reaction cross section, each of which is due to an FSI between either the proton and neutron, or the

  6. Measurements of the global 21-cm signal from the Cosmic Dawn

    NASA Astrophysics Data System (ADS)

    Bernardi, Gianni

    2018-05-01

    The sky-averaged (global) 21-cm signal is a very promising probe of the Cosmic Dawn, when the first luminous sources were formed and started to shine in a substantially neutral intergalactic medium. I here report on the status and early result of the Large-Aperture Experiment to Detect the Dark Age that focuses on observations of the global 21-cm signal in the 16 <~ z <~ 30 range.

  7. Medium Suppression of In medium Nucleon-Nucleon Cross Sections Predicted with Various Microscopic Calculations

    NASA Astrophysics Data System (ADS)

    Xing, Yong-Zhong; Lu, Fei-Ping; Wei, Xiao-Ping; Zheng, Yu-Ming

    2014-08-01

    The nucleon-nucleon cross sections in the dense nuclear matter are microscopically calculated by using Dirac—Brueckner—Hartree—Fock (DBHF) approximation with different covariant representations of the T-matrix, i.e., complete pseudo-vector (CPV), pseudoscalar (PS) and pseudo-vector (PV) choices. Special attention is paid to the discrepancies among the cross sections calculated with these different T-matrix project choices. The results show that the medium suppression of the cross section given by DBHF in the CPV choice is not only smaller than those obtained in both PS and PV choices, but also smaller than the predictions with a nonrelativistic Brueckner—Hartree—Fock (BHF) method including three body force (3BF). The further analysis reveals that the influence of the different choices on the cross section in the DBHF approximation is mainly determined by the state of smaller total angular momentum due to the medium effect being strongly suppressed in the higher angular momentum.

  8. Common medium versus advanced IVF medium for cryopreserved oocytes in heterologous cycles.

    PubMed

    Poverini, R; Lisi, R; Lisi, F; Berlinghieri, V; Bielli, W; Carfagna, P; Costantino, A; Iacomino, D; Nicodemo, G

    2018-12-01

    Granulocyte-macrophage colony-stimulation factor plays different crucial roles during embryo implantation and subsequent development. Here we aimed to evaluate the effects of embryo cell culture medium, with the inclusion of granulocyte-macrophage colony-stimulation factor (GM-CSF), on embryo development and pregnancy rate. To this end, we took advantage of our retrospective observational study to correlate the outcomes from two different culture media. We included in this study 25 unselected patient from our IVF Center that underwent heterologous IVF cycle with crypreserved oocytes. We analyze the fertilization rate, pregnancy rate, and embryo quality at different day of transfer obtained from two different media composition. Our results show that the rate of fertilization and the pregnancy rate were increased using medium added with this particular type of cytokines (GM-CSF).

  9. Medium Deep High Temperature Heat Storage

    NASA Astrophysics Data System (ADS)

    Bär, Kristian; Rühaak, Wolfram; Schulte, Daniel; Welsch, Bastian; Chauhan, Swarup; Homuth, Sebastian; Sass, Ingo

    2015-04-01

    Heating of buildings requires more than 25 % of the total end energy consumption in Germany. Shallow geothermal systems for indirect use as well as shallow geothermal heat storage systems like aquifer thermal energy storage (ATES) or borehole thermal energy storage (BTES) typically provide low exergy heat. The temperature levels and ranges typically require a coupling with heat pumps. By storing hot water from solar panels or thermal power stations with temperatures of up to 110 °C a medium deep high temperature heat storage (MDHTS) can be operated on relatively high temperature levels of more than 45 °C. Storage depths of 500 m to 1,500 m below surface avoid conflicts with groundwater use for drinking water or other purposes. Permeability is typically also decreasing with greater depth; especially in the crystalline basement therefore conduction becomes the dominant heat transport process. Solar-thermal charging of a MDHTS is a very beneficial option for supplying heat in urban and rural systems. Feasibility and design criteria of different system configurations (depth, distance and number of BHE) are discussed. One system is designed to store and supply heat (300 kW) for an office building. The required boreholes are located in granodioritic bedrock. Resulting from this setup several challenges have to be addressed. The drilling and completion has to be planned carefully under consideration of the geological and tectonical situation at the specific site.

  10. Light vector mesons in the nuclear medium

    NASA Astrophysics Data System (ADS)

    Wood, M. H.; Nasseripour, R.; Weygand, D. P.; Djalali, C.; Tur, C.; Mosel, U.; Muehlich, P.; Adams, G.; Amaryan, M. J.; Ambrozewicz, P.; Anghinolfi, M.; Asryan, G.; Avakian, H.; Bagdasaryan, H.; Baillie, N.; Ball, J. P.; Baltzell, N. A.; Barrow, S.; Battaglieri, M.; Bedlinskiy, I.; Bektasoglu, M.; Bellis, M.; Benmouna, N.; Berman, B. L.; Biselli, A. S.; Blaszczyk, L.; Bouchigny, S.; Boiarinov, S.; Bradford, R.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Butuceanu, C.; Calarco, J. R.; Careccia, S. L.; Carman, D. S.; Carnahan, B.; Casey, L.; Chen, S.; Cheng, L.; Cole, P. L.; Collins, P.; Coltharp, P.; Crabb, D.; Crannell, H.; Crede, V.; Cummings, J. P.; Dashyan, N.; de Vita, R.; de Sanctis, E.; Degtyarenko, P. V.; Denizli, H.; Dennis, L.; Deur, A.; Dharmawardane, K. V.; Dickson, R.; Dodge, G. E.; Doughty, D.; Dugger, M.; Dytman, S.; Dzyubak, O. P.; Egiyan, H.; Egiyan, K. S.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Feldman, G.; Feuerbach, R. J.; Fradi, A.; Funsten, H.; Garçon, M.; Gavalian, G.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gordon, C. I. O.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Gyurjyan, V.; Hadjidakis, C.; Hafidi, K.; Hakobyan, H.; Hakobyan, R. S.; Hanretty, C.; Hardie, J.; Hassall, N.; Hersman, F. W.; Hicks, K.; Hleiqawi, I.; Holtrop, M.; Hyde-Wright, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Ito, M. M.; Jenkins, D.; Jo, H. S.; Johnstone, J. R.; Joo, K.; Juengst, H. G.; Kalantarians, N.; Kellie, J. D.; Khandaker, M.; Khetarpal, P.; Kim, W.; Klein, A.; Klein, F. J.; Klimenko, A. V.; Kossov, M.; Krahn, Z.; Kramer, L. H.; Kubarovsky, V.; Kuhn, J.; Kuhn, S. E.; Kuleshov, S. V.; Lachniet, J.; Laget, J. M.; Langheinrich, J.; Lawrence, D.; Li, Ji; Livingston, K.; Lu, H. Y.; MacCormick, M.; Markov, N.; Mattione, P.; McAleer, S.; McKinnon, B.; McNabb, J. W. C.; Mecking, B. A.; Mehrabyan, S.; Melone, J. J.; Mestayer, M. D.; Meyer, C. A.; Mibe, T.; Mikhailov, K.; Minehart, R.; Mirazita, M.; Miskimen, R.; Mokeev, V.; Moriya, K.; Morrow, S. A.; Moteabbed, M.; Mueller, J.; Munevar, E.; Mutchler, G. S.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niczyporuk, B. B.; Niroula, M. R.; Niyazov, R. A.; Nozar, M.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Pasyuk, E.; Paterson, C.; Pereira, S. Anefalos; Pierce, J.; Pivnyuk, N.; Pocanic, D.; Pogorelko, O.; Pozdniakov, S.; Preedom, B. M.; Price, J. W.; Prok, Y.; Protopopescu, D.; Raue, B. A.; Riccardi, G.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Ronchetti, F.; Rosner, G.; Rossi, P.; Sabatié, F.; Salamanca, J.; Salgado, C.; Santoro, J. P.; Sapunenko, V.; Schumacher, R. A.; Serov, V. S.; Sharabian, Y. G.; Sharov, D.; Shvedunov, N. V.; Smith, E. S.; Smith, L. C.; Sober, D. I.; Sokhan, D.; Stavinsky, A.; Stepanyan, S.; Stepanyan, S. S.; Stokes, B. E.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tedeschi, D. J.; Tkabladze, A.; Tkachenko, S.; Todor, L.; Ungaro, M.; Vineyard, M. F.; Vlassov, A. V.; Watts, D. P.; Weinstein, L. B.; Williams, M.; Wolin, E.; Yegneswaran, A.; Zana, L.; Zhang, B.; Zhang, J.; Zhao, B.; Zhao, Z. W.

    2008-07-01

    The light vector mesons (ρ,ω, and ϕ) were produced in deuterium, carbon, titanium, and iron targets in a search for possible in-medium modifications to the properties of the ρ meson at normal nuclear densities and zero temperature. The vector mesons were detected with the CEBAF Large Acceptance Spectrometer (CLAS) via their decays to e+e-. The rare leptonic decay was chosen to reduce final-state interactions. A combinatorial background was subtracted from the invariant mass spectra using a well-established event-mixing technique. The ρ-meson mass spectrum was extracted after the ω and ϕ signals were removed in a nearly model-independent way. Comparisons were made between the ρ mass spectra from the heavy targets (A>2) with the mass spectrum extracted from the deuterium target. With respect to the ρ-meson mass, we obtain a small shift compatible with zero. Also, we measure widths consistent with standard nuclear many-body effects such as collisional broadening and Fermi motion.

  11. Cast-to-shape electrokinetic trapping medium

    DOEpatents

    Shepodd, Timothy J.; Franklin, Elizabeth; Prickett, Zane T.; Artau, Alexander

    2004-08-03

    A three-dimensional microporous polymer network material, or monolith, cast-to-shape in a microchannel. The polymer monolith, produced by a phase separation process, is capable of trapping and retaining charged protein species from a mixture of charged and uncharged species under the influence of an applied electric field. The retained charged protein species are released from the porous polymer monolith by a pressure driven flow in the substantial absence of the electric field. The pressure driven flow is independent of direction and thus neither means to reverse fluid flow nor a multi-directional flow field is required, a single flow through the porous polymer monolith can be employed, in contrast to prior art systems. The monolithic polymer material produced by the invention can function as a chromatographic medium. Moreover, by virtue of its ability to retain charged protein species and quantitatively release the retained species the porous polymer monolith can serve as a means for concentrating charged protein species from, for example, a dilute solution.

  12. Cast-to-shape electrokinetic trapping medium

    DOEpatents

    Shepodd, Timothy J [Livermore, CA; Franklin, Elizabeth [Rolla, MO; Prickett, Zane T [Golden, CO; Artau, Alexander [Pleasanton, CA

    2006-05-30

    A three-dimensional microporous polymer network material, or monolith, cast-to-shape in a microchannel. The polymer monolith, produced by a phase separation process, is capable of trapping and retaining charged protein species from a mixture of charged and uncharged species under the influence of an applied electric field. The retained charged protein species are released from the porous polymer monolith by a pressure driven flow in the substantial absence of the electric field. The pressure driven flow is independent of direction and thus neither means to reverse fluid flow nor a multi-directional flow field is required, a single flow through the porous polymer monolith can be employed, in contrast to prior art systems. The monolithic polymer material produced by the invention can function as a chromatographic medium. Moreover, by virtue of its ability to retain charged protein species and quantitatively release the retained species the porous polymer monolith can serve as a means for concentrating charged protein species from, for example, a dilute solution.

  13. Boundary Regularity for the Porous Medium Equation

    NASA Astrophysics Data System (ADS)

    Björn, Anders; Björn, Jana; Gianazza, Ugo; Siljander, Juhana

    2018-05-01

    We study the boundary regularity of solutions to the porous medium equation {u_t = Δ u^m} in the degenerate range {m > 1} . In particular, we show that in cylinders the Dirichlet problem with positive continuous boundary data on the parabolic boundary has a solution which attains the boundary values, provided that the spatial domain satisfies the elliptic Wiener criterion. This condition is known to be optimal, and it is a consequence of our main theorem which establishes a barrier characterization of regular boundary points for general—not necessarily cylindrical—domains in {{R}^{n+1}} . One of our fundamental tools is a new strict comparison principle between sub- and superparabolic functions, which makes it essential for us to study both nonstrict and strict Perron solutions to be able to develop a fruitful boundary regularity theory. Several other comparison principles and pasting lemmas are also obtained. In the process we obtain a rather complete picture of the relation between sub/superparabolic functions and weak sub/supersolutions.

  14. UV observations of local interstellar medium.

    NASA Astrophysics Data System (ADS)

    Kurt, V.; Mironova, E.; Fadeev, E.

    2008-12-01

    The methods of the interstellar matter study are described. The brief information of space missions aimed at observations in the unreachable for ground based telescopes UV spectral range (IUE, As- tron, HST and GALEX.) is presented. The history of discovery of H and He atoms entering the Solar System from the local interstellar medium (LISM) is given in brief. The results of observations performed by the group from Stern- berg Astronomical Institute (SAI MSU) and Space Research Institute (IKI RAS) performed with the help of the missions Prognoz-5, Prognoz-6 and the stations Zond-1, Venera and Mars and aimed at estimation of all basic LISM parameters (the velocity of the Sun in relation to LISM, directions of movement, densities of H and He atoms, LISM temperature) are presented. We also describe the present-day investigations of LISM performed with SOHO and ULYSSES mis- sions including the direct registration of He atoms entering the Solar System. The problem of interaction between the incoming flow of the ISM atoms ("in- terstellar wind") and the area of two shocks at the heliopause border (100-200 AU) is discussed. The LISM parameters obtained using the available data are presented in two tables.

  15. Rescuing the intracluster medium of NGC 5813

    NASA Astrophysics Data System (ADS)

    Soker, Noam; Hillel, Shlomi; Sternberg, Assaf

    2016-06-01

    We use recent X-ray observations of the intracluster medium (ICM) of the galaxy group NGC 5813 to confront theoretical studies of ICM thermal evolution with the newly derived ICM properties. We argue that the ICM of the cooling flow in the galaxy group NGC 5813 is more likely to be heated by mixing of post-shock gas from jets residing in hot bubbles with the ICM, than by shocks or turbulent-heating. Shocks thermalize only a small fraction of their energy in the inner regions of the cooling flow; in order to adequately heat the inner part of the ICM, they would overheat the outer regions by a large factor, leading to its ejection from the group. Heating by mixing, which was found to be much more efficient than turbulent-heating and shocks-heating, hence, rescues the outer ICM of NGC 5813 from its predestined fate according to cooling flow feedback scenarios that are based on heating by shocks.

  16. A Multiphase Model for the Intracluster Medium

    NASA Technical Reports Server (NTRS)

    Nagai, Daisuke; Sulkanen, Martin E.; Evrard, August E.

    1999-01-01

    Constraints on the clustered mass density of the universe derived from the observed population mean intracluster gas fraction of x-ray clusters may be biased by reliance on a single-phase assumption for the thermodynamic structure of the intracluster medium (ICM). We propose a descriptive model for multiphase structure in which a spherically symmetric ICM contains isobaric density perturbations with a radially dependent variance. Fixing the x-ray emission and emission weighted temperature, we explore two independently observable signatures of the model in the parameter space. For bremsstrahlung dominated emission, the central Sunyaev-Zel'dovich (SZ) decrement in the multiphase case is increased over the single-phase case and multiphase x-ray spectra in the range 0.1-20 keV are flatter in the continuum and exhibit stronger low energy emission lines than their single-phase counterpart. We quantify these effects for a fiducial 10e8 K cluster and demonstrate how the combination of SZ and x-ray spectroscopy can be used to identify a preferred location in the plane of the model parameter space. From these parameters the correct value of mean intracluster gas fraction in the multiphase model results, allowing an unbiased estimate of clustered mass density to he recovered.

  17. SILICATE COMPOSITION OF THE INTERSTELLAR MEDIUM

    SciTech Connect

    Fogerty, S.; Forrest, W.; Watson, D. M.

    2016-10-20

    The composition of silicate dust in the diffuse interstellar medium and in protoplanetary disks around young stars informs our understanding of the processing and evolution of the dust grains leading up to planet formation. An analysis of the well-known 9.7 μ m feature indicates that small amorphous silicate grains represent a significant fraction of interstellar dust and are also major components of protoplanetary disks. However, this feature is typically modeled assuming amorphous silicate dust of olivine and pyroxene stoichiometries. Here, we analyze interstellar dust with models of silicate dust that include non-stoichiometric amorphous silicate grains. Modeling the optical depth alongmore » lines of sight toward the extinguished objects Cyg OB2 No. 12 and ζ Ophiuchi, we find evidence for interstellar amorphous silicate dust with stoichiometry intermediate between olivine and pyroxene, which we simply refer to as “polivene.” Finally, we compare these results to models of silicate emission from the Trapezium and protoplanetary disks in Taurus.« less

  18. Featured Image: Structures in the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-02-01

    This beautiful false-color image (which covers 57 degrees2; click for the full view!) reveals structures in the hydrogen gas that makes up the diffuse atomic interstellar medium at intermediate latitudes in our galaxy. The imagewas created by representing three velocity channels with colors red for gas moving at 7.59 km/s, green for 5.12 km/s, and blue for 2.64 km/s and it shows the dramatically turbulent and filamentary structure of this gas. This image is one of many stunning, high-resolution observations that came out of the DRAO HI Intermediate Galactic Latitude Survey, a program that used the Synthesis Telescope at the Dominion Radio Astrophysical Observatory in British Columbia to map faint hydrogen emission at intermediate latitudes in the Milky Way. The findings from the program were recently published in a study led by Kevin Blagrave (Canadian Institute for Theoretical Astrophysics, University of Toronto); to find out more about what they learned, check out the paper below!CitationK. Blagrave et al 2017 ApJ 834 126. doi:10.3847/1538-4357/834/2/126

  19. On Graphene in the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Chen, X. H.; Li, Aigen; Zhang, Ke

    2017-11-01

    The possible detection of C24, a planar graphene that was recently reported to be in several planetary nebulae by García-Hernández et al., inspires us to explore whether and how much graphene could exist in the interstellar medium (ISM) and how it would reveal its presence through its ultraviolet (UV) extinction and infrared (IR) emission. In principle, interstellar graphene could arise from the photochemical processing of polycyclic aromatic hydrocarbon (PAH) molecules, which are abundant in the ISM, due to the complete loss of their hydrogen atoms, and/or from graphite, which is thought to be a major dust species in the ISM, via fragmentation caused by grain–grain collisional shattering. Both quantum-chemical computations and laboratory experiments have shown that the exciton-dominated electronic transitions in graphene cause a strong absorption band near 2755 \\mathringA . We calculate the UV absorption of graphene and place an upper limit of ∼5 ppm of C/H (i.e., ∼1.9% of the total interstellar C) on the interstellar graphene abundance. We also model the stochastic heating of graphene C24 in the ISM, excited by single starlight photons of the interstellar radiation field and calculate its IR emission spectra. We also derive the abundance of graphene in the ISM to be <5 ppm of C/H by comparing the model emission spectra with that observed in the ISM.

