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Sample records for diverse galaxy structures

  1. Diverse structural evolution at z > 1 in cosmologically simulated galaxies

    NASA Astrophysics Data System (ADS)

    Snyder, Gregory F.; Lotz, Jennifer; Moody, Christopher; Peth, Michael; Freeman, Peter; Ceverino, Daniel; Primack, Joel; Dekel, Avishai

    2015-08-01

    From mock Hubble Space Telescope images, we quantify non-parametric statistics of galaxy morphology, thereby predicting the emergence of relationships among stellar mass, star formation, and observed rest-frame optical structure at 1 < z < 3. We measure automated diagnostics of galaxy morphology in cosmological simulations of the formation of 22 central galaxies with 9.3 < log10M*/M⊙ < 10.7. These high-spatial-resolution zoom-in calculations enable accurate modelling of the rest-frame UV and optical morphology. Even with small numbers of galaxies, we find that structural evolution is neither universal nor monotonic: galaxy interactions can trigger either bulge or disc formation, and optically bulge-dominated galaxies at this mass may not remain so forever. Simulated galaxies with M* > 1010M⊙ contain relatively more disc-dominated light profiles than those with lower mass, reflecting significant disc brightening in some haloes at 1 < z < 2. By this epoch, simulated galaxies with specific star formation rates below 10- 9.7 yr- 1 are more likely than normal star-formers to have a broader mix of structural types, especially at M* > 1010 M⊙. We analyse a cosmological major merger at z ˜ 1.5 and find that the newly proposed Multimode-Intensity-Deviation (MID) morphology diagnostics trace later merger stages while Gini-M20 trace earlier ones. MID is sensitive also to clumpy star-forming discs. The observability time of typical MID-enhanced events in our simulation sample is <100 Myr. A larger sample of cosmological assembly histories may be required to calibrate such diagnostics in the face of their sensitivity to viewing angle, segmentation algorithm, and various phenomena such as clumpy star formation and minor mergers.

  2. The Zurich Environmental Study (ZENS) of Galaxies in Groups along the Cosmic Web. II. Galaxy Structural Measurements and the Concentration of Morphologically Classified Satellites in Diverse Environments

    NASA Astrophysics Data System (ADS)

    Cibinel, A.; Carollo, C. M.; Lilly, S. J.; Miniati, F.; Silverman, J. D.; van Gorkom, J. H.; Cameron, E.; Finoguenov, A.; Norberg, P.; Peng, Y.; Pipino, A.; Rudick, C. S.

    2013-10-01

    We present structural measurements for the galaxies in the 0.05 < z < 0.0585 groups of the Zurich Environmental Study, aimed at establishing how galaxy properties depend on four environmental parameters: group halo mass (M GROUP), group-centric distance (R/R 200), ranking into central or satellite, and large-scale structure density (δLSS). Global galaxy structure is quantified both parametrically and non-parametrically. We correct all these measurements for observational biases due to point-spread function blurring and surface brightness effects as a function of galaxy size, magnitude, steepness of light profile, and ellipticity. Structural parameters are derived also for bulges, disks, and bars. We use the galaxy bulge-to-total ratios (B/T) together with the calibrated non-parametric structural estimators to implement a quantitative morphological classification that maximizes purity in the resulting morphological samples. We investigate how the concentration C of satellite galaxies depends on galaxy mass for each Hubble type and on M GROUP, R/R 200, and δLSS. At galaxy masses M >= 1010 M ⊙, the concentration of disk satellites increases with increasing stellar mass separately within each morphological bin of B/T. The known increase in concentration with stellar mass for disk satellites is thus due, at least in part, to an increase in galaxy central stellar density at constant B/T. The correlation between concentration and galaxy stellar mass becomes progressively steeper for later morphological types. The concentration of disk satellites shows a barely significant dependence on δLSS or R/R 200. The strongest environmental effect is found with group mass for >1010 M ⊙ disk-dominated satellites, which are ~10% more concentrated in high mass groups than in lower mass groups. Based on observations collected at the European Southern Observatory, La Silla Chile, Program ID 177.A-0680.

  3. THE ZURICH ENVIRONMENTAL STUDY (ZENS) OF GALAXIES IN GROUPS ALONG THE COSMIC WEB. II. GALAXY STRUCTURAL MEASUREMENTS AND THE CONCENTRATION OF MORPHOLOGICALLY CLASSIFIED SATELLITES IN DIVERSE ENVIRONMENTS

    SciTech Connect

    Cibinel, A.; Carollo, C. M.; Lilly, S. J.; Miniati, F.; Cameron, E.; Peng, Y.; Pipino, A.; Rudick, C. S.; Silverman, J. D.; Van Gorkom, J. H.; Finoguenov, A.; Norberg, P. E-mail: marcella@phys.ethz.ch

    2013-10-20

    We present structural measurements for the galaxies in the 0.05 < z < 0.0585 groups of the Zurich Environmental Study, aimed at establishing how galaxy properties depend on four environmental parameters: group halo mass (M{sub GROUP}), group-centric distance (R/R{sub 200}), ranking into central or satellite, and large-scale structure density (δ{sub LSS}). Global galaxy structure is quantified both parametrically and non-parametrically. We correct all these measurements for observational biases due to point-spread function blurring and surface brightness effects as a function of galaxy size, magnitude, steepness of light profile, and ellipticity. Structural parameters are derived also for bulges, disks, and bars. We use the galaxy bulge-to-total ratios (B/T) together with the calibrated non-parametric structural estimators to implement a quantitative morphological classification that maximizes purity in the resulting morphological samples. We investigate how the concentration C of satellite galaxies depends on galaxy mass for each Hubble type and on M{sub GROUP}, R/R{sub 200}, and δ{sub LSS}. At galaxy masses M ≥ 10{sup 10} M{sub ☉}, the concentration of disk satellites increases with increasing stellar mass separately within each morphological bin of B/T. The known increase in concentration with stellar mass for disk satellites is thus due, at least in part, to an increase in galaxy central stellar density at constant B/T. The correlation between concentration and galaxy stellar mass becomes progressively steeper for later morphological types. The concentration of disk satellites shows a barely significant dependence on δ{sub LSS} or R/R{sub 200}. The strongest environmental effect is found with group mass for >10{sup 10} M{sub ☉} disk-dominated satellites, which are ∼10% more concentrated in high mass groups than in lower mass groups.

  4. Shaping galaxy evolution with galaxy structure

    NASA Astrophysics Data System (ADS)

    Cheung, Edmond

    A fundamental pursuit of astronomy is to understand galaxy evolution. The enormous scales and complex physics involved in this endeavor guarantees a never-ending journey that has enamored both astronomers and laymen alike. But despite the difficulty of this task, astronomers have still attempted to further this goal. Among of these astronomers is Edwin Hubble. His work, which includes the famous Hubble sequence, has immeasurably influenced our understanding of galaxy evolution. In this thesis, we present three works that continues Hubble's line of study by using galaxy structure to learn about galaxy evolution. First, we examine the dependence of galaxy quiescence on inner galactic structure with the AEGIS/ DEEP2 survey at 0.5In this thesis, we present three works that continues Hubble's line of study by using galaxy structure to learn about galaxy evolution. First, we examine the dependence of galaxy quiescence on inner galactic structure with the AEGIS/ DEEP2 survey at 0.5galaxies from quiescent galaxies. Our method indicates that the inner stellar mass is the most correlated parameter of quenching, implying that the process that quenches galaxies must also buildup their inner structure. Second, we explore the relationship between galactic bars and their host galaxies with Galaxy Zoo 2 at z˜0. The correlations of bar properties and galaxy properties are consistent with simulations of bar formation and evolution, indicating that bars affect their host galaxies. Finally, we investigate whether bars can drive supermassive black hole growth with data from Chandra and Galaxy Zoo: Hubble at 0.2galaxies to a matched sample of inactive, control galaxies shows that there is no statistically significant excess of bars in active hosts. Our result shows that bars are not the primary fueling mechanism of supermassive black hole

  5. Galaxy tools to study genome diversity

    PubMed Central

    2013-01-01

    Background Intra-species genetic variation can be used to investigate population structure, selection, and gene flow in non-model vertebrates; and due to the plummeting costs for genome sequencing, it is now possible for small labs to obtain full-genome variation data from their species of interest. However, those labs may not have easy access to, and familiarity with, computational tools to analyze those data. Results We have created a suite of tools for the Galaxy web server aimed at handling nucleotide and amino-acid polymorphisms discovered by full-genome sequencing of several individuals of the same species, or using a SNP genotyping microarray. In addition to providing user-friendly tools, a main goal is to make published analyses reproducible. While most of the examples discussed in this paper deal with nuclear-genome diversity in non-human vertebrates, we also illustrate the application of the tools to fungal genomes, human biomedical data, and mitochondrial sequences. Conclusions This project illustrates that a small group can design, implement, test, document, and distribute a Galaxy tool collection to meet the needs of a particular community of biologists. PMID:24377391

  6. Structural Properties of Barred Galaxies

    NASA Astrophysics Data System (ADS)

    Kim, Taehyun; Gadotti, D. A.; Sheth, K.; Lee, M.; S4G Team

    2014-01-01

    We have performed two-dimensional multicomponent decomposition of 144 local barred spiral galaxies using 3.6 micron images from the Spitzer Survey of Stellar Structure in Galaxies. Our model fit includes up to four components (bulge, disk, bar, and a point source) and, most importantly, takes into account disk breaks. We present that ignoring the disk break and using a single disk scale length in the model fit for Type II (down- bending) disk galaxies can lead to differences of 40% in the disk scale length, 10% in bulge-to-total luminosity ratio (B/T), and 25% in bar-to-total luminosity ratios. We show that for galaxies with B/T > 0.1, the break radius to bar radius, r_br/R_bar, varies between 1 and 3, but as a function of B/T the ratio remains roughly constant. This suggests that in bulge-dominated galaxies the disk break is likely related to the outer Lindblad Resonance (OLR) of the bar, and thus the OLR also moves outwards at the same rate as the bar grows. For galaxies with B/T < 0.1, r_br/R_bar, spans a wide range from 1 to 6. This suggests that the mechanism that produces the break in these galaxies may be different from that in galaxies with more massive bulges. Consistent with previous studies, we conclude that disk breaks in galaxies with small bulges may originate from bar resonances that may be also coupled with the spiral arms, or be related to star formation thresholds. We quantifiy shapes of bar radial surface brightness profiles by measuring their Sersic indices and show that bars in higher B/T galaxies have flatter radial surface brightness profile than bulgeless galaxies do. In particular, bulgeless galaxies mostly have bars with steep profiles. We show that the normalized bar length is correlated with B/T, which is consistent with bars growing longer with time.

  7. The Alignment of Galaxy Structures

    NASA Astrophysics Data System (ADS)

    Biernacka, M.; Panko, E.; Bajan, K.; Godłowski, W.; Flin, P.

    2015-11-01

    We analyzed the orientation of the sample of ACO galaxy clusters. We examined the alignment in a subsample of 1056 galaxy structures taken from the Panko-Flin (2006) Catalog with known BM morphological types. We were looking for a correlation between the orientation of the cluster and the positions of neighboring clusters. The Binggeli effect (the excess of small values of the Δθ angles between the direction toward neighboring clusters and the cluster position angle) is observed, having a range up to about 45 h-1 Mpc. The strongest effect was found for elongated BM type I clusters. This is probably connected with the origins of the supergiant galaxy and with cluster formation along a long filament or plane in a supercluster.

  8. Assessing and understanding diversity in galaxy star formation histories

    NASA Astrophysics Data System (ADS)

    Abramson, Louis Evan

    Galaxy star formation histories (SFHs) form a central thread of the cosmological narrative. Assessing and understanding them is therefore a central mission of the study of galaxy evolution. Although an ever-better picture is emerging of the build-up of the stellar mass of the average galaxy over time, the relevance of this track to the growth of individual galaxies is unclear. Largely, this ambiguity is due to the availability of only loose, ensemble-level constraints at any redshift appreciably greater than zero. In this thesis, I outline how these constraints --- principally the cosmic star formation rate density, stellar mass function, and the star formation rate/stellar mass relation --- shape empirically based SFH models, especially in terms of the diversity of paths leading to a given end-state. Along the way, I show that three models propose very different answers to this question, corresponding (largely) to three different interpretations of the scatter in instantaneous galaxy growth rates at fixed stellar mass. I describe how these interpretations affect one's stance on the fundamental importance of so-called galaxy "bimodality" and quenching mechanisms, the influence of environment, and the role starbursts play in galaxy evolution. Ultimately, I conclude that there is insufficient evidence at present to select one interpretation over all others, but suggest that the situation might soon be resolved by upcoming observations that could clearly identify which model (or hybrid) is the most accurate description of galaxy growth.

  9. The unexpected diversity of dwarf galaxy rotation curves

    NASA Astrophysics Data System (ADS)

    Oman, Kyle A.; Navarro, Julio F.; Fattahi, Azadeh; Frenk, Carlos S.; Sawala, Till; White, Simon D. M.; Bower, Richard; Crain, Robert A.; Furlong, Michelle; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2015-10-01

    We examine the circular velocity profiles of galaxies in Λ cold dark matter (CDM) cosmological hydrodynamical simulations from the EAGLE and LOCAL GROUPS projects and compare them with a compilation of observed rotation curves of galaxies spanning a wide range in mass. The shape of the circular velocity profiles of simulated galaxies varies systematically as a function of galaxy mass, but shows remarkably little variation at fixed maximum circular velocity. This is especially true for low-mass dark-matter-dominated systems, reflecting the expected similarity of the underlying CDM haloes. This is at odds with observed dwarf galaxies, which show a large diversity of rotation curve shapes, even at fixed maximum rotation speed. Some dwarfs have rotation curves that agree well with simulations, others do not. The latter are systems where the inferred mass enclosed in the inner regions is much lower than expected for CDM haloes and include many galaxies where previous work claims the presence of a constant density `core'. The `cusp versus core' issue is thus better characterized as an `inner mass deficit' problem than as a density slope mismatch. For several galaxies, the magnitude of this inner mass deficit is well in excess of that reported in recent simulations where cores result from baryon-induced fluctuations in the gravitational potential. We conclude that one or more of the following statements must be true: (i) the dark matter is more complex than envisaged by any current model; (ii) current simulations fail to reproduce the diversity in the effects of baryons on the inner regions of dwarf galaxies; and/or (iii) the mass profiles of `inner mass deficit' galaxies inferred from kinematic data are incorrect.

  10. nIFTY galaxy cluster simulations - III. The similarity and diversity of galaxies and subhaloes

    NASA Astrophysics Data System (ADS)

    Elahi, Pascal J.; Knebe, Alexander; Pearce, Frazer R.; Power, Chris; Yepes, Gustavo; Cui, Weiguang; Cunnama, Daniel; Kay, Scott T.; Sembolini, Federico; Beck, Alexander M.; Davé, Romeel; February, Sean; Huang, Shuiyao; Katz, Neal; McCarthy, Ian G.; Murante, Giuseppe; Perret, Valentin; Puchwein, Ewald; Saro, Alexandro; Teyssier, Romain

    2016-05-01

    We examine subhaloes and galaxies residing in a simulated Λ cold dark matter galaxy cluster (M^crit_{200}=1.1× 10^{15} h^{-1} M_{⊙}) produced by hydrodynamical codes ranging from classic smooth particle hydrodynamics (SPH), newer SPH codes, adaptive and moving mesh codes. These codes use subgrid models to capture galaxy formation physics. We compare how well these codes reproduce the same subhaloes/galaxies in gravity-only, non-radiative hydrodynamics and full feedback physics runs by looking at the overall subhalo/galaxy distribution and on an individual object basis. We find that the subhalo population is reproduced to within ≲10 per cent for both dark matter only and non-radiative runs, with individual objects showing code-to-code scatter of ≲0.1 dex, although the gas in non-radiative simulations shows significant scatter. Including feedback physics significantly increases the diversity. Subhalo mass and Vmax distributions vary by ≈20 per cent. The galaxy populations also show striking code-to-code variations. Although the Tully-Fisher relation is similar in almost all codes, the number of galaxies with 109 h- 1 M⊙ ≲ M* ≲ 1012 h- 1 M⊙ can differ by a factor of 4. Individual galaxies show code-to-code scatter of ˜0.5 dex in stellar mass. Moreover, systematic differences exist, with some codes producing galaxies 70 per cent smaller than others. The diversity partially arises from the inclusion/absence of active galactic nucleus feedback. Our results combined with our companion papers demonstrate that subgrid physics is not just subject to fine-tuning, but the complexity of building galaxies in all environments remains a challenge. We argue that even basic galaxy properties, such as stellar mass to halo mass, should be treated with errors bars of ˜0.2-0.4 dex.

  11. Morphology and Structures of Nearby Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Seo, Mira; Ann, HongBae

    2015-08-01

    We performed an analysis of the structure of nearby dwarf galaxies based on a 2-dimensional decomposition of galaxy images using GALFIT. The present sample consists of ~1,100 dwarf galaxies with redshift less than z = 0.01, which is is derived from the morphology catalog of the Visually classified galaxies in the local universe (Ann, Seo, and Ha 2015). In this catalog, dwarf galaxies are divided into 5 subtypes: dS0, dE, dSph, dEbc, dEblue with distinction of the presence of nucleation in dE, dSph, and dS0. We found that dSph and dEblue galaxies are fainter than other subtypes of dwarf galaxies. In most cases, single component, represented by the Sersic profile with n=1~1.5, well describes the luminosity distribution of dwarf galaxies in the present sample. However, a significant fraction of dS0, dEbc, and dEbue galaxies show sub-structures such as spiral arms and rings. We will discuss the morphology dependent evolutionary history of the local dwarf galaxies.

  12. The diverse formation histories of simulated disc galaxies

    NASA Astrophysics Data System (ADS)

    Aumer, Michael; White, Simon D. M.; Naab, Thorsten

    2014-07-01

    We analyse the formation histories of 19 galaxies from cosmological smoothed particle hydrodynamics zoom-in resimulations. We construct mock three-colour images and show that the models reproduce observed trends in the evolution of galaxy colours and morphologies. However, only a small fraction of galaxies contains bars. Many galaxies go through phases of central mass growth by in situ star formation driven by gas-rich mergers or misaligned gas infall. These events lead to accretion of low angular momentum gas to the centres and leave imprints on the distributions of z = 0 stellar circularities, radii and metallicities as functions of age. Observations of the evolution of structural properties of samples of disc galaxies at z = 2.5-0.0 infer continuous mass assembly at all radii. Our simulations can only explain this if there is a significant contribution from mergers or misaligned infall, as expected in a Λ cold dark matter universe. Quiescent merger histories lead to high kinematic disc fractions and inside-out growth, but show little central growth after the last `destructive' merger at z > 1.5. For sufficiently strong feedback, as assumed in our models, a moderate amount of merging does not seem to be a problem for the z = 0 disc galaxy population, but may rather be a requirement. The average profiles of simulated disc galaxies agree with observations at z ≥ 1.5. At z ≤ 1, there is too much growth in size and too little growth in central mass, possibly due to the underabundance of bars. The discrepancies may partly be caused by differences between the star formation histories of the simulations and those assumed for observations.

  13. Study of galaxy structures by correlation analysis

    SciTech Connect

    Salvador-Sole, E.; Sanroma, M. )

    1989-10-01

    In a previous paper the authors presented a new method that makes it possible to infer the surface number density profile of galaxies in groups and clusters. This method is based on the correlation analysis of galaxy positions in a plate and applies to radially symmetric systems with uncorrelated positions of their particles. Here it is shown that, under these same assumptions, the method makes it possible to obtain the surface density profile of any additive positive property, as well as other related quantities, such as the line-of-sight velocity dispersion of galaxies. Moreover, the method can deal not only with structures that are radially symmetric but also with ones that are elliptically symmetric and axisymmetric. Finally, it is shown that the analogous method in one dimension makes it possible to obtain another important profile for the analysis of galaxy structures, namely, the line-of-sight velocity distribution. 5 refs.

  14. Radio structures in QSO-galaxy pairs

    NASA Technical Reports Server (NTRS)

    Akujor, Chidi E.

    1990-01-01

    It is now generally agreed that if quasars and nearby low redshift galaxies are associated, then there should be luminous connections between them. However, most of the observational evidence being presented is in the optical domain, whereas such evidence should also exist at radio frequencies. The author is, therefore, investigating some quasar-galaxy pairs at radio frequencies to search for luminous connections and other structural peculiarities. Radio maps of some of these sources are presented.

  15. SEYFERT GALAXIES: NUCLEAR RADIO STRUCTURE AND UNIFICATION

    SciTech Connect

    Lal, Dharam V.; Shastri, Prajval; Gabuzda, Denise C.

    2011-04-10

    A radio study of a carefully selected sample of 20 Seyfert galaxies that are matched in orientation-independent parameters, which are measures of intrinsic active galactic nucleus power and host galaxy properties, is presented to test the predictions of the unified scheme hypothesis. Our sample sources have core flux densities greater than 8 mJy at 5 GHz on arcsec scales due to the feasibility requirements. These simultaneous parsec-scale and kiloparsec-scale radio observations reveal (1) that Seyfert 1 and Seyfert 2 galaxies have an equal tendency to show compact radio structures on milliarcsecond scales, (2) the distributions of parsec-scale and kiloparsec-scale radio luminosities are similar for both Seyfert 1 and Seyfert 2 galaxies, (3) there is no evidence for relativistic beaming in Seyfert galaxies, (4) similar distributions of source spectral indices in spite of the fact that Seyferts show nuclear radio flux density variations, and (5) the distributions of the projected linear size for Seyfert 1 and Seyfert 2 galaxies are not significantly different as would be expected in the unified scheme. The latter could be mainly due to a relatively large spread in the intrinsic sizes. We also find that a starburst alone cannot power these radio sources. Finally, an analysis of the kiloparsec-scale radio properties of the CfA Seyfert galaxy sample shows results consistent with the predictions of the unified scheme.