  20. Pulverized glass as an alternative filter medium

    SciTech Connect

    Piccirillo, J.B.; Letterman, R.D.

    1998-07-01

    A significant amount of low-value, recycled glass is stockpiled at recycling facilities or landfilled. This study was conducted to investigate the use of pulverized recycled glass as a filter medium in slow sand filtration. The glass was pulverized using a flail mill-type pulverizer. The size distribution of the pulverizer output was adjusted by sieving to meet the grain size requirements of the Ten States Standards and the USEPA for filter media were compared to a fourth unit containing silica sand media. The filter influent was spiked with clay, coliform group bacteria and the cysts and oocyst of Giardia lamblia andmore » Cryptosporidium parvum. Over an 8 month period of continuous operation, the performance of the glass sand filter media was as good as or better than the silica sand, with removals of 56% to 96% for turbidity; 99.78% to 100.0% for coliform bacteria; 99.995% to 99.997% for giardia cysts; and 99.92% to 99.97% for cryptosporidium oocysts. According to a cost-benefit analysis, converting waste glass into filter media may be economically advantageous for recycling facilities.« less

  1. Effective equations governing an active poroelastic medium

    PubMed Central

    2017-01-01

    In this work, we consider the spatial homogenization of a coupled transport and fluid–structure interaction model, to the end of deriving a system of effective equations describing the flow, elastic deformation and transport in an active poroelastic medium. The ‘active’ nature of the material results from a morphoelastic response to a chemical stimulant, in which the growth time scale is strongly separated from other elastic time scales. The resulting effective model is broadly relevant to the study of biological tissue growth, geophysical flows (e.g. swelling in coals and clays) and a wide range of industrial applications (e.g. absorbant hygiene products). The key contribution of this work is the derivation of a system of homogenized partial differential equations describing macroscale growth, coupled to transport of solute, that explicitly incorporates details of the structure and dynamics of the microscopic system, and, moreover, admits finite growth and deformation at the pore scale. The resulting macroscale model comprises a Biot-type system, augmented with additional terms pertaining to growth, coupled to an advection–reaction–diffusion equation. The resultant system of effective equations is then compared with other recent models under a selection of appropriate simplifying asymptotic limits. PMID:28293138

  2. New Insights Concerning the Local Interstellar medium

    NASA Astrophysics Data System (ADS)

    Linsky, Jeffrey L.; Redfield, Seth

    2015-08-01

    We have been analyzing HST high-resolution ultraviolet spectra of nearby stars to measure the radial velocities, turbulence, temperature, and depletions on warm diffuse interstellar gas within a few parsecs of the Sun. These data reveal a picture of many partially-ionized warm gas clouds, each with their own vector velocity and physical characteristics. This picture has been recently challenged by Gry and Jenkins (2014), who argue for a single nonrigid cloud surrounding the Sun. We present a test of these two very different morphological structure by checking how well each predicts the radial velocities in a new data set (Malamut et al. 2014) that was not available when both models were constructed. We find that the multicloud model (Redfield & Linsky 2008) provides a much better fit to the new data. We compare the new IBEX results for the temperature and velocity of inflowing He gas (McComas et al. 2015) with the properties of the Local Interstellar Cloud and the G cloud. We also show a preliminary three-dimensional model for the local interstellar medium.

  3. Casimir stress in an inhomogeneous medium

    SciTech Connect

    Philbin, T.G.; Xiong, C.; Leonhardt, U.

    2010-03-15

    The Casimir effect in an inhomogeneous dielectric is investigated using Lifshitz's theory of electromagnetic vacuum energy. A permittivity function that depends continuously on one Cartesian coordinate is chosen, bounded on each side by homogeneous dielectrics. The result for the Casimir stress is infinite everywhere inside the inhomogeneous region, a divergence that does not occur for piece-wise homogeneous dielectrics with planar boundaries. A Casimir force per unit volume can be extracted from the infinite stress but it diverges on the boundaries between the inhomogeneous medium and the homogeneous dielectrics. An alternative regularization of the vacuum stress is considered that removes themore » contribution of the inhomogeneity over small distances, where macroscopic electromagnetism is invalid. The alternative regularization yields a finite Casimir stress inside the inhomogeneous region, but the stress and force per unit volume diverge on the boundaries with the homogeneous dielectrics. The case of inhomogeneous dielectrics with planar boundaries thus falls outside the current understanding of the Casimir effect.« less

  4. Random medium model for cusping of plane waves.

    PubMed

    Li, Jia; Korotkova, Olga

    2017-09-01

    We introduce a model for a three-dimensional (3D) Schell-type stationary medium whose degree of potential's correlation satisfies the Fractional Multi-Gaussian (FMG) function. Compared with the scattered profile produced by the Gaussian Schell-model (GSM) medium, the Fractional Multi-Gaussian Schell-model (FMGSM) medium gives rise to a sharp concave intensity apex in the scattered field. This implies that the FMGSM medium also accounts for a larger than Gaussian's power in the bucket (PIB) in the forward scattering direction, hence being a better candidate than the GSM medium for generating highly-focused (cusp-like) scattered profiles in the far zone. Compared to other mathematical models for the medium's correlation function which can produce similar cusped scattered profiles the FMG function offers unprecedented tractability being the weighted superposition of Gaussian functions. Our results provide useful applications to energy counter problems and particle manipulation by weakly scattered fields.

  5. Characterization of Residual Medium Peptides from Yersinia pestis Cultures

    SciTech Connect

    Clowers, Brian H.; Wunschel, David S.; Kreuzer, Helen W.

    2013-04-03

    Using a range of common microbial medium formulations (TSB, BHI, LB, and G-media), two attenuated strains of Y. pestis (KIM D27 (pgm-) and KIMD1 lcr-) were cultivated in triplicate. These cellular suspensions were used to develop a method of extracting residual medium peptides from the final microbial preparation to assess their relative abundance and identity. Across the conditions examined, which included additional cellular washing and different forms of microbial inactivation, residual medium peptides were detected. Despite the range of growth medium sources used and the associated manufacturing processes used in their production, a high degree of peptide similarity was observedmore » for a given medium recipe. These results demonstrate that residual medium peptides are retained using traditional microbial cultivation techniques and may be used to inform forensic investigations with respect to production deduction.« less

  6. Invited papers presented to a workshop on thermodynamics and kinetics of dust formation in the space medium. [condensation, nucleation, and interstellar dust

    NASA Technical Reports Server (NTRS)

    Robertson, P. C.

    1978-01-01

    Abstracts of 25 papers relating to condensation processes in the early solar system are presented. Special emphasis is given to the transition of an initial vapor phase in the space medium, the characterization of condensation environments, and condensation processes in the space medium. The question of whether some fraction of the solar system solids (particularly exemplified by meteoritic solids) may be interstellar grains that gathered in the region of the proto-sun, rather than being products of local condensation is addressed.

  7. A magnified young galaxy from about 500 million years after the Big Bang.

    PubMed

    Zheng, Wei; Postman, Marc; Zitrin, Adi; Moustakas, John; Shu, Xinwen; Jouvel, Stephanie; Høst, Ole; Molino, Alberto; Bradley, Larry; Coe, Dan; Moustakas, Leonidas A; Carrasco, Mauricio; Ford, Holland; Benítez, Narciso; Lauer, Tod R; Seitz, Stella; Bouwens, Rychard; Koekemoer, Anton; Medezinski, Elinor; Bartelmann, Matthias; Broadhurst, Tom; Donahue, Megan; Grillo, Claudio; Infante, Leopoldo; Jha, Saurabh W; Kelson, Daniel D; Lahav, Ofer; Lemze, Doron; Melchior, Peter; Meneghetti, Massimo; Merten, Julian; Nonino, Mario; Ogaz, Sara; Rosati, Piero; Umetsu, Keiichi; van der Wel, Arjen

    2012-09-20

    Re-ionization of the intergalactic medium occurred in the early Universe at redshift z ≈ 6-11, following the formation of the first generation of stars. Those young galaxies (where the bulk of stars formed) at a cosmic age of less than about 500 million years (z ≲ 10) remain largely unexplored because they are at or beyond the sensitivity limits of existing large telescopes. Understanding the properties of these galaxies is critical to identifying the source of the radiation that re-ionized the intergalactic medium. Gravitational lensing by galaxy clusters allows the detection of high-redshift galaxies fainter than what otherwise could be found in the deepest images of the sky. Here we report multiband observations of the cluster MACS J1149+2223 that have revealed (with high probability) a gravitationally magnified galaxy from the early Universe, at a redshift of z = 9.6 ± 0.2 (that is, a cosmic age of 490 ± 15 million years, or 3.6 per cent of the age of the Universe). We estimate that it formed less than 200 million years after the Big Bang (at the 95 per cent confidence level), implying a formation redshift of ≲14. Given the small sky area that our observations cover, faint galaxies seem to be abundant at such a young cosmic age, suggesting that they may be the dominant source for the early re-ionization of the intergalactic medium.

  8. [TMOSKOVHE COMPARATIVE CHARACTERISTIC OF GROWTH MEDIUMS FOR SEPARATION OF CORYNEBACTERIA].

    PubMed

    Shepelin, A P; Polosenko, O V; Borisova, O Yu; Pimenova, A S; Gadua, N T

    2016-01-01

    The comparative tests of growth mediums for isolation and accumulation of diphtheria bacteria were implemented. The testing consisted of six series of growth medium "Corynebacagar" produced by the state research center of applied microbiology and biotechnology and three series of blood tellurite agar. The concluding results of identification of biological indicators of all series of growth nutrient mediums are presented The "Corynebacagar" is recommended for application in health care practice for primary inoculation of pathological material during implementation of cultural analysis on diphtheria.

  9. Effect of Acidity of a Medium on Riboflavin Photodestruction

    NASA Astrophysics Data System (ADS)

    Astanov, S. Kh.; Turdiev, M.; Sharipov, M. Z.; Kurtaliev, É. N.; Nizomov, N. N.

    2016-03-01

    Effect of acidity of a medium on the spectroscopic characteristics of riboflavin aqueous solutions is investigated by the method of fluorescent and absorption spectroscopy. Significant deformation of the electronic spectra of riboflavin aqueous solutions irradiated with unfiltered light of a PRK-2 lamp is observed. It is established that riboflavin photostability in an acid medium is about twice as much as the photostability in a neutral medium, which is caused by the formation of a protonated species.

  10. [The poster as a communication medium].

    PubMed

    Tovar Samanez, C

    1987-01-01

    The poster as a medium of communication serves to transmit a message by means of a graphical synthesis. It elicits attention by its originality, contrast, and focus on the center of interest. The poster is effective if the images and slogans can be identified easily. Its visual attractiveness is also essential. The understanding of the message is the function of the cultural characteristics of the public with symbols, metaphors, gestures, and detailed description. The appeal of the message allows the public to accept it on sensorial, emotional, social, intellectual, and economical levels. Adverse motivations should not be confused with the positive appeal (prejudice, preconceived ideas, and bias). Confusion and ambiguity can carry conflicting messages, therefore negative examples should be avoided. The force of the message targets the memory carrying conviction and calling to action. The target group and objective must be defined as to age, occupation, location, and sex. The message also has to be defined precisely for the target audience. It is in the analysis of the context whereby the poster is received as to notions of the target topic, alternative attitudes relative to the promotion of the message, obstacles that are encountered in the mentality of the target, and cultural characteristics of the target audience. The text of the slogan must be given before drawing the poster. The designing of the poster should be creative with association of ideas, metaphors and symbols, descriptive images, fusion of symbolic and descriptive forms, humor, the fusion of graphics with letters, and the fusion of letters with images. Completed forms of the poster use illustration, photography, typography, calligraphy, and photo montage.

  11. Exploring the Interstellar Medium with SOFIA

    NASA Technical Reports Server (NTRS)

    Erickson, Edwin F.

    2004-01-01

    SOFIA, the Stratospheric Observatory for Infrared Astronomy, is being developed to operate at wavelengths from 0.3 microns to 1.6 mm over a 20 year lifetime. Its 2.5 m effective diameter telescope will be diffraction limited (approximately 8.5 arc seconds FWHM at 100 microns) at wavelengths beyond about 5 microns. Its B747SP aircraft platform will allow coverage of the entire sky and enable observation of ephemeral events. Nine first-generation focal plane instruments are being built, and more will be added later. These attributes assure SOFIA a vital role in future studies of the interstellar medium (ISM), in addition to topics such as the solar system. SOFIA observers will explore the gamut of ISM topics: star formation; the Galactic Center; debris disks; recycling of materials through the stellar life cycle; the origin and evolution of biogenic materials; shock, photodissociation, and photoexcitation physics; gas and grain chemistry. Imaging, spectroscopy, and eventually polarimetry covering much of the infrared spectrum will all be part of SOFIA's arsenal in the attack on these and other important problems. The talk will describe the observatory, its status, its science instruments and anticipated program. SOFIA is a joint program of NASA in the U.S. and DLR in Germany. Broad participation by the international science community in SOFIA observations will be encouraged via annual proposal opportunities and user-friendly tools. Roughly 80% of the observing time will be granted by the U.S. and 20% by Germany. For further information, see http://sofia.arc.nasa.gov.

  12. Medium effects on fluorescence of ciprofloxacin hydrochloride

    NASA Astrophysics Data System (ADS)

    Yang, Rui; Fu, Yan; Li, Long-Di; Liu, Jia-Ming

    2003-10-01

    The medium (pH, organic solvents, cyclodextrin (CD) or surfactants) effects on the fluorescence of ciprofloxacin hydrochloride (CPFX·HCl) were studied in detail. It is found that the three acid constants of ciprofloxacin (CPFX) are near to each other. Therefore the relation curve between pH and fluorescence intensity has no strident change and keeps relative stable in the pH range of 2-7. When pH was in the range of 5.5-6.0, the fluorescence intensity of CPFX reached the max. The kind and amount of organic solvent added to the luminescent system have various effects. Ethanol quenched fluorescence and the fluorescence excitation wavelength is red shift at first and then blue shift. Acetone has complicated effects on the fluorescence properties of CPFX·HCl solution. The experiment result shows that acetone is really a quencher when its volume content in the system is from 0 to 20%, but when its content is 90%, the signal intensity is unexpectedly one and a half times as much as that of no acetone. This means that there is a strong interaction between the acetone and CPFX; CPFX·H + could be included into the γ-CD but the capping effect is not notable. The effect of cationic surfactant cetyltrimethylammonium bromide and non-ionic surfactant TX-100 and TX-80 on CPFX fluorescence was unimpressive, but the anionic surfactant's effect is aberrant. The fluorescence intensity of CPFX·HCl solution experiences three stages of increasing, decreasing and increasing in turn, as sodium dodecyl sulfate is adding gradually. But for sodium lauryl sulfonate, there are only two stages of decreasing and increasing with the concentration increasing. It is problematic to illustrate clearly the effect mechanism of acetone and anionic surfactant at present. Undoubtedly, the experimental results in this paper should be useful in practice works and the research is worth studying still further.

  13. Relativistic hydrodynamic jets in the intracluster medium

    NASA Astrophysics Data System (ADS)

    Choi, Eunwoo

    2017-08-01

    We have performed the first three-dimensional relativistic hydrodynamic simulations of extragalactic jets of pure leptonic and baryonic plasma compositions propagating into a hydrostatic intracluster medium (ICM) environment. The numerical simulations use a general equation of state for a multicomponent relativistic gas, which closely reproduces the Synge equation of state for a relativistic perfect gas. We find that morphological and dynamical differences between leptonic and baryonic jets are much less evident than those between hot and cold jets. In all these models, the jets first propagate with essentially constant velocities within the core radius of the ICM and then accelerate progressively so as to increase the jet advance velocity by a factor of between 1.2 and 1.6 at the end of simulations, depending upon the models. The temporal evolution of the average cavity pressure is not consistent with that expected by the extended theoretical model even if the average cavity pressure decreases as a function of time with a power law. Our simulations produce synthetic radio images that are dominated by bright hot spots and appear similar to observations of the extended radio galaxies with collimated radio jets. These bright radio lobes would be visible as dark regions in X-ray images and are morphologically similar to observed X-ray cavities in the ICM. This supports the expectation that the bow shock surrounding the head of the jet is important mechanism for producing X-ray cavities in the ICM. Although there are quantitative differences among the models, the total radio and X-ray intensity curves show qualitatively similar trends in all of them.

  14. Solid H2 in the interstellar medium

    NASA Astrophysics Data System (ADS)

    Füglistaler, A.; Pfenniger, D.