  16. Information of Structures in Galaxy Distribution

    NASA Astrophysics Data System (ADS)

    Fang, Fan

    2006-06-01

    We introduce an information-theoretic measure, the Rényi information, to describe the galaxy distribution in space. We discuss properties of the information measure and demonstrate its relationship with the probability distribution function and multifractal descriptions. Using the First Look Survey galaxy samples observed by the Infrared Array Camera on board the Spitzer Space Telescope, we present measurements of the Rényi information, as well as the counts-in-cells distribution and multifractal properties of galaxies in mid-infrared wavelengths. Guided by a multiplicative cascade simulation based on a binomial model, we verify our measurements and discuss the spatial selection effects on measuring information of the spatial structures. We derive structure scan functions at scales where selection effects are small for the Spitzer samples. We discuss the results and the potential of applying the Rényi information to the measurement of other spatial structures.

  17. The Origin of the Diversity of Dwarf Spheroidal Galaxies

    NASA Astrophysics Data System (ADS)

    Revaz, Yves; Jablonka, Pascale

    2010-06-01

    We present a large sample of 166 fully self-consistent hydrodynamical N-body/Tree-SPH simulations of isolated dwarf spheroidal galaxies [1]. It has enabled us to identify the key physical parameters and mechanisms at the origin of the observed variety in the Local Group dSph properties. Using the recent data of the ESO Large Programme DART, we have constrained the star formation history of four Milky Way dSphs, Sextans, Carina, Sculptor and Fornax. For the first time, [Mg/Fe] vs [Fe/H] diagrams derived from high-resolution spectroscopy of hundreds of individual stars are confronted with model predictions. Global relations of dSph are successfully reproduced. Our study shows that the total initial mass of these systems is the main driver of their evolution and explains the diversity in luminosity and metallicity observed in the Local Group dSphs.

  18. AEGIS: The Diversity of Bright Near-IR Selected Distant RedGalaxies

    SciTech Connect

    Conselice, C.J.; Newman, J.A.; Georgakakis, A.; Almaini, O.; Coil, A.L.; Cooper, M.C.; Eisenhardt, P.; Foucaud, S.; Koekemoer, A.; Lotz, J.; Noeske, K.; Weiner, B.; Willmer, C.N.A

    2006-10-13

    We use deep and wide near infrared (NIR) imaging from the Palomar telescope combined with DEEP2 spectroscopy and Hubble Space Telescope (HST) and Chandra Space Telescope imaging to investigate the nature of galaxies that are red in NIR colors. We locate these 'distant red galaxies' (DRGs) through the color cut (J - K){sub vega} > 2.3 over 0.7 deg{sup 2}, where we find 1010 DRG candidates down to K{sub s} = 20.5. We combine 95 high quality spectroscopic redshifts with photometric redshifts from BRIJK photometry to determine the redshift and stellar mass distributions for these systems, and morphological/structural and X-ray properties for 107 DRGs in the Extended Groth Strip. We find that many bright (J - K){sub vega} > 2.3 galaxies with K{sub s} < 20.5 are at redshifts z < 2, with 64% between 1 < z < 2. The stellar mass distributions for these galaxies is broad, ranging from 10{sup 9} - 10{sup 12} M{sub {circle_dot}} , but with most z > 2 systems massive with M{sub *} > 10{sup 11} M{sub {circle_dot}}. HST imaging shows that the structural properties and morphologies of DRGs are also diverse, with the majority elliptical/compact (57%), and the remainder edge-on spirals (7%), and peculiar galaxies (29%). The DRGs at z < 1.4 with high quality spectroscopic redshifts are generally compact, with small half-light radii, and span a range in rest-frame optical properties. The spectral energy distributions for these objects differ from higher redshift DRGs: they are bluer by one magnitude in observed (I - J) color. A pure IR color selection of high redshift populations is not sufficient to identify unique populations, and other colors, or spectroscopic redshifts are needed to produce homogeneous samples.

  19. Mesoscale Magnetic Structures in Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Shukurov, Anvar

    Virtually all spiral galaxies host magnetic fields ordered at scales comparable to the galactic size (Beck et al., 1996; Beck, 2000, 2001). Observations of polarized radio emission at improved resolution and sensitivity have revealed details of the global magnetic structures that can shed new light on the problem of their origin. Reversals of the regular magnetic field along radius and/or azimuth and magnetic arms are such features, whose scale exceeds significantly the correlation scale of interstellar turbulence but remains smaller than the overall galactic dimension. Despite a few decades of debate, there remains doubt as to what features of the observed field could have been inherited from the pre-galactic past, and which have been formed and maintained more recently in a relatively mature galaxy. In what follows, we briefly review the current understanding of the origin of the mesoscale magnetic structures and their implications for the origin of galactic magnetic fields.

  20. AEGIS: The Diversity of Bright Near-IR-selected Distant Red Galaxies

    NASA Astrophysics Data System (ADS)

    Conselice, C. J.; Newman, J. A.; Georgakakis, A.; Almaini, O.; Coil, A. L.; Cooper, M. C.; Eisenhardt, P.; Foucaud, S.; Koekemoer, A.; Lotz, J.; Noeske, K.; Weiner, B.; Willmer, C. N. A.

    2007-05-01

    We use deep and wide near-infrared (NIR) imaging from the Palomar telescope combined with DEEP2 spectroscopy and HST and Chandra imaging to investigate the nature of galaxies that are red in NIR colors. We locate these ``distant red galaxies'' (DRGs) through the color cut (J-K)Vega>2.3 over 0.7 deg2, where we find 1010 DRG candidates down to Ks=20.5. We combine 95 high-quality spectroscopic redshifts with photometric redshifts from BRIJK photometry to determine the redshift and stellar mass distributions for these systems, and the morphological/structural and X-ray properties for 107 DRGs in the Extended Groth Strip. We find that many bright (J-K)Vega>2.3 galaxies with Ks<20.5 are at redshifts z<2, with 64% in the range 1galaxies are broad, ranging from 109 to 1012 Msolar, but with most z>2 systems being massive with M*>1011 Msolar. HST imaging shows that the structural properties and morphologies of DRGs are also diverse, with the majority elliptical/compact (57%) and the remainder edge-on spiral (7%) and peculiar (29%). The DRGs at z<1.4 with high-quality spectroscopic redshifts are generally compact, with small half-light radii, and span a range in rest-frame optical properties. The spectral energy distribution for the DRGs at z<1.4 differs from higher redshift DRGs: they are bluer by 1 mag in observed (I-J) color. A pure IR color selection of high-redshift populations is not sufficient to identify unique populations, and other colors or spectroscopic redshifts are needed to produce homogeneous samples.

  1. The Horizon-AGN Simulation: Morphological Diversity of Galaxies ,Promoted by AGN Feedback

    NASA Astrophysics Data System (ADS)

    Dubois, Yohan; Peirani, Sébastien; Pichon, Christophe; Devriendt, Julien; Gavazzi, Raphaël; Welker, Charlotte; Volonteri, Marta

    2016-09-01

    The interplay between cosmic gas accretion onto galaxies and galaxy mergers drives the observed morphological diversity of galaxies. By comparing the state-of-the-art hydrodynamical cosmological simulations HORIZON-AGN and HORIZON-NOAGN, we unambiguously identify the critical role of Active Galactic Nuclei (AGN) in setting up the correct galaxy morphology for the massive end of the population. With AGN feedback, typical kinematic and morpho-metric properties of galaxy populations as well as the galaxy-halo mass relation are in much better agreement with observations. Only AGN feedback allows massive galaxies at the center of groups and clusters to become ellipticals, while without AGN feedback those galaxies reform discs. It is the merger-enhanced AGN activity that is able to freeze the morphological type of the post-merger remnant by durably quenching its quiescent star formation. Hence morphology is shown not to be purely driven by mass but also by the nature of cosmic accretion: at constant galaxy mass, ellipticals are galaxies that are mainly assembled through mergers, while discs are preferentially built from the in situ star formation fed by smooth cosmic gas infall.

  2. Biased galaxy formation and large-scale structure

    NASA Astrophysics Data System (ADS)

    Berlind, Andreas Alan

    The biased relation between the galaxy and mass distributions lies at the intersection of large scale structure in the universe and the process of galaxy formation. I study the nature of galaxy bias and its connections to galaxy clustering and galaxy formation physics. Galaxy bias has traditionally been viewed as an obstacle to constraining cosmological parameters by studying galaxy clustering. I examine the effect of bias on measurements of the cosmological density parameter Wm by techniques that exploit the gravity-induced motions of galaxies. Using a variety of environmental bias models applied to N-body simulations, I find that, in most cases, the quantity estimated by these techniques is the value of W0.6m/bs , where bs is the ratio of rms galaxy fluctuations to rms mass fluctuations on large scales. Moreover, I find that different methods should, in principle, agree with each other and it is thus unlikely that non-linear or scale-dependent bias is responsible for the discrepancies that exist among current measurements. One can also view the influence of bias on galaxy clustering as a strength rather than a weakness, since it provides us with a potentially powerful way to constrain galaxy formation theories. With this goal in mind, I develop the "Halo Occupation Distribution" (HOD), a physically motivated and complete formulation of bias that is based on the distribution of galaxies within virialized dark matter halos. I explore the sensitivity of galaxy clustering statistics to features of the HOD and focus on how the HOD may be empirically constrained from galaxy clustering data. I make the connection to the physics of galaxy formation by studying the HOD predicted by the two main theoretical methods of modeling galaxy formation. I find that, despite many differences between them, the two methods predict the same HOD, suggesting that galaxy bias is determined by robust features of the hierarchical galaxy formation process rather than details of gas cooling

  3. Our Milky Way structure in the context of local galaxies

    NASA Astrophysics Data System (ADS)

    Shen, Juntai

    2015-08-01

    The Milky Way is the closest galaxy to us, and has been studied extensively due to its proximity. Understanding its structure and dynamics will help us understand spiral galaxies in general. I will review the latest research progress in the structure, kinematics, and dynamics of the Milky Way in the context of local galaxies. I will cover most structural components (the bulge/bar, disk, and spiral structures) and discuss the implications of some new results on the formation history of our home galaxy.

  4. The GHOSTS survey - II. The diversity of halo colour and metallicity profiles of massive disc galaxies

    NASA Astrophysics Data System (ADS)

    Monachesi, Antonela; Bell, Eric F.; Radburn-Smith, David J.; Bailin, Jeremy; de Jong, Roelof S.; Holwerda, Benne; Streich, David; Silverstein, Grace

    2016-04-01

    We study the stellar halo colour properties of six nearby massive highly inclined disc galaxies using Hubble space telescope Advanced Camera for Surveys and Wide Field Camera 3 observations in both F606W and F814W filters from the GHOSTS (Galaxy Halos, Outer disks, Substructure, Thick disks, and Star clusters) survey. The observed fields probe the stellar outskirts out to projected distances of ˜50-70 kpc from their galactic centre along the minor axis. The 50 per cent completeness levels of the colour-magnitude diagrams are typically at 2 mag below the tip of the red giant branch (RGB). We find that all galaxies have extended stellar haloes out to ˜50 kpc and two out to ˜70 kpc. We determined the halo colour distribution and colour profile for each galaxy using the median colours of stars in the RGB. Within each galaxy, we find variations in the median colours as a function of radius which likely indicates population variations, reflecting that their outskirts were built from several small accreted objects. We find that half of the galaxies (NGC 0891, NGC 4565, and NGC 7814) present a clear negative colour gradient in their haloes, reflecting a declining metallicity; the other have no significant colour or population gradient. In addition, notwithstanding the modest sample size of galaxies, there is no strong correlation between their halo colour/metallicity or gradient with galaxy's properties such as rotational velocity or stellar mass. The diversity in halo colour profiles observed in the GHOSTS galaxies qualitatively supports the predicted galaxy-to-galaxy scatter in halo stellar properties, a consequence of the stochasticity inherent in the assembling history of galaxies.

  5. Structural diversity in social contagion.

    PubMed

    Ugander, Johan; Backstrom, Lars; Marlow, Cameron; Kleinberg, Jon

    2012-04-17

    The concept of contagion has steadily expanded from its original grounding in epidemic disease to describe a vast array of processes that spread across networks, notably social phenomena such as fads, political opinions, the adoption of new technologies, and financial decisions. Traditional models of social contagion have been based on physical analogies with biological contagion, in which the probability that an individual is affected by the contagion grows monotonically with the size of his or her "contact neighborhood"--the number of affected individuals with whom he or she is in contact. Whereas this contact neighborhood hypothesis has formed the underpinning of essentially all current models, it has been challenging to evaluate it due to the difficulty in obtaining detailed data on individual network neighborhoods during the course of a large-scale contagion process. Here we study this question by analyzing the growth of Facebook, a rare example of a social process with genuinely global adoption. We find that the probability of contagion is tightly controlled by the number of connected components in an individual's contact neighborhood, rather than by the actual size of the neighborhood. Surprisingly, once this "structural diversity" is controlled for, the size of the contact neighborhood is in fact generally a negative predictor of contagion. More broadly, our analysis shows how data at the size and resolution of the Facebook network make possible the identification of subtle structural signals that go undetected at smaller scales yet hold pivotal predictive roles for the outcomes of social processes. PMID:22474360

  6. Multicolor CCD photometry of six lenticular and spiral galaxies. Structure of the galaxies

    NASA Astrophysics Data System (ADS)

    Gusev, A. S.

    2006-03-01

    The results of multicolor surface photometry of the S0 galaxies NGC 524, NGC 1138, and NGC 7280 and the spiral galaxies NGC 532, NGC 783, and NGC 1589 are reported. U BV RI observations were acquired with the 1.5-m telescope of the Maidanak Observatory (Uzbekistan), while JHK data were taken from the 2MASS catalog. The overall structure of the galaxies is analyzed and the galaxy images decomposed into bulge and disk components. The parameters of the galaxy components—rings, bars, spiral arms, and dust lanes—are determined. The bulge/disk decompositions based on averaged one-dimensional photometric profiles yield incorrect parameters for the bulges of the S0-Sa galaxies with bars and/or rings, whose inner regions are dominated by the radiation of the bulge.

  7. The diverse evolutionary paths of simulated high-z massive, compact galaxies to z = 0

    NASA Astrophysics Data System (ADS)

    Wellons, Sarah; Torrey, Paul; Ma, Chung-Pei; Rodriguez-Gomez, Vicente; Pillepich, Annalisa; Nelson, Dylan; Genel, Shy; Vogelsberger, Mark; Hernquist, Lars

    2016-02-01

    Massive quiescent galaxies have much smaller physical sizes at high redshift than today. The strong evolution of galaxy size may be caused by progenitor bias, major and minor mergers, adiabatic expansion, and/or renewed star formation, but it is difficult to test these theories observationally. Herein, we select a sample of 35 massive, compact galaxies (M* = 1-3 × 1011 M⊙, M*/R1.5 > 1010.5 M⊙/kpc1.5) at z = 2 in the cosmological hydrodynamical simulation Illustris and trace them forwards to z = 0 to uncover their evolution and identify their descendants. By z = 0, the original factor of 3 difference in stellar mass spreads to a factor of 20. The dark matter halo masses similarly spread from a factor of 5 to 40. The galaxies' evolutionary paths are diverse: about half acquire an ex situ envelope and are the core of a more massive descendant, a third survive undisturbed and gain very little mass, 15 per cent are consumed in a merger with a more massive galaxy, and a small remainder are thoroughly mixed by major mergers. The galaxies grow in size as well as mass, and only ˜10 per cent remain compact by z = 0. The majority of the size growth is driven by the acquisition of ex situ mass. The most massive galaxies at z = 0 are the most likely to have compact progenitors, but this trend possesses significant dispersion which precludes a direct linkage to compact galaxies at z = 2. The compact galaxies' merger rates are influenced by their z = 2 environments, so that isolated or satellite compact galaxies (which are protected from mergers) are the most likely to survive to the present day.

  8. INTERNAL STRUCTURE OF PROTOCLUSTER GALAXIES: ACCELERATED STRUCTURAL EVOLUTION IN OVERDENSE ENVIRONMENTS?

    SciTech Connect

    Zirm, Andrew W.; Toft, Sune; Tanaka, Masayuki E-mail: sune@dark-cosmology.dk

    2012-01-10

    We present a high spatial resolution Hubble Space Telescope/NICMOS imaging survey in the field of a known protocluster surrounding the powerful radio galaxy MRC1138-262 at z = 2.16. Previously, we have shown that this field exhibits a substantial surface overdensity of red J-H galaxies. Here we focus on the stellar masses and galaxy effective radii in an effort to compare and contrast the properties of likely protocluster galaxies with their field counterparts and to look for correlations between galaxy structure and (projected) distance relative to the radio galaxy. We find a hint that quiescent, cluster galaxies are on average less dense than quiescent field galaxies of similar stellar mass and redshift. In fact, we find that only two (of eight) quiescent protocluster galaxies are of similar density to the majority of the massive, quiescent compact galaxies (Semi-Evolved Elephantine Dense galaxies; SEEDs) found in several field surveys. Furthermore, there is some indication that the structural Sersic n parameter is higher (n {approx} 3-4) on average for cluster galaxies compared to the field SEEDs (n {approx} 1-2). This result may imply that the accelerated galaxy evolution expected (and observed) in overdense regions also extends to structural evolution presuming that massive galaxies began as dense (low n) SEEDs and have already evolved to be more in line with local galaxies of the same stellar mass.

  9. STRUCTURES OF LOCAL GALAXIES COMPARED TO HIGH-REDSHIFT STAR-FORMING GALAXIES

    SciTech Connect

    Petty, Sara M.; De Mello, DuIlia F.; Gallagher, John S.; Gardner, Jonathan P.; Lotz, Jennifer M.; Matt Mountain, C.; Smith, Linda J.

    2009-08-15

    The rest-frame far-ultraviolet morphologies of eight nearby interacting and starburst galaxies (Arp 269, M 82, Mrk 8, NGC 520, NGC 1068, NGC 3079, NGC 3310, and NGC 7673) are compared with 54 galaxies at z {approx} 1.5 and 46 galaxies at z {approx} 4 observed in the Great Observatories Origins Deep Survey (GOODS) taken with the Advanced Camera for Surveys onboard the Hubble Space Telescope. The nearby sample is artificially redshifted to z {approx} 1.5 and 4 by applying luminosity and size scaling. We compare the simulated galaxy morphologies to real z {approx} 1.5 and 4 UV-bright galaxy morphologies. We calculate the Gini coefficient (G), the second-order moment of the brightest 20% of the galaxy's flux (M {sub 20}), and the Sersic index (n). We explore the use of nonparametric methods with two-dimensional profile fitting and find the combination of M {sub 20} with n an efficient method to classify galaxies as having merger, exponential disk, or bulge-like morphologies. When classified according to G and M {sub 20} 20/30% of real/simulated galaxies at z {approx} 1.5 and 37/12% at z {approx} 4 have bulge-like morphologies. The rest have merger-like or intermediate distributions. Alternatively, when classified according to the Sersic index, 70% of the z {approx} 1.5 and z {approx} 4 real galaxies are exponential disks or bulge-like with n>0.8, and {approx} 30% of the real galaxies are classified as mergers. The artificially redshifted galaxies have n values with {approx} 35% bulge or exponential at z {approx} 1.5 and 4. Therefore, {approx} 20%-30% of Lyman-break galaxies have structures similar to local starburst mergers, and may be driven by similar processes. We assume merger-like or clumpy star-forming galaxies in the GOODS field have morphological structure with values n < 0.8 and M {sub 20}> - 1.7. We conclude that Mrk 8, NGC 3079, and NGC 7673 have structures similar to those of merger-like and clumpy star-forming galaxies observed at z {approx} 1.5 and 4.

  10. Shaping Galaxies:Internal Structure of the z˜2 Galaxy Population

    NASA Astrophysics Data System (ADS)

    Chang, Y.-Y.; van der Wel, A.; Rix, H.-W.; Wuyts, S.; Zibetti, S.; Ramkumar, B.; Holden, B.

    2013-10-01

    We use high-resolution VLT/HAWK-I and HST/WFC3 imaging to study the structural evolution of early-type galaxies since z˜2. Mass-selected samples are drawn from pre-existing photometric redshift surveys, which are then separated into actively star-forming and passive galaxies. The (projected) axis-ratio distributions are compared with those of lower redshift samples, and we reconstruct intrinsic axis-ratio distributions by assuming that galaxies are simple, axi-symmetric systems. We find that at all redshifts z<˜2 more massive galaxies are rounder. That is, at all epochs stars are predominantly formed in disk-like systems, whereas early-type galaxies are more bulge dominated, especially at higher masses.

  11. A Revised Parallel-Sequence Galaxy Classification: Structure and Formation of S0 and Spheroidal Galaxies

    NASA Astrophysics Data System (ADS)

    Kormendy, John; Bender, R.

    2012-01-01

    We update van den Bergh's (1976, ApJ, 206, 883) parallel sequence galaxy classification in which S0 galaxies form a sequence S0a-S0b-S0c that parallels the sequence Sa-Sb-Sc of spiral galaxies. The ratio B/T of bulge to total light defines the position of a galaxy in this tuning fork diagram. Our classification makes one main improvement. We extend the S0a-S0b-S0c sequence to spheroidal (Sph) galaxies that are positioned in parallel to irregular galaxies in a similarly extended Sa-Sb-Sc-Im sequence. This provides a natural home for spheroidals, which previously were thought to be low-surface-brightness ellipticals. To motivate our juxtaposition of spheroidals and irregulars, we present photometry and bulge-disk decompositions of late-type S0s that bridge the gap between the more common S0b and Sph galaxies. We find several S0s in the Virgo cluster that have B/T <= 0.1. They are the S0cs that were missing from van den Bergh's paper. We update the structural parameter correlations of Sph, spiral and irregular, and elliptical galaxies. We show that spheroidals of increasing luminosity form a continuous sequence with the disks (but not bulges) of S0c-S0b-S0a galaxies. Remarkably, this Sph-S0-disk sequence is almost identical to that of irregular and spiral galaxies. We suggest that spheroidal galaxies are transformed, "red and dead" Scd-Im galaxies in the same way that many S0 galaxies are transformed, red and dead Sa-Sc spiral galaxies. Plausible transformation processes include ram-pressure gas stripping, gravitational harassment, and starvation by cutting off the late infall of cold gas. We suggest that many different processes act together to engineer S0 and Sph galaxies. This work was supported by NSF grant AST-0607490.