    2018-06-01

    Context. Condensation of H2 in the interstellar medium (ISM) has long been seen as a possibility, either by deposition on dust grains or thanks to a phase transition combined with self-gravity. H2 condensation might explain the observed low efficiency of star formation and might help to hide baryons in spiral galaxies. Aims: Our aim is to quantify the solid fraction of H2 in the ISM due to a phase transition including self-gravity for different densities and temperatures in order to use the results in more complex simulations of the ISM as subgrid physics. Methods: We used molecular dynamics simulations of fluids at different temperatures and densities to study the formation of solids. Once the simulations reached a steady state, we calculated the solid mass fraction, energy increase, and timescales. By determining the power laws measured over several orders of magnitude, we extrapolated to lower densities the higher density fluids that can be simulated with current computers. Results: The solid fraction and energy increase of fluids in a phase transition are above 0.1 and do not follow a power law. Fluids out of a phase transition are still forming a small amount of solids due to chance encounters of molecules. The solid mass fraction and energy increase of these fluids are linearly dependent on density and can easily be extrapolated. The timescale is below one second, the condensation can be considered instantaneous. Conclusions: The presence of solid H2 grains has important dynamic implications on the ISM as they may be the building blocks for larger solid bodies when gravity is included. We provide the solid mass fraction, energy increase, and timescales for high density fluids and extrapolation laws for lower densities.

  15. Chemically Defined Medium and Caenorhabditis elegans: A Powerful Approach

    NASA Technical Reports Server (NTRS)

    Szewczyk, N. J.; Kozak, E.; Conley, C. A.

    2003-01-01

    C. elegans has been established as a powerful genetic system. Growth in a chemically defined medium (C. elegans Maintenance Medium (CeMM)) now allows standardization and systematic manipulation of the nutrients that animals receive. Liquid cultivation allows automated culturing and experimentation and should be of me in large-scale growth and screening of animals. Here we present our initial results from developing culture systems with CeMM. We find that CeMM is versatile and culturing is simple. CeMM can be used in a solid or liquid state, it can be stored unused for at least a year, unattended actively growing cultures may be maintained longer than with standard techniques, and standard C. elegans protocols work well with animals grown in defined medium. We also find that there are caveats of using defined medium. Animals in defined medium grow more slowly than on standard medium, appear to display adaptation to the defined medium, and display altered growth rates as they change defined medium composition. As was suggested with the introduction of C. elegans as a potential genetic system, use of defined medium with C. elegans should prove a powerful tool.

  16. Solid hydrogen coated graphite particles in the interstellar medium. I.

    NASA Technical Reports Server (NTRS)

    Swamy, K. S. K.; Wickramasinghe, N. C.

    1969-01-01

    Solid para hydrogen coated graphite particles expulsion into interstellar medium from star formation regions, considering mantles stability and particles extinction efficiency, albedo and phase function

  17. [THE NATIONAL NUTRIENT MEDIUM FOR DIAGNOSTIC OF PURULENT BACTERIAL MENINGITIS].

    PubMed

    Podkopaev, Ya V; Domotenko, L V; Morozova, T P; Khramov, M K; Shepelin, A P

    2015-05-01

    The national growth mediums were developed for isolating and cultivating of main agents of purulent bacterial meningitis--haemophilus agar, chocolate agar, PBM-agar. The growing and selective characteristics of developed growth mediums are examined. The haemophilus agar ensures growth of Haemophilus influenzae. The chocolate agar, PBM-agar ensure growth of Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae. By growing characteristics, the national growth mediums match foreign analogues. Under application of growth mediums with selective additions it is possible to achieve selective isolation of main agents of purulent bacterial meningitis with inhibition of growth of microbes-associates.

  18. REVIEWS OF TOPICAL PROBLEMS The quark-gluon medium

    NASA Astrophysics Data System (ADS)

    Dremin, Igor M.; Leonidov, Andrei V.

    2011-02-01

    The properties of the quark-gluon medium observed in high-energy nucleus-nucleus collisions are discussed. The main experimental facts about these collisions are briefly described and compared with data about proton-proton collisions. Both microscopic and macroscopic approaches to their description are reviewed. The chromodynamics of the quark-gluon medium at high energies is mainly considered. The energy loss of partons moving in this medium is treated. The principal conclusion is that the medium possesses some collective properties which are crucial for understanding the experimental observations.

  19. THE INTERSTELLAR MEDIUM IN THE KEPLER SEARCH VOLUME

    SciTech Connect

    Johnson, Marshall C.; Redfield, Seth; Jensen, Adam G., E-mail: mjohnson@astro.as.utexas.edu

    2015-07-10

    The properties of the interstellar medium (ISM) surrounding a planetary system can impact planetary climate through a number of mechanisms, including changing the size of the astrosphere (one of the major shields for cosmic rays) as well as direct deposition of material into planetary atmospheres. In order to constrain the ambient ISM conditions for exoplanetary systems, we present observations of interstellar Na i and K i absorption toward seventeen early type stars in the Kepler prime mission field of view (FOV). We identify 39 Na i and 8 K i velocity components, and attribute these to 11 ISM clouds. Sixmore » of these are detected toward more than one star, and for these clouds we put limits on the cloud properties, including distance and hydrogen number density. We identify one cloud with significant (≳1.5 cm{sup −3}) hydrogen number density located within the nominal ∼100 pc boundary of the Local Bubble. We identify systems with confirmed planets within the Kepler FOV that could lie within these ISM clouds, and estimate upper limits on the astrosphere sizes of these systems under the assumption that they do lie within these clouds. Under this condition, the Kepler-20, 42, and 445 multiplanet systems could have compressed astrospheres much smaller than the present-day heliosphere. Among the known habitable zone planet hosts, Kepler-186 could have an astrosphere somewhat smaller than the heliosphere, while Kepler-437 and KOI-4427 could have astrospheres much larger than the heliosphere. The thick disk star Kepler-444 may have an astrosphere just a few AU in radius.« less

  20. Medium Chain Triglycerides in Paediatric Practice

    PubMed Central

    Gracey, Michael; Burke, Valerie; Anderson, Charlotte M.

    1970-01-01

    Medium chain triglycerides (MCT) bypass the steps necessary for the absorption of long chain fats (LCT), and so have theoretical grounds for their use in various disease states, particularly malabsorptive disorders. In childhood, MCT have particular advantages since they allow restriction of dietary long chain fats without limiting the intake of protein necessary for growth while providing adequate calories. In malabsorptive states, MCT have been used mostly in cystic fibrosis, where they may reduce steatorrhoea. However, the long-term growth patterns of these children are dependent on the extent and severity of their chest disease. MCT may be a useful source of calories for those with anorexia due to infection or liver disease and in babies recovering from meconium ileus. The decrease in offensive stools, flatus, and abdominal discomfort improves well-being and social acceptability which is important for many schoolchildren and adolescents. Rectal prolapse may be helped. Where there is loss of the small intestinal absorptive surface, particularly after massive small bowel resection, MCT can help to maintain weight and nutrition. They may also be a useful supplementary nutritional measure in patients severely affected with coeliac disease while awaiting response to a gluten-free diet, and in patients with regional enteritis. In children with liver disease, MCT provide a ready source of calories while avoiding the loss of fat in their stools. Infants with neonatal hepatitis or biliary atresia remain well nourished, and some older children with liver disease grow more rapidly and have fewer and less offensive stools and less abdominal discomfort. Where an abnormal number of faecal organisms colonize the small intestine (`contaminated small bowel syndrome' or `blind loop syndrome') intraluminal bile salts become deconjugated and cause steatorrhoea. A combination of antibiotic and surgical treatment is usually indicated, but MCT can be used to improve nutrition before

  1. Early afterglows in wind environments revisited

    NASA Astrophysics Data System (ADS)

    Zou, Y. C.; Wu, X. F.; Dai, Z. G.

    2005-10-01

    When a cold shell sweeps up the ambient medium, a forward shock and a reverse shock will form. We analyse the reverse-forward shocks in a wind environment, including their dynamics and emission. An early afterglow is emitted from the shocked shell, e.g. an optical flash may emerge. The reverse shock behaves differently in two approximations: the relativistic and Newtonian cases, which depend on the parameters, e.g. the initial Lorentz factor of the ejecta. If the initial Lorentz factor is much less than 114E1/453Δ-1/40,12A-1/4*,-1, the early reverse shock is Newtonian. This may take place for the wider of a two-component jet, an orphan afterglow caused by a low initial Lorentz factor and so on. The synchrotron self-absorption effect is significant especially for the Newtonian reverse shock case, as the absorption frequency νa is larger than the cooling frequency νc and the minimum synchrotron frequency νm for typical parameters. For the optical to X-ray band, the flux is nearly unchanged with time during the early period, which may be a diagnostic for the low initial Lorentz factor of the ejecta in a wind environment. We also investigate the early light curves with different wind densities and compare them with those in the interstellar medium model.

  2. Method for inhibiting gum formation in liquid hydrocarbon mediums

    SciTech Connect

    Reid, D.K.

    1990-07-17

    This patent describes a method of inhibiting the formation of gum and sediment in a liquid hydrocarbonaceous medium. It comprises: adding to the medium an inhibiting amount of an alkyl 1,2-dihydroquinoline or polymerized alkyl 1,2-dihydroquinoline.

  3. Visual Medium in the Service and Disservice of Education

    ERIC Educational Resources Information Center

    Wong, Wan-chi

    2001-01-01

    There are different ways of exploring and examining the visual medium in the service and disservice of education. A discursive form rather than a visual medium is chosen in this attempt. Utilizing the conceptualizations of Suzanne Langer, Christine Nystrom observed that American symbolic environments have undergone a massive shift from discursive…

  4. Percolation Laws of a Fractal Fracture-Pore Double Medium

    NASA Astrophysics Data System (ADS)

    Zhao, Yangsheng; Feng, Zengchao; Lv, Zhaoxing; Zhao, Dong; Liang, Weiguo

    2016-12-01

    The fracture-pore double porosity medium is one of the most common media in nature, for example, rock mass in strata. Fracture has a more significant effect on fluid flow than a pore in a fracture-pore double porosity medium. Hence, the fracture effect on percolation should be considered when studying the percolation phenomenon in porous media. In this paper, based on the fractal distribution law, three-dimensional (3D) fracture surfaces, and two-dimensional (2D) fracture traces in rock mass, the locations of fracture surfaces or traces are determined using a random function of uniform distribution. Pores are superimposed to build a fractal fracture-pore double medium. Numerical experiments were performed to show percolation phenomena in the fracture-pore double medium. The percolation threshold can be determined from three independent variables (porosity n, fracture fractal dimension D, and initial value of fracture number N0). Once any two are determined, the percolation probability exists at a critical point with the remaining parameter changing. When the initial value of the fracture number is greater than zero, the percolation threshold in the fracture-pore medium is much smaller than that in a pore medium. When the fracture number equals zero, the fracture-pore medium degenerates to a pore medium, and both percolation thresholds are the same.

  5. Wave propagation in a strongly heterogeneous elastic porous medium: Homogenization of Biot medium with double porosities

    NASA Astrophysics Data System (ADS)

    Rohan, Eduard; Naili, Salah; Nguyen, Vu-Hieu

    2016-08-01

    We study wave propagation in an elastic porous medium saturated with a compressible Newtonian fluid. The porous network is interconnected whereby the pores are characterized by two very different characteristic sizes. At the mesoscopic scale, the medium is described using the Biot model, characterized by a high contrast in the hydraulic permeability and anisotropic elasticity, whereas the contrast in the Biot coupling coefficient is only moderate. Fluid motion is governed by the Darcy flow model extended by inertia terms and by the mass conservation equation. The homogenization method based on the asymptotic analysis is used to obtain a macroscopic model. To respect the high contrast in the material properties, they are scaled by the small parameter, which is involved in the asymptotic analysis and characterized by the size of the heterogeneities. Using the estimates of wavelengths in the double-porosity networks, it is shown that the macroscopic descriptions depend on the contrast in the static permeability associated with pores and micropores and on the frequency. Moreover, the microflow in the double porosity is responsible for fading memory effects via the macroscopic poroviscoelastic constitutive law. xml:lang="fr"

  6. Contrast medium usage reduction in abdominal computed tomography by using high-iodinated concentration contrast medium

    NASA Astrophysics Data System (ADS)

    Suwannasri, A.; Kaewlai, R.; Asavaphatiboon, S.

    2016-03-01

    This study was to determine if administration of a low volume high-concentration iodinated contrast medium can preserve image quality in comparison with regular-concentration intravenous contrast medium in patient undergoing contrast-enhancement abdominal computed tomography (CT). Eighty-four patients were randomly divided into 3 groups of similar iodine delivery rate; A: 1.2 cc/kg of iomeprol-400, B: 1.0 cc/kg of iomeprol-400 and C: 1.5 cc/kg of ioversol-350. Contrast enhancement of the liver parenchyma, pancreas and aorta was quantitatively measured in Hounsfield units and qualitative assessed by a radiologist. T-test was used to evaluate contrast enhancement, and Chi-square test was used to evaluate qualitative image assessment, at significance level of 0.05 with 95% confidence intervals. There were no statistically significant differences in contrast enhancement of liver parenchyma and pancreas between group A and group C in both quantitative and qualitative analyses. Group C showed superior vascular enhancement to group A and B on quantitative analysis.

  7. Rapid mounting of adult Drosophila structures in Hoyer's medium.

    PubMed

    Stern, David L; Sucena, Elio

    2012-01-01

    The Drosophila cuticle carries a rich array of morphological details. Thus, cuticle examination has had a central role in the history of genetics. This protocol describes a procedure for mounting adult cuticles in Hoyer's medium, a useful mountant for both larval and adult cuticles. The medium digests soft tissues rapidly, leaving the cuticle cleared for observation. In addition, samples can be transferred directly from water to Hoyer's medium. However, specimens mounted in Hoyer's medium degrade over time. For example, the fine denticles on the larval dorsum are best observed soon after mounting; they begin to fade after 1 week, and can disappear completely after several months. More robust features, such as the ventral denticle belts, will persist for a longer period of time. Because adults cannot profitably be mounted whole in Hoyer's medium, some dissection is necessary.

  8. Isogeometric frictionless contact analysis with the third medium method

    NASA Astrophysics Data System (ADS)

    Kruse, R.; Nguyen-Thanh, N.; Wriggers, P.; De Lorenzis, L.

    2018-01-01

    This paper presents an isogeometric formulation for frictionless contact between deformable bodies, based on the recently proposed concept of the third medium. This concept relies on continuum formulations not only for the contacting bodies but also for a fictitious intermediate medium in which the bodies can move and interact. Key to the formulation is a suitable definition of the constitutive behavior of the third medium. In this work, based on a number of numerical tests, the role of the material parameters of the third medium is systematically assessed. We also assess the rate of spatial convergence for higher-order discretizations, stemming from the regularization of the non-smooth contact problem inherent to the third medium approach. Finally, problems with self contact are considered and turn out to be an attractive application of the method.

  9. System and method for treatment of a medium

    SciTech Connect

    Singh, Surinder Prabhjot; Acharya, Harish Radhakrishna; Perry, Robert James

    2017-05-23

    A system and method for treatment of a medium is disclosed. The system includes a plurality of separator zones and a plurality of heat transfer zones. Each of the separator zone and the heat transfer zone among the plurality of separator zones and heat transfer zones respectively, are disposed alternatively in a flow duct. Further, each separator zone includes an injector device for injecting a sorbent into the corresponding separator zone. Within the corresponding separator zone, the injected sorbent is reacted with a gaseous medium flowing in the flow duct, so as to generate a reacted gaseous medium and amore » reacted sorbent. Further, each heat transfer zone exchanges heat between the reacted gaseous medium fed from the corresponding separator zone and a heat transfer medium.« less

  10. Optical activity via Kerr nonlinearity in a spinning chiral medium

    NASA Astrophysics Data System (ADS)

    Khan, Anwar Ali; Bacha, Bakht Amin; Khan, Rahmat Ali

    2016-11-01

    Optical activity is investigated in a chiral medium by employing the four level cascade atomic model, in which the optical responses of the atomic medium are studied with Kerr nonlinearity. Light entering into a chiral medium splits into circular birefringent beams. The angle of divergence between the circular birefringent beams and the polarization states of the two light beams is manipulated with Kerr nonlinearity. In the stationary chiral medium the angle of divergence between the circular birefringent beams is calculated to be 1.3 radian. Furthermore, circular birefringence is optically controlled in a spinning chiral medium, where the maximum rotary photon drag angle for left (right) circularly polarized beam is ±1.1 (±1.5) microradian. The change in the angle of divergence between circular birefringent beams by rotary photon drag is calculated to be 0.4 microradian. The numerical results may help to understand image designing, image coding, discovery of photonic crystals and optical sensing technology.

  11. Supernovae driven turbulence in the interstellar medium

    NASA Astrophysics Data System (ADS)

    Gent, Frederick A.