  12. The influence of halo evolution on galaxy structure

    NASA Astrophysics Data System (ADS)

    White, Simon

    2015-03-01

    If Einstein-Newton gravity holds on galactic and larger scales, then current observations demonstrate that the stars and interstellar gas of a typical bright galaxy account for only a few percent of its total nonlinear mass. Dark matter makes up the rest and cannot be faint stars or any other baryonic form because it was already present and decoupled from the radiation plasma at z = 1000, long before any nonlinear object formed. The weak gravito-sonic waves so precisely measured by CMB observations are detected again at z = 4 as order unity fluctuations in intergalactic matter. These subsequently collapse to form today's galaxy/halo systems, whose mean mass profiles can be accurately determined through gravitational lensing. High-resolution simulations link the observed dark matter structures seen at all these epochs, demonstrating that they are consistent and providing detailed predictions for all aspects of halo structure and growth. Requiring consistency with the abundance and clustering of real galaxies strongly constrains the galaxy-halo relation, both today and at high redshift. This results in detailed predictions for galaxy assembly histories and for the gravitational arena in which galaxies live. Dark halos are not expected to be passive or symmetric but to have a rich and continually evolving structure which will drive evolution in the central galaxy over its full life, exciting warps, spiral patterns and tidal arms, thickening disks, producing rings, bars and bulges. Their growth is closely related to the provision of new gas for galaxy building.

  13. Catalytic asymmetric sulfenylation to structurally diverse dithioketals.

    PubMed

    Liao, Kui; Zhou, Feng; Yu, Jin-Sheng; Gao, Wei-Ming; Zhou, Jian

    2015-11-21

    We report the first example of the highly enantioselective synthesis of structurally diverse chiral dithioketals via asymmetric sulfenylation of various types of S-based nucleophiles, catalyzed by a cheap cinchona alkaloid derivative, dihydroquinine. PMID:26399606

  14. Inorganic pyrophosphatases: structural diversity serving the function

    NASA Astrophysics Data System (ADS)

    Samygina, V. R.

    2016-05-01

    The review is devoted to ubiquitous enzymes, inorganic pyrophosphatases, which are essential in all living organisms. Despite the long history of investigations, these enzymes continue to attract interest. The review focuses on the three-dimensional structures of various representatives of this class of proteins. The structural diversity, the relationship between the structure and some properties of pyrophosphatases and various mechanisms of enzyme action related to the structural diversity of these enzymes are discussed. Interactions of pyrophosphatase with other proteins and possible practical applications are considered. The bibliography includes 56 references.

  15. Near-infrared Structure of Fast and Slow-rotating Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Schechtman-Rook, Andrew; Bershady, Matthew A.

    2014-11-01

    We investigate the stellar disk structure of six nearby edge-on spiral galaxies using high-resolution JHK s-band images and three-dimensional radiative transfer models. To explore how mass and environment shape spiral disks, we selected galaxies with rotational velocities between 69 km s-1 diversity of disk structure. Of the fast-rotating (V rot > 150 km s-1) galaxies, only NGC 4013 has the super-thin+thin+thick nested disk structure seen in NGC 891 and the Milky Way, albeit with decreased oblateness, while NGC 1055, a disturbed massive spiral galaxy, contains disks with hz <~ 200 pc. NGC 4565, another fast-rotator, contains a prominent ring at a radius ~5 kpc but no super-thin disk. Despite these differences, all fast-rotating galaxies in our sample have inner truncations in at least one of their disks. These truncations lead to Freeman Type II profiles when projected face-on. Slow-rotating galaxies are less complex, lacking inner disk truncations and requiring fewer disk components to reproduce their light distributions. Super-thin disk components in undisturbed disks contribute ~25% of the total K s-band light, up to that of the thin-disk contribution. The presence of super-thin disks correlates with infrared flux ratios; galaxies with super-thin disks have f{K_s}/f60 μ m ≤ 0.12 for integrated light, consistent with super-thin disks being regions of ongoing star-formation. Attenuation-corrected vertical color gradients in (J - K s) correlate with the observed disk structure and are consistent with population gradients with young-to-intermediate ages closer to the mid-plane, indicating that disk heating—or cooling—is a ubiquitous phenomenon.

  16. Integrating food web diversity, structure and stability.

    PubMed

    Rooney, Neil; McCann, Kevin S

    2012-01-01

    Given the unprecedented rate of species extinctions facing the planet, understanding the causes and consequences of species diversity in ecosystems is of paramount importance. Ecologists have investigated both the influence of environmental variables on species diversity and the influence of species diversity on ecosystem function and stability. These investigations have largely been carried out without taking into account the overarching stabilizing structures of food webs that arise from evolutionary and successional processes and that are maintained through species interactions. Here, we argue that the same large-scale structures that have been purported to convey stability to food webs can also help to understand both the distribution of species diversity in nature and the relationship between species diversity and food web stability. Specifically, the allocation of species diversity to slow energy channels within food webs results in the skewed distribution of interactions strengths that has been shown to confer stability to complex food webs. We end by discussing the processes that might generate and maintain the structured, stable and diverse food webs observed in nature. PMID:21944861

  17. Early-type dwarf galaxies with multicomponent stellar structure: Are they remnants of disc galaxies strongly transformed by their environment?

    NASA Astrophysics Data System (ADS)

    Aguerri, J. Alfonso L.

    2016-03-01

    Context. The surface brightness distribution of ~30-40% of the early-type dwarf galaxies with - 18 ≤ MB ≤ -15 in the Virgo and the Coma clusters is fitted by models that include two structural components (Sérsic + exponential) as for bright disc galaxies. Aims: The goal of the present study is to determine whether early-type dwarf galaxies with a two-component stellar structure in the Virgo and the Coma clusters are low-luminosity copies of bright disc galaxies or are the remnants of bright galaxies strongly transformed by cluster environmental effects. Methods: I analysed the location of bright disc galaxies and early-type dwarfs in the rb,e/h- n plane. The location in this plane of the two-component dwarf galaxies was compared with the remnants of tidally disrupted disc galaxies reported by numerical simulations. Results: Bright unbarred disc galaxies show a strong correlation in the rb,e/h-n plane. Galaxies with larger Sérsic shape parameters show a higher rb,e/h ratio. In contrast, two-component early-type dwarf galaxies do not follow the same correlation. A fraction (~55%) of them are located outside the locus defined in this plane by having 95% of bright disc galaxies. This distribution indicates that they are not a low-mass replica of bright disc galaxies. The different location in the rb,e/h- n plane of two-component early-type dwarfs and bright galaxies can be qualitatively explain whether the former are remnants of disc galaxies strongly transformed by tidal processes. Conclusions: The progenitors of ~20-25% of early-type dwarf galaxies with - 18 ≤ MB ≤ -15 in the Virgo and Coma clusters could be bright disc galaxies transformed by effects of the environment. These tidally transformed galaxies can be selected according to their location in the rb,e/h-n plane.

  18. Galaxies

    SciTech Connect

    Not Available

    1981-01-01

    Normal galaxies, radio galaxies, and Seyfert galaxies are considered. The large magellanic cloud and the great galaxy in Andromedia are highlighted. Quasars and BL lacertae objects are also discussed and a review of the spectral observations of all of these galaxies and celestial objects is presented.

  19. Probing asymmetric structures in the outskirts of galaxies

    SciTech Connect

    Wen, Zhang Zheng; Zheng, Xian Zhong; An, Fang Xia E-mail: xzzheng@pmo.ac.cn

    2014-06-01

    Upcoming large imaging surveys will allow detailed studies of the structure and morphology of galaxies aimed at addressing how galaxies form and evolve. Computational approaches are needed to characterize their morphologies over large samples. We introduce an automatic method to quantify the outer structure of galaxies. The key to our approach is the division of a galaxy image into two sections delineated by the isophote, which encloses half the total brightness of the galaxy. We call the central section the inner half-flux region (IHR) and the outer section the outer half-flux region (OHR). From this division, we derive two parameters: A {sub o}, which measures the asymmetry of the OHR, and D {sub o}, which measures the deviation of the intensity weighted centroid of the OHR from that of the IHR relative to the effective radius. We derive the two parameters from HST/ACS z {sub 850}-band images for a sample of 764 galaxies with z {sub 850} < 22 mag and 0.35 < z < 0.9 selected from the GEMS and GOODS-South surveys. We show that the sample galaxies having strong asymmetric structures, particularly tidal tails, are well-separated from those with regular morphologies in the A {sub o}-D {sub o} space. Meanwhile, the widely used CAS and Gini-M {sub 20} methods turn out to be insensitive to such morphological features. We stress that the A {sub o}-D {sub o} method is an efficient way to select galaxies with significant asymmetric features like tidal tails and study galaxy mergers in the dynamical phase traced by these delicate features.

  20. The Structure of Galaxies I: Surface Photometry Techniques

    NASA Astrophysics Data System (ADS)

    Schombert, J.; Smith, A. K.

    2012-04-01

    This project uses the 2MASS all-sky image database to study the structure of galaxies over a range of luminosities, sizes and morphological types. This first paper in this series will outline the techniques, reliability and data products to our surface photometry program. Our program will analyze all acceptable galaxies (meeting our criteria for isolation from companions and bright stars) from the Revised Shapley-Ames and Uppsala galaxy catalogs. Resulting photometry and surface brightness profiles are released using a transparent scheme of data storage which includes not only all the processed data but knowledge of the processing steps and calibrating parameters.

  1. Structural diversity of supercoiled DNA

    NASA Astrophysics Data System (ADS)

    Irobalieva, Rossitza N.; Fogg, Jonathan M.; Catanese, Daniel J.; Sutthibutpong, Thana; Chen, Muyuan; Barker, Anna K.; Ludtke, Steven J.; Harris, Sarah A.; Schmid, Michael F.; Chiu, Wah; Zechiedrich, Lynn

    2015-10-01

    By regulating access to the genetic code, DNA supercoiling strongly affects DNA metabolism. Despite its importance, however, much about supercoiled DNA (positively supercoiled DNA, in particular) remains unknown. Here we use electron cryo-tomography together with biochemical analyses to investigate structures of individual purified DNA minicircle topoisomers with defined degrees of supercoiling. Our results reveal that each topoisomer, negative or positive, adopts a unique and surprisingly wide distribution of three-dimensional conformations. Moreover, we uncover striking differences in how the topoisomers handle torsional stress. As negative supercoiling increases, bases are increasingly exposed. Beyond a sharp supercoiling threshold, we also detect exposed bases in positively supercoiled DNA. Molecular dynamics simulations independently confirm the conformational heterogeneity and provide atomistic insight into the flexibility of supercoiled DNA. Our integrated approach reveals the three-dimensional structures of DNA that are essential for its function.

  2. Structural diversity of supercoiled DNA

    PubMed Central

    Irobalieva, Rossitza N.; Fogg, Jonathan M.; Catanese, Daniel J.; Sutthibutpong, Thana; Chen, Muyuan; Barker, Anna K.; Ludtke, Steven J.; Harris, Sarah A.; Schmid, Michael F.; Chiu, Wah; Zechiedrich, Lynn

    2015-01-01

    By regulating access to the genetic code, DNA supercoiling strongly affects DNA metabolism. Despite its importance, however, much about supercoiled DNA (positively supercoiled DNA, in particular) remains unknown. Here we use electron cryo-tomography together with biochemical analyses to investigate structures of individual purified DNA minicircle topoisomers with defined degrees of supercoiling. Our results reveal that each topoisomer, negative or positive, adopts a unique and surprisingly wide distribution of three-dimensional conformations. Moreover, we uncover striking differences in how the topoisomers handle torsional stress. As negative supercoiling increases, bases are increasingly exposed. Beyond a sharp supercoiling threshold, we also detect exposed bases in positively supercoiled DNA. Molecular dynamics simulations independently confirm the conformational heterogeneity and provide atomistic insight into the flexibility of supercoiled DNA. Our integrated approach reveals the three-dimensional structures of DNA that are essential for its function. PMID:26455586

  3. Transformations of galaxies - III. Encounter dynamics and tidal response as functions of galaxy structure

    NASA Astrophysics Data System (ADS)

    Barnes, Joshua E.

    2016-01-01

    Tidal interactions between disc galaxies depend on galaxy structure, but the details of this relationship are incompletely understood. I have constructed a three-parameter grid of bulge/disc/halo models broadly consistent with Λ cold dark matter, and simulated an extensive series of encounters using these models. Halo mass and extent strongly influence the dynamics of orbit evolution. In close encounters, the transfer of angular momentum mediated by the dynamical response of massive, extended haloes can reverse the direction of orbital motion of the central galaxies after their first passage. Tidal response is strongly correlated with the ratio ve/vc of escape to circular velocity within the participating discs. Moreover, the same ratio also correlates with the rate at which tidal tails are reaccreted by their galaxies of origin; consequently, merger remnants with `twin tails', such as NGC 7252, may prove hard to reproduce unless (ve/vc)2 ≲ 5.5. The tidal morphology of an interacting system can provide useful constraints on progenitor structure. In particular, encounters in which halo dynamics reverses orbital motion exhibit a distinctive morphology which may be recognized observationally. Detailed models attempting to reproduce observations of interacting galaxies should explore the likely range of progenitor structures along with other encounter parameters.

  4. The link between galaxy structure and star formation across cosmic time

    NASA Astrophysics Data System (ADS)

    Fang, Jerome Joseph

    -wavelength datasets produced by the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). By finely dissecting our sample into narrow mass and redshift slices, we are able to uncover several striking trends, including evidence for mass-dependent evolution in terms of disk formation and the buildup of metals and dust, i.e., massive galaxies are more evolved at all epochs. However, at fixed mass, no correlation between structure and specific star-formation rate is seen for galaxies on the star-forming "main sequence." This behavior persists at all redshifts, despite the considerable diversity in size and shape among star-forming galaxies. This suggests that, on the main sequence, star formation is regulated primarily by external factors, e.g., halo accretion rate, rather than the internal structure of the galaxy.

  5. Report on the Workshop Deconstructing Galaxies: Structure and Morphology in the Era of Large Surveys

    NASA Astrophysics Data System (ADS)

    Gadotti, D. A.; Sánchez-Janssen, R.

    2014-03-01

    Over 120 researchers — observers and theoreticians — gathered to present new results and discuss ongoing investigations on the structure of galaxies. The study of the structure and morphology of galaxies is one of the major tools that astronomers have to address how galaxies form and evolve. Recent progress in the field has enabled a boost in our understanding of the properties of the different structural components in nearby galaxies, as well as in galaxies at intermediate redshifts (z ~ 1-2).

  6. Red Galaxy Structures Toward a Large Quasar Group Field

    NASA Astrophysics Data System (ADS)

    Williger, Gerard M.; Feil, E. C.; Haberzettl, L.; Clowes, R.; Campusano, L.; Haines, C. P.; Valls-Gabaud, D.; Lehnert, M.; Nesvadba, N.; LQG Team

    2014-01-01

    We present data from deep FUV-NUV-griz images toward a 2 sq degree region in the Clowes-Campusano Large Quasar Group field, which contains structures of quasars on the >100 Mpc scale at 0.8 and 1.2. Large Quasar Groups may be the signal posts for galaxy structures analogous to superclusters at high redshift. Using the six band photometry, we calculate photometric redshifts for red-selected galaxies to identify supercluster-size structures, and compare their locations with the quasars in the field.

  7. Kinematic and Structural Evolution of Field and Cluster Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Ziegler, B. L.; Kutdemir, E.; Da Rocha, C.; Böhm, A.; Peletier, R. F.; Verdugo, M.

    2010-10-01

    To understand the processes that build up galaxies we investigate the stellar structure and gas kinematics of spiral and irregular galaxies out to redshift 1. We target 92 galaxies in four cluster ( z = 0.3 & 0.5 ) fields to study the environmental influence. Their stellar masses derived from multiband VLT/FORS photometry are distributed around but mostly below the characteristic Schechter-fit mass. From HST/ACS images we determine morphologies and structural parameters like disk length, position angle and ellipticity. Combining the spectra of three slit positions per galaxy using the MXU mode of VLT/FORS2 we construct the two-dimensional velocity field from gas emission lines for 16 cluster members and 33 field galaxies. The kinematic position angle and flatness are derived by a Fourier expansion of elliptical velocity profiles. To trace possible interaction processes, we define three irregularity indicators based on an identical analysis of local galaxies from the SINGS project. Our distant sample displays a higher fraction of disturbed velocity fields with varying percentages (10%, 30% and 70%) because they trace different features. While we find far fewer candidates for major mergers than the SINS sample at z ˜ 2, our data are sensitive enough to trace less violent processes. Most irregular signatures are related to star formation events and less massive disks are affected more than Milky-Way type objects. We detect similarly high fractions of irregular objects both for the distant field and cluster galaxies with similar distributions. We conclude that we may witness the building-up of disk galaxies still at redshifts z ˜ 0.5 via minor mergers and gas accretion, while some cluster members may additionally experience stripping, evaporation or harassment interactions.

  8. The diversity of growth histories of Milky Way-mass galaxies

    NASA Astrophysics Data System (ADS)

    Terrazas, Bryan A.; Bell, Eric F.; Henriques, Bruno M. B.; White, Simon D. M.

    2016-06-01

    We use the semi-analytic model developed by Henriques et al. to explore the origin of star formation history diversity for galaxies that lie at the centre of their dark matter haloes and have present-day stellar masses in the range 5-8 × 1010 M⊙, similar to that of the Milky Way. In this model, quenching is the dominant physical mechanism for introducing scatter in the growth histories of these galaxies. We find that present-day quiescent galaxies have a larger variety of growth histories than star-formers since they underwent `staggered quenching' - a term describing the correlation between the time of quenching and present-day halo mass. While halo mass correlates broadly with quiescence, we find that quiescence is primarily a function of black hole mass, where galaxies quench when heating from their active galactic nuclei becomes sufficient to offset the redshift-dependent cooling rate. In this model, the emergence of a prominent quiescent population is the main process that flattens the stellar mass-halo mass relation at mass scales at or above that of the Milky Way.

  9. THE CARNEGIE-IRVINE GALAXY SURVEY. III. THE THREE-COMPONENT STRUCTURE OF NEARBY ELLIPTICAL GALAXIES

    SciTech Connect

    Huang, Song; Ho, Luis C.; Peng, Chien Y.; Li, Zhao-Yu; Barth, Aaron J.

    2013-03-20

    Motivated by recent developments in our understanding of the formation and evolution of massive galaxies, we explore the detailed photometric structure of a representative sample of 94 bright, nearby elliptical galaxies, using high-quality optical images from the Carnegie-Irvine Galaxy Survey. The sample spans a range of environments and stellar masses, from M{sub *} = 10{sup 10.2} to 10{sup 12.0} M{sub Sun }. We exploit the unique capabilities of two-dimensional image decomposition to explore the possibility that local elliptical galaxies may contain photometrically distinct substructure that can shed light on their evolutionary history. Compared with the traditional one-dimensional approach, these two-dimensional models are capable of consistently recovering the surface brightness distribution and the systematic radial variation of geometric information at the same time. Contrary to conventional perception, we find that the global light distribution of the majority ({approx}>75%) of elliptical galaxies is not well described by a single Sersic function. Instead, we propose that local elliptical galaxies generically contain three subcomponents: a compact (R{sub e} {approx}< 1 kpc) inner component with luminosity fraction f Almost-Equal-To 0.1-0.15; an intermediate-scale (R{sub e} Almost-Equal-To 2.5 kpc) middle component with f Almost-Equal-To 0.2-0.25; and a dominant (f = 0.6), extended (R{sub e} Almost-Equal-To 10 kpc) outer envelope. All subcomponents have average Sersic indices n Almost-Equal-To 1-2, significantly lower than the values typically obtained from single-component fits. The individual subcomponents follow well-defined photometric scaling relations and the stellar mass-size relation. We discuss the physical nature of the substructures and their implications for the formation of massive elliptical galaxies.

  10. Gravitational Lenses and the Structure and Evolution of Galaxies

    NASA Technical Reports Server (NTRS)

    Kochanek, Christopher

    2003-01-01

    The grant has supported the completion of 16 papers and 4 conference proceedings to date. During the first year of the project we completed five papers, each of which represents a new direction in the theory and interpretation of gravitational lenses. In the first paper, "The Importance of Einstein Rings", we developed the first theory for the formation and structure of the Einstein rings formed by lensing extended sources like the host galaxies of quasar and radio sources. We applied the theory to three lenses with lensed host galaxies. For the time delay lens PG 1115+080 we found that the structure of the Einstein ring ruled out models of the gravitational potential which permitted a large Hubble constant (70 km/s Mpc). In the second paper, :Cusped Mass Models Of Gravitational Lenses", we introduced a new class of lens models where the central density is characterized by a cusp ( rho proportional to tau(sup -gamma), 1 less than gamma less than 2) as in most modern models and theories of galaxies rather than a finite core radius. In the third paper, "Global Probes of the Impact of Baryons on Dark Matter Halos", we made the first globally consistent models for the separation distribution of gravitational lenses including both galaxy and cluster lenses. We show that the key physics for the origin of the sharp separation cutoff in the separation distribution near 3 arc sec is the effect of the cooling baryons in galaxies on the density structure of the system.

  11. Statistical model semiquantitatively approximates arabinoxylooligosaccharides' structural diversity.

    PubMed

    Dotsenko, Gleb; Nielsen, Michael Krogsgaard; Lange, Lene

    2016-05-13

    A statistical model describing the random distribution of substituted xylopyranosyl residues in arabinoxylooligosaccharides is suggested and compared with existing experimental data. Structural diversity of arabinoxylooligosaccharides of various length, originating from different arabinoxylans (wheat flour arabinoxylan (arabinose/xylose, A/X = 0.47); grass arabinoxylan (A/X = 0.24); wheat straw arabinoxylan (A/X = 0.15); and hydrothermally pretreated wheat straw arabinoxylan (A/X = 0.05)), is semiquantitatively approximated using the proposed model. The suggested approach can be applied not only for prediction and quantification of arabinoxylooligosaccharides' structural diversity, but also for estimate of yield and selection of the optimal source of arabinoxylan for production of arabinoxylooligosaccharides with desired structural features. PMID:27043469

  12. Galaxy Proto-clusters as an Interface Between Structure, Cluster, and Galaxy Formation

    NASA Astrophysics Data System (ADS)

    Chiang, Yi-Kuan

    2016-01-01

    Proto-clusters, the progenitor large-scale structures of present day galaxy clusters, are unique laboratories to study dark matter assembly, cosmic baryon cycle, galaxy growth, and environmental impact on galaxy evolution. In this dissertation talk, I will present our recent progress in this subject, both theoretical and observational. Using a set of cosmological N-body simulations and semi-analytic galaxy models, we extract the mass, size, and overdensity evolution for ˜3000 simulated clusters from z=8 to z=0. In line with the scenario of cosmic downsizing, the models predict that the fraction of cosmic star formation rate occurs in (proto-)clusters increases from <1% at z=0 to 20-30% at z=8. This result demonstrates that the seemingly sharp distinction when discussing field and cluster galaxy evolution has to be blurred at high redshift, and a significant fraction of cosmic reionization was done by cluster progenitors. Observationally, we focus on the epoch of z≈2 when the first cluster scale halos (1014 M⊙) were about to form. We perform a systematic proto-cluster search using a photometric redshift catalog in the COSMOS field, revealing a large sample of 36 candidate proto-clusters at 1.6structures in this catalog have been confirmed spectroscopically. I will present the confirmation and detailed characterization of a ``proto-Virgo'' cluster in this field at z=2.44 with Mz=0 = 1014.5±0.4 M⊙ using a sample of Lyα emitters (LAE) in the HETDEX Pilot Survey with a highly homogeneous selection function in 3D redshift space. Compared to the cosmic mean, this structure shows a LAE overdensity of 4 on a scale of few tens cMpc, a 5 times higher fraction of extended Lya blobs, a 2 times higher median stellar mass of NIR selected galaxies with photometric redshift, and a significantly enhanced intergalactic gas revealed in the Lyα absorption maps of Lee et al. (2014, 2015). With these results, I will discuss proto-clusters in the context of

  13. Understanding the Structure and Evolution of Nearby Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Zheng, Zheng

    2014-01-01

    In order to understand the structure and evolution of disk galaxies, we studied the stellar and gaseous components as well as the star formation rate in nearby disk galaxies. We used PS1 medium deep survey images to derive five-band (grizy) surface brightness profiles down to 30 ABmag/arcsec^2 for about 700 galaxies. From these stellar mass and mass-to-light ratio radial profiles are derived. The stellar mass radial profiles tend to bend-up at large radii, this often traces an extended old stellar population. The mass-to-light ratio profiles tend to rise outside the r25 radii. We also find a larger fraction of up-bending surface brightness profiles than Polen & Trujillo (2006). This may be because their sample is biased towards low surface brightness galaxies. We used HIPASS data as well as VLA HI 21cm data to study the gas component and dynamics of disk galaxies. We used the GALEX UV images to study the star formation of a HI-selected star-forming sample of about 400 galaxies, compiling a database of FUV and NUV radial profiles and related parameters. We used this to study the star forming efficiency (SFE, star formation rate per unit area divided by gas surface mass density) of the sample galaxies. We found that the UV based SFE has a tighter relationship with HI mass than an H_alpha based SFE as typically used in previous studies and the UV SFE is flat across wide range of stellar mass. We constructed a simple model to predict the distribution of interstellar medium and star formation rate in an equilibrium disk with constant two-fluid Toomre Q. This model can reproduces the SFE relations we derived.

  14. Galaxy Structure: Core Radii, and Central Mass Deficits

    NASA Astrophysics Data System (ADS)

    Graham, A. W.; Trujillo, I.; Erwin, P.

    2004-05-01

    We investigate the nuclear and global structure of elliptical galaxies, and the apparent disparity between the Nuker and Sérsic light-profile models. We show that the so-called ``power-law" galaxies in fact have Sérsic r1/n profiles over their entire observed radial range. Consequently, only three (Sérsic-profile) parameters are required to simultaneously describe both the inner (HST-resolved) and outer profiles of low-luminosity (M > -20.5 B-mag) elliptical galaxies. We also find that ``core galaxies" have Sérsic profiles with a (partially evacuated) single power-law core. We have developed a modified (5-parameter) Sérsic profile with a power-law core to model the complete radial extent of luminous galaxies with cores. In addition to quantifying the global stellar distribution in these systems, we have derived new estimates of their core radii and other central properties. Comparison of the central stellar deficits with the galaxies' black hole masses suggests that the number of (dissipationless) major mergers that have produced luminous elliptical galaxies is around 1-2, rather than 8-10, which agrees with theory and implies that the galactic merger history of the Universe is roughly an order of magnitude less violent than previous observational analyses had suggested. Support for proposal number HST-AR-09927.01-A was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  15. Imaging the mass structure of distant lens galaxies

    NASA Astrophysics Data System (ADS)

    Koopmans, Leon

    2005-07-01

    The surface brightness distribution of extended gravitationally lensed arcs and Einstein rings contains super-resolved information about the lensed object, and, more excitingly, about the smooth and clumpy mass distribution of the lens galaxies. The source and lens information can non-parametrically be separated, resulting in a direct "gravitational-mass image" of the inner mass-distribution of cosmologically-distant galaxies {Koopmans 2005}.With this goal in mind, we propose deep HST ACS-F555W/F814W and NICMOS-F160W imaging of 15 gravitational-lens systems with spatially resolved lensed sources, selected from the 17 new lens systems discovered by the Sloan Lens ACS Survey {Bolton et al. 2004}. Each system has been selected from the SDSS and confirmed in a time-efficient HST-ACS snapshot program {cycle-13}; they show highly-magnified arcs or Einstein rings, lensed by a massive early-type lens galaxy. High-fidelity multi-color HST images are required {not delivered by the 420-sec snapshot images} to isolate these lensed images {properly cleaned, dithered and extinction-corrected} from the lens galaxy surface brightness distribution, and apply our "gravitational-mass imaging" technique.The sample of galaxy mass distributions - determined through this method from the arcs and Einstein ring HST images - will be studied to: {i} measure the smooth mass distribution of the lens galaxies {Dark and luminous mass are separated using the HST images and the stellar M/L values derived from a joint stellar-dynamical analysis of each system}; {ii} quantify statistically and individually the incidence of mass-substructure {with or without obvious luminous counter-parts such as dwarf galaxies}. Since dark-matter substructure should be considerably more prevalent at higher redshift, both results provide a direct test of this prediction of the CDM hierarchical structure-formation model.

  16. Disentangling Structures in the Cluster of Galaxies Abell 133

    NASA Technical Reports Server (NTRS)

    Way, Michael J.; DeVincenzi, Donald (Technical Monitor)

    2002-01-01

    A dynamical analysis of the structure of the cluster of galaxies Abell 133 will be presented using multi-wavelength data combined from multiple space and earth based observations. New and familiar statistical clustering techniques are used in combination in an attempt to gain a fully consistent picture of this interesting nearby cluster of galaxies. The type of analysis presented should be typical of cluster studies in the future, especially those to come from the surveys like the Sloan Digital Sky Survey and the 2DF.

  17. Computer experiments on the structure and dynamics of spiral galaxies

    NASA Technical Reports Server (NTRS)

    Hohl, F.

    1972-01-01

    The evolution of an initially balanced rotating disk of stars with an initial velocity dispersion given by Toomre's local criterion was investigated by means of a computer model for isolated disks of stars. It was found that the disk is unstable against very large scale modes. A stable axisymmetric disk with a velocity dispersion much larger than that given by Toomre's criterion was generated. The final mass distribution for the disk gives a high density central core and a disk population of stars that is closely approximated by an exponential variation. Various methods and rates of cooling the hot axisymmetric disks were investigated. It was found that the cooling resulted in the development of two-arm spiral structures which persisted as long as cooling continued. An experiment was performed to induce spiral structure in a galaxy by means of the close passage of a companion galaxy. Parameters similar to those expected for M51 and its companion were used. It was found that because of the high velocity dispersion of the disturbed disk galaxy, only a weak two-arm spiral structure appeared. The evolution of a uniformly rotating disk galaxy which is a stationary solution of the collisionless Boltzmann equation was investigated for various values of the initial rms velocity dispersion. It was found that the disk becomes stable at a value of the velocity dispersion predicted by theory.

  18. Giant ringlike radio structures around galaxy cluster Abell 3376.

    PubMed

    Bagchi, Joydeep; Durret, Florence; Neto, Gastão B Lima; Paul, Surajit

    2006-11-01

    In the current paradigm of cold dark matter cosmology, large-scale structures are assembling through hierarchical clustering of matter. In this process, an important role is played by megaparsec (Mpc)-scale cosmic shock waves, arising in gravity-driven supersonic flows of intergalactic matter onto dark matter-dominated collapsing structures such as pancakes, filaments, and clusters of galaxies. Here, we report Very Large Array telescope observations of giant ( approximately 2 Mpc by 1.6 Mpc), ring-shaped nonthermal radio-emitting structures, found at the outskirts of the rich cluster of galaxies Abell 3376. These structures may trace the elusive shock waves of cosmological large-scale matter flows, which are energetic enough to power them. These radio sources may also be the acceleration sites where magnetic shocks are possibly boosting cosmic-ray particles with energies of up to 10(18) to 10(19) electron volts. PMID:17082451

  19. Structural properties of central galaxies in groups and clusters

    NASA Astrophysics Data System (ADS)

    Guo, Yicheng; McIntosh, Daniel H.; Mo, H. J.; Katz, Neal; van den Bosch, Frank C.; Weinberg, Martin; Weinmann, Simone M.; Pasquali, Anna; Yang, Xiaohu

    2009-09-01

    Using a statistically representative sample of 911 central galaxies (CENs) from the Sloan Digital Sky Survey (SDSS) Data Release 4 group catalogue, we study how the structure (shape and size) of the first rank (by stellar mass) group and cluster members depends on (1) galaxy stellar mass (Mstar), (2) the global environment defined by the dark matter halo mass (Mhalo) of the host group and (3) the local environment defined by their special halocentric position. We quantify the structure of SDSS galaxies with a GALFIT-based pipeline that fits two-dimensional Sérsic models to the r-band image data. Through tests with simulated and real galaxy images, we demonstrate that our pipeline can recover Sérsic parameters without significant bias. We find that the fitting results are most sensitive to the background sky level determination, and we strongly recommend using the SDSS global value. We also find that uncertainties in the background sky level translate into a strong covariance between the total magnitude, the half-light radius (r50) and the Sérsic index (n), especially for bright/massive galaxies. Applying our pipeline to the CEN sample, we find that n of CENs depends strongly on Mstar, but only weakly or not at all on Mhalo. The n-Mstar relation holds for CENs over the full range of halo masses that we consider. Less massive CENs tend to be disc like and high-mass systems are typically spheroids, with a considerable scatter in n at all galaxy masses. Similarly, CEN sizes depend on galaxy stellar mass and luminosity, with early- and late-type galaxies exhibiting different slopes for the size-luminosity (r50-L) and the size-stellar mass (r50-Mstar) scaling relations. Moreover, to test the impact of local environment on CENs, we compare the structure of CENs with that satellite galaxies (SATs) of comparable Mstar. We find that low-mass (<1010.75h-2Msolar) SATs have somewhat larger median Sérsic indices than CENs of a similar Mstar. Furthermore, low-mass, late

  20. Excitation and Evolution of Structure in Galaxies

    NASA Technical Reports Server (NTRS)

    Weinberg, Martin D.

    1996-01-01

    Even casual examination shows that most disk galaxies are not truly symmetric but exhibit a variety of morphological peculiarities of which spiral arms and bars are the most pronounced. After decades of effort, we now know that these features may be driven by environmental disturbance acting directly on the disk, in addition to self-excitation of a local disturbance (e.g. by swing amplification). However, all disks are embedded within halos and therefore are not dynamically independent. Are halos susceptible to such disturbances as well? If so, can the affect disks and on what time scales? y Until recently, conventional wisdom was that halos acted to stabilize disks but otherwise remained relatively inert. The argument behind this assumption is as follows. Halos, spheroids and bulges are supported against their own gravity by the random motion of their stars, a so-called "hot" distribution. On all but the largest scales, they look like a nearly homogeneous thermal bath of stars. Because all self-sustaining patterns or waves in a homogeneous universe of stars with a Maxwellian velocity distribution are predicted to damp quickly (e.g. Ikeuchi et al. 1974), one expects that any pattern will be strongly damped in halos and spheroids as well. However, recent work suggests that halos do respond to tidal encounters by companions or cluster members and are susceptible to induction of long-lived modes.

  1. Near-infrared structure of fast and slow-rotating disk galaxies

    SciTech Connect

    Schechtman-Rook, Andrew; Bershady, Matthew A.

    2014-11-10

    We investigate the stellar disk structure of six nearby edge-on spiral galaxies using high-resolution JHK {sub s}-band images and three-dimensional radiative transfer models. To explore how mass and environment shape spiral disks, we selected galaxies with rotational velocities between 69 km s{sup –1} diversity of disk structure. Of the fast-rotating (V {sub rot} > 150 km s{sup –1}) galaxies, only NGC 4013 has the super-thin+thin+thick nested disk structure seen in NGC 891 and the Milky Way, albeit with decreased oblateness, while NGC 1055, a disturbed massive spiral galaxy, contains disks with h{sub z} ≲ 200 pc. NGC 4565, another fast-rotator, contains a prominent ring at a radius ∼5 kpc but no super-thin disk. Despite these differences, all fast-rotating galaxies in our sample have inner truncations in at least one of their disks. These truncations lead to Freeman Type II profiles when projected face-on. Slow-rotating galaxies are less complex, lacking inner disk truncations and requiring fewer disk components to reproduce their light distributions. Super-thin disk components in undisturbed disks contribute ∼25% of the total K {sub s}-band light, up to that of the thin-disk contribution. The presence of super-thin disks correlates with infrared flux ratios; galaxies with super-thin disks have f{sub K{sub s}}/f{sub 60} {sub μm}≤0.12 for integrated light, consistent with super-thin disks being regions of ongoing star-formation. Attenuation-corrected vertical color gradients in (J – K {sub s}) correlate with the observed disk structure and are consistent with population gradients with young-to-intermediate ages closer to the mid-plane, indicating that disk heating—or cooling—is a ubiquitous phenomenon.

  2. A Classical Morphological Analysis of Galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S4G)

    NASA Astrophysics Data System (ADS)

    Buta, Ronald J.; Sheth, Kartik; Athanassoula, E.; Bosma, A.; Knapen, Johan H.; Laurikainen, Eija; Salo, Heikki; Elmegreen, Debra; Ho, Luis C.; Zaritsky, Dennis; Courtois, Helene; Hinz, Joannah L.; Muñoz-Mateos, Juan-Carlos; Kim, Taehyun; Regan, Michael W.; Gadotti, Dimitri A.; Gil de Paz, Armando; Laine, Jarkko; Menéndez-Delmestre, Karín; Comerón, Sébastien; Erroz Ferrer, Santiago; Seibert, Mark; Mizusawa, Trisha; Holwerda, Benne; Madore, Barry F.

    2015-04-01

    The Spitzer Survey of Stellar Structure in Galaxies (S4G) is the largest available database of deep, homogeneous middle-infrared (mid-IR) images of galaxies of all types. The survey, which includes 2352 nearby galaxies, reveals galaxy morphology only minimally affected by interstellar extinction. This paper presents an atlas and classifications of S4G galaxies in the Comprehensive de Vaucouleurs revised Hubble-Sandage (CVRHS) system. The CVRHS system follows the precepts of classical de Vaucouleurs morphology, modified to include recognition of other features such as inner, outer, and nuclear lenses, nuclear rings, bars, and disks, spheroidal galaxies, X patterns and box/peanut structures, OLR subclass outer rings and pseudorings, bar ansae and barlenses, parallel sequence late-types, thick disks, and embedded disks in 3D early-type systems. We show that our CVRHS classifications are internally consistent, and that nearly half of the S4G sample consists of extreme late-type systems (mostly bulgeless, pure disk galaxies) in the range Scd-Im. The most common family classification for mid-IR types S0/a to Sc is SA while that for types Scd to Sm is SB. The bars in these two type domains are very different in mid-IR structure and morphology. This paper examines the bar, ring, and type classification fractions in the sample, and also includes several montages of images highlighting the various kinds of “stellar structures” seen in mid-IR galaxy morphology.

  3. The luminosity structure and objective classification of galaxies

    NASA Technical Reports Server (NTRS)

    Han, Mingshen

    1995-01-01

    The luminosity structure of spiral galaxies is studied using the technique of principal component analysis. It is found that approximately 94% of the variation in the luminosity distribution of galaxies can be accounted for by just two principal components. The principal luminosity components may contain valuable information about star formation history or whatever luminosity-regulating process occurs in galaxies. Practically, these principal components provide a new approach for the investigation of the luminosity structures of galaxies and their dependence on other properties. They also serve as an excellent objective classification system for galaxies. We introduce in this paper such a classification scheme and explore its various properties. The new system shows a number of very impressive characteristics. Most important, it can well segregate virtually all the important galactic properties we tested and does so much better than the conventional morphological classification systems. Of particular interest is that some distance-dependent parameters can also be determined to a surprisingly good accuracy; for example, absolute magnitude may be determined to an accuracy of approximately 0.6 mag (yet further improvement is believed to be highly possible). Second, the system is objective, and the classification procedure can be automated to a large degree; also the new system can apply to much smaller and fainter images than do eye-based clasification systems. These properties make the new system suitable for practical application, especially on very large (and deeper) digital image catalogs. Third, the classification is expressed in dimensionless numbers, yet the simple notation bears significant and easily understandable meaning, making it easy and convenient to use. Finally, the new system has another extremely useful feature: it provides a very powerful and convenient platform not only for classification, but also for easily recording, examining, and studying the

  4. Structural analysis of the Sextans dwarf spheroidal galaxy

    NASA Astrophysics Data System (ADS)

    Roderick, T. A.; Jerjen, H.; Da Costa, G. S.; Mackey, A. D.

    2016-04-01

    We present wide-field g and i band stellar photometry of the Sextans dwarf spheroidal galaxy and its surrounding area out to four times its half-light radius (rh = 695 pc), based on images obtained with the Dark Energy Camera at the 4-m Blanco telescope at CTIO. We find clear evidence of stellar substructure associated with the galaxy, extending to a distance of 82' (2 kpc) from its centre. We perform a statistical analysis of the over-densities and find three distinct features, as well as an extended halo-like structure, to be significant at the 99.7% confidence level or higher. Unlike the extremely elongated and extended substructures surrounding the Hercules dwarf spheroidal galaxy, the over-densities seen around Sextans are distributed evenly about its centre, and do not appear to form noticeable tidal tails. Fitting a King model to the radial distribution of Sextans stars yields a tidal radius rt = 83.2' ± 7.1' (2.08±0.18 kpc), which implies the majority of detected substructure is gravitationally bound to the galaxy. This finding suggests that Sextans is not undergoing significant tidal disruption from the Milky Way, supporting the scenario in which the orbit of Sextans has a low eccentricity.

  5. Structural analysis of the Sextans dwarf spheroidal galaxy

    NASA Astrophysics Data System (ADS)

    Roderick, T. A.; Jerjen, H.; Da Costa, G. S.; Mackey, A. D.

    2016-07-01

    We present wide-field g- and i-band stellar photometry of the Sextans dwarf spheroidal galaxy and its surrounding area out to four times its half-light radius (rh = 695 pc), based on images obtained with the Dark Energy Camera at the 4-m Blanco telescope at CTIO. We find clear evidence of stellar substructure associated with the galaxy, extending to a distance of 82 arcmin (2 kpc) from its centre. We perform a statistical analysis of the overdensities and find three distinct features, as well as an extended halo-like structure, to be significant at the 99.7 per cent confidence level or higher. Unlike the extremely elongated and extended substructures surrounding the Hercules dwarf spheroidal galaxy, the overdensities seen around Sextans are distributed evenly about its centre, and do not appear to form noticeable tidal tails. Fitting a King model to the radial distribution of Sextans stars yields a tidal radius rt = 83.2 arcmin ± 7.1 arcmin (2.08 ± 0.18 kpc), which implies the majority of detected substructure is gravitationally bound to the galaxy. This finding suggests that Sextans is not undergoing significant tidal disruption from the Milky Way, supporting the scenario in which the orbit of Sextans has a low eccentricity.

  6. Structural diversity of the epigenetics pocketome.

    PubMed

    Cabaye, Alexandre; Nguyen, Kong T; Liu, Lihua; Pande, Vineet; Schapira, Matthieu

    2015-07-01

    Protein families involved in chromatin-templated events are emerging as novel target classes in oncology and other disease areas. The ability to discover selective inhibitors against chromatin factors depends on the presence of structural features that are unique to the targeted sites. To evaluate challenges and opportunities toward the development of selective inhibitors, we calculated all pair wise structural distances between 575 structures from the protein databank representing 163 unique binding pockets found in protein domains that write, read or erase post-translational modifications on histones, DNA, and RNA. We find that the structural similarity of binding sites does not always follow the sequence similarity of protein domains. Our analysis reveals increased risks of activity across target-class for compounds competing with the cofactor of protein arginine methyltransferases, lysine acetyltransferases, and sirtuins, while exploiting the conformational plasticity of a protein target is a path toward selective inhibition. The structural diversity landscape of the epigenetics pocketome can be explored via an open-access graphic user interface at thesgc.org/epigenetics_pocketome. PMID:25974248

  7. DDE Transposases: Structural Similarity and Diversity

    PubMed Central

    Nesmelova, Irina V.; Hackett, Perry B.