    2012-11-01

    I model the multi-phase interstellar medium (ISM) randomly heated and shocked by supernovae (SN), with gravity, differential rotation and other parameters we understand to be typical of the solar neighbourhood. The simulations are in a 3D domain extending horizontally 1x1 kpc^2 and vertically 2 kpc, symmetric about the galactic mid-plane. They routinely span gas number densities 10^{-5}-10^2 cm^{-3}, temperatures 10-10^8 K, speeds up to 10^3 km s^{-1} and Mach number up to 25. Radiative cooling is applied from two widely adopted parameterizations, and compared directly to assess the sensitivity of the results to cooling. There is strong evidence to describe the ISM as comprising well defined cold, warm and hot regions, typified by T 10^2 ; 10^4 and 10^6 K, which are statistically close to thermal and total pressure equilibrium. This result is not sensitive to the choice of parameters considered here. The distribution of the gas density within each can be robustly modelled as lognormal. Appropriate distinction is required between the properties of the gases in the supernova active mid-plane and the more homogeneous phases outside this region. The connection between the fractional volume of a phase and its various proxies is clarified. An exact relation is then derived between the fractional volume and the filling factors defined in terms of the volume and probabilistic averages. These results are discussed in both observational and computational contexts. The correlation scale of the random flows is calculated from the velocity autocorrelation function; it is of order 100 pc and tends to grow with distance from the mid-plane. The origin and structure of the magnetic fields in the ISM is also investigated in nonideal MHD simulations. A seed magnetic field, with volume average of roughly 4 nG, grows exponentially to reach a statistically steady state within 1.6 Gyr. Following Germano (1992), volume averaging is applied with a Gaussian kernel to separate magnetic field

  12. Introducing CoDa (Cosmic Dawn): Radiation-Hydrodynamics of Galaxy Formation in the Early Universe

    NASA Astrophysics Data System (ADS)

    Ocvirk, Pierre; Gillet, Nicolas; Shapiro, Paul; Aubert, Dominique; Iliev, Ilian; Romain, Teyssier; Yepes, Gustavo; Choi, Jun-hwan; Sullivan, David; Knebe, Alexander; Gottloeber, Stefan; D'Aloisio, Anson; Park, Hyunbae; Hoffman, Yehuda

    2015-08-01

    CoDa (Cosmic Dawn) is the largest fully coupled radiation hydrodynamics simulation of the reionization of the local Universe to date. It was performed using RAMSES-CUDATON running on 8192 nodes (i.e. 8192 GPUs) on the titan supercomputer at Oak Ridge National Laboratory to simulate a 64 h-1Mpc side box down to z=4.23. In this simulation, reionization proceeds self-consistently, driven by stellar radiation. We compare the simulation's reionization history, ionizing flux density, the cosmic star formation history and the CMB Thompson scattering optical depth with their observational values. Luminosity functions are also in rather good agreement with high redshift observations, although very bright objects (MAB1600 < -21) are overabundant in CoDa. We investigate the evolution of the intergalactic medium, and find that gas filaments present a sheathed structure, with a hot envelope surrounding a cooler core. They are however not able to self-shield, while regions denser than 10^-4.5 H atoms per comoving h^-3cm^3 are. Haloes below M ˜ 3.10^9 M⊙ are severely affected by the expanding, rising UV background: their ISM is quickly photo-heated to temperatures above our star formation threshold and therefore stop forming stars after local reionization has occured. Overall, the haloes between 10^(10-11) M⊙ dominate the star formation budget of the box for most of the Epoch of Reionization. Several additional studies will follow, looking for instance at environmental effects on galaxy properties, and the regimes of accretion.

  13. A Comparative Study on the Effectiveness of English-Medium and Turkish-Medium Accounting Education: Gazi University Case

    ERIC Educational Resources Information Center

    Zaif, Figen; Karapinar, Aydin; Yangin Eksi, Gonca

    2017-01-01

    The authors explore the effect of medium of instruction on students' attainments at a large state university in Turkey in the Department of Business Administration. The findings indicate no statistically significant difference in grades of 386 students with respect to medium of instruction. As for entry rankings however, those in the…

  14. Reflection-refraction of attenuated waves at the interface between a thermo-poroelastic medium and a thermoelastic medium

    NASA Astrophysics Data System (ADS)

    Sharma, M. D.

    2018-07-01

    Phenomenon of reflection and refraction is considered at the plane interface between a thermoelastic medium and thermo-poroelastic medium. Both the media are isotropic and behave dissipative to wave propagation. Incident wave in thermo-poroelastic medium is considered inhomogeneous with deviation allowed between the directions of propagation and maximum attenuation. For this incidence, four attenuated waves reflect back in thermo-poroelastic medium and three waves refract to the continuing thermoelastic medium. Each of these reflected/refracted waves is inhomogeneous and propagates with a phase shift. The propagation characteristics (velocity, attenuation, inhomogeneity, phase shift, amplitude, energy) of reflected and refracted waves are calculated as functions of propagation direction and inhomogeneity of the incident wave. Variations in these propagation characteristics with the incident direction are illustrated through a numerical example.

  15. Observations of absorption lines from highly ionized atoms. [of interstellar medium

    NASA Technical Reports Server (NTRS)

    Jenkins, Edward B.

    1987-01-01

    In the ultraviolet spectra of hot stars, absorption lines can be seen from highly ionized species in the interstellar medium. Observations of these features which have been very influential in revising the perception of the medium's various physical states, are discussed. The pervasiveness of O 6 absorption lines, coupled with complementary observations of a diffuse background in soft X-rays and EUV radiation, shows that there is an extensive network of low density gas (n approx. few x 0.001/cu cm) existing at coronal temperatures log T = 5.3 or 6.3. Shocks created by supernova explosions or mass loss from early-type stars can propagate freely through space and eventually transfer a large amount of energy to the medium. To create the coronal temperatures, the shocks must have velocities in excess of 150 km/sec; shocks at somewhat lower velocity (v = 100 km/sec) can be directly observed in the lines of Si3. Observations of other lines in the ultraviolet, such as Si 4V and C 5, may highlight the widespread presence of energetic UV radiation from very hot, dwarf stars. More advanced techniques in visible and X-ray astronomical spectroscopy may open up for inspection selected lines from atoms in much higher stages of ionization.

  16. Nanoparticle growth and surface chemistry changes in cell-conditioned culture medium.

    PubMed

    Kendall, Michaela; Hodges, Nikolas J; Whitwell, Harry; Tyrrell, Jess; Cangul, Hakan

    2015-02-05

    When biomolecules attach to engineered nanoparticle (ENP) surfaces, they confer the particles with a new biological identity. Physical format may also radically alter, changing ENP stability and agglomeration state within seconds. In order to measure which biomolecules are associated with early ENP growth, we studied ENPs in conditioned medium from A549 cell culture, using dynamic light scattering (DLS) and linear trap quadrupole electron transfer dissociation mass spectrometry. Two types of 100 nm polystyrene particles (one uncoated and one with an amine functionalized surface) were used to measure the influence of surface type. In identically prepared conditioned medium, agglomeration was visible in all samples after 1 h, but was variable, indicating inter-sample variability in secretion rates and extracellular medium conditions. In samples conditioned for 1 h or more, ENP agglomeration rates varied significantly. Agglomerate size measured by DLS was well correlated with surface sequestered peptide number for uncoated but not for amine coated polystyrene ENPs. Amine-coated ENPs grew much faster and into larger agglomerates associated with fewer sequestered peptides, but including significant sequestered lactose dehydrogenase. We conclude that interference with extracellular peptide balance and oxidoreductase activity via sequestration is worthy of further study, as increased oxidative stress via this new mechanism may be important for cell toxicity. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  17. Tidal River Elbe - a sediment budget for the grain size fraction of medium sand

    NASA Astrophysics Data System (ADS)

    Winterscheid, Axel

    2016-04-01

    Human interventions have a historic and ongoing impact on estuarine sediment budgets across many estuaries worldwide. An early inference was the construction of embankments resulting in a constant loss of intertidal flats. Additionally, settlement activities and large scale land use changes in the upstream catchment areas had also an effect on sediment inflow rates. Today, the navigation channels in estuaries have been deepened for larger and more efficient vessels to reach a well-developed infrastructure of harbors and industrial areas often located far inland. In the past few years and just within the North-East Atlantic, the total annual amount of dredged sediments dumped at sea varied from 80 to 130 million tons (OSPAR Commission). In most estuaries across Europe the resulting human impact on the sediment fluxes and morphodynamics is significant. A good understanding of estuarine processes is essential for determining useful and meaningful measures to mitigate negative effects and to improve the current situation. Maintenance dredging and its environmental effects are therefore in the focus of public attention. Against this background, it is the aim of the presentation to identify and therefore to separate the particular effect that maintenance dredging has on sediment fluxes and budgets in the estuarine environment. Case study is the Tidal River Elbe in Germany, and here we set the focus on the grain size fraction of medium sand. In the past, river engineering measures forced the natural dynamics to form a concentrated stream flow along a fixed channel, except at a number of locations where side channels still exist. In addition to that, the main channel was deepened several times. The last deepening was in 1999/2000. The most significant deepening, however, took place from 1957 to 1962. Until then, an erosion-stable layer of marine clay (in German called "Klei") formed a flat bottom along most sections of the main channel. After removal of this layer of

  18. Optoelectronic Instrument Monitors pH in a Culture Medium

    NASA Technical Reports Server (NTRS)

    Anderson, Melody M.; Pellis, Neal; Jeevarajan, Anthony S.; Taylor, Thomas D.

    2004-01-01

    An optoelectronic instrument monitors the pH of an aqueous cell-culture medium in a perfused rotating-wall-vessel bioreactor. The instrument is designed to satisfy the following requirements: It should be able to measure the pH of the medium continuously with an accuracy of 0.1 in the range from 6.5 to 7.5. It should be noninvasive. Any material in contact with the culture medium should be sterilizable as well as nontoxic to the cells to be grown in the medium. The biofilm that inevitably grows on any surface in contact with the medium should not affect the accuracy of the pH measurement. It should be possible to obtain accurate measurements after only one calibration performed prior to a bioreactor cell run. The instrument should be small and lightweight. The instrument includes a quartz cuvette through which the culture medium flows as it is circulated through the bioreactor. The cuvette is sandwiched between light source on one side and a photodetector on the other side. The light source comprises a red and a green light-emitting diode (LED) that are repeatedly flashed in alternation with a cycle time of 5 s. The responses of the photodiode to the green and red LEDs are processed electronically to obtain a quantity proportional to the ratio between the amounts of green and red light transmitted through the medium.

  19. Oxidative stress differentially impacts male and female bovine embryos depending on the culture medium and the stress condition.

    PubMed

    Dallemagne, Matthew; Ghys, Emmanuelle; De Schrevel, Catalina; Mwema, Ariane; De Troy, Delphine; Rasse, Catherine; Donnay, Isabelle

    2018-09-01

    Male and female embryos are known to differ for their metabolism and response to environmental factors very early in development. The present study aimed to evaluate the response to oxidative stress of male and female bovine embryos at the morula-blastocyst stages in terms of developmental rates, total cell number and apoptotic rates in two culture conditions. Embryos where cultured in a medium supplemented with either 5% fetal calf serum (FCS) or 4 mg/mL bovine serum albumin and a mixture of insulin, transferrin and selenium (BSA-ITS). Oxidative stress was applied at Day-5 post insemination (pi) by adding either AAPH or menadione to the culture medium, and blastocysts were analyzed at Day-7pi. The impact on development and blastocyst quality was dependent on the culture medium and the stress inducer but differed between male and female embryos. Male embryos resisted better to oxidative stress in FCS supplemented medium, no matter the stress inducer. Accordingly, the impact on blastocyst cell number tended to be higher in female blastocysts after stress induction with AAPH in FCS supplemented medium. On the other hand, in BSA-ITS supplemented medium, female embryos were more resistant to AAPH induced stress, while menadione had no impact on sex ratio. The weaker resistance of males to AAPH in this medium is in accordance with their trend to show a higher increase in apoptotic rates than females in this condition. In conclusion, this study shows that oxidative stress has differential impact on male and female bovine blastocysts depending on the culture condition and on the way oxidative stress is induced. Copyright © 2018 Elsevier Inc. All rights reserved.

  20. Heuristic Green's function of the time dependent radiative transfer equation for a semi-infinite medium.

    PubMed

    Martelli, Fabrizio; Sassaroli, Angelo; Pifferi, Antonio; Torricelli, Alessandro; Spinelli, Lorenzo; Zaccanti, Giovanni

    2007-12-24

    The Green's function of the time dependent radiative transfer equation for the semi-infinite medium is derived for the first time by a heuristic approach based on the extrapolated boundary condition and on an almost exact solution for the infinite medium. Monte Carlo simulations performed both in the simple case of isotropic scattering and of an isotropic point-like source, and in the more realistic case of anisotropic scattering and pencil beam source, are used to validate the heuristic Green's function. Except for the very early times, the proposed solution has an excellent accuracy (> 98 % for the isotropic case, and > 97 % for the anisotropic case) significantly better than the diffusion equation. The use of this solution could be extremely useful in the biomedical optics field where it can be directly employed in conditions where the use of the diffusion equation is limited, e.g. small volume samples, high absorption and/or low scattering media, short source-receiver distances and early times. Also it represents a first step to derive tools for other geometries (e.g. slab and slab with inhomogeneities inside) of practical interest for noninvasive spectroscopy and diffuse optical imaging. Moreover the proposed solution can be useful to several research fields where the study of a transport process is fundamental.

  1. An invisible medium for circularly polarized electromagnetic waves.

    PubMed

    Tamayama, Y; Nakanishi, T; Sugiyama, K; Kitano, M

    2008-12-08

    We study the no reflection condition for a planar boundary between vacuum and an isotropic chiral medium. In general chiral media, elliptically polarized waves incident at a particular angle satisfy the no reflection condition. When the wave impedance and wavenumber of the chiral medium are equal to the corresponding parameters of vacuum, one of the circularly polarized waves is transmitted to the medium without reflection or refraction for all angles of incidence. We propose a circular polarizing beam splitter as a simple application of the no reflection effect. (c) 2008 Optical Society of America

  2. Spectral stability of supercontinuum generation in condensed mediums

    NASA Astrophysics Data System (ADS)

    Wang, Jier; Zhang, Yizhu; Shen, Huifeng; Jiang, Yuhai; Wang, Zhongyang

    2017-07-01

    The features of the supercontinuum generation (SCG) using intense femtosecond pulses are systematically investigated in condensed mediums [sapphire, BK7 glass, ultraviolet (UV)-fused silica, and fluoride crystals]. By optimizing the experimental conditions and choosing suitable mediums, the bandwidth of the SCG can be extended to the UV regime with good spectral stability. This study demonstrates that materials with high bandgap present high efficiency for SCG, particularly in the short wavelength region. The achievable short wavelength and low power-density threshold of the SCG exhibit complicated correlations with the bandgap of condensed mediums.

  3. Mean dyadic Green's function for a two layer random medium

    NASA Technical Reports Server (NTRS)

    Zuniga, M. A.

    1981-01-01

    The mean dyadic Green's function for a two-layer random medium with arbitrary three-dimensional correlation functions has been obtained with the zeroth-order solution to the Dyson equation by applying the nonlinear approximation. The propagation of the coherent wave in the random medium is similar to that in an anisotropic medium with different propagation constants for the characteristic transverse electric and transverse magnetic polarizations. In the limit of a laminar structure, two propagation constants for each polarization are found to exist.

  4. Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium

    PubMed Central

    Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying

    2015-01-01

    A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic waves propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic waves in a nonlinear medium. The results obtained by using the present method are accurately concordant with the results of using traditional coupled-wave equations. As an example of application, we discuss how a third wave affects the sum- and difference-frequency generation of two waves propagation in the nonlinear medium. PMID:26073066

  5. Birefringence in a chiral medium, via temporal cloaking

    NASA Astrophysics Data System (ADS)

    Khan, Humayun; Haneef, Muhammad

    2017-05-01

    This paper reports theoretical investigation of birefringence in a chiral medium for the creation of temporal cloaking. The chiral medium splits the input probe beam into left/right circular polarized beams. These left/right circular polarized beams are then controlled and modified within the chiral medium. The left circular polarized beam delays by 24 ns whereas the right circular polarized beam advances by  -23 ns at a control field of rabbi frequency 6γ . This opens a 47 ns time gap for temporal cloaking to hide information without noise corruption and energy loss. The results have potential applications in communication devices for secure propagation of light pulse.

  6. Multifractality of laser beam spatial intensity in a turbulent medium

    NASA Astrophysics Data System (ADS)

    Barille, Régis; Lapenna, Paolo

    2006-05-01

    We present the results of a laser beam passing through a turbulent medium. First we measure the geometric parameters and the spatial coherence of the beam as a function of wind velocities. A multifractal detrended fluctuation analysis algorithm is applied to determine the multifractal scaling behavior of the intensity patterns. The measurements are fitted with models used in the analysis of river runoff records. We show the surprising result that the multifractality decreases when the spatial coherence of the laser is decreased. Universal scaling properties could be applied to the spatial characterization of a laser propagating in a turbulent medium or random medium.

  7. Acoustic characteristics of the medium with gradient change of impedance

    NASA Astrophysics Data System (ADS)

    Hu, Bo; Yang, Desen; Sun, Yu; Shi, Jie; Shi, Shengguo; Zhang, Haoyang

    2015-10-01

    The medium with gradient change of acoustic impedance is a new acoustic structure which developed from multiple layer structures. In this paper, the inclusion is introduced and a new set of equations is developed. It can obtain better acoustic properties based on the medium with gradient change of acoustic impedance. Theoretical formulation has been systematically addressed which demonstrates how the idea of utilizing this method. The sound reflection and absorption coefficients were obtained. At last, the validity and the correctness of this method are assessed by simulations. The results show that appropriate design of parameters of the medium can improve underwater acoustic properties.

  8. Organic chemistry and biology of the interstellar medium

    NASA Technical Reports Server (NTRS)

    Sagan, C.

    1973-01-01

    Interstellar organic chemistry is discussed as the field of study emerging from the discovery of microwave lines of formaldehyde and of hydrogen cyanide in the interstellar medium. The reliability of molecular identifications and comparisons of interstellar and cometary compounds are considered, along with the degradational origin of simple organics. It is pointed out that the contribution of interstellar organic chemistry to problems in biology is not substantive but analogical. The interstellar medium reveals the operation of chemical processes which, on earth and perhaps on vast numbers of planets throughout the universe, led to the origin of life, but the actual molecules of the interstellar medium are unlikely to play any significant biological role.

  9. Propagation of waves in a medium with high radiation pressure

    NASA Technical Reports Server (NTRS)

    Bisnovatyy-Kogan, G. S.; Blinnikov, S. I.

    1979-01-01

    The propagation and mutual transformation of acoustic and thermal waves are investigated in media with a high radiative pressure. The equations of hydrodynamics for matter and the radiative transfer equations in a moving medium in the Eddington approximation are used in the investigation. Model problems of waves in a homogeneous medium with an abrupt jump in opacity and in a medium of variable opacity are presented. The characteristic and the times of variability are discussed. Amplitude for the brightness fluctuations for very massive stars are discussed.

  10. Early Childhood Systems: Transforming Early Learning

    ERIC Educational Resources Information Center

    Kagan, Sharon Lynn, Ed.; Kauertz, Kristie, Ed.