    2010-01-01

    DNA transposons are mobile DNA elements that can move from one DNA molecule to another and thereby deliver genetic information into human chromosomes in order to confer a new function or replace a defective gene. This process requires a transposase enzyme. During transposition DD[E/D]-transposases undergo a series of conformational changes. We summarize the structural features of DD[E/D]-transposases for which three-dimensional structures are available and that relate to transposases, which are being developed for use in mammalian cells. Similar to other members of the polynucleotidyl transferase family, the catalytic domains of DD[E/D]-transposases share a common feature: an RNase H-like fold that draws three catalytically active residues, the DDE motif, into close proximity. Beyond this fold, the structures of catalytic domains vary considerably, and the DD[E/D]-transposases display marked structural diversity within their DNA-binding domains. Yet despite such structural variability, essentially the same end result is achieved. PMID:20615441

  8. Line-of-sight structure toward strong lensing galaxy clusters

    SciTech Connect

    Bayliss, Matthew B.; Johnson, Traci; Sharon, Keren; Gladders, Michael D.; Oguri, Masamune

    2014-03-01

    We present an analysis of the line-of-sight structure toward a sample of 10 strong lensing cluster cores. Structure is traced by groups that are identified spectroscopically in the redshift range, 0.1 ≤ z ≤ 0.9, and we measure the projected angular and comoving separations between each group and the primary strong lensing clusters in each corresponding line of sight. From these data we measure the distribution of projected angular separations between the primary strong lensing clusters and uncorrelated large-scale structure as traced by groups. We then compare the observed distribution of angular separations for our strong lensing selected lines of sight against the distribution of groups that is predicted for clusters lying along random lines of sight. There is clear evidence for an excess of structure along the line of sight at small angular separations (θ ≤ 6') along the strong lensing selected lines of sight, indicating that uncorrelated structure is a significant systematic that contributes to producing galaxy clusters with large cross sections for strong lensing. The prevalence of line-of-sight structure is one of several biases in strong lensing clusters that can potentially be folded into cosmological measurements using galaxy cluster samples. These results also have implications for current and future studies—such as the Hubble Space Telescope Frontier Fields—that make use of massive galaxy cluster lenses as precision cosmological telescopes; it is essential that the contribution of line-of-sight structure be carefully accounted for in the strong lens modeling of the cluster lenses.

  9. Structural diversity of bacterial flagellar motors

    PubMed Central

    Chen, Songye; Beeby, Morgan; Murphy, Gavin E; Leadbetter, Jared R; Hendrixson, David R; Briegel, Ariane; Li, Zhuo; Shi, Jian; Tocheva, Elitza I; Müller, Axel; Dobro, Megan J; Jensen, Grant J

    2011-01-01

    The bacterial flagellum is one of nature's most amazing and well-studied nanomachines. Its cell-wall-anchored motor uses chemical energy to rotate a microns-long filament and propel the bacterium towards nutrients and away from toxins. While much is known about flagellar motors from certain model organisms, their diversity across the bacterial kingdom is less well characterized, allowing the occasional misrepresentation of the motor as an invariant, ideal machine. Here, we present an electron cryotomographical survey of flagellar motor architectures throughout the Bacteria. While a conserved structural core was observed in all 11 bacteria imaged, surprisingly novel and divergent structures as well as different symmetries were observed surrounding the core. Correlating the motor structures with the presence and absence of particular motor genes in each organism suggested the locations of five proteins involved in the export apparatus including FliI, whose position below the C-ring was confirmed by imaging a deletion strain. The combination of conserved and specially-adapted structures seen here sheds light on how this complex protein nanomachine has evolved to meet the needs of different species. PMID:21673657

  10. Galaxy And Mass Assembly (GAMA): understanding the wavelength dependence of galaxy structure with bulge-disc decompositions

    NASA Astrophysics Data System (ADS)

    Kennedy, Rebecca; Bamford, Steven P.; Häußler, Boris; Baldry, Ivan; Bremer, Malcolm; Brough, Sarah; Brown, Michael J. I.; Driver, Simon; Duncan, Kenneth; Graham, Alister W.; Holwerda, Benne W.; Hopkins, Andrew M.; Kelvin, Lee S.; Lange, Rebecca; Phillipps, Steven; Vika, Marina; Vulcani, Benedetta

    2016-08-01

    With a large sample of bright, low-redshift galaxies with optical-near-IR imaging from the GAMA survey we use bulge-disc decompositions to understand the wavelength-dependent behaviour of single-Sérsic structural measurements. We denote the variation in single-Sérsic index with wavelength as {N}, likewise for effective radius we use {R}. We find that most galaxies with a substantial disc, even those with no discernable bulge, display a high value of {N}. The increase in Sérsic index to longer wavelengths is therefore intrinsic to discs, apparently resulting from radial variations in stellar population and/or dust reddening. Similarly, low values of {R} (< 1) are found to be ubiquitous, implying an element of universality in galaxy colour gradients. We also study how bulge and disc colour distributions vary with galaxy type. We find that, rather than all bulges being red and all discs being blue in absolute terms, both components become redder for galaxies with redder total colours. We even observe that bulges in bluer galaxies are typically bluer than discs in red galaxies, and that bulges and discs are closer in colour for fainter galaxies. Trends in total colour are therefore not solely due to the colour or flux dominance of the bulge or disc.

  11. Galaxy And Mass Assembly (GAMA): Understanding the wavelength dependence of galaxy structure with bulge-disc decompositions

    NASA Astrophysics Data System (ADS)

    Kennedy, Rebecca; Bamford, Steven P.; Häußler, Boris; Baldry, Ivan; Bremer, Malcolm; Brough, Sarah; Brown, Michael J. I.; Driver, Simon; Duncan, Kenneth; Graham, Alister W.; Holwerda, Benne W.; Hopkins, Andrew M.; Kelvin, Lee S.; Lange, Rebecca; Phillipps, Steven; Vika, Marina; Vulcani, Benedetta

    2016-05-01

    With a large sample of bright, low-redshift galaxies with optical-near-IR imaging from the GAMA survey we use bulge-disc decompositions to understand the wavelength-dependent behavior of single-Sérsic structural measurements. We denote the variation in single-Sérsic index with wavelength as N, likewise for effective radius we use R. We find that most galaxies with a substantial disc, even those with no discernable bulge, display a high value of N. The increase in Sérsic index to longer wavelengths is therefore intrinsic to discs, apparently resulting from radial variations in stellar population and/or dust reddening. Similarly, low values of R (< 1) are found to be ubiquitous, implying an element of universality in galaxy colour gradients. We also study how bulge and disc colour distributions vary with galaxy type. We find that, rather than all bulges being red and all discs being blue in absolute terms, both components become redder for galaxies with redder total colours. We even observe that bulges in bluer galaxies are typically bluer than discs in red galaxies, and that bulges and discs are closer in colour for fainter galaxies. Trends in total colour are therefore not solely due to the colour or flux dominance of the bulge or disc.

  12. Origin of structures in disc galaxies: internal or external processes?

    NASA Astrophysics Data System (ADS)

    Athanassoula, E.

    2015-03-01

    Disc galaxies have a number of structures, such as bars, spirals, rings, discy bulges, m = 1 asymmetries, thick discs, warps etc. I will summarise what is known about their origin and in particular whether it is due to an external or an internal process. The former include interactions, major or minor mergers etc, while the latter include instabilities, or driving by another component of the same galaxy, as e.g. the bar or the halo. In cases where more than one process is eligible, I will analyse whether it is possible to distinguish between different origins, and what it would take to do so. This discussion will show that, at least in some cases, it is difficult to distinguish between an internal and an external origin.

  13. We Are Family: Using Diverse Family Structure Literature with Children

    ERIC Educational Resources Information Center

    Gilmore, Deanna Peterschick; Bell, Kari

    2006-01-01

    The structure of the American family has changed over the years. Although the traditional father, mother, child structure still dominates, other family patterns are emerging. In this article the authors present: (1) current statistics relating to diverse family structures; (2) reasons for using diverse family structure literature with children;…

  14. ATLASGAL: A Galaxy-wide sample of dense filamentary structures

    NASA Astrophysics Data System (ADS)

    Li, Guang-Xing; Urquhart, James S.; Leurini, Silvia; Csengeri, Timea; Wyrowski, Friedrich; Menten, Karl M.; Schuller, Frederic

    2016-06-01

    Context. Filamentary structures are ubiquitous in the interstellar medium. Investigating their connection to the large-scale structure of the Galaxy and their role in star formation is leading to a paradigm shift in our understanding of star formation. Aims: We study the properties of filamentary structures from the ATLASGAL survey, which is the largest and most sensitive systematic ground-based survey of the inner Galactic plane at submillimeter wavelengths. Methods: We use the DisPerSE algorithm to identify spatially coherent structures located across the inner-Galaxy (300° < ℓ < 60° and |b| < 1.5). As a result we produce a catalogue of ~1800 structures; these were then independently classified by the five lead authors into one of the following types: marginally resolved, elongated structures, filaments, network of filaments and complexes. This resulted in the identification of 517 filamentary structures. We determine their physical properties and investigate their overall Galactic distribution. Results: We find that almost 70% of the total 870 μm flux associated with these structures resides in filaments and networks of filaments and we estimate that they are likely to be associated with a similar fraction of the mass. Correlating these structures with tracers of massive star formation we also find that a similar fraction of the massive star forming clumps are associated with filaments and networks of filaments, which highlights the importance of these types of structures to star formation in the Galaxy. We have determined distances, masses and physical sizes for 241 of the filamentary structures. We find a median distance of 3.8 kpc, a mean mass of a few 103 M⊙, a mean length of ~6 pc and a mass-to-length ratio of (M/L) ~200-2000 M⊙ pc-1. We also find that these filamentary structures are tightly correlated with the spiral arms in longitude and velocity, and that their semi-major axis is preferentially aligned parallel to the Galactic mid-plane and

  15. Optical imaging for the Spitzer Survey of Stellar Structure in Galaxies. Data release and notes on interacting galaxies

    NASA Astrophysics Data System (ADS)

    Knapen, Johan H.; Erroz-Ferrer, Santiago; Roa, Javier; Bakos, Judit; Cisternas, Mauricio; Leaman, Ryan; Szymanek, Nik

    2014-09-01

    Context. The Spitzer Survey for Stellar Structure in Galaxies (S4G) and its more recently approved extension will lead to a set of 3.6 and 4.5 μm images for 2829 galaxies, which can be used to study many different aspects of the structure and evolution of local galaxies. Aims: We have collected and re-reduced optical images of 1768 of the survey galaxies, aiming to make these available to the community as ready-to-use FITS files to be used in conjunction with the mid-IR images. Our sky-subtraction and mosaicking procedures were optimised for imaging large galaxies. We also produce false-colour images of some of these galaxies to be used for illustrative and public outreach purposes. Methods: We collected and re-processed images in five bands from the Sloan Digital Sky Survey for 1657 galaxies, which are publicly released with the publication of this paper. We observed, in only the g-band, an additional 111 S4G galaxies in the northern hemisphere with the 2.5 m Liverpool Telescope, so that optical imaging is released for 1768 galaxies, or for 62% of the S4G sample. We visually checked all images. We noted interactions and close companions in our optical data set and in the S4G sample, confirming them by determining the galaxies' radial velocities and magnitudes in the NASA-IPAC Extragalactic Database. Results: We find that 17% of the S4G galaxies (21% of those brighter than 13.5 mag) have a close companion (within a radius of five times the diameter of the sample galaxy, a recession velocity within ± 200 km s-1 and not more than 3 mag fainter) and that around 5% of the bright part of the S4G sample show significant morphological evidence of an ongoing interaction. This confirms and further supports previous estimates of these fractions. Conclusions: The over 8000 science images described in this paper, the re-processed Sloan Digital Sky Survey ones, the new Liverpool Telescope images, the set of 29 false-colour pictures, and the catalogue of companion and

  16. Gravitational Lenses and the Structure and Evolution of Galaxies

    NASA Technical Reports Server (NTRS)

    Oliversen, Ronald J. (Technical Monitor); Kochanek, Christopher

    2004-01-01

    During the first year of the project we completed five papers, each of which represents a new direction in the theory and interpretation of gravitational lenses. In the first paper, The Importance of Einstein Rings, we developed the first theory for the formation and structure of the Einstein rings formed by lensing extended sources like the host galaxies of quasar and radio sources. In the second paper, Cusped Mass Models Of Gravitational Lenses, we introduced a new class of lens models. In the third paper, Global Probes of the Impact of Baryons on Dark Matter Halos, we made the first globally consistent models for the separation distribution of gravitational lenses including both galaxy and cluster lenses. The last two papers explore the properties of two lenses in detail. During the second year we have focused more closely on the relationship of baryons and dark matter. In the third year we have been further examining the relationship between baryons and dark matter. In the present year we extended our statistical analysis of lens mass distributions using a self-similar model for the halo mass distribution as compared to the luminous galaxy.

  17. The Local Universe of Disk Galaxies: Energy, Mass, and Structure

    NASA Astrophysics Data System (ADS)

    Driver, Simon P.

    2015-08-01

    This talk will explore three themes: (1) Our understanding of the space density of disk systems in the nearby (z<0.1) Universe, their global properties including their panchromatic (FUV-far-IR) information (energy outputs), their dust properties (masses and temperatures), their (specific) star-formation rates, and ultimately the amount of stellar mass locked up in disc components. (2) The completeness of our local surveys, with a particular focus on the severe impact of low surface brightness selection bias, and how these can be overcome using the upcoming deep imaging studies. (3) The complexity of automated structural decomposition and experiences and results from profiling 8000 galaxies at z<0.06 allowing us to derive key relations such as the mass-size relation of disc systems. The data shown is drawn from the Galaxy And Mass Assembly survey. The GAMA survey builds upon the SDSS legacy by extending 2mags deeper spectroscopically (r<19.8mag) and also including panchromatic data from GALEX, VST, VISTA, WISE and Herschel-Atlas and shortly ASKAP for 300,000 galaxies over 250sq deg of sky. This talk will be aligned with the GAMA Panchromatic Data Release where all imaging data products will be publicly released.

  18. The extended structure of the dwarf irregular galaxy Sagittarius

    NASA Astrophysics Data System (ADS)

    Beccari, G.; Bellazzini, M.; Fraternali, F.; Battaglia, G.; Perina, S.; Sollima, A.; Oosterloo, T. A.; Testa, V.; Galleti, S.

    2014-10-01

    We present a detailed study of the stellar and H i structure of the dwarf irregular galaxy Sagittarius. We use new deep and wide field photometry to trace the surface brightness profile of the galaxy out to ≃5.0' (corresponding to ≃1600 pc) and down to μV ≃ 30.0 mag/arcsec2, thus showing that the stellar body of the galaxy is much more extended than previously believed, and it is similarly (or more) extended than the overall H i distribution. The whole major-axis profile is consistent with a pure exponential, with a scale radius of ≃340 pc. The surface density maps reveal that the distribution of old and intermediate-age stars is smooth and remarkably flattened out to its edges, while the associated H i has a much rounder shape, is off-centred and presents multiple density maxima and a significant hole. No clear sign of systemic rotation is detectable in the complex H i velocity field. No metallicity gradient is detected in the old and intermediate age population of the galaxy, and we confirm that this population has a much more extended distribution than young stars (age ≲ 1 Gyr). Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under the Program 089.D-0052(A).Table of stellar photometry (IN6) is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/570/A78

  19. Gas and stellar spiral structures in tidally perturbed disc galaxies

    NASA Astrophysics Data System (ADS)

    Pettitt, Alex R.; Tasker, Elizabeth J.; Wadsley, James W.

    2016-06-01

    Tidal interactions between disc galaxies and low-mass companions are an established method for generating galactic spiral features. In this work, we present a study of the structure and dynamics of spiral arms driven in interactions between disc galaxies and perturbing companions in 3D N-body/smoothed hydrodynamical numerical simulations. Our specific aims are to characterize any differences between structures formed in the gas and stars from a purely hydrodynamical and gravitational perspective, and to find a limiting case for spiral structure generation. Through analysis of a number of different interacting cases, we find that there is very little difference between arm morphology, pitch angles and pattern speeds between the two media. The main differences are a minor offset between gas and stellar arms, clear spurring features in gaseous arms, and different radial migration of material in the stronger interacting cases. We investigate the minimum mass of a companion required to drive spiral structure in a galactic disc, finding the limiting spiral generation cases with companion masses of the order of 1 × 109 M⊙, equivalent to only 4 per cent of the stellar disc mass, or 0.5 per cent of the total galactic mass of a Milky Way analogue.

  20. ON THE SHAPES AND STRUCTURES OF HIGH-REDSHIFT COMPACT GALAXIES

    SciTech Connect

    Chevance, Melanie; Damjanov, Ivana; Abraham, Roberto G.; Weijmans, Anne-Marie; Simard, Luc; Van den Bergh, Sidney; Caris, Evelyn; Glazebrook, Karl

    2012-08-01

    Recent deep Hubble Space Telescope WFC3 imaging suggests that a majority of compact quiescent massive galaxies at z {approx} 2 may contain disks. To investigate this claim, we have compared the ellipticity distribution of 31 carefully selected high-redshift massive quiescent compact galaxies to a set of mass-selected ellipticity and Sersic index distributions obtained from two-dimensional structural fits to {approx}40, 000 nearby galaxies from the Sloan Digital Sky Survey. A Kolmogorov-Smirnov test shows that the distribution of ellipticities for the high-redshift galaxies is consistent with the ellipticity distribution of a similarly chosen sample of massive early-type galaxies. However, the distribution of Sersic indices for the high-redshift sample is inconsistent with that of local early-type galaxies, and instead resembles that of local disk-dominated populations. The mismatch between the properties of high-redshift compact galaxies and those of both local early-type and disk-dominated systems leads us to conclude that the basic structures of high-redshift compact galaxies probably do not closely resemble those of any single local galaxy population. Any galaxy population analog to the high-redshift compact galaxies that exists at the current epoch is either a mix of different types of galaxies, or possibly a unique class of objects on their own.

  1. Structures in Galaxies: Nature versus Nurture. Input from Theory and Simulations

    NASA Astrophysics Data System (ADS)

    Athanassoula, E.

    2010-10-01

    Galaxies, in particular disc galaxies, contain a number of structures and substructures with well defined morphological, photometric and kinematic properties. Considerable theoretical effort has been put into explaining their formation and evolution, both analytically and with numerical simulations. In some theories, structures form during the natural evolution of the galaxy, i.e. they are a result of nature. For others, it is the interaction with other galaxies, or with the intergalactic medium—i.e. nurture—that accounts for a structure. Either way, the existence and properties of these structures reveal important information on the underlying potential of the galaxy, i.e. on the amount and distribution of matter—including the dark matter—in it, and on the evolutionary history of the galaxy. Here, I will briefly review the various formation scenarios and the respective role of nature and nurture in the formation, evolution and properties of the main structures and substructures.

  2. Metastudy of the Spiral Structure of Our Home Galaxy

    NASA Astrophysics Data System (ADS)

    Vallée, Jacques P.

    2002-02-01

    The current maps of the Milky Way disk still have large differences, much like early maps of the Earth's continents made in the 16th century had sizeable differences in the locations of continents and many areas labeled ``terra incognita.'' Exactly where are the spiral arms in our home Galaxy (in radius and longitude)? Here a meta-analysis is made of the recent (1995-2001) observational data on the pitch angle (p) and the number (m) of spiral arms in our home Galaxy. In order to clarify our image of the structure of the Milky Way, logarithmic model arms of the form ln(r/r0)=k(θ-θ0) are fitted to the observed tangents to the spiral arms and to the observed position angle (P.A.) of the Galaxy's central bar. The main results are that p=12deg inward and m=4, with logarithmic spiral arm parameters r0=2.3 kpc and θ0=0deg for the Norma arm. The value of θ0 for the other three arms is modeled by rotating the Norma arm in steps of 90°. These values are similar to those found by Ortiz & Lépine using earlier observational data, with some differences. The best model predicts an interarm distance near the Sun of S=2.5 kpc (from the Sagittarius to the Perseus arm) and a distance from the Sun to the Sagittarius arm of 0.9 kpc. These values are compared to our limited and uncertain data from the observed nearby spiral arms. These predicted values near the Sun differ substantially from the predictions of Ortiz & Lépine, as discussed in the text.

  3. Evolution of galaxy structure using visual morphologies in CANDELS and Hydro-ART simulations

    NASA Astrophysics Data System (ADS)

    Mozena, Mark W.

    2013-08-01

    The general properties, morphologies, and classes of galaxies in the local Universe are well studied. Most local galaxies are morphologically members of the Hubble sequence and can be crudely separated into elliptical red quiescent galaxies or disky blue star-forming galaxies. This Hubble sequence of relaxed structures has been shown to dominate galaxy populations out to a redshift of z~1. The description of galaxies at earlier times is not well known nor is it understood how and at what epoch the Hubble sequence formed. Of particular interest is the structure of galaxies at z~2. This epoch was an active time for galaxy growth and was the peak epoch for star formation rate, active galactic nuclei activity, and mergers between galaxies. With the installation of the near-infrared Wide Field Camera 3 (WFC3) on the Hubble Space Telescope in 2009, large area photometric surveys of galaxies were able to be performed for the first time at moderate redshifts (z~2) in wavebands that effectively trace the older stellar populations and stellar mass of the galaxies rather than the clumpy star-forming regions. Using WFC3 HST images, an in-depth morphology classification system was developed to probe the galaxy populations at higher redshifts (focusing on z~2). These visual classifications were used with other galaxy parameters (stellar mass, color, star formation rate, radius, Sersic profiles, etc) to identify and quantify the moderate redshift galaxy populations and study how these populations changed with time to form the relaxed Hubble sequence Universe we observe today. Additionally, these same tools that were used to probe galaxy populations at z~2 in the observed Universe were also used on simulated galaxy images produced from state-of-the-art cosmological simulations. These Hydro-ART simulations build artificial galaxies that are compared to observations so as to shed light on the relevant mechanisms in galaxy evolution. By classifying and comparing the populations

  4. Star formation along the Hubble sequence. Radial structure of the star formation of CALIFA galaxies

    NASA Astrophysics Data System (ADS)

    González Delgado, R. M.; Cid Fernandes, R.; Pérez, E.; García-Benito, R.; López Fernández, R.; Lacerda, E. A. D.; Cortijo-Ferrero, C.; de Amorim, A. L.; Vale Asari, N.; Sánchez, S. F.; Walcher, C. J.; Wisotzki, L.; Mast, D.; Alves, J.; Ascasibar, Y.; Bland-Hawthorn, J.; Galbany, L.; Kennicutt, R. C.; Márquez, I.; Masegosa, J.; Mollá, M.; Sánchez-Blázquez, P.; Vílchez, J. M.