    2012-01-01

    In this seminal volume, leading authorities strategize about how to create early childhood systems that transcend politics and economics to serve the needs of all young children. The authors offer different interpretations of the nature of early childhood systems, discuss the elements necessary to support their development, and examine how…

  11. The down-regulation of the mitogenic fibrinogen receptor (MFR) in serum-containing medium does not occur in defined medium.

    PubMed

    Levesque, J P; Hatzfeld, A; Domart, I; Hatzfeld, J

    1990-02-01

    Normal human hemopoietic cells such as early bone marrow progenitors, or lymphoma-derived cell lines such as Raji or JM cells, possess a low-affinity receptor specific for fibrinogen. This receptor triggers a mitogenic effect. It differs from the glycoprotein IIb-IIIa which is involved in fibrinogen-induced platelet aggregation. We demonstrate here that this mitogenic fibrinogen receptor (MFR) can be internalized or reexpressed, depending on culture conditions. Internalization was temperature-dependent. At 37 degrees C in the presence of cycloheximide or actinomycin D, the half-life of cell surface MFRs was 2 h, independent of receptor occupancy. Binding of fibrinogen to the MFR resulted in a down-regulation which was fibrinogen dose-dependent. This occurred in serum-supplemented medium but not in defined medium supplemented with fatty acids. Reexpression of MFRs could be induced in 28 to 42 h by serum removal. The down-regulation of mitogenic receptors in plasma or serum could explain why normal cells do not proliferate in the peripheral blood.

  12. Notochordal cell conditioned medium stimulates mesenchymal stem cell differentiation toward a young nucleus pulposus phenotype

    PubMed Central

    2010-01-01

    Introduction Mesenchymal stem cells (MSCs) offer promise for intervertebral disc (IVD) repair and regeneration because they are easily isolated and expanded, and can differentiate into several mesenchymal tissues. Notochordal (NC) cells contribute to IVD development, incorporate into the nucleus pulposus (NP), and stimulate mature disc cells. However, there have been no studies investigating the effects of NC cells on adult stem cell differentiation. The premise of this study is that IVD regeneration is more similar to IVD development than to IVD maintenance, and we hypothesize that soluble factors from NC cells differentiate MSCs to a phenotype characteristic of nucleus pulposus (NP) cells during development. The eventual clinical goal would be to isolate or chemically/recombinantly produce the active agent to induce the therapeutic effects, and to use it as either an injectable therapy for early intervention on disc disease, or in developing appropriately pre-differentiated MSC cells in a tissue engineered NP construct. Methods Human MSCs from bone marrow were expanded and pelleted to form high-density cultures. MSC pellets were exposed to either control medium (CM), chondrogenic medium (CM with dexamethasone and transforming growth factor, (TGF)-β3) or notochordal cell conditioned medium (NCCM). NCCM was prepared from NC cells maintained in serum free medium for four days. After seven days culture, MSC pellets were analyzed for appearance, biochemical composition (glycosaminoglycans and DNA), and gene expression profile (sox-9, collagen types-II and III, laminin-β1 and TIMP1(tissue inhibitor of metalloproteinases-1)). Results Significantly higher glycosaminoglycan accumulation was seen in NCCM treated pellets than in CM or TGFβ groups. With NCCM treatment, increased gene expression of collagen III, and a trend of increasing expression of laminin-β1 and decreased expression of sox-9 and collagen II relative to the TGFβ group was observed. Conclusions

  13. [The corrosion of pure iron in five different mediums].

    PubMed

    Xu, Li; Zhu, Shengfa; Huang, Nan; Li, Xinchang; Zhang, Yu

    2009-08-01

    The sectional test was adopted in this study to investigate the corrosion of pure iron in 0.15 mol/L NaCl solution, Ringer solution, PBS(-) solution, SBF solution and M199 cell culture medium at three different times. The result shows that different mediums have different corrosion effects on pure iron. The arrangement according to the medium's corrosion ability from the strongest to weakest is 0.15 mol/L NaCl solution (Ringer solution), PBS(-) solution, SBF solution and M199 cell culture medium. The results of scanning electron microscopy and energy dispersive X-ray spectrum analyses show that the addition of HPO4(2-), H2POC4-, Ca2+, Mg2+, SO4(2-) and the organic component can inhibit the corrosion to some degree.

  14. On Emulation of Flueric Devices in Excitable Chemical Medium

    PubMed Central

    Adamatzky, Andrew

    2016-01-01

    Flueric devices are fluidic devices without moving parts. Fluidic devices use fluid as a medium for information transfer and computation. A Belousov-Zhabotinsky (BZ) medium is a thin-layer spatially extended excitable chemical medium which exhibits travelling excitation wave-fronts. The excitation wave-fronts transfer information. Flueric devices compute via jets interaction. BZ devices compute via excitation wave-fronts interaction. In numerical model of BZ medium we show that functions of key flueric devices are implemented in the excitable chemical system: signal generator, and, xor, not and nor Boolean gates, delay elements, diodes and sensors. Flueric devices have been widely used in industry since late 1960s and are still employed in automotive and aircraft technologies. Implementation of analog of the flueric devices in the excitable chemical systems opens doors to further applications of excitation wave-based unconventional computing in soft robotics, embedded organic electronics and living technologies. PMID:27997561

  15. Modification of Einstein A Coefficient in Dissipative Gas Medium

    NASA Technical Reports Server (NTRS)

    Cao, Chang-Qi; Cao, Hui; Qin, Ke-Cheng

    1996-01-01

    Spontaneous radiation in dissipative gas medium such as plasmas is investigated by Langevin equations and the modified Weisskopf-Wigner approximation. Since the refractive index of gas medium is expected to be nearly unity, we shall first neglect the medium polarization effect. We show that absorption in plasmas may in certain case modify the Einstein A coefficient significantly and cause a pit in the A coefficient-density curves for relatively low temperature plasmas and also a pit in the A coefficient-temperature curves. In the next, the effect of medium polarization is taken into account in addition. To our surprise, its effect in certain case is quite significant. The dispersive curves show different behaviors in different region of parameters.

  16. Medium- and Heavy-Duty Vehicles | Transportation Research | NREL

    Science.gov Websites

    . May 19, 2014 Fleet DNA Tool Provides Real-World "Genetics" for Commercial Fleets Vehicle performance demands of today's commercial vehicles. This clearinghouse of medium- and heavy-duty commercial

  17. High Aflatoxin Production on a Chemically Defined Medium 1

    PubMed Central

    Reddy, T. V.; Viswanathan, L.; Venkitasubramanian, T. A.

    1971-01-01

    Aspergillus parasiticus ATCC 15517 produced 28 to 30 mg of aflatoxin per 100 ml of a medium containing sucrose, asparagine, and salts in stationary and shaken cultures. In the absence of asparagine in the medium, the toxin yields fell drastically, and the thin-layer chromatograms of the chloroform extracts of the cultures indicated the total absence of aflatoxin G1 and the presence of new intense blue and green fluorescent bands having RF values lower than aflatoxins. Initial pH was critical and had to be around 4.5 for good growth and high toxin production on this medium. Optimum concentrations of KH2PO4 and MgSO4·7H2O in the medium were much lower than those normally used in fungal growth media. PMID:5119206

  18. On Emulation of Flueric Devices in Excitable Chemical Medium.

    PubMed

    Adamatzky, Andrew

    2016-01-01

    Flueric devices are fluidic devices without moving parts. Fluidic devices use fluid as a medium for information transfer and computation. A Belousov-Zhabotinsky (BZ) medium is a thin-layer spatially extended excitable chemical medium which exhibits travelling excitation wave-fronts. The excitation wave-fronts transfer information. Flueric devices compute via jets interaction. BZ devices compute via excitation wave-fronts interaction. In numerical model of BZ medium we show that functions of key flueric devices are implemented in the excitable chemical system: signal generator, and, xor, not and nor Boolean gates, delay elements, diodes and sensors. Flueric devices have been widely used in industry since late 1960s and are still employed in automotive and aircraft technologies. Implementation of analog of the flueric devices in the excitable chemical systems opens doors to further applications of excitation wave-based unconventional computing in soft robotics, embedded organic electronics and living technologies.

  19. Electromagnetic energy flux vector for a dispersive linear medium.

    PubMed

    Crenshaw, Michael E; Akozbek, Neset

    2006-05-01

    The electromagnetic energy flux vector in a dispersive linear medium is derived from energy conservation and microscopic quantum electrodynamics and is found to be of the Umov form as the product of an electromagnetic energy density and a velocity vector.

  20. Fem Formulation of Heat Transfer in Cylindrical Porous Medium

    NASA Astrophysics Data System (ADS)

    Azeem; Khaleed, H. M. T.; Soudagar, Manzoor Elahi M.

    2017-08-01

    Heat transfer in porous medium can be derived from the fundamental laws of flow in porous region ass given by Henry Darcy. The fluid flow and energy transport inside the porous medium can be described with the help of momentum and energy equations. The heat transfer in cylindrical porous medium differs from its counterpart in radial and axial coordinates. The present work is focused to discuss the finite element formulation of heat transfer in cylindrical porous medium. The basic partial differential equations are derived using Darcy law which is the converted into a set of algebraic equations with the help of finite element method. The resulting equations are solved by matrix method for two solution variables involved in the coupled equations.

  1. How AACR2 Will Affect a Medium Sized Library.

    ERIC Educational Resources Information Center

    Pang, Isabel S.

    1980-01-01

    Measures the impact of AACR2 on the catalog of a medium sized college library, using data collected from the Library of Congress announced changes. How to deal with these changes and estimate their costs is discussed. (Author/RAA)

  2. The growth of Paracoccus halodenitrificans in a defined medium

    NASA Technical Reports Server (NTRS)

    Hochstein, L. I.; Tomlinson, G. A.

    1984-01-01

    A synthetic medium, consisting of inorganic salts and any of a number of carbon sources, supported the aerobic growth of Paracoccus halodenitrificans when supplemented with thiamine. The same medium plus a nitrogenous oxide supported anaerobic growth when additionally supplemented with methionine. The observation that vitamin B12 or betaine replaced methionine suggested that P. halodenitrificans had a defect in the cobalamin dependent pathway for methionine biosynthesis, as well as the inability to synthesize betanine when growing anaerobically.

  3. On motion in a resisting medium: A historical perspective

    NASA Astrophysics Data System (ADS)

    Hackborn, William W.

    2016-02-01

    This paper examines, compares, and contrasts ideas about motion, especially the motion of a body in a resisting medium, proposed by Galileo, Newton, and Tartaglia, the author of the first text on exterior ballistics, within the context of the Aristotelian philosophy prevalent when these scholars developed their ideas. This historical perspective offers insights on the emergence of a scientific paradigm for motion, particularly with respect to the challenge of incorporating into this paradigm the role played by the medium.

  4. The growth of paracoccus halodenitrificans in a defined medium

    NASA Technical Reports Server (NTRS)

    Hochstein, L. I.; Tomlinson, G. A.

    1983-01-01

    A synthetic medium, consisting of inorganic salts and any of a number of carbon sources, supported the aerobic growth of Paracoccus halodenitrificans when supplemented with thiamine. The same medium plus a nitrogenous oxide supported anaerobic growth when additionally supplemented with methionine. The observation that vitamin B12 or betaine replaced methionine suggested that P. halodenitrificans had a defect in the cobalamin dependent pathway for methionine biosynthesis, as well as the inability to synthesize betaine when growing anaerobically.

  5. Elastic medium equivalent to Fresnel's double-refraction crystal.

    PubMed

    Carcione, José M; Helbig, Klaus

    2008-10-01

    In 1821, Fresnel obtained the wave surface of an optically biaxial crystal, assuming that light waves are vibrations of the ether in which longitudinal vibrations (P waves) do not propagate. An anisotropic elastic medium mathematically analogous to Fresnel's crystal exists. The medium has four elastic constants: a P-wave modulus, associated with a spherical P wave surface, and three elastic constants, c(44), c(55), and c(66), associated with the shear waves, which are mathematically equivalent to the three dielectric permittivity constants epsilon(11), epsilon(22), and epsilon(33) as follows: mu(0)epsilon(11)<==>rho/c(44), mu(0)epsilon(22)<==>rho/c(55), mu(0)epsilon(33)<==>rho/c(66), where mu(0) is the magnetic permeability of vacuum and rho is the mass density. These relations also represent the equivalence between the elastic and electromagnetic wave velocities along the principal axes of the medium. A complete mathematical equivalence can be obtained by setting the P-wave modulus equal to zero, but this yields an unstable elastic medium (the hypothetical ether). To obtain stability the P-wave velocity has to be assumed infinite (incompressibility). Another equivalent Fresnel's wave surface corresponds to a medium with anomalous polarization. This medium is physically unstable even for a nonzero P-wave modulus.

  6. Boric acid-enhanced embedding medium for cryomicrotomy.

    PubMed

    Lim, Jin Ik; Park, Hun-Kuk

    2012-05-01

    A polyvinyl alcohol (PVA)/polyethylene glycol (PEG)-based resin is commonly used as a cryoembedding medium for the histological analysis of frozen tissue sections. However, it is not easy to obtain sufficient numbers of satisfactory reproducible sections owing to the differences between the mechanical properties of the medium and embedded tissue and the low cohesive force of the medium. We describe a modified PVA-based cryoembedding medium, composed of PVA (10wt% and 15wt%) with the addition of boric acid (from 0 to 5wt%), that can improve the sectioning properties and efficiency of frozen tissue for histological analysis. The amount of load under the same compressive displacement as well as cohesive force increased with increasing boric acid and PVA contents. 15wt% PVA and 3wt% boric acid was determined as an optimal composition for cryoembedding material based on the sectioning efficiency measured by the numbers of unimpaired sectioned slices and the amount of load under the same compressive displacement test. On the basis of the results of routine hematoxylin and eosin staining of cryosections of tissue embedded in a medium with 3wt% boric acid and PVA, it was concluded that the modified PVA cryoembedding medium can improve the efficiency of cryosectioning for subsequent histological or histochemical analysis of various tissues. Copyright © 2011 Elsevier GmbH. All rights reserved.

  7. Traditional vs. Non-Traditional Calendar: A Case Analysis of Faculty, Students and Administrative Opinions in a Medium-Sized Public Community College. Report 78-79-02.

    ERIC Educational Resources Information Center

    Parrish, Richard M.; Pascale, Marie

    After reviewing types of college calendars (traditional semester, early semester, trimester, and quarter) and previous research on the use of various school calendars, this paper describes a survey conducted by Ocean County College, a medium-sized college currently using a traditional semester calendar, to determine the views of students, faculty,…

  8. Choice of Scottish Gaelic-Medium and Welsh-Medium Education at the Primary and Secondary School Stages: Parent and Pupil Perspectives

    ERIC Educational Resources Information Center

    O'Hanlon, Fiona

    2015-01-01

    Results are presented of a comparative study of the reasons for parental choice of Scottish Gaelic-medium and Welsh-medium primary education in the year 2000 and of the reasons for pupils' decisions to continue with Gaelic or Welsh-medium education at secondary school in 2007. Parents in both contexts cited the quality of Celtic-medium education…

  9. Larval assemblages of large and medium-sized pelagic species in the Straits of Florida

    NASA Astrophysics Data System (ADS)

    Richardson, David E.; Llopiz, Joel K.; Guigand, Cedric M.; Cowen, Robert K.

    2010-07-01

    Critical gaps in our understanding of the distributions, interactions, life histories and preferred habitats of large and medium-size pelagic fishes severely constrain the implementation of ecosystem-based, spatially structured fisheries management approaches. In particular, spawning distributions and the environmental characteristics associated with the early life stages are poorly documented. In this study, we consider the diversity, assemblages, and associated habitat of the larvae of large and medium-sized pelagic species collected during 2 years of monthly surveys across the Straits of Florida. In total, 36 taxa and 14,295 individuals were collected, with the highest diversity occurring during the summer and in the western, frontal region of the Florida Current. Only a few species (e.g. Thunnus obesus, T. alalunga, Tetrapturus pfluegeri) considered for this study were absent. Small scombrids (e.g. T. atlanticus, Katsuwonus pelamis, Auxis spp.) and gempylids dominated the catch and were orders of magnitude more abundant than many of the rare species (e.g. Thunnus thynnus,Kajikia albida). Both constrained (CCA) and unconstrained (NMDS) multivariate analyses revealed a number of species groupings including: (1) a summer Florida edge assemblage (e.g. Auxis spp., Euthynnus alleterattus, Istiophorus platypterus); (2) a summer offshore assemblage (e.g. Makaira nigricans, T. atlanticus, Ruvettus pretiosus, Lampris guttatus); (3) an ubiquitous assemblage (e.g. K. pelamis, Coryphaena hippurus, Xiphias gladius); and (4) a spring/winter assemblage that was widely dispersed in space (e.g. trachipterids). The primary environmental factors associated with these assemblages were sea-surface temperature (highest in summer-early fall), day length (highest in early summer), thermocline depth (shallowest on the Florida side) and fluorescence (highest on the Florida side). Overall, the results of this study provide insights into how a remarkable diversity of pelagic species

  10. Reflection statistics of weakly disordered optical medium when its mean refractive index is different from an outside medium

    NASA Astrophysics Data System (ADS)

    Pradhan, Prabhakar; John Park, Daniel; Capoglu, Ilker; Subramanian, Hariharan; Damania, Dhwanil; Cherkezyan, Lusik; Taflove, Allen; Backman, Vadim

    2017-06-01

    Statistical properties of light waves reflected from a one-dimensional (1D) disordered optical medium [n(x) = n0+ dn(x), =0] have been well studied, however, most of the studies have focused on the situation when the mean refractive index of the optical medium matched with the outside medium, i.e., n0= nout=1. Further, considering dn(x) as a Gaussian color noise refractive index medium with exponential spatial correlation decay length lc and k as the incident wave vector, it has been shown that for smaller correlation length limit, i.e., klc <<1, both the mean reflection coefficient and std of r, σ(r), have same value, and they follow the relation = σ(r) ∝ lc. However, when the refractive index of the sample medium is different from the outside medium, the reflection statistics may have interesting features, which has not been well studied or understood. We studied the reflection statistics of a 1D weakly disordered optical medium with the mean background refractive index n0 being different from the outside medium nout (≠n0), to see the effect of mismatching (i.e., value of n0- nout) on the reflection statistics. In the mismatched case, the results show that the mean reflection coefficient follows a form similar to that of the matched refractive-index case, i.e., lc, with a linear increased shift, which is due to 1D uniform background reflection from a slab. However, σ(r) is shown to be σ(r) ∝ (lc)1/2, which is different from the matched case. This change in std of r is attributed to the interference between the mismatched-crerated edge mediated multiple scattering that are coupled with the random scattering. Applications to light scattering from random layered media and biological cells are discussed.