    2016-05-01

    The spatially resolved stellar population content of today's galaxies holds important information for understanding the different processes that contribute to the star formation and mass assembly histories of galaxies. The aim of this paper is to characterize the radial structure of the star formation rate (SFR) in galaxies in the nearby Universe as represented by a uniquely rich and diverse data set drawn from the CALIFA survey. The sample under study contains 416 galaxies observed with integral field spectroscopy, covering a wide range of Hubble types and stellar masses ranging from M⋆ ~ 109 to 7 × 1011 M⊙. Spectral synthesis techniques are applied to the datacubes to derive 2D maps and radial profiles of the intensity of the star formation rate in the recent past (ΣSFR), as well as related properties, such as the local specific star formation rate (sSFR), defined as the ratio between ΣSFR and the stellar mass surface density (μ⋆). To emphasize the behavior of these properties for galaxies that are on and off the main sequence of star formation (MSSF), we stack the individual radial profiles in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd), and several stellar masses. Our main results are: (a) the intensity of the star formation rate shows declining profiles that exhibit very small differences between spirals with values at R = 1 half light radius (HLR) within a factor two of ΣSFR ~ 20 M⊙Gyr-1pc-2. The dispersion in the ΣSFR(R) profiles is significantly smaller in late type spirals (Sbc, Sc, Sd). This confirms that the MSSF is a sequence of galaxies with nearly constant ΣSFR. (b) sSFR values scale with Hubble type and increase radially outward with a steeper slope in the inner 1 HLR. This behavior suggests that galaxies are quenched inside-out and that this process is faster in the central, bulge-dominated part than in the disks. (c) As a whole and at all radii, E and S0 are off the MSSF with SFR much smaller than spirals of the

  5. The structure and evolution of a forming galaxy cluster at z = 1.62

    NASA Astrophysics Data System (ADS)

    Hatch, N. A.; Muldrew, S. I.; Cooke, E. A.; Hartley, W. G.; Almaini, O.; Simpson, C. J.; Conselice, C. J.

    2016-06-01

    We present a comprehensive picture of the Cl 0218.3-0510 protocluster at z = 1.623 across 10 comoving Mpc. Using filters that tightly bracket the Balmer and 4000 Å breaks of the protocluster galaxies we obtain precise photometric redshifts resulting in a protocluster galaxy sample that is 89 ± 5 per cent complete and has a contamination of only 12 ± 5 per cent. Both star-forming and quiescent protocluster galaxies are located, which allows us to map the structure of the forming cluster for the first time. The protocluster contains six galaxy groups, the largest of which is the nascent cluster. Only a small minority of the protocluster galaxies are in the nascent cluster (11 per cent) or in the other galaxy groups (22 per cent), as most protocluster galaxies reside between the groups. Unobscured star-forming galaxies predominantly reside between the protocluster's groups, whereas red galaxies make up a large fraction of the groups' galactic content, so observing the protocluster through only one of these types of galaxies results in a biased view of the protocluster's structure. The structure of the protocluster reveals how much mass is available for the future growth of the cluster and we use the Millennium Simulation, scaled to a Planck cosmology, to predict that Cl 0218.3-0510 will evolve into a 2.7^{+3.9}_{-1.7}× 10^{14} M_{{⊙}} cluster by the present day.

  6. EARLY-TYPE GALAXIES WITH TIDAL DEBRIS AND THEIR SCALING RELATIONS IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G)

    SciTech Connect

    Kim, Taehyun; Sheth, Kartik; Munoz-Mateos, Juan-Carlos; Lee, Myung Gyoon; Gadotti, Dimitri A.; Knapen, Johan H.; Schinnerer, Eva; Ho, Luis C.; Madore, Barry F.; Laurikainen, Eija; Salo, Heikki; Athanassoula, E.; Bosma, Albert; Comeron, Sebastien; Regan, Michael W.; Menendez-Delmestre, Karin; De Paz, Armando Gil; and others

    2012-07-01

    Tidal debris around galaxies can yield important clues on their evolution. We have identified tidal debris in 11 early-type galaxies (T {<=} 0) from a sample of 65 early types drawn from the Spitzer Survey of Stellar Structure in Galaxies (S{sup 4}G). The tidal debris includes features such as shells, ripples, and tidal tails. A variety of techniques, including two-dimensional decomposition of galactic structures, were used to quantify the residual tidal features. The tidal debris contributes {approx}3%-10% to the total 3.6 {mu}m luminosity of the host galaxy. Structural parameters of the galaxies were estimated using two-dimensional profile fitting. We investigate the locations of galaxies with tidal debris in the fundamental plane and Kormendy relation. We find that galaxies with tidal debris lie within the scatter of early-type galaxies without tidal features. Assuming that the tidal debris is indicative of recent gravitational interaction or merger, this suggests that these galaxies have either undergone minor merging events so that the overall structural properties of the galaxies are not significantly altered, or they have undergone a major merging events but already have experienced sufficient relaxation and phase mixing so that their structural properties become similar to those of the non-interacting early-type galaxies.

  7. Galaxy Zoo: evidence for diverse star formation histories through the green valley

    NASA Astrophysics Data System (ADS)

    Smethurst, R. J.; Lintott, C. J.; Simmons, B. D.; Schawinski, K.; Marshall, P. J.; Bamford, S.; Fortson, L.; Kaviraj, S.; Masters, K. L.; Melvin, T.; Nichol, R. C.; Skibba, R. A.; Willett, K. W.

    2015-06-01

    Does galaxy evolution proceed through the green valley via multiple pathways or as a single population? Motivated by recent results highlighting radically different evolutionary pathways between early- and late-type galaxies, we present results from a simple Bayesian approach to this problem wherein we model the star formation history (SFH) of a galaxy with two parameters, [t, τ] and compare the predicted and observed optical and near-ultraviolet colours. We use a novel method to investigate the morphological differences between the most probable SFHs for both disc-like and smooth-like populations of galaxies, by using a sample of 126 316 galaxies (0.01 < z < 0.25) with probabilistic estimates of morphology from Galaxy Zoo. We find a clear difference between the quenching time-scales preferred by smooth- and disc-like galaxies, with three possible routes through the green valley dominated by smooth- (rapid time-scales, attributed to major mergers), intermediate- (intermediate time-scales, attributed to minor mergers and galaxy interactions) and disc-like (slow time-scales, attributed to secular evolution) galaxies. We hypothesize that morphological changes occur in systems which have undergone quenching with an exponential time-scale τ < 1.5 Gyr, in order for the evolution of galaxies in the green valley to match the ratio of smooth to disc galaxies observed in the red sequence. These rapid time-scales are instrumental in the formation of the red sequence at earlier times; however, we find that galaxies currently passing through the green valley typically do so at intermediate time-scales.†

  8. Wavelet analysis of baryon acoustic structures in the galaxy distribution

    NASA Astrophysics Data System (ADS)

    Arnalte-Mur, P.; Labatie, A.; Clerc, N.; Martínez, V. J.; Starck, J.-L.; Lachièze-Rey, M.; Saar, E.; Paredes, S.

    2012-06-01

    Context. Baryon acoustic oscillations (BAO) are imprinted in the density field by acoustic waves travelling in the plasma of the early universe. Their fixed scale can be used as a standard ruler to study the geometry of the universe. Aims: The BAO have been previously detected using correlation functions and power spectra of the galaxy distribution. We present a new method to detect the real-space structures associated with BAO. These baryon acoustic structures are spherical shells of relatively small density contrast, surrounding high density central regions. Methods: We design a specific wavelet adapted to search for shells, and exploit the physics of the process by making use of two different mass tracers, introducing a specific statistic to detect the BAO features. We show the effect of the BAO signal in this new statistic when applied to the Λ - cold dark matter (ΛCDM) model, using an analytical approximation to the transfer function. We confirm the reliability and stability of our method by using cosmological N-body simulations from the MareNostrum Institut de Ciències de l'Espai (MICE). Results: We apply our method to the detection of BAO in a galaxy sample drawn from the Sloan Digital Sky Survey (SDSS). We use the "main" catalogue to trace the shells, and the luminous red galaxies (LRG) as tracers of the high density central regions. Using this new method, we detect, with a high significance, that the LRG in our sample are preferentially located close to the centres of shell-like structures in the density field, with characteristics similar to those expected from BAO. We show that stacking selected shells, we can find their characteristic density profile. Conclusions: We delineate a new feature of the cosmic web, the BAO shells. As these are real spatial structures, the BAO phenomenon can be studied in detail by examining those shells. Full Table 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc

  9. Galaxy Structure as a Driver of the Star Formation Sequence Slope and Scatter

    NASA Astrophysics Data System (ADS)

    Whitaker, Katherine E.; Franx, Marijn; Bezanson, Rachel; Brammer, Gabriel B.; van Dokkum, Pieter G.; Kriek, Mariska T.; Labbé, Ivo; Leja, Joel; Momcheva, Ivelina G.; Nelson, Erica J.; Rigby, Jane R.; Rix, Hans-Walter; Skelton, Rosalind E.; van der Wel, Arjen; Wuyts, Stijn

    2015-09-01

    It is well established that (1) star-forming galaxies follow a relation between their star formation rate (SFR) and stellar mass ({M}\\star ), the “star formation sequence,” and (2) the SFRs of galaxies correlate with their structure, where star-forming galaxies are less concentrated than quiescent galaxies at fixed mass. Here, we consider whether the scatter and slope of the star formation sequence is correlated with systematic variations in the Sérsic indices, n, of galaxies across the SFR-{M}\\star plane. We use a mass-complete sample of 23,848 galaxies at 0.5 < z < 2.5 selected from the 3D-HST photometric catalogs. Galaxy light profiles parameterized by n are based on Hubble Space Telescope Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey near-infrared imaging. We use a single SFR indicator empirically calibrated from stacks of Spitzer/MIPS 24 μm imaging, adding the unobscured and obscured star formation. We find that the scatter of the star formation sequence is related in part to galaxy structure; the scatter due to variations in n at fixed mass for star-forming galaxies ranges from 0.14 ± 0.02 dex at z ˜ 2 to 0.30 ± 0.04 dex at z < 1. While the slope of the {log} {SFR}-{log} {M}\\star relation is of order unity for disk-like galaxies, galaxies with n > 2 (implying more dominant bulges) have significantly lower {SFR}/{M}\\star than the main ridgeline of the star formation sequence. These results suggest that bulges in massive z ˜ 2 galaxies are actively building up, where the stars in the central concentration are relatively young. At z < 1, the presence of older bulges within star-forming galaxies lowers global {SFR}/{M}\\star , decreasing the slope and contributing significantly to the scatter of the star formation sequence.

  10. Mapping the gas kinematics and ionization structure of four ultraluminous IRAS galaxies

    NASA Astrophysics Data System (ADS)

    Wilman, R. J.; Crawford, C. S.; Abraham, R. G.

    1999-10-01

    We present a study of the morphology, kinematics and ionization structure of the extended emission-line regions in four intermediate-redshift (0.118galaxies, derived from ARGUS two-dimensional fibre spectroscopy. The gas kinematics in the hyperluminous system IRAS F20460+1925 lack coherent structure, with a full width at half-maximum (FWHM) >1000kms-1 within 1arcsec of the nucleus, suggesting that any merger is well-advanced. Emission-line intensity ratios point to active galactic nucleus (AGN) photoionization for the excitation of this gas at the systemic velocity. An isolated blob ~8kpc from the nucleus with a much smaller velocity dispersion may lie in a structure similar to the photoionization cones seen in lower-luminosity objects. A second, spatially unresolved, narrow-line component is also present on nucleus, blueshifted by ~=990kms-1 from the systemic and plausibly powered by photoionizing shocks. IRAS F23060+0505 has more ordered kinematics, with a region of increased FWHM coincident with the blue half of a dipolar velocity field. The systemic velocity rotation curve is asymmetric in appearance, as a result either of the on-going merger or of nuclear dust obscuration. From a higher-resolution ISIS spectrum, we attribute the blue asymmetry in the narrow-line profiles to a spatially resolved nuclear outflow. Emission-line intensity ratios suggest shock+precursor ionization for the systemic component, consistent with the X-ray view of a heavily obscured AGN. The lower-luminosity objects IRAS F01217+0122 and F01003-2238 complete the sample. The former has a featureless velocity field with a high FWHM, a high-ionization AGN spectrum and a ~1Gyr old starburst continuum. IRAS F01003-2238 has a dipolar velocity field and an Hii region emission-line spectrum with a strong blue continuum. After correction for intrinsic extinction, the latter can be reproduced with ~107 O5 stars, sufficient to power the bolometric luminosity of the

  11. Formation of ring structures in galactic disks during close passages of galaxies

    NASA Astrophysics Data System (ADS)

    Tutukov, A. V.; Fedorova, A. V.

    2016-01-01

    The formation of ring structures in galactic disks is investigated. It is shown that, in addition to the known mechanism of forming rings in "head-on" collisions between galaxies, ring structures can be formed during close passages of galaxies if the perturbing galaxy moves in a plane close to the equatorial plane of the perturbed disk galaxy, opposite to the direction of rotation of the disk. Numerical simulations of the formation of structures in the disk of a massive galaxy undergoing a passage with another galaxy are considered. The results of these cmputations show the formation of pronounced ring structures in the galactic disk when the initial inclination of the trajectory of the perturbing galaxy to the equatorial plane of the perturbed galaxy is no more than ~25°. However, the probability of close passages of galaxies with these parameters is small, as is the probability of head-on collisions. The characteristic time scale for the existence of pronounced rings is of order the dynamical time scale at the edge of the galaxy, 200-300 million years, close to the corresponding time for head-on collisions. The evolution of the rings has the same character in both cases: they gradually expand and move toward the periphery of the galaxy. The results of these simulations can also be applied to a close passage of one star by another star with a protoplanetary disk. According to the computation results, the characteristic time scale for the existence of pronounced rings in such a protoplanetary disk depends mainly on the size of the disk; this time scale can reach several tens of thousands of years for a disk radius of about 1000 AU. The formation of ring structures in such a disk could influence the formation and evolution of planetesimals, and possibly the character of the formation of planets and the distribution of their orbital semi-major axes.

  12. Structural Analysis of the Resident Assistant Cultural Diversity Questionnaire

    ERIC Educational Resources Information Center

    Johnson, Vanessa D.; Kang, Young-Shin; Thompson, George F.

    2011-01-01

    This study investigated the five-factor structure of the Resident Assistant Cultural Diversity (RACD) instrument, which assesses resident assistant (RA) confidence in addressing issues of cultural diversity in college and university residence halls. The instrument has five components that explore RA confidence: (1) belief in the need for cultural…

  13. Using the Millennium II simulation to test CDM predictions for the structure of massive galaxies

    NASA Astrophysics Data System (ADS)

    Cooper, Andrew P.; Kauffmann, Guinevere; Wang, Jing; White, Simon D. M.

    2013-07-01

    We have combined the semi-analytic galaxy formation model of Guo et al. (2011) with a novel particle-tagging technique to predict galaxy surface brightness profiles in a representative sample of ~1900 massive dark matter haloes (1012-1014 M⊙) from the Millennium II ΛCDM N body simulation. We focus on the outer regions of galaxies and stars accreted in mergers. Our simulations cover scales from the stellar haloes of Milky Way-like galaxies to the `cD envelopes' of groups and clusters, and resolve low surface brightness substructure such as the tidal streams of dwarf galaxies. We find that the spatial distribution of stars in low surface brightness regions is tightly correlated with DM halo mass and that collisionless merging during the hierarchical assembly of galaxies largely determines the structure of spheroidal stellar components. Our ΛCDM model agrees well with the available data.

  14. How Supernova Feedback Affects Observed Galaxy Sizes and Structures

    NASA Astrophysics Data System (ADS)

    Joung, M. K. Ryan; Cen, R.; Bryan, G. L.

    2009-01-01

    Feedback from massive stars is perhaps the least understood aspect of galaxy formation. Based on adaptive mesh refinement (AMR) cosmological simulations and stellar population synthesis models, we compute half-light radii of high redshift galaxies and use them to compare simulated and observed size-mass and size-luminosity relations in the rest-frame UV/optical. The sizes of the simulated galaxies depend on the assumed strength of supernova feedback; we investigate the origin of this relation. We discuss minimum requirements for correct numerical modeling of supernova feedback in starburst galaxies.

  15. Stellar structure of the dwarf irregular galaxy DDO 216

    NASA Astrophysics Data System (ADS)

    Tikhonov, N. A.

    2006-03-01

    Observations with the 6-mBTA telescope and archival Hubble Space Telescope data were used for the photometry of stars in the dwarf edge-on irregular galaxy DDO 216 (Peg DIG). We determined the change in the number density of stars of various ages along the major and minor axes of the galaxy. We found that the young stars of the galaxy concentrate toward the center, while its old stars, red giants, form an extended thick disk 5 kpc in diameter and 2 kpc in thickness around the galaxy.

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

    SciTech Connect

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

    2012-07-11

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

  17. THE CONNECTION BETWEEN GALAXIES AND DARK MATTER STRUCTURES IN THE LOCAL UNIVERSE

    SciTech Connect

    Reddick, Rachel M.; Wechsler, Risa H.; Behroozi, Peter S.; Tinker, Jeremy L. E-mail: rwechsler@stanford.edu

    2013-07-01

    We provide new constraints on the connection between galaxies in the local universe, identified by the Sloan Digital Sky Survey, and dark matter halos and their constituent substructures in the {Lambda}-cold dark matter model using WMAP7 cosmological parameters. Predictions for the abundance and clustering properties of dark matter halos, and the relationship between dark matter hosts and substructures, are based on a high-resolution cosmological simulation, the Bolshoi simulation. We associate galaxies with dark matter halos and subhalos using subhalo abundance matching, and perform a comprehensive analysis which investigates the underlying assumptions of this technique including (1) which halo property is most closely associated with galaxy stellar masses and luminosities, (2) how much scatter is in this relationship, and (3) how much subhalos can be stripped before their galaxies are destroyed. The models are jointly constrained by new measurements of the projected two-point galaxy clustering and the observed conditional stellar mass function of galaxies in groups. We find that an abundance matching model that associates galaxies with the peak circular velocity of their halos is in good agreement with the data, when scatter of 0.20 {+-} 0.03 dex in stellar mass at a given peak velocity is included. This confirms the theoretical expectation that the stellar mass of galaxies is tightly correlated with the potential wells of their dark matter halos before they are impacted by larger structures. The data put tight constraints on the satellite fraction of galaxies as a function of galaxy stellar mass and on the scatter between halo and galaxy properties, and rule out several alternative abundance matching models that have been considered. This will yield important constraints for galaxy formation models, and also provides encouraging indications that the galaxy-halo connection can be modeled with sufficient fidelity for future precision studies of the dark universe.

  18. Structure of the Seyfert 2 galaxy Mkn 955

    NASA Astrophysics Data System (ADS)

    Vennik, J.; Funes, J. G.; Rafanelli, P.; Richter, G. M.

    Structural components of the barred Sy 2 galaxy Mkn 955 have been studied using the B, R and Hα images, obtained at the Vatican Advanced Technology Telescope 1.8-m VATT, as well as the HST WFPC2 archival F606W image. The B-R colour index image reveals the presence of a blue (B-R = 1.20) circumnuclear (diameter ~ 5'', i. e. 3.4 kpc) starburst ring. The strong red bar (with the length of 28'', axis ratio b/a = 0.42, P.A. = 112o, B-R = 1.45) is possibly embedded in a (red) lens, which is delimited by a blue (B-R = 1.12) tilted inner ring (or inner spiral arms). The continuum subtracted Hα image reveals high star formaton (SF) intensity in and around the active center, and the modest level of SF distributed along the rim of the inner ring. The adaptive filtered broadband images reveal the presence of a faint distorted outer ring or outer spiral arms, which begin just outside the inner tilted ring and at the ends of the bar, and could mark past interactions. Several small galaxies are distributed in the vicinity of Mkn 955, with the most probable low-surface-brightness blue companion (BT = 18.8, B-R = 0.87) located 106'' to the west of Mkn 955. Light profiles along the bar major and minor axes have been extracted and the (unresolved) nucleus, bulge, exponential disk and bar + lens + ring components could have been distinguished on these profiles. The scale parameters of the individual components have been determined.

  19. Galaxy Structure as a Driver of the Star Formation Sequence Slope and Scatter

    NASA Astrophysics Data System (ADS)

    Whitaker, Katherine E.; 3D-HST Collaboration

    2016-01-01

    It is well established that (1) star-forming galaxies follow a relation between their star formation rate (SFR) and stellar mass (M*), the "star formation sequence," and (2) the SFRs of galaxies correlate with their structure, where star-forming galaxies are less concentrated than quiescent galaxies at fixed mass. In this talk, we consider whether the scatter and slope of the star formation sequence is correlated with systematic variations in the Sérsic indices, n, of galaxies across the SFR-M* plane. Using a mass-complete sample of 23,848 galaxies at 0.5 < z < 2.5 selected from the 3D-HST photometric catalogs, we find that the scatter of the star formation sequence is related in part to galaxy structure; the scatter due to variations in n at fixed mass for star-forming galaxies ranges from 0.14 ± 0.02 dex at z ˜ 2 to 0.30 ± 0.04 dex at z < 1. While the slope of the log(SFR)-log(M*) relation is of order unity for disk-like galaxies, galaxies with n > 2 (implying more dominant bulges) have significantly lower SFR/M* than the main ridgeline of the star formation sequence. These results suggest that bulges in massive z ˜ 2 galaxies are actively building up, where the stars in the central concentration are relatively young. At z < 1, the presence of older bulges within star-forming galaxies lowers global SFR/M*, decreasing the slope and contributing significantly to the scatter of the star formation sequence.