  11. Are First Impressions of Unknown Children and Early Adolescents Affected by the Facial Attractiveness of Their Best Friend?

    ERIC Educational Resources Information Center

    Zarbatany, Lynne; Marshall, Kiera G.

    2015-01-01

    This study assessed the effects of a best friend's facial attractiveness on first impressions of medium-attractive children and early adolescents. Younger (N = 114, 48 boys and 66 girls, M[subscript age] = 8.16 years) and older (N = 168, 83 boys and 85 girls, M[subscript age] = 12.32 years) participants rated photos of unknown medium-attractive…

  12. Reframing Early Childhood Leadership

    ERIC Educational Resources Information Center

    Stamopoulos, Elizabeth

    2012-01-01

    Rapid changes in Australian education have intensified the role of early childhood leaders and led to unprecedented challenges. The Australian Curriculum (ACARA, 2011), mandated Australian "National Quality Framework" (NQF) for Early Childhood Education & Care (DEEWR, 2010b) and the "National Early Years Learning Framework"…

  13. Effective-Medium Models for Marine Gas Hydrates, Mallik Revisited

    NASA Astrophysics Data System (ADS)

    Terry, D. A.; Knapp, C. C.; Knapp, J. H.

    2011-12-01

    Hertz-Mindlin type effective-medium dry-rock elastic models have been commonly used for more than three decades in rock physics analysis, and recently have been applied to assessment of marine gas hydrate resources. Comparisons of several effective-medium models with derivative well-log data from the Mackenzie River Valley, Northwest Territories, Canada (i.e. Mallik 2L-38 and 5L-38) were made several years ago as part of a marine gas hydrate joint industry project in the Gulf of Mexico. The matrix/grain supporting model (one of the five models compared) was clearly a better representation of the Mallik data than the other four models (2 cemented sand models; a pore-filling model; and an inclusion model). Even though the matrix/grain supporting model was clearly better, reservations were noted that the compressional velocity of the model was higher than the compressional velocity measured via the sonic logs, and that the shear velocities showed an even greater discrepancy. Over more than thirty years, variations of Hertz-Mindlin type effective medium models have evolved for unconsolidated sediments and here, we briefly review their development. In the past few years, the perfectly smooth grain version of the Hertz-Mindlin type effective-medium model has been favored over the infinitely rough grain version compared in the Gulf of Mexico study. We revisit the data from the Mallik wells to review assertions that effective-medium models with perfectly smooth grains are a better predictor than models with infinitely rough grains. We briefly review three Hertz-Mindlin type effective-medium models, and standardize nomenclature and notation. To calibrate the extended effective-medium model in gas hydrates, we use a well accepted framework for unconsolidated sediments through Hashin-Shtrikman bounds. We implement the previously discussed effective-medium models for saturated sediments with gas hydrates and compute theoretical curves of seismic velocities versus gas hydrate

  14. Prospect of stem cell conditioned medium in regenerative medicine.

    PubMed

    Pawitan, Jeanne Adiwinata

    2014-01-01

    Stem cell-derived conditioned medium has a promising prospect to be produced as pharmaceuticals for regenerative medicine. To investigate various methods to obtain stem cell-derived conditioned medium (CM) to get an insight into their prospect of application in various diseases. Systematic review using keywords "stem cell" and "conditioned medium" or "secretome" and "therapy." Data concerning treated conditions/diseases, type of cell that was cultured, medium and supplements to culture the cells, culture condition, CM processing, growth factors and other secretions that were analyzed, method of application, and outcome were noted, grouped, tabulated, and analyzed. Most of CM using studies showed good results. However, the various CM, even when they were derived from the same kind of cells, were produced by different condition, that is, from different passage, culture medium, and culture condition. The growth factor yields of the various types of cells were available in some studies, and the cell number that was needed to produce CM for one application could be computed. Various stem cell-derived conditioned media were tested on various diseases and mostly showed good results. However, standardized methods of production and validations of their use need to be conducted.

  15. Linear analysis of active-medium two-beam accelerator

    NASA Astrophysics Data System (ADS)

    Voin, Miron; Schächter, Levi

    2015-07-01

    We present detailed development of the linear theory of wakefield amplification by active medium and its possible application to a two-beam accelerator (TBA) is discussed. A relativistic train of triggering microbunches traveling along a vacuum channel in an active medium confined by a cylindrical waveguide excites Cherenkov wake in the medium. The wake is a superposition of azimuthally symmetric transverse magnetic modes propagating along a confining waveguide, with a phase velocity equal to the velocity of the triggering bunches. The structure may be designed in such a way that the frequency of one of the modes is close to active-medium resonant frequency, resulting in amplification of the former and domination of a single mode far behind the trigger bunches. Another electron bunch placed in proper phase with the amplified wakefield may be accelerated by the latter. Importantly, the energy for acceleration is provided by the active medium and not the drive bunch as in a traditional TBA. Based on a simplified model, we analyze extensively the impact of various parameters on the wakefield amplification process.

  16. Microbial synthesis of medium-chain chemicals from renewables.

    PubMed

    Sarria, Stephen; Kruyer, Nicholas S; Peralta-Yahya, Pamela

    2017-12-01

    Linear, medium-chain (C8-C12) hydrocarbons are important components of fuels as well as commodity and specialty chemicals. As industrial microbes do not contain pathways to produce medium-chain chemicals, approaches such as overexpression of endogenous enzymes or deletion of competing pathways are not available to the metabolic engineer; instead, fatty acid synthesis and reversed β-oxidation are manipulated to synthesize medium-chain chemical precursors. Even so, chain lengths remain difficult to control, which means that purification must be used to obtain the desired products, titers of which are typically low and rarely exceed milligrams per liter. By engineering the substrate specificity and activity of the pathway enzymes that generate the fatty acyl intermediates and chain-tailoring enzymes, researchers can boost the type and yield of medium-chain chemicals. Development of technologies to both manipulate chain-tailoring enzymes and to assay for products promises to enable the generation of g/L yields of medium-chain chemicals.

  17. Petroleum Jelly: A Novel Medium for Ocular Ultrasound.

    PubMed

    Engelbert, Patrick R; Palma, James K

    2015-08-01

    Ocular ultrasound is a useful emergency department imaging modality for evaluation of many conditions, such as retinal detachment, vitreous detachment, vitreous hemorrhage, and elevated intracranial pressure. Obtaining satisfactory ocular ultrasound images requires the use of a medium that eliminates the air interface between the patient's eye and the transducer. Ultrasound gel is most commonly used; however, the use of a transparent dressing applied to the closed eye prior to the application of gel has also been described as a suitable technique. Ocular ultrasound is performed with the high-frequency linear array transducer using a medium to eliminate the air interface between the eye and the transducer. Although ultrasound gel is most frequently used, it can cause minor eye irritation. Placing a transparent dressing over a closed eye prior to application of gel can eliminate the eye irritation. However, our experience in training >500 students in ocular ultrasound has shown that air is frequently introduced underneath the dressing, which leads to poor-quality images. This article introduces petroleum jelly as a medium for ocular ultrasound. By applying a layer of petroleum jelly over the closed eye and allowing it to warm via body heat for 30 to 45 s, this medium can both minimize patient discomfort and provide easily obtainable, high-quality ocular ultrasound images. This article introduces petroleum jelly as a safe, comfortable, and effective medium for ocular ultrasound examination. Published by Elsevier Inc.

  18. Mitochondrial DNA content in embryo culture medium is significantly associated with human embryo fragmentation.

    PubMed

    Stigliani, S; Anserini, P; Venturini, P L; Scaruffi, P

    2013-10-01

    Is the amount of cell-free DNA released by human embryos into culture medium correlated with embryo morphological features? The mitochondrial DNA (mtDNA) content of culture medium is significantly associated with the fragmentation rate on Days 2 and 3 of embryo development, whether the oocyte came from women ≤ 35 or >35 years old. Cellular fragmentation is often utilized as one of the morphological parameters for embryo quality assessment. The amount of cellular fragments is considered to be an important morphological parameter for embryo implantation potential. It has been hypothesized that fragments are apoptotic bodies or anuclear cytoplasmatic pieces of blastomeres, although no definitive conclusion has been drawn about their pathogenesis. Human fertilized oocytes were individually cultured from Day 1 to Days 2 and 3. A total of 800 samples (166 spent media from Day 2 and 634 from Day 3) were enrolled into the present study. Double-stranded DNA (dsDNA) was quantified in 800 spent embryo culture media by Pico Green dye fluorescence assay. After DNA purification, genomic DNA (gDNA) and mtDNA were profiled by specific quantitative PCR. Statistical analyses defined correlations among DNA contents, embryo morphology and maternal age. Different independent tests confirmed the presence of DNA into embryo culture medium and, for the first time, we demonstrate that both gDNA and mtDNA are detectable in the secretome. The amount of DNA is larger in embryos with bad quality cleavage compared with high-grade embryos, suggesting that the DNA profile of culture medium is an objective marker for embryo quality assessment. In particular, DNA profiles are significantly associated with fragmentation feature (total dsDNA: P = 0.0010; mtDNA; P = 0.0247) and advanced maternal age. It is necessary to establish whether DNA profiling of spent embryo culture medium is a robust onsite test that can improve the prediction of blastulation, implantation and/or pregnancy rate. The

  19. Extruder system and method for treatment of a gaseous medium

    SciTech Connect

    Silvi, Norberto; Perry, Robert James; Singh, Surinder Prabhjot

    A system for treatment of a gaseous medium, comprises an extruder having a barrel. The extruder further comprises a first inlet port, a second inlet port, and a plurality of outlet ports coupled to the barrel. The first inlet port is configured for feeding a lean sorbent, the second inlet port is configured for feeding a gaseous medium, and the plurality of outlet ports are configured for releasing a plurality of components removed from the gaseous medium. Further, the extruder comprises a plurality of helical elements coupled to a plurality of kneading elements, mounted on a shaft, and disposed withinmore » the barrel. The barrel and the plurality of helical and kneading elements together form an absorption unit and a desorption unit. The first and second inlet ports are formed in the absorption unit and the plurality of outlet ports are formed in the absorption and desorption units.« less

  20. Customer relationship management implementation in the small and medium enterprise

    NASA Astrophysics Data System (ADS)

    Nugroho, Agus; Suharmanto, Agus; Masugino

    2018-03-01

    To win the global competition and sustain the business, small and medium enterprise shall implement a reliable information technology application to support their customer data base, production and sales as well as marketing management. This paper addresses the implementation of Customer Relationship Management (CRM) in small and medium enterprise, CV. Densuko Jaya. It is a small and medium enterprises in Semarang, Central Java, Republic of Indonesia deal with rubber processing industry supply chain. ADDIE model utilized in study to setup the CRM functionality at these enterprises. The aim of the authors is to present the benefits resulting from the application of CRM technologies at these enterprises to solve their chronicle issues in the field of integrated customer data base, production management process and sales automation in order to boost their business in the near future. Training and coaching have been delivered to the enterprises staffs and management to ensure that they can execute the system.

  1. Medium-Induced QCD Cascade: Democratic Branching and Wave Turbulence

    NASA Astrophysics Data System (ADS)

    Blaizot, J.-P.; Iancu, E.; Mehtar-Tani, Y.

    2013-08-01

    We study the average properties of the gluon cascade generated by an energetic parton propagating through a quark-gluon plasma. We focus on the soft, medium-induced emissions which control the energy transport at large angles with respect to the leading parton. We show that the effect of multiple branchings is important. In contrast with what happens in a usual QCD cascade in vacuum, medium-induced branchings are quasidemocratic, with offspring gluons carrying sizable fractions of the energy of their parent gluon. This results in an efficient mechanism for the transport of energy toward the medium, which is akin to wave turbulence with a scaling spectrum ˜1/ω. We argue that the turbulent flow may be responsible for the excess energy carried by very soft quanta, as revealed by the analysis of the dijet asymmetry observed in Pb-Pb collisions at the LHC.

  2. The Interstellar Medium in External Galaxies: Summaries of contributed papers

    NASA Technical Reports Server (NTRS)

    Hollenbach, David J. (Editor); Thronson, Harley A., Jr. (Editor)

    1990-01-01

    The Second Wyoming Conference entitled, The Interstellar Medium in External Galaxies, was held on July 3 to 7, 1989, to discuss the current understanding of the interstellar medium in external galaxies and to analyze the basic physical processes underlying interstellar phenomena. The papers covered a broad range of research on the gas and dust in external galaxies and focused on such topics as the distribution and morphology of the atomic, molecular, and dust components; the dynamics of the gas and the role of the magnetic field in the dynamics; elemental abundances and gas depletions in the atomic and ionized components; cooling flows; star formation; the correlation of the nonthermal radio continuum with the cool component of the interstellar medium; the origin and effect of hot galactic halos; the absorption line systems seen in distant quasars; and the effect of galactic collisions.

  3. Taming instability of magnetic field in chiral medium

    NASA Astrophysics Data System (ADS)

    Tuchin, Kirill

    2018-01-01

    Magnetic field is unstable in a medium with time-independent chiral conductivity. Owing to the chiral anomaly, the electromagnetic field and the medium exchange helicity which results in time-evolution of the chiral conductivity. Using the fastest growing momentum and helicity state of the vector potential as an ansatz, the time-evolution of the chiral conductivity and magnetic field is solved analytically. The solution for the hot and cold equations of state shows that the magnetic field does not develop an instability due to helicity conservation. Moreover, as a function of time, it develops a peak only if a significant part of the initial helicity is stored in the medium. The initial helicity determines the height and position of the peak.

  4. Minkowski spacetime does not apply to a homogeneously accelerating medium

    NASA Astrophysics Data System (ADS)

    Coleman, Brian

    Home and comoving inertial frame parameters of an individual point of an idealized medium of launch length L uniformly co-accelerating between identical fixed-thrust rockets, are well known. This is not the case with the varying inter-rocket radar periods and related implications regarding a changing 'noninertial own-length' Λ which differs from a front rocket's retrospective separation L from the simultaneously relatively moving rear rocket. On the other hand, the nonhomogeneous acceleration case involving every comoving frame's unchanging perception of a contrived 'rigor mortis' medium (so-called 'rigid motion' traditionally associated with 'Rindler coordinates') whereby Λ = L = L , constitutes the sole extended accelerating medium scenario where the entrenched Minkowski metric is actually applicable. Paraphrasing Wolfgang Pauli, not only is Minkowski spacetime not correct [in the general sense], it is not even wrong [in the restricted sense].

  5. An alternative bacteriological medium for the isolation of Aeromonas spp.

    USGS Publications Warehouse

    Jenkins, J.A.; Taylor, P.W.

    1995-01-01

    Two solid bacteriologic media were compared for cultivating Aeromonas spp. from piscine sources: the Rimler-Shotts (RS) medium and a starch-glutamate-ampicillin-penicillin-based medium (SGAP-10C) used for the recovery of Aeromonas spp. from water samples. The selective and differential capacities of the media were assessed March through October 1992 by recovery rate and phenotype of 99 isolates representing 15 genera of bacteria. Recovery frequency of Aeromonas spp. (n = 62) was similar at 97% on RS and 95% on SGAP-10C. The SGAP-10C medium proved to be more specific than RS toward Aeromonas species (P ≤ 0.005). Use of SGAP-10C at 24 C for 48 hr offers a better choice for the laboratory recovery of Aeromonas spp. from clinical fish specimens.

  6. Physical structure changes of solid medium by steam explosion sterilization.

    PubMed

    Zhao, Zhi-Min; Wang, Lan; Chen, Hong-Zhang

    2016-03-01

    Physical structure changes of solid medium were investigated to reveal effects of steam explosion sterilization on solid-state fermentation (SSF). Results indicated that steam explosion changed the structure of solid medium at both molecular and three-dimensional structural levels, which exposed hydrophilic groups and enlarged pores and cavities. It was interesting to find that pores where capillary water located were the active sites for SSF, due to the close relationship among capillary water relaxation time, specific surface area and fermentation performance. Therefore, steam explosion sterilization increased the effective contact area for microbial cells on solid medium, which contributed to improving SSF performance. Combined with the previous research, mechanisms of SSF improvement by steam explosion sterilization contained both chemical and physical effects. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Intergalactic Encounters: Desire and the Political Immediacy of Children's Drawing

    ERIC Educational Resources Information Center

    Schulte, Christopher M.