  20. Automated Quantification of Arbitrary Arm-Segment Structure in Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Davis, Darren Robert

    This thesis describes a system that, given approximately-centered images of spiral galaxies, produces quantitative descriptions of spiral galaxy structure without the need for per-image human input. This structure information consists of a list of spiral arm segments, each associated with a fitted logarithmic spiral arc and a pixel region. This list-of-arcs representation allows description of arbitrary spiral galaxy structure: the arms do not need to be symmetric, may have forks or bends, and, more generally, may be arranged in any manner with a consistent spiral-pattern center (non-merging galaxies have a sufficiently well-defined center). Such flexibility is important in order to accommodate the myriad structure variations observed in spiral galaxies. From the arcs produced from our method it is possible to calculate measures of spiral galaxy structure such as winding direction, winding tightness, arm counts, asymmetry, or other values of interest (including user-defined measures). In addition to providing information about the spiral arm "skeleton" of each galaxy, our method can enable analyses of brightness within individual spiral arms, since we provide the pixel regions associated with each spiral arm segment. For winding direction, arm tightness, and arm count, comparable information is available (to various extents) from previous efforts; to the extent that such information is available, we find strong correspondence with our output. We also characterize the changes to (and invariances in) our output as a function of modifications to important algorithm parameters. By enabling generation of extensive data about spiral galaxy structure from large-scale sky surveys, our method will enable new discoveries and tests regarding the nature of galaxies and the universe, and will facilitate subsequent work to automatically fit detailed brightness models of spiral galaxies.

  1. Galaxy Zoo : Evidence for a Diversity of Routes through the Green Valley

    NASA Astrophysics Data System (ADS)

    Lintott, Chris; Smethurst, Rebecca; Simmons, Brooke; Galaxy Zoo

    2015-01-01

    Understanding the ways in which galaxies change as they move from blue to red is critical to understanding the build up of the present-day galaxy population, and can best be addressed by looking at systems in the process of transitioning. We present the results of a new analysis of the population of galaxies which passes through the 'green valley' evident in optical colour-mass diagrams. Using data from SDSS and Galex, and a Bayesian analysis of their most probable star formation histories, we show that multiple routes through the green valley exist. By using Galaxy Zoo morphologies, we are able to draw on probabilistic estimates of morphology and find - in contrast to previous work - that there is evidence for slow, intermediate and rapid transitions from blue to red. Constraining these populations provides evidence for rapid morphological change in some populations, presumably through major mergers, and underpins our understanding of the build up of the red sequence.

  2. Design and fabrication of diverse metamaterial structures by holographic lithography.

    PubMed

    Yang, Yi; Li, Qiuze; Wang, Guo Ping

    2008-07-21

    We demonstrate a holographic lithography for the fabrication of diverse metamaterial structures by using an optical prism. Cylindrical nanoshells, U-shaped resonator arrays, and double-split ring arrays are obtained experimentally by real time modulating the phase relation of the interference beams. This easy-to-use method may provide a roadway for the design and fabrication of future metamaterials requiring diverse structures for effectively manipulating electromagnetic properties at optical frequencies. PMID:18648445

  3. Giant radio galaxies as effective probes of X-ray gas in large-scale structure

    NASA Astrophysics Data System (ADS)

    Saripalli, Lakshmi; Subrahmanyan, Ravi; Malarecki, Jurek; Jones, Heath; Staveley-Smith, Lister

    2015-08-01

    Giant radio galaxies are AGNs with relativistic jets that dynamically evolve into Mpc scale synchrotron lobes around the host elliptical. The thermal gas environment influences the jet advance and lobe formation. Since the host ellipticals are in filamentary low-density galaxy environments, the ambient gas for the Mpc-scale radio structures is likely the warm-hot X-ray gas inhabiting the intergalactic medium. We have, therefore, used large radio galaxies as probes of the distribution of hot and tenuous gas on mega-parsec scales in these relatively low density large-scale structures.For a sample of 19 giant radio galaxies we obtained radio continuum images of the synchrotron structures, and redshifts of a total of nearly 9000 galaxies in their vicinity. The 2-degree field redshift data traces the large-scale galaxy structure around the radio sources. The radio-optical data allows an estimation of the pressure, temperature and distribution of hot thermal gas associated with the large-scale structure in the vicinity of the radio AGN (Malarecki, Staveley-Smith, Saripalli, Subrahmanyan, Jones, Duffy, Rioja 2013, MNRAS 432, 200).Strong correspondence between radio galaxy lobes and galaxy distribution is observed. The data suggests that galaxies trace gas, and that radio jets and lobes of giant radio galaxies are sensitive tracers of gas on mega-parsec scales and may be used as effective probes of the difficult-to-detect IGM (Malarecki, Jones, Saripalli, Stavele-Smith, Subrahmanyan, 2015, MNRAS in press; arXiv150203954).

  4. Group-galaxy correlations in redshift space as a probe of the growth of structure

    NASA Astrophysics Data System (ADS)

    Mohammad, F. G.; de la Torre, S.; Bianchi, D.; Guzzo, L.; Peacock, J. A.

    2016-05-01

    We investigate the use of the cross-correlation between galaxies and galaxy groups to measure redshift-space distortions (RSD) and thus probe the growth rate of cosmological structure. This is compared to the classical approach based on using galaxy auto-correlation. We make use of realistic simulated galaxy catalogues that have been constructed by populating simulated dark matter haloes with galaxies through halo occupation prescriptions. We adapt the classical RSD dispersion model to the case of the group-galaxy cross-correlation function and estimate the RSD parameter β by fitting both the full anisotropic correlation function ξs(rp, π) and its multipole moments. In addition, we define a modified version of the latter statistics by truncating the multipole moments to exclude strongly non-linear distortions at small transverse scales. We fit these three observable quantities in our set of simulated galaxy catalogues and estimate statistical and systematic errors on β for the case of galaxy-galaxy, group-group, and group-galaxy correlation functions. When ignoring off-diagonal elements of the covariance matrix in the fitting, the truncated multipole moments of the group-galaxy cross-correlation function provide the most accurate estimate, with systematic errors below 3 per cent when fitting transverse scales larger than 10 h-1 Mpc. Including the full data covariance enlarges statistical errors but keep unchanged the level of systematic error. Although statistical errors are generally larger for groups, the use of group-galaxy cross-correlation can potentially allow the reduction of systematics while using simple linear or dispersion models.

  5. Exploring the Extended Structure of the Sculptor Dwarf Spheroidal Galaxy

    NASA Astrophysics Data System (ADS)

    Westfall, K. B.; Ostheimer, J. C.; Frinchaboy, P. M.; Patterson, R. J.; Majewski, S. R.; Kunkel, W. E.

    2000-12-01

    We have undertaken a large area (>3 deg2) survey of the Sculptor dSph using the 1-m Swope telescope. The region surveyed includes roughly 1 deg2 centered on the Sculptor core, with the remaining survey area extending to the east and stretching to almost twice the tidal radius (rt=76.5m) to the northeast and southeast. We have imaged in the Washington M,T2 and DDO51 filters, a combination that allows us to discriminate dwarf and giant stars based on the gravity sensitivity of DDO51. The extended structure of Sculptor can be mapped via those stars selected both as giant stars and as having a combination of M and M-T2 consistent with the red giant branch of Sculptor. We also make use of the areal distribution of blue horizontal branch stars, which delineate the extended structure of Sculptor relatively well in this field at high Galactic latitude. Using the HYDRA spectrograph on the Blanco 4-m, we have obtained more than a dozen radial velocities for candidate Sculptor stars that we have identified well outside (1) the core radius, and (2) the radii explored by previous surveys. A preliminary conclusion from our work so far is that Sculptor does not show as extensive a population of extratidal stars as we have identified in similar work we have conducted around the Carina (Majewski et al. 2000, AJ, 119, 760) and Ursa Minor (Palma et al. 2000, BAAS) dwarf galaxies. Indeed, if a lack of significant extended material around Sculptor is borne out by further study over more area and other position angles, then an interesting correlation begins to emerge: Among four galaxies we have surveyed in this way (Car, UMi, Leo II, and Scl), the relative fraction of the dSph's found outside the nominal tidal radius appears to correlate with the published values of M/L. This may suggest that the derived masses for the dwarf spheroidals may be systematically overestimated to a degree set by the amount of dynamical non-equilibrium in the system. This work was supported by NSF, NASA, the

  6. The red extended structure of IC 10, the nearest blue compact galaxy

    NASA Astrophysics Data System (ADS)

    Gerbrandt, Stephanie A. N.; McConnachie, Alan W.; Irwin, Mike

    2015-11-01

    The Local Group starburst galaxy IC 10 is the closest example of a blue compact galaxy. Here, we use optical gi imaging from Canada-France-Hawaii Telescope/MegaCam and near infrared JHK imaging from United Kingdom Infrared Telescope/Wide Field Camera to conduct a comprehensive survey of the structure of IC 10. We examine the spatial distribution of its resolved young, intermediate and old stellar populations to large radius and low effective surface brightness levels. Akin to other dwarfs with multiple populations of different ages, stellar populations of decreasing average age are increasingly concentrated in this galaxy. We find that the young, starbursting population and the asymptotic giant branch population are both offset from the geometric centre of the older red giant branch (RGB) population by a few hundred parsecs, implying that the younger star formation occurred significantly away from the centre of the galaxy. The RGB population traces an extended structure that is typical of blue compact galaxies, with an effective radius of ˜5.75 arcmin (˜1.25 kpc). These measurements show that IC 10 is much more extended than has previously been realized, and this blue compact galaxy is one of the most extended dwarf galaxies in the Local Group. The outermost isophotes of this galaxy are very regular in shape and essentially circular in morphology. Based on this analysis, we do not find any evidence to suggest that IC 10 has undergone a recent, significant, interaction with an unknown companion.

  7. MASSIVE GALAXIES AT HIGH z: ASSEMBLY PATTERNS, STRUCTURE, AND DYNAMICS IN THE FAST PHASE OF GALAXY FORMATION

    SciTech Connect

    Onorbe, J.; Dominguez-Tenreiro, R.; Knebe, A.; Martinez-Serrano, F. J.; Serna, A.

    2011-05-10

    Relaxed, massive galactic objects have been identified at redshifts z = 4, 5, and 6 in hydrodynamical simulations run in a large cosmological volume. This allowed us to analyze the assembly patterns of the high-mass end of the galaxy distribution at these high z's, by focusing on their structural and dynamical properties. Our simulations indicate that massive objects at high redshift already follow certain scaling relations. These relations define virial planes at the halo scale, whereas at the galactic scale they define intrinsic dynamical planes that are, however, tilted relative to the virial plane. Therefore, we predict that massive galaxies must lie on fundamental planes from their formation. We briefly discuss the physical origin of the tilt in terms of the physical processes underlying massive galaxy formation at high z, in the context of a two-phase galaxy formation scenario. Specifically, we have found that it lies on the different behavior of the gravitationally heated gas as compared with cold gas previously involved in caustic formation and the mass dependence of the energy available to heat the gas.

  8. The structural diversity of artificial genetic polymers.

    PubMed

    Anosova, Irina; Kowal, Ewa A; Dunn, Matthew R; Chaput, John C; Van Horn, Wade D; Egli, Martin

    2016-02-18

    Synthetic genetics is a subdiscipline of synthetic biology that aims to develop artificial genetic polymers (also referred to as xeno-nucleic acids or XNAs) that can replicate in vitro and eventually in model cellular organisms. This field of science combines organic chemistry with polymerase engineering to create alternative forms of DNA that can store genetic information and evolve in response to external stimuli. Practitioners of synthetic genetics postulate that XNA could be used to safeguard synthetic biology organisms by storing genetic information in orthogonal chromosomes. XNA polymers are also under active investigation as a source of nuclease resistant affinity reagents (aptamers) and catalysts (xenozymes) with practical applications in disease diagnosis and treatment. In this review, we provide a structural perspective on known antiparallel duplex structures in which at least one strand of the Watson-Crick duplex is composed entirely of XNA. Currently, only a handful of XNA structures have been archived in the Protein Data Bank as compared to the more than 100 000 structures that are now available. Given the growing interest in xenobiology projects, we chose to compare the structural features of XNA polymers and discuss their potential to access new regions of nucleic acid fold space. PMID:26673703

  9. The structural diversity of artificial genetic polymers

    PubMed Central

    Anosova, Irina; Kowal, Ewa A.; Dunn, Matthew R.; Chaput, John C.; Van Horn, Wade D.; Egli, Martin

    2016-01-01

    Synthetic genetics is a subdiscipline of synthetic biology that aims to develop artificial genetic polymers (also referred to as xeno-nucleic acids or XNAs) that can replicate in vitro and eventually in model cellular organisms. This field of science combines organic chemistry with polymerase engineering to create alternative forms of DNA that can store genetic information and evolve in response to external stimuli. Practitioners of synthetic genetics postulate that XNA could be used to safeguard synthetic biology organisms by storing genetic information in orthogonal chromosomes. XNA polymers are also under active investigation as a source of nuclease resistant affinity reagents (aptamers) and catalysts (xenozymes) with practical applications in disease diagnosis and treatment. In this review, we provide a structural perspective on known antiparallel duplex structures in which at least one strand of the Watson–Crick duplex is composed entirely of XNA. Currently, only a handful of XNA structures have been archived in the Protein Data Bank as compared to the more than 100 000 structures that are now available. Given the growing interest in xenobiology projects, we chose to compare the structural features of XNA polymers and discuss their potential to access new regions of nucleic acid fold space. PMID:26673703

  10. THE LUMINOSITY PROFILE AND STRUCTURAL PARAMETERS OF THE ANDROMEDA GALAXY

    SciTech Connect

    Courteau, Stephane; Widrow, Lawrence M.; McDonald, Michael; Guhathakurta, Puragra; Zhu Yucong

    2011-09-20

    We have constructed an extended composite luminosity profile for the Andromeda galaxy, M31, and have decomposed it into three basic luminous structural components: a bulge, a disk, and a halo. The dust-free Spitzer/Infrared Array Camera (IRAC) imaging and extended spatial coverage of ground-based optical imaging and deep star counts allow us to map M31's structure from its center to 22 kpc along the major axis. We apply, and address the limitations of, different decomposition methods for the one-dimensional luminosity profiles and two-dimensional images. These methods include nonlinear least-squares and Bayesian Monte Carlo Markov chain analyses. The basic photometric model for M31 has a Sersic bulge with shape index n {approx_equal} 2.2 {+-} .3 and effective radius R{sub e} = 1.0 {+-} 0.2 kpc, and a dust-free exponential disk of scale length R{sub d} = 5.3 {+-} .5 kpc; the parameter errors reflect the range between different decomposition methods. Despite model covariances, the convergence of solutions based on different methods and current data suggests a stable set of structural parameters. The ellipticities ({epsilon} = 1 - b/a) of the bulge and the disk from the IRAC image are 0.37 {+-} 0.03 and 0.73 {+-} 0.03, respectively. The bulge parameter n is rather insensitive to bandpass effects and its value (2.2) suggests a first rapid formation via mergers followed by secular growth from the disk. The M31 halo has a two-dimensional power-law index {approx_equal} - 2.5 {+-} 0.2 (or -3.5 in three-dimensional), comparable to that of the Milky Way. We find that the M31 bulge light is mostly dominant over the range R{sub min} {approx}< 1.2 kpc. The disk takes over in the range 1.2 kpc {approx}< R{sub min} {approx}< 9 kpc, whereas the halo dominates at R{sub min} {approx}> 9 kpc. The stellar nucleus, bulge, disk, and halo components each contribute roughly 0.05%, 23%, 73%, and 4% of the total light of M31 out to 200 kpc along the minor axis. Nominal errors for the

  11. Linking the structural properties of galaxies and their star formation histories with STAGES

    NASA Astrophysics Data System (ADS)

    Hoyos, Carlos; Aragón-Salamanca, Alfonso; Gray, Meghan E.; Wolf, Christian; Maltby, David T.; Bell, Eric F.; Böhm, Asmus; Jogee, Shardha

    2016-01-01

    We study the links between star formation history and structure for a large mass-selected galaxy sample at 0.05 ≤ zphot ≤ 0.30. The galaxies inhabit a very broad range of environments, from cluster cores to the field. Using Hubble Space Telescope (HST) images, we quantify their structure following Hoyos et al., and divide them into disturbed and undisturbed. We also visually identify mergers. Additionally, we provide a quantitative measure of the degree of disturbance for each galaxy (`roughness'). The majority of elliptical and lenticular galaxies have relaxed structure, showing no signs of ongoing star formation. Structurally disturbed galaxies, which tend to avoid the lowest density regions, have higher star formation activity and younger stellar populations than undisturbed systems. Cluster spirals with reduced/quenched star formation have somewhat less disturbed morphologies than spirals with `normal' star formation activity, suggesting that these `passive' spirals have started their morphological transformation into S0s. Visually identified mergers and galaxies not identified as mergers but with similar roughness have similar specific star formation rates and stellar ages. The degree of enhanced star formation is thus linked to the degree of structural disturbance, regardless of whether it is caused by major mergers or not. This suggests that merging galaxies are not special in terms of their higher-than-normal star formation activity. Any physical process that produces `roughness', or regions of enhanced luminosity density, will increase the star formation activity in a galaxy with similar efficiency. An alternative explanation is that star formation episodes increase the galaxies' roughness similarly, regardless of whether they are merger induced or not.

  12. The Relation between Galaxy Structure and Spectral Type: Implications for the Buildup of the Quiescent Galaxy Population at 0.5 < z < 2.0

    NASA Astrophysics Data System (ADS)

    Yano, Michael; Kriek, Mariska; van der Wel, Arjen; Whitaker, Katherine E.

    2016-02-01

    We present the relation between galaxy structure and spectral type, using a K-selected galaxy sample at 0.5 < z < 2.0. Based on similarities between the UV-to-NIR spectral energy distributions (SEDs), we classify galaxies into 32 spectral types. The different types span a wide range in evolutionary phases, and thus—in combination with available CANDELS/F160W imaging—are ideal to study the structural evolution of galaxies. Effective radii (Re) and Sérsic parameters (n) have been measured for 572 individual galaxies, and for each type, we determine Re at fixed stellar mass by correcting for the mass-size relation. We use the rest-frame U - V versus V - J diagram to investigate evolutionary trends. When moving into the direction perpendicular to the star-forming sequence, in which we see the Hα equivalent width and the specific star formation rate (sSFR) decrease, we find a decrease in Re and an increase in n. On the quiescent sequence we find an opposite trend, with older redder galaxies being larger. When splitting the sample into redshift bins, we find that young post-starburst galaxies are most prevalent at z > 1.5 and significantly smaller than all other galaxy types at the same redshift. This result suggests that the suppression of star formation may be associated with significant structural evolution at z > 1.5. At z < 1, galaxy types with intermediate sSFRs (10-11.5-10-10.5 yr-1) do not have post-starburst SED shapes. These galaxies have similar sizes as older quiescent galaxies, implying that they can passively evolve onto the quiescent sequence, without increasing the average size of the quiescent galaxy population.

  13. Galaxy7TM: flexible GPCR-ligand docking by structure refinement.

    PubMed

    Lee, Gyu Rie; Seok, Chaok

    2016-07-01

    G-protein-coupled receptors (GPCRs) play important physiological roles related to signal transduction and form a major group of drug targets. Prediction of GPCR-ligand complex structures has therefore important implications to drug discovery. With previously available servers, it was only possible to first predict GPCR structures by homology modeling and then perform ligand docking on the model structures. However, model structures generated without explicit consideration of specific ligands of interest can be inaccurate because GPCR structures can be affected by ligand binding. The Galaxy7TM server, freely accessible at http://galaxy.seoklab.org/7TM, improves an input GPCR structure by simultaneous ligand docking and flexible structure refinement using GALAXY methods. The server shows better performance in both ligand docking and GPCR structure refinement than commonly used programs AutoDock Vina and Rosetta MPrelax, respectively. PMID:27131365

  14. Galaxy7TM: flexible GPCR–ligand docking by structure refinement

    PubMed Central

    Lee, Gyu Rie; Seok, Chaok

    2016-01-01

    G-protein-coupled receptors (GPCRs) play important physiological roles related to signal transduction and form a major group of drug targets. Prediction of GPCR–ligand complex structures has therefore important implications to drug discovery. With previously available servers, it was only possible to first predict GPCR structures by homology modeling and then perform ligand docking on the model structures. However, model structures generated without explicit consideration of specific ligands of interest can be inaccurate because GPCR structures can be affected by ligand binding. The Galaxy7TM server, freely accessible at http://galaxy.seoklab.org/7TM, improves an input GPCR structure by simultaneous ligand docking and flexible structure refinement using GALAXY methods. The server shows better performance in both ligand docking and GPCR structure refinement than commonly used programs AutoDock Vina and Rosetta MPrelax, respectively. PMID:27131365

  15. 9. DETAIL OF DIVERSION STRUCTURE WEST OF DERBY LAKE (SECTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. DETAIL OF DIVERSION STRUCTURE WEST OF DERBY LAKE (SECTION 2) SHOWING DIVERSION GATE TO LAKE LADORA. - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  16. Spatial Structures in the Globular Cluster Distribution of the 10 Brightest Virgo Galaxies

    NASA Astrophysics Data System (ADS)

    D'Abrusco, R.; Fabbiano, G.; Zezas, A.