    2015-01-01

    The author of this article creates a semblance between Deleuze and Guattari's conception of a politics of desire and the four realities, as outlined by Brent and Marjorie Wilson. By making this theoretical move, the author advances the idea that children's drawing unfolds from one moment to the next through the assemblages of desire that are most…

  8. Effective role of medium supplementation in microalgal lipid accumulation.

    PubMed

    Fazeli Danesh, Azadeh; Mooij, Peter; Ebrahimi, Sirous; Kleerebezem, Robbert; van Loosdrecht, Mark

    2018-05-01

    The present study investigated the interaction between starch and lipid accumulation in a green microalgae enrichment culture. The objective was to optimize the lipid content by manipulation of the medium in regular batch culture. Two medium designs were evaluated: First a high ortho-P concentration with vitamin supplementary (Pi-vitamins supplemented medium), second normal growth medium (control). Both media contained a low amount of nitrogen which was consumed during batch growth in three days. The batch experiments continued for another 4 days with the absence of soluble nitrogen in the medium. When the mixed microalgal culture was incubated in the Pi-vitamin supplemented medium, the lipid, and starch content of the culture increased within the first 3 days to 102.0 ± 5.2 mg/L (12.7 ± 0.6% of DW) and 31.7 ± 1.6 mg/L (4.0 ± 0.2% of DW), respectively. On the last day of the experiment, the lipid, and starch content in Pi-vitamin medium increased to 663.1 ± 32.5 mg/L (33.4 ± 1.6% of DW) and 127.5 ± 5.2 mg/L (6.4 ± 0.3% of DW). However, the lipid and starch content in the control process, reached to 334.7 ± 16.4 mg/L (20.1 ± 1.0% of DW) and 94.3 ± 4.6 mg/L (5.7 ± 0.3% of DW), respectively. The high Pi-vitamin medium induced storing lipid formation clearly while the starch formation was not affected. The lipid contents reported here are among the high reported in the literature, note that already under full growth conditions significant lipid levels occurred in the algal enrichment culture. The high lipid productivity of the reported mixed microalgae culture provides an efficient route for efficient algal biodiesel production. © 2018 Wiley Periodicals, Inc.

  9. Nucleon QCD sum rules in the instanton medium

    SciTech Connect

    Ryskin, M. G.; Drukarev, E. G., E-mail: drukarev@pnpi.spb.ru; Sadovnikova, V. A.

    2015-09-15

    We try to find grounds for the standard nucleon QCD sum rules, based on a more detailed description of the QCD vacuum. We calculate the polarization operator of the nucleon current in the instanton medium. The medium (QCD vacuum) is assumed to be a composition of the small-size instantons and some long-wave gluon fluctuations. We solve the corresponding QCD sum rule equations and demonstrate that there is a solution with the value of the nucleon mass close to the physical one if the fraction of the small-size instantons contribution is w{sub s} ≈ 2/3.

  10. Measuring medium-induced gluons via jet grooming

    NASA Astrophysics Data System (ADS)

    Tywoniuk, Konrad; Mehtar-Tani, Yacine

    2017-11-01

    Jet substructure observables and applications of jet grooming techniques in heavy-ion collisions are still in its infancy and provide new alleys for studying medium modifications of perturbative degrees of freedom. We note that these measurements, given the right transverse momentum range, can be uniquely sensitive to rare medium-induced emissions inside of the jet cone. This corresponds to an infrared enhancement that would, for instance, affect the distribution of the groomed momentum-sharing variable zg measured using the SoftDrop procedure.

  11. Coconut as a Medium for the Experimental Production of Aflatoxin

    PubMed Central

    Arseculeratne, S. N.; De Silva, L. M.; Wijesundera, S.; Bandunatha, C. H. S. R.

    1969-01-01

    Fresh, grated coconut has been found to be an excellent medium for aflatoxin production by Aspergillus flavus. Under optimal conditions, yields of 8 mg of total aflatoxin per g of substrate were obtained. Continuous agitation of the growth medium under moist conditions at 24 C produced highest yields. Aflatoxin was assayed both biologically and chromatographically. The aflatoxin content of cultures varied biphasically with the duration of incubation. It is suggested that this pattern could result from the sequential operation of factors promoting aflatoxin formation on the one hand and a detoxifying mechanism on the other. Images PMID:5803632

  12. Discrete Morse flow for Ricci flow and porous medium equation

    NASA Astrophysics Data System (ADS)

    Ma, Li; Witt, Ingo

    2018-06-01

    In this paper, we study the discrete Morse flow for the Ricci flow on the American football, which is the 2-sphere with the north and south poles removed and equipped with a metric g0 of constant scalar curvature, and for the porous medium equation on a bounded regular domain in the plane. We show that under suitable assumptions on the initial metric g(0) one has a weak approximate discrete Morse flow for the approximated Ricci flow and porous medium equation on any time interval.

  13. Cryopreservation of Human Pluripotent Stem Cells in Defined Medium

    PubMed Central

    Liu, Weiwei; Chen, Guokai

    2014-01-01

    This protocol describes a cryopreservation procedure using an enzyme-free dissociation method to harvest cells and preserve cells in albumin-free chemically defined E8 medium for human pluripotent stem cells (hPSCs). The dissociation by EDTA/PBS produces small cell aggregates that allow high survival efficiency in passaging and cryopreservation. The preservation in E8 medium eliminates serum or other animal products, and is suitable for the increasing demand for high quality hPSCs in translational research. In combination with the special feature of EDTA/PBS dissociation, this protocol allows efficient cryopreservation in more time-saving manner. PMID:25366897

  14. CYLINDRICAL WAVES OF FINITE AMPLITUDE IN DISSIPATIVE MEDIUM (in Russian)

    SciTech Connect

    Naugol'nykh, K.A.; Soluyan, S.I.; Khokhlov, R.V.

    1962-07-01

    Propagation of diverging and converging cylindrical waves in a nonlinear, viscous, heat conducting medium is analyzed using approximation methods. The KrylovBogolyubov method was used for small Raynold's numbers, and the method of S. I. Soluyan et al. (Vest. Mosk. Univ. ser. phys. and astronomy 3, 52-81, 1981), was used for large Raynold's numbers. The formation and dissipation of shock fronts and spatial dimensions of shock phenomena were analyzed. It is shown that the problem of finiteamplitude cylindrical wave propagation is identical to the problem of plane wave propagations in a medium with variable viscosity. (tr-auth)

  15. Active microwave remote sensing of an anisotropic random medium layer

    NASA Technical Reports Server (NTRS)

    Lee, J. K.; Kong, J. A.

    1985-01-01

    A two-layer anisotropic random medium model has been developed to study the active remote sensing of the earth. The dyadic Green's function for a two-layer anisotropic medium is developed and used in conjunction with the first-order Born approximation to calculate the backscattering coefficients. It is shown that strong cross-polarization occurs in the single scattering process and is indispensable in the interpretation of radar measurements of sea ice at different frequencies, polarizations, and viewing angles. The effects of anisotropy on the angular responses of backscattering coefficients are also illustrated.

  16. Characterization of In-Use Medium Duty Electric Vehicle Driving and Charging Behavior: Preprint

    SciTech Connect

    Duran, A.; Ragatz, A.; Prohaska, R.

    2014-11-01

    The U.S. Department of Energy's American Recovery and Reinvestment Act (ARRA) deployment and demonstration projects are helping to commercialize technologies for all-electric vehicles (EVs). Under the ARRA program, data from Smith Electric and Navistar medium duty EVs have been collected, compiled, and analyzed in an effort to quantify the impacts of these new technologies. Over a period of three years, the National Renewable Energy Laboratory (NREL) has compiled data from over 250 Smith Newton EVs for a total of over 100,000 days of in-use operation. Similarly, data have been collected from over 100 Navistar eStar vehicles, with over 15,000 operatingmore » days having been analyzed. NREL has analyzed a combined total of over 4 million kilometers of driving and 1 million hours of charging data for commercial operating medium duty EVs. In this paper, the authors present an overview of medium duty EV operating and charging behavior based on in-use data collected from both Smith and Navistar vehicles operating in the United States. Specifically, this paper provides an introduction to the specifications and configurations of the vehicles examined; discusses the approach and methodology of data collection and analysis, and presents detailed results regarding daily driving and charging behavior. In addition, trends observed over the course of multiple years of data collection are examined, and conclusions are drawn about early deployment behavior and ongoing adjustments due to new and improving technology. Results and metrics such as average daily driving distance, route aggressiveness, charging frequency, and liter per kilometer diesel equivalent fuel consumption are documented and discussed.« less

  17. Medium-chain triglycerides in infant formulas and their relation to plasma ketone body concentrations.

    PubMed

    Wu, P Y; Edmond, J; Auestad, N; Rambathla, S; Benson, J; Picone, T

    1986-04-01

    A mild ketosis is known to prevail in the mother, fetus, and newborn infant during the 3rd trimester and in the early neonatal period. It has been shown that during an equivalent period in the rat ketone bodies are readily oxidized and serve as key substrates for lipogenesis in brain. Since medium-chain triglycerides are known to be ketogenic, preterm infants may benefit from dietary medium-chain triglycerides beyond the point of enhanced fat absorption. Our objective was to determine the ketogenic response in preterm infants (gestational age: 33 +/- 0.8 wk) fed three different isocaloric formulas by measuring the concentrations of 3-hydroxybutyrate and acetoacetate in the plasma of these infants. At the time of entrance to the study the infants were receiving 110 kcal/kg/24 h. Study I (11 infants): the infants were fed sequentially in the order; PM 60/40 (PM), Special Care Formula (SCF), and Similac 20 (SIM). In SCF greater than 50% of the fat consists of medium-chain length fatty acids while PM and SIM contain about 25%. The concentration of 3-hydroxybutyrate in plasma was significantly higher when infants were fed SCF than PM and SIM [0.14 +/- 0.03, 0.06 +/- 0.01, and 0.05 +/- 0.01 mM, respectively (p less than 0.01)]. Study II (12 infants); the infants were fed SCF, then SIM, or the reverse. The concentration of acetoacetate in plasma was 0.05 +/- 0.01 and 0.03 +/- 0.01 mM when infants were fed SCF and SIM, respectively (0.1 greater than p greater than 0.05). The concentrations of 3-hydroxybutyrate in plasma were similar to those measured in study I for the respective formulas.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Medium-term outcome of Toronto aortic valve replacement: single center experience.

    PubMed

    Li, Wei; Price, Susanna; O'Sullivan, Christine A; Kumar, Pankaj; Jin, Xu Y; Henein, Michael Y; Pepper, John R

    2008-09-26

    Long-term competence of any aortic prosthesis is critical to its clinical durability. Bioprosthetic valves, and in particular the stentless type have been proposed to offer superior haemodynamic profiles with consequent potential for superior left-ventricular mass regression. These benefits however are balanced by the potential longevity of the implanted valve. The aims of this study were to assess medium-term Toronto aortic valve function and its effect on left-ventricular function. Between 1992 and 1996 86 patients underwent Toronto aortic valve replacement for aortic valve disease and were followed up annually. Prospectively collected data was analyzed for all patients where detailed echocardiographic follow-up was available. Echocardiographic studies were analyzed at 2+/-0.6 and 6+/-1.4 years after valve replacement. Data collected included left-ventricular systolic and diastolic dimensions, fractional shortening and left-ventricular mass. In addition, data on aortic valve and root morphology, peak aortic velocities, time velocity integral, stroke volume and the mechanism of valve failure where relevant, were also collected. Complete echocardiographic data were available for eighty-four patients, age 69+/-9 years, 62 male. Additional coronary artery bypass grafting was performed in 38% of patients. Twelve (14%) valves had failed during follow-up, 7 (8%) requiring re-operation. Valve failure was associated with morphologically bicuspid native aortic valve (9/12), and progressive dilatation of the aortic sinuses, sino-tubular junction and ascending aorta (11/12). Left-ventricular mass index remained high (184+/-75 g/m(2)) and did not continue to regress between early and medium-term follow-up (175.8+/-77 g/m(2)). Although more than 90% of implanted Toronto aortic valves remained haemodynamically stable with low gradient at medium-term follow-up, young age and larger aortic dimensions in patients with valve failure suggest better outcome if used in the elderly

  19. Heavy quark complex potential in a strongly magnetized hot QGP medium

    NASA Astrophysics Data System (ADS)

    Singh, Balbeer; Thakur, Lata; Mishra, Hiranmaya

    2018-05-01

    We study the effect of a strong constant magnetic field, generated in relativistic heavy ion collisions, on the heavy quark complex potential. We work in the strong magnetic field limit with the lowest Landau level approximation. We find that the screening of the real part of the potential increases with the increase in the magnetic field. Therefore, we expect less binding of the Q Q ¯ pair in the presence of a strong magnetic field. The imaginary part of the potential increases in magnitude with the increase in magnetic field, leading to an increase of the width of the quarkonium state with the magnetic field. All of these effects result in the early dissociation of Q Q ¯ states in a magnetized hot quark-gluon plasma medium.

  20. Parental Experiences of Raising a Child With Medium Chain Acyl-CoA Dehydrogenase Deficiency.

    PubMed

    Piercy, Hilary; Machaczek, Katarzyna; Ali, Parveen; Yap, Sufin

    2017-01-01

    Newborn screening enabling early diagnosis of medium chain acyl-CoA dehydrogenase deficiency (MCADD) has dramatically improved health outcomes in children with MCADD. Achieving those outcomes depends on effective management by parents. Understanding parental management strategies and associated anxieties and concerns is needed to inform provision of appropriate care and support. Semistructured interviews were conducted with a purposive sample of parents of children aged 2 to 12 years. Thematic analysis identified two main themes. Managing dietary intake examined how parents managed day-to-day dietary intake to ensure adequate intake and protection of safe fasting intervals. Managing and preventing illness events explored parental experiences of managing illness events and their approach to preventing these events. Management strategies were characterized by caution and vigilance and influenced by a lack of confidence in others to manage the condition. The study identifies the need for increased awareness of the condition, particularly in relation to emergency treatment.

  1. Cuphea: a new plant source of medium-chain fatty acids.

    PubMed

    Graham, S A

    1989-01-01

    The plant genus Cuphea (family Lythraceae) promises to provide a new source of industrially and nutritionally important medium-chain fatty acids, especially of lauric acid now supplied exclusively by coconut and palm kernel oils from foreign sources. The seed lipids of Cuphea were first discovered in the 1960s to contain high percentages of several medium-chain fatty acids, including caprylic, capric, lauric, and myristic acid. Research is still in the early stages, but it is intensifying toward the goal of developing the genus into a new temperate climate crop for production of specialty oils. Given the diversity of Cuphea seed lipid composition and the wide ecological and distributional range of the genus, it may be possible to tailor crops to produce selected fatty acids on demand under a variety of growing conditions. Cuphea comprises about 260 species, most native to the New World tropics. Its morphology, classification, chromosome numbers, distribution, ecology, and folk uses are presented. Seed structure is described and seed lipid composition for 73 species is summarized. Problems in domestication and agronomic progress are reviewed. Knowledge of the biosynthetic mechanism controlling the lipids produced by Cuphea remains very limited. Future research in this area, and particularly successful employment of gene transfer techniques, may allow genes controlling the mechanism to be transferred to an already established seed oil producer such as rapeseed. Presently, both traditional plant breeding techniques and newer biotechnological methods are directed toward Cuphea oilseed development.

  2. Temperature uniformity of the bulk medium produced in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Ray, Lanny

    2006-10-01

    The success of hydrodynamic models of elliptic flow in relativistic heavy ion collisions is often touted as evidence for rapid thermal equilibration. However, large momentum scale two-particle correlations indicate that a significant fraction of the final-state hadrons retain jet-like correlation structure associated with early stage, non-equilibrated low-Q^2 partons [1]. In addition, correlations on transverse momentum (pt1xpt2) suggest that low-Q^2 parton momentum is partially dissipated causing fluctuations in the effective temperature (thermal and/or collective motion) of the bulk medium[2]. We first show that both global and local temperature fluctuation models describe the available (pt1xpt2) correlation data equally well. Results of an analytical model are then presented which tests the sensitivity of (pt1xpt2) correlations to the first few lower-order cumulants of the two-point temperature distribution for the event ensemble. Unique signatures in the predicted (pt1xpt2) correlations are observed for each cumulant term studied. The prospects for direct measurement of the absolute temperature distribution in the bulk medium produced in relativistic heavy-ion collisions using (pt1xpt2) and other correlation measures are discussed. [1] J. Adams et al., Phys. Rev. C 73, 064907 (2006); J. Phys.G. 32, L37 (2006). [2]J. Adams et al., nucl-ex/0408012.

  3. A novel sample preparation method to avoid influence of embedding medium during nano-indentation

    NASA Astrophysics Data System (ADS)

    Meng, Yujie; Wang, Siqun; Cai, Zhiyong; Young, Timothy M.; Du, Guanben; Li, Yanjun

    2013-02-01

    The effect of the embedding medium on the nano-indentation measurements of lignocellulosic materials was investigated experimentally using nano-indentation. Both the reduced elastic modulus and the hardness of non-embedded cell walls were found to be lower than those of the embedded samples, proving that the embedding medium used for specimen preparation on cellulosic material during nano-indentation can modify cell-wall properties. This leads to structural and chemical changes in the cell-wall constituents, changes that may significantly alter the material properties. Further investigation was carried out to detect the influence of different vacuum times on the cell-wall mechanical properties during the embedding procedure. Interpretation of the statistical analysis revealed no linear relationships between vacuum time and the mechanical properties of cell walls. The quantitative measurements confirm that low-viscosity resin has a rapid penetration rate early in the curing process. Finally, a novel sample preparation method aimed at preventing resin diffusion into lignocellulosic cell walls was developed using a plastic film to wrap the sample before embedding. This method proved to be accessible and straightforward for many kinds of lignocellulosic material, but is especially suitable for small, soft samples.

  4. Numerical Simulations of Supernova Remnant Evolution in a Cloudy Interstellar Medium

    SciTech Connect

    Slavin, Jonathan D.; Smith, Randall K.; Foster, Adam

    The mixed morphology class of supernova remnants has centrally peaked X-ray emission along with a shell-like morphology in radio emission. White and Long proposed that these remnants are evolving in a cloudy medium wherein the clouds are evaporated via thermal conduction once being overrun by the expanding shock. Their analytical model made detailed predictions regarding temperature, density, and emission profiles as well as shock evolution. We present numerical hydrodynamical models in 2D and 3D including thermal conduction, testing the White and Long model and presenting results for the evolution and emission from remnants evolving in a cloudy medium. We findmore » that, while certain general results of the White and Long model hold, such as the way the remnants expand and the flattening of the X-ray surface brightness distribution, in detail there are substantial differences. In particular we find that the X-ray luminosity is dominated by emission from shocked cloud gas early on, leading to a bright peak, which then declines and flattens as evaporation becomes more important. In addition, the effects of thermal conduction on the intercloud gas, which is not included in the White and Long model, are important and lead to further flattening of the X-ray brightness profile as well as lower X-ray emission temperatures.« less

  5. Three-dimensional Rayleigh-Taylor convection of miscible fluids in a porous medium

    NASA Astrophysics Data System (ADS)

    Suekane, Tetsuya; Nakanishi, Yuji; Wang, Lei

    2017-11-01

    Natural convection of miscible fluids in a porous medium is relevant for fields, such as geoscience and geoengineering, and for the geological storage of CO2. In this study, we use X-ray computer tomography to visualize 3D fingering structures associated with the Rayleigh-Taylor instability between miscible fluids in a porous medium. In the early stages of the onset of the Rayleigh-Taylor instability, a fine crinkling pattern gradually appears at the interface. As the wavelength and amplitude increase, descending fingers form on the interface and extend vertically downward; moreover, ascending and highly symmetric fingers form. The adjacent fingers are cylindrical in shape and coalesce to form large fingers. Fingers appearing on the interface tend to become finer with increasing Rayleigh number, which is consistent with linear perturbation theory. If the Péclet number exceeds 10, the transverse dispersion increases the finger diameter and enhances finger coalescence, strongly impacting the decay in finger number density. When mechanical dispersion is negligible, the finger-extension velocity, the mass-transfer rate, and the onset time scale with Rayleigh number. Mechanical dispersion not only reduces the onset time but also enhances mass transport, which indicates that mechanical dispersion influences the long-term dissolution process of CO2 injected into aquifers.

  6. Discharges to prison from medium secure psychiatric units in England and Wales.

    PubMed

    Doyle, Michael; Coid, Jeremy; Archer-Power, Laura; Dewa, Lindsay; Hunter-Didrichsen, Alice; Stevenson, Rachel; Wainwright, Verity; Kallis, Costas; Ullrich, Simone; Shaw, Jenny

    2014-09-01

    Early findings from a national study of discharges from 32 National Health Service medium secure units revealed that nearly twice as many patients than expected were discharged back to prison. To compare the characteristics of those discharged back to prison with those discharged to the community, and consider the implications for ongoing care and risk. Prospective cohort follow-up design. All forensic patients discharged from 32 medium secure units across England and Wales over a 12-month period were identified. Those discharged to prison were compared with those who were discharged to the community. Nearly half of the individuals discharged to prison were diagnosed with a serious mental illness and over a third with schizophrenia. They were a higher risk, more likely to have a personality disorder, more symptomatic and less motivated than those discharged to the community. Findings suggest that alternative models of prison mental healthcare should be considered to reduce risks to the patient and the public. Royal College of Psychiatrists.

  7. Cosmology and the early universe

    NASA Astrophysics Data System (ADS)

    Joshi, Abhigna

    2017-01-01

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

  8. Early detection and rapid response

    USGS Publications Warehouse

    Westbrooks, Randy G.; Eplee, Robert E.; Simberloff, Daniel; Rejmánek, Marcel

    2011-01-01

    Prevention is the first line of defense against introduced invasive species - it is always preferable to prevent the introduction of new invaders into a region or country. However, it is not always possible to detect all alien hitchhikers imported in cargo, or to predict with any degree of certainty which introduced species will become invasive over time. Fortunately, the majority of introduced plants and animals don't become invasive. But, according to scientists at Cornell University, costs and losses due to species that do become invasive are now estimated to be over $137 billion/year in the United States. Early detection and rapid response (EDRR) is the second line of defense against introduced invasive species - EDRR is the preferred management strategy for preventing the establishment and spread of invasive species. Over the past 50 years, there has been a gradual shift away from large and medium scale federal/state single-agency-led weed eradication programs in the United States, to smaller interagency-led projects involving impacted and potential stakeholders. The importance of volunteer weed spotters in detecting and reporting suspected new invasive species has also been recognized in recent years.

  9. Propagation and Evolution of CMEs in the Interplanetary Medium: Analysis of Remote Sensing and In situ Observations

    NASA Technical Reports Server (NTRS)

    Figueroa-Vinas, Adolfo; Nieves-Chinchilla, Teresa; Vourlidas, Angelos; Gomez-Herrero, Raul; Malandraki, Olga; Szabo, Adam; Dresing, Nina; Davila, Joseph M.

    2010-01-01

    EUV disk imagers and white light coronagraphs have provided for many years information on the early formation and evolution of corona) mass ejections (CMEs). More recently, the novel heliospheric imaging instruments aboard the STEREO mission are providing crucial remote sensing information on the interplanetary evolution of these events while in situ instruments complete the overall characterization of the interplanetary CMEs. In this work, we present an analysis of CMEs from the Sun to the interplanetary medium using combined data from THE SOHO, STEREO, WIND, and ACE spacecraft. The events were selected to cover the widest possible spectrum of different ambient solar wind, magnetic field configurations, plasma parameters, etc. to allow uncovering those aspects that are important in understanding the propagation and evolution mechanisms of CMEs in the interplanetary medium.

  10. Probing the mechanisms of drug release from amorphous solid dispersions in medium-soluble and medium-insoluble carriers.

    PubMed

    Sun, Dajun D; Lee, Ping I

    2015-08-10

    The objective of the current study is to mechanistically differentiate the dissolution and supersaturation behaviors of amorphous drugs from amorphous solid dispersions (ASDs) based on medium-soluble versus medium-insoluble carriers under nonsink dissolution conditions through a direct head-to-head comparison. ASDs of indomethacin (IND) were prepared in several polymers which exhibit different solubility behaviors in acidic (pH1.2) and basic (pH7.4) dissolution media. The selected polymers range from water-soluble (e.g., PVP and Soluplus) and water-insoluble (e.g., ethylcellulose and Eudragit RL PO) to those only soluble in an acidic or basic dissolution medium (e.g., Eudragit E100, Eudragit L100, and HPMCAS). At 20wt.% drug loading, DSC and powder XRD analysis confirmed that the majority of incorporated IND was present in an amorphous state. Our nonsink dissolution results confirm that whether the carrier matrix is medium soluble determines the release mechanism of amorphous drugs from ASD systems which has a direct impact on the rate of supersaturation generation, thus in turn affecting the evolution of supersaturation in amorphous systems. For example, under nonsink dissolution conditions, the release of amorphous IND from medium-soluble carriers is governed by a dissolution-controlled mechanism leading to an initial surge of supersaturation followed by a sharp decline in drug concentration due to rapid nucleation and crystallization. In contrast, the dissolution of IND ASD from medium-insoluble carriers is more gradual as drug release is regulated by a diffusion-controlled mechanism by which drug supersaturation is built up gradually and sustained over an extended period of time without any apparent decline. Since several tested carrier polymers can be switched from soluble to insoluble by simply changing the pH of the dissolution medium, the results obtained here provide unequivocal evidence of the proposed transition of kinetic solubility profiles from the

  11. Library Webmasters in Medium-Sized Academic Libraries

    ERIC Educational Resources Information Center

    Kneip, Jason

    2007-01-01

    Library webmasters in medium-sized academic libraries were surveyed about their educational backgrounds, job responsibilities, and training and experience levels in Web development. The article summarizes the findings of the survey with recommendations for libraries and library and information science programs. (Contains 7 tables, 5 figures,and 5…

  12. An improved stress corrosion test medium for aluminum alloys

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Coston, J. E.

    1981-01-01

    A laboratory test method that is only mildly corrosive to aluminum and discriminating for use in classifying the stress corrosion cracking resistance of aluminum alloys is presented along with the method used in evaluating the media selected for testing. The proposed medium is easier to prepare and less expensive than substitute ocean water.

  13. Feasibility of Adopting English-Medium Instruction at Iranian Universities

    ERIC Educational Resources Information Center

    Ghorbani, Mohammad Reza; Alavi, Sahar Zahed

    2014-01-01

    This study was an attempt to explore the potential possibilities of implementing English as the medium of instruction (EMI) at Iranian universities. The sequential exploratory mixed methods design was used to collect the perspectives of both students and content-area lecturers at the state University of Bojnord through e-mail interviews and survey…

  14. Film as a "Thoughtful" Medium for Teaching History

    ERIC Educational Resources Information Center

    Stoddard, Jeremy D.

    2012-01-01

    This collective case study of teachers and students in two ninth-grade US history classes examines the role that films can play as a "thoughtful" medium for teaching history. Specifically, the study focuses on the nature and range of authentic intellectual work that students are engaged in with film in the classroom (Newmann, F., B.…

  15. Factors Affecting the Acceptability of Microforms as a Reading Medium.

    ERIC Educational Resources Information Center

    Spencer, Herbert; Reynolds, Linda

    Based on visits to representative microform users and an extensive survey of relevant literature, a study was undertaken to assess the relative importance of factors affecting the acceptability of microforms as reading mediums. The following variables were considered: (1) microform characteristics; (2) equipment design; (3) work station design;…

  16. Workplace Health Promotion within Small and Medium-Sized Enterprises

    ERIC Educational Resources Information Center

    Moore, Ann; Parahoo, Kader; Fleming, Paul

    2010-01-01

    Purpose: The purpose of this study is to explore managers' understanding of workplace health promotion (WHP) and experiences of WHP activity within small and medium-sized enterprises (SMEs) in a Health and Social Care Trust area of Northern Ireland. The paper aims to focus on engagement with activities within the context of prevention of…

  17. Medium Resolution Spectroscopy of Boyajian's Star (KIC 8462852)

    NASA Astrophysics Data System (ADS)

    Steele, I. A.; Lamb, G. P.; Copperwheat, C. M.; Jermak, H. E.

    2017-05-01

    ATel #10405 reports that a several percent dip in the brightness of KIC 8462852 is underway. We report medium resolution spectroscopy (R=2500) taken with the FRODOSpec fibre fed integral field spectrograph of the 2.0 meter Liverpool Telescope, La Palma obtained on 20th May 2017 starting at 01:20UT.

  18. Computer Programming: A Medium for Teaching Problem Solving.

    ERIC Educational Resources Information Center

    Casey, Patrick J.

    1997-01-01

    Argues that including computer programming in the curriculum as a medium for instruction is a feasible alternative for teaching problem solving. Discusses the nature of problem solving; the problem-solving elements of discovery, motivation, practical learning situations and flexibility which are inherent in programming; capabilities of computer…

  19. Medium term hurricane catastrophe models: a validation experiment

    NASA Astrophysics Data System (ADS)

    Bonazzi, Alessandro; Turner, Jessica; Dobbin, Alison; Wilson, Paul; Mitas, Christos; Bellone, Enrica

    2013-04-01

    Climate variability is a major source of uncertainty for the insurance industry underwriting hurricane risk. Catastrophe models provide their users with a stochastic set of events that expands the scope of the historical catalogue by including synthetic events that are likely to happen in a defined time-frame. The use of these catastrophe models is widespread in the insurance industry but it is only in recent years that climate variability has been explicitly accounted for. In the insurance parlance "medium term catastrophe model" refers to products that provide an adjusted view of risk that is meant to represent hurricane activity on a 1 to 5 year horizon, as opposed to long term models that integrate across the climate variability of the longest available time series of observations. In this presentation we discuss how a simple reinsurance program can be used to assess the value of medium term catastrophe models. We elaborate on similar concepts as discussed in "Potential Economic Value of Seasonal Hurricane Forecasts" by Emanuel et al. (2012, WCAS) and provide an example based on 24 years of historical data of the Chicago Mercantile Hurricane Index (CHI), an insured loss proxy. Profit and loss volatility of a hypothetical primary insurer are used to score medium term models versus their long term counterpart. Results show that medium term catastrophe models could help a hypothetical primary insurer to improve their financial resiliency to varying climate conditions.

  20. Aircraft requirements for low/medium density markets

    NASA Technical Reports Server (NTRS)

    Ausrotas, R.; Dodge, S.; Faulkner, H.; Glendinning, I.; Hays, A.; Simpson, R.; Swan, W.; Taneja, N.; Vittek, J.

    1973-01-01

    A study was conducted to determine the demand for and the economic factors involved in air transportation in a low and medium density market. The subjects investigated are as follows: (1) industry and market structure, (2) aircraft analysis, (3) economic analysis, (4) field surveys, and (5) computer network analysis. Graphs are included to show the economic requirements and the aircraft performance characteristics.

  1. In-Medium Parton Branching Beyond Eikonal Approximation

    NASA Astrophysics Data System (ADS)

    Apolinário, Liliana

    2017-03-01

    The description of the in-medium modifications of partonic showers has been at the forefront of current theoretical and experimental efforts in heavy-ion collisions. It provides a unique laboratory to extend our knowledge frontier of the theory of the strong interactions, and to assess the properties of the hot and dense medium (QGP) that is produced in ultra-relativistic heavy-ion collisions at RHIC and the LHC. The theory of jet quenching, a commonly used alias for the modifications of the parton branching resulting from the interactions with the QGP, has been significantly developed over the last years. Within a weak coupling approach, several elementary processes that build up the parton shower evolution, such as single gluon emissions, interference effects between successive emissions and corrections to radiative energy loss of massive quarks, have been addressed both at eikonal accuracy and beyond by taking into account the Brownian motion that high-energy particles experience when traversing a hot and dense medium. In this work, by using the setup of single gluon emission from a color correlated quark-antiquark pair in a singlet state (qbar{q} antenna), we calculate the in-medium gluon radiation spectrum beyond the eikonal approximation. The results show that we are able to factorize broadening effects from the modifications of the radiation process itself. This constitutes the final proof that a probabilistic picture of the parton shower evolution holds even in the presence of a QGP.

  2. Dynamic vapor sorption isotherms of medium grain rice varieties

    USDA-ARS?s Scientific Manuscript database

    It is known that the two popular medium rice varieties, namely M202 and M206, in California have different fissuring resistances. Therefore, the main goal of this study was to investigate the sorption behavior of these two varieties by a new approach using dynamic vapor sorption (DVS) method for elu...

  3. Orientations towards English among English-Medium Instruction Students

    ERIC Educational Resources Information Center

    Karakas, Ali

    2015-01-01

    Based on the empirical data of my PhD research, this paper analyses the perceptions of 351 undergraduate students enrolled at English-medium universities towards English in terms of the language ideology framework. The students were purposively sampled from three programs at three Turkish universities. The data were drawn from student opinion…

  4. Influence of the medium's dimensionality on defect-mediated turbulence.

    PubMed

    St-Yves, Ghislain; Davidsen, Jörn

    2015-03-01

    Spatiotemporal chaos in oscillatory and excitable media is often characterized by the presence of phase singularities called defects. Understanding such defect-mediated turbulence and its dependence on the dimensionality of a given system is an important challenge in nonlinear dynamics. This is especially true in the context of ventricular fibrillation in the heart, where the importance of the thickness of the ventricular wall is contentious. Here, we study defect-mediated turbulence arising in two different regimes in a conceptual model of excitable media and investigate how the statistical character of the turbulence changes if the thickness of the medium is changed from (quasi-) two- dimensional to three dimensional. We find that the thickness of the medium does not have a significant influence in, far from onset, fully developed turbulence while there is a clear transition if the system is close to a spiral instability. We provide clear evidence that the observed transition and change in the mechanism that drives the turbulent behavior is purely a consequence of the dimensionality of the medium. Using filament tracking, we further show that the statistical properties in the three-dimensional medium are different from those in turbulent regimes arising from filament instabilities like the negative line tension instability. Simulations also show that the presence of this unique three-dimensional turbulent dynamics is not model specific.

  5. 21 CFR 866.2350 - Microbiological assay culture medium.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Microbiological assay culture medium. 866.2350 Section 866.2350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2350...

  6. 21 CFR 866.2320 - Differential culture medium.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Differential culture medium. 866.2320 Section 866.2320 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2320 Differential culture...

  7. 21 CFR 866.2360 - Selective culture medium.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Selective culture medium. 866.2360 Section 866.2360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2360 Selective culture...

  8. 21 CFR 866.2330 - Enriched culture medium.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Enriched culture medium. 866.2330 Section 866.2330 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2330 Enriched culture...

  9. 21 CFR 866.2360 - Selective culture medium.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Selective culture medium. 866.2360 Section 866.2360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2360 Selective culture...

  10. 21 CFR 866.2390 - Transport culture medium.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Transport culture medium. 866.2390 Section 866.2390 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2390 Transport culture...

  11. 21 CFR 866.2350 - Microbiological assay culture medium.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Microbiological assay culture medium. 866.2350 Section 866.2350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2350...

  12. 21 CFR 866.2390 - Transport culture medium.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Transport culture medium. 866.2390 Section 866.2390 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2390 Transport culture...

  13. 21 CFR 866.2300 - Multipurpose culture medium.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Multipurpose culture medium. 866.2300 Section 866.2300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2300 Multipurpose culture...

  14. 21 CFR 866.2320 - Differential culture medium.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Differential culture medium. 866.2320 Section 866.2320 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2320 Differential culture...

  15. 21 CFR 866.2360 - Selective culture medium.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Selective culture medium. 866.2360 Section 866.2360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2360 Selective culture...

  16. 21 CFR 866.2350 - Microbiological assay culture medium.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Microbiological assay culture medium. 866.2350 Section 866.2350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2350...

  17. 21 CFR 866.2360 - Selective culture medium.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Selective culture medium. 866.2360 Section 866.2360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2360 Selective culture...

  18. 21 CFR 866.2320 - Differential culture medium.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Differential culture medium. 866.2320 Section 866.2320 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2320 Differential culture...

  19. 21 CFR 866.2330 - Enriched culture medium.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Enriched culture medium. 866.2330 Section 866.2330 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2330 Enriched culture...

  20. 21 CFR 866.2390 - Transport culture medium.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Transport culture medium. 866.2390 Section 866.2390 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2390 Transport culture...