    2015-05-01

    We report the discovery of significant localized structures in the projected two-dimensional spatial distributions of the Globular Cluster (GC) systems of the 10 brightest galaxies in the Virgo Cluster. We use catalogs of GCs extracted from the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Virgo Cluster Survey (ACSVCS) imaging data, complemented, when available, by additional archival ACS data. These structures have projected sizes ranging from ˜5″ to a few arcminutes (˜1 to ˜25 kpc). Their morphologies range from localized, circular to coherent, complex shapes resembling arcs and streams. The largest structures are preferentially aligned with the major axis of the host galaxy. A few relatively smaller structures follow the minor axis. Differences in the shape and significance of the GC structures can be noticed by investigating the spatial distribution of GCs grouped by color and luminosity. The largest coherent GC structures are located in low-density regions within the Virgo cluster. This trend is more evident in the red GC population, which is believed to form in mergers involving late-type galaxies. We suggest that GC over-densities may be driven by either accretion of satellite galaxies, major dissipationless mergers, or wet dissipation mergers. We discuss caveats to these scenarios, and estimate the masses of the potential progenitors galaxies. These masses range in the interval {{10}8.5}-{{10}9.5} {{M}⊙ }, larger than those of the Local Group dwarf galaxies.

  17. The structural origin of metabolic quantitative diversity.

    PubMed

    Koshiba, Seizo; Motoike, Ikuko; Kojima, Kaname; Hasegawa, Takanori; Shirota, Matsuyuki; Saito, Tomo; Saigusa, Daisuke; Danjoh, Inaho; Katsuoka, Fumiki; Ogishima, Soichi; Kawai, Yosuke; Yamaguchi-Kabata, Yumi; Sakurai, Miyuki; Hirano, Sachiko; Nakata, Junichi; Motohashi, Hozumi; Hozawa, Atsushi; Kuriyama, Shinichi; Minegishi, Naoko; Nagasaki, Masao; Takai-Igarashi, Takako; Fuse, Nobuo; Kiyomoto, Hideyasu; Sugawara, Junichi; Suzuki, Yoichi; Kure, Shigeo; Yaegashi, Nobuo; Tanabe, Osamu; Kinoshita, Kengo; Yasuda, Jun; Yamamoto, Masayuki

    2016-01-01

    Relationship between structural variants of enzymes and metabolic phenotypes in human population was investigated based on the association study of metabolite quantitative traits with whole genome sequence data for 512 individuals from a population cohort. We identified five significant associations between metabolites and non-synonymous variants. Four of these non-synonymous variants are located in enzymes involved in metabolic disorders, and structural analyses of these moderate non-synonymous variants demonstrate that they are located in peripheral regions of the catalytic sites or related regulatory domains. In contrast, two individuals with larger changes of metabolite levels were also identified, and these individuals retained rare variants, which caused non-synonymous variants located near the catalytic site. These results are the first demonstrations that variant frequency, structural location, and effect for phenotype correlate with each other in human population, and imply that metabolic individuality and susceptibility for diseases may be elicited from the moderate variants and much more deleterious but rare variants. PMID:27528366

  18. The structural origin of metabolic quantitative diversity

    PubMed Central

    Koshiba, Seizo; Motoike, Ikuko; Kojima, Kaname; Hasegawa, Takanori; Shirota, Matsuyuki; Saito, Tomo; Saigusa, Daisuke; Danjoh, Inaho; Katsuoka, Fumiki; Ogishima, Soichi; Kawai, Yosuke; Yamaguchi-Kabata, Yumi; Sakurai, Miyuki; Hirano, Sachiko; Nakata, Junichi; Motohashi, Hozumi; Hozawa, Atsushi; Kuriyama, Shinichi; Minegishi, Naoko; Nagasaki, Masao; Takai-Igarashi, Takako; Fuse, Nobuo; Kiyomoto, Hideyasu; Sugawara, Junichi; Suzuki, Yoichi; Kure, Shigeo; Yaegashi, Nobuo; Tanabe, Osamu; Kinoshita, Kengo; Yasuda, Jun; Yamamoto, Masayuki

    2016-01-01

    Relationship between structural variants of enzymes and metabolic phenotypes in human population was investigated based on the association study of metabolite quantitative traits with whole genome sequence data for 512 individuals from a population cohort. We identified five significant associations between metabolites and non-synonymous variants. Four of these non-synonymous variants are located in enzymes involved in metabolic disorders, and structural analyses of these moderate non-synonymous variants demonstrate that they are located in peripheral regions of the catalytic sites or related regulatory domains. In contrast, two individuals with larger changes of metabolite levels were also identified, and these individuals retained rare variants, which caused non-synonymous variants located near the catalytic site. These results are the first demonstrations that variant frequency, structural location, and effect for phenotype correlate with each other in human population, and imply that metabolic individuality and susceptibility for diseases may be elicited from the moderate variants and much more deleterious but rare variants. PMID:27528366

  19. Structure and Dynamics of Normal Spiral Galaxies: Stellar Orbital Order and Chaos

    NASA Astrophysics Data System (ADS)

    Perez Villegas, Maria de Los Angeles; Pichardo, B.

    2013-01-01

    We built a family of non-axisymmetric potential models for normal spiral galaxies as defined in the simplest classification of galaxies: the Hubble sequence. For this purpose a three-dimensional self-gravitating model for spiral arms (PERLAS) is superimposed to galactic axisymmetric potentials. We analyze the orbital dynamics as a function of pitch angle, ranging from 4° to 40°, for an Sa galaxy, from 8° to 45°, for an Sb galaxy, and from 10° to 60°, for an Sc galaxy. Self-consistency is indirectly tested through periodic orbital analysis, and through density response studies for each morphological type. Based on ordered behavior, periodic orbits studies show that for pitch angles up to approximately 15°, 18°, and 20° for Sa, Sb and Sc galaxies, respectively, the density response closely supports the imposed potential likely allowing the existence of a long-lasting spiral structure. Beyond those limits, the density response tends to ``avoid'' the potential imposed by keeping smaller pitch angles in the density response, in these cases the spiral arms could not be explained as long-lasting structures, but they would rather be explained as transient features. On the other hand, from an extensive orbital study in phase space based on chaotic behavior, we also find that for Sa galaxies with pitch angles lager than ˜30°, for Sb galaxies with pitch angles lager than ˜40°, and for Sc galaxies with pitch angles larger than ˜50°, chaos becomes pervasive, destroying the ordered phase space prograde region surrounding the main periodic orbits and even destroying them. This result seems to be in good agreement with observations of pitch angles in typical isolated normal spiral galaxies.

  20. Structure and Dynamics of Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Tremblay, Joseph Benoi T.

    1997-06-01

    We present several data-based studies of the dynamics and morphology of early-type galaxies, with an emphasis on the distribution of dark matter. In the first study (Chapter 2), we attempt to map the distribution of dark matter around the giant elliptical galaxy M87 using the velocities of 43 globular clusters reported by Mould et al. (AJ, 99, 1823 (1990)). Assuming spherical symmetry in configuration and velocity space, we find a most likely, power-law dependence of dark matter density on radius of p(r) ∝ r-1.8, where the exponent lies between 0.2 and 3.0 with 99% confidence. We estimate that a sample of roughly 200 velocities would be required to determine the mass-density exponent to a precision of ±0.5. In the second part of the thesis (Chapters 3 and 4), we present the results of a study of the galaxy pair NGC 3384 (SB0)/NGC 3379 (E1) in the Leo I group using the Rutgers Fabry-Perot interferometer. We measured the velocities of 148 planetary nebulae around the two galaxies from the Doppler-shifted (OIII) emission line. The planetary nebula system in NGC 3384 exhibits an orderly rotation field aligned with the photometric axes of the galaxy. The mass of NGC 3384 is infered to be 1.6 x 1011 M⊙ within our last data point at 13 kpc. In the case of NGC 3379, no significant rotation of the planetary nebula system was detected. The mass of NGC 3379 is estimated to be 3 x 1011 M⊙ within 9 kpc, assuming a spherical, isotropic distribution of nebulae. The third part of the thesis (Chapters 5 and 6) consists of a fully nonparametric study of the distribution of elliptical galaxy intrinsic shapes. If elliptical galaxies of all intrinsic luminosities are considered as a single group, the frequency function of intrinsic shapes is found to be inconsistent with the axisymmetric hypothesis at the 99% level. However, many triaxial shape distributions can be found that reproduce the data. If elliptical galaxies are segregated according to intrinsic luminosity, we find a

  1. Herschel-ATLAS: the surprising diversity of dust-selected galaxies in the local submillimetre Universe

    NASA Astrophysics Data System (ADS)

    Clark, C. J. R.; Dunne, L.; Gomez, H. L.; Maddox, S.; De Vis, P.; Smith, M. W. L.; Eales, S. A.; Baes, M.; Bendo, G. J.; Bourne, N.; Driver, S. P.; Dye, S.; Furlanetto, C.; Grootes, M. W.; Ivison, R. J.; Schofield, S. P.; Robotham, A. S. G.; Rowlands, K.; Valiante, E.; Vlahakis, C.; van der Werf, P.; Wright, A. H.; de Zotti, G.

    2015-09-01

    We present the properties of the first 250 μm blind sample of nearby galaxies (15 < D < 46 Mpc) containing 42 objects from the Herschel Astrophysical Terahertz Large Area Survey. Herschel's sensitivity probes the faint end of the dust luminosity function for the first time, spanning a range of stellar mass (7.4 < M⋆ < 11.3 log10 M⊙), star formation activity (-11.8 < SSFR < -8.9 log10 yr-1), gas fraction (3-96 per cent), and colour (0.6 < FUV-KS < 7.0 mag). The median cold dust temperature is 14.6 K, colder than in the Herschel Reference Survey (18.5 K) and Planck Early Release Compact Source Catalogue (17.7 K). The mean dust-to-stellar mass ratio in our sample is higher than these surveys by factors of 3.7 and 1.8, with a dust mass volume density of (3.7 ± 0.7) × 105 M⊙ Mpc-3. Counter-intuitively, we find that the more dust rich a galaxy, the lower its UV attenuation. Over half of our dust-selected sample are very blue in FUV-KS colour, with irregular and/or highly flocculent morphology; these galaxies account for only 6 per cent of the sample's stellar mass but contain over 35 per cent of the dust mass. They are the most actively star-forming galaxies in the sample, with the highest gas fractions and lowest UV attenuation. They also appear to be in an early stage of converting their gas into stars, providing valuable insights into the chemical evolution of young galaxies.

  2. Modeling Forest Structure and Vascular Plant Diversity in Piedmont Forests

    NASA Astrophysics Data System (ADS)

    Hakkenberg, C.

    2014-12-01

    When the interacting stressors of climate change and land cover/land use change (LCLUC) overwhelm ecosystem resilience to environmental and climatic variability, forest ecosystems are at increased risk of regime shifts and hyperdynamism in process rates. To meet the growing range of novel biotic and environmental stressors on human-impacted ecosystems, the maintenance of taxonomic diversity and functional redundancy in metacommunities has been proposed as a risk spreading measure ensuring that species critical to landscape ecosystem functioning are available for recruitment as local systems respond to novel conditions. This research is the first in a multi-part study to establish a dynamic, predictive model of the spatio-temporal dynamics of vascular plant diversity in North Carolina Piedmont mixed forests using remotely sensed data inputs. While remote sensing technologies are optimally suited to monitor LCLUC over large areas, direct approaches to the remote measurement of plant diversity remain a challenge. This study tests the efficacy of predicting indices of vascular plant diversity using remotely derived measures of forest structural heterogeneity from aerial LiDAR and high spatial resolution broadband optical imagery in addition to derived topo-environmental variables. Diversity distribution modelling of this sort is predicated upon the idea that environmental filtering of dispersing species help define fine-scale (permeable) environmental envelopes within which biotic structural and compositional factors drive competitive interactions that, in addition to background stochasticity, determine fine-scale alpha diversity. Results reveal that over a range of Piedmont forest communities, increasing structural complexity is positively correlated with measures of plant diversity, though the nature of this relationship varies by environmental conditions and community type. The diversity distribution model is parameterized and cross-validated using three high

  3. 28. CONCRETE DIVERSION STRUCTURE ON THE WEST SIDE OF D ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    28. CONCRETE DIVERSION STRUCTURE ON THE WEST SIDE OF D STREET ABOUT ONE-QUARTER MILE SOUTH OF 9TH AVNEUE (SECTION 26); THE LATERAL CONTINUES NORTHEAST WHILE A SIDE DITCH PROCEEDS NORTHWARD. THE DIVERSION STRUCTURE SHOWN IN CO-43-A-27 IS VISIBLE IN THE DISTANCE. - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  4. The co-evolution of spiral structure and mass distribution in disk galaxies

    NASA Astrophysics Data System (ADS)

    Seigar, Marc

    2005-07-01

    We propose to use a new diagnostic tool to study the mass buildup in disk galaxies as a function of look-back time out to z 1. The tight correlation between spiral arm pitch angle and rotation curve shear rate {Seigar et al. 2005} demonstrates that the tightness of spiral structure in disk galaxies depends on the central mass concentration {including dark matter}, as this determines the shear rate. Galaxies with high central mass concentration have a higher shear rate and more tightly wound spiral structure than those with low mass concentration. As a result, the evolution of spiral structure over time can be used to search for evolution in the mass distribution in spiral galaxies. The main goal of this project is to determine evolution in the mass distribution of disk galaxies, using spiral arm pitch angles as a quanitative indicator. In order to do this we will use nearly face-on disk galaxies with measurable spiral structure, observed in the GOODS fields.

  5. Polycyclic Polyprenylated Acylphloroglucinol Congeners Possessing Diverse Structures from Hypericum henryi.

    PubMed

    Yang, Xing-Wei; Li, Ming-Ming; Liu, Xia; Ferreira, Daneel; Ding, Yuanqing; Zhang, Jing-Jing; Liao, Yang; Qin, Hong-Bo; Xu, Gang

    2015-04-24

    Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a class of hybrid natural products sharing the mevalonate/methylerythritol phosphate and polyketide biosynthetic pathways and showing considerable structural and bioactive diversity. In a systematic phytochemical investigation of Hypericum henryi, 40 PPAP-type derivatives, including the new compounds hyphenrones G-Q, were obtained. These compounds represent 12 different structural types, including four unusual skeletons exemplified by 5, 8, 10, and 17. The 12 different core structures found are explicable in terms of their biosynthetic origin. The structure of a known PPAP, perforatumone, was revised to hyphenrone A (5) by NMR spectroscopic and biomimetic synthesis methods. Several compounds exhibited inhibitory activities against acetylcholinesterase and human tumor cell lines. This study deals with the structural diversity, function, and biogenesis of natural PPAPs. PMID:25871261

  6. The structure and evolution of interacting binary galaxies

    NASA Astrophysics Data System (ADS)

    Borne, K. D.

    1983-08-01

    A numerical code was constructed for the study of the evolution of interacting binary galaxies. This "multiple three-body" algorithm (MTBA) essentially involves N concurrent three-body integrations. MTBA incorporates a violent relaxation phase that allows the particles to redistribute themselves in the gravitational field of the perturber prior to the full binary orbital evolution calculation. This redistribution is important for systems with an initially strong tidal potential; their predicted merger times are 50-100% larger than previously estimated. Merger times are tabulated both for circular and for elliptical orbits. Typical close binary galaxies will merge in about twice their initial binary oribtal periods. A specific interacting binary simulation is described in detail in the first paper. Many of the results reported here are consistent with those obtained from the larger, more expensive N-body simulations. MTBA is altered so that each "galaxy" is represented by a configuration of test particles.

  7. Structural diversity in lithium aryloxides, Part 2

    SciTech Connect

    BOYLE,TIMOTHY J.; PEDROTTY,DAWN M.; ALAM,TODD M.; VICK,SARA C.; RODRIGUEZ,MARK A.

    2000-06-06

    A series of arylalcohols [H-OAr where OAr = OC{sub 6}H{sub 5} (OPh), OC{sub 6}H{sub 4}(2-Me) (oMP), OC{sub 6}H{sub 3}(2,6-Me){sub 2} (DMP), OC{sub 6}H{sub 4}(2-Pr{prime}) (oPP), OC{sub 6}H{sub 3}(2,6-Pr{prime}){sub 2} (DIP), OC{sub 6}H{sub 4}(2-Bu{prime}) (oBP), OC{sub 6}H{sub 3}(2,6-Bu{prime}){sub 2} (DBP) where Me = CH{sub 3}, Pr{prime} = CHMe{sub 2}, and Bu{prime} = CMe{sub 3}] were reacted with LiN(SiMe{sub 3}){sub 2} in pyridine (py) to generate the appropriate ``Li(OAr)(py){sub x}'' complex. The resultant products were characterized by single crystal X-ray diffraction as: [Li(OPh)(py){sub 2}]{sub 2} (1), [Li(oMP)(py){sub 2}]{sub 2} (2), [Li(DMP)(py){sub 2}]{sub 2} (3), [Li(oPP)(py){sub 2}]{sub 2} (4), [Li(DIP)(py){sub 2}]{sub 2} (5), [Li(oBP)(py){sub 2}]{sub 2} (6), and [Li(DBP)(py)]{sub 2} (7). Compounds 1--6 adopt a dinuclear, edge-shared tetrahedral complex. For 7, due to the steric crowding of the DBP ligand, only one py is coordinated yielding a dinuclear fused trigonal planar arrangement. Two additional structure types were also characterized for the DIP ligand as [Li(DIP)(H-DIP)(py)]{sub 2} (5b) and [Li{sub 2}(DIP){sub 2}(py){sub 3}] (5c). {sup 6,7}Li and {sup 13}C NMR solid state MAS spectroscopy indicated that the bulk powder was consistent with the crystalline material. Solution state NMR spectroscopy revealed a symmetric molecule existed in solution for 1--7.

  8. The compact radio structure of radio-loud NLS1 galaxies and the relationship to CSS sources

    NASA Astrophysics Data System (ADS)

    Gu, M.; Chen, Y.; Komossa, S.; Yuan, W.; Shen, Z.

    2016-02-01

    Narrow-line Seyfert 1 galaxies are thought to be young AGNs with relatively small black hole masses and high accretion rates. Radio-loud narrow-line Seyfert 1 galaxies (RLNLS1s) are very special, because some of them show blazar-like characteristics, while others resemble compact steep-spectrum sources. Relativistic jets were shown to exist in a few RLNLS1s based on VLBI observations and confirmed by the gamma-ray flaring of some of them. These properties may possibly be contrary to typical radio-loud AGNs, in light of the low black-hole masses, and high accretion rates. We present the compact radio structure of fourteen RLNLS1 galaxies from Very Long Baseline Array observations at 5 GHz in 2013. Although all these sources are very radio-loud with {R > 100}, their jet properties are diverse, in terms of their milli-arcsecond (mas) scale (pc scale) morphology and their overall radio spectral shape. The core brightness temperatures of our sources are significantly lower than those of blazars, therefore, the beaming effect is generally not significant in our sources, compared to blazars. This implies that the bulk jet speed may likely be low in our sources. The relationship between RLNLS1s and compact steep-spectrum sources, and the implications on jet formation are discussed based on the pc-scale jet properties.

  9. A structure-based database of antibody variable domain diversity

    SciTech Connect

    Bond, C.J.; Wiesmann, C.; Marsters, Jr., J.C.; Sidhu, S.S.

    2010-07-13

    The diversity of natural antibodies is limited by the genetic mechanisms that engender diversity and the functional requirements of antigen binding. Using an in vitro-evolved autonomous heavy chain variable domain (V{sub H}H-RIG), we have investigated the limits of structurally-tolerated diversity in the three complementarity-determining regions and a fourth loop within the third framework region. We determined the X-ray crystal structure of the V{sub H}H-RIG domain at 1.9 {angstrom} resolution and used it to guide the design of phage-displayed libraries encompassing the four loops. The libraries were subjected to selections for structural stability, and a database of structurally-tolerated sequences was compiled from the sequences of approximately 1000 unique clones. The results reveal that all four loops accommodate significantly greater diversity than is observed in nature. Thus, it appears that most sequence biases in the natural immune repertoire arise from factors other than structural constraints and, consequently, it should be possible to enhance the functions of antibodies significantly through in vitro evolution.

  10. Dulling Occam's Razor: ICM Enrichment, the Elliptical Galaxy IMF, and the Diversity of Star Formation

    NASA Astrophysics Data System (ADS)

    Loewenstein, Michael

    2013-04-01

    Stars born in galaxy cluster potential wells must be responsible for the high level of enrichment measured in the intracluster medium (ICM); however, there is increasing tension between this truism and the parsimonious assumption that the stars in the generally old population studied optically in cluster galaxies emerged from the same formation sites at the same epochs. We construct a phenomenological cluster model to demonstrate that ICM enrichment is underestimated by a factor >2 for standard assumptions, and quantify the adjustments to the star formation efficiency and initial mass function (IMF), and SNIa production efficiency, required to rectify this while being consistent with the observed ICM abundance pattern. Given recent evidence of a steep IMF in elliptical galaxies that conflicts with the nucleosynthetic requirements of the ICM, we are led to conclude that the stellar population responsible for enriching the ICM is currently hidden and offer some suggestions as to where. This study proves that the star formation cannot be invariant in space and time.

  11. THE DIVERSE HOT GAS CONTENT AND DYNAMICS OF OPTICALLY SIMILAR LOW-MASS ELLIPTICAL GALAXIES

    SciTech Connect

    Bogdan, Akos; David, Laurence P.; Jones, Christine; Forman, William R.; Kraft, Ralph P.

    2012-10-10

    The presence of hot X-ray-emitting gas is ubiquitous in massive early-type galaxies. However, much less is known about the content and physical status of the hot X-ray gas in low-mass ellipticals. In the present paper, we study the X-ray gas content of four low-mass elliptical galaxies using archival Chandra X-ray observations. The sample galaxies, NGC 821, NGC 3379, NGC 4278, and NGC 4697, have approximately identical K-band luminosities, and hence stellar masses, yet their X-ray appearance is strikingly different. We conclude that the unresolved emission in NGC 821 and NGC 3379 is built up from a multitude of faint compact objects, such as coronally active binaries and cataclysmic variables. Despite the non-detection of X-ray gas, these galaxies may host low density, and hence low luminosity, X-ray gas components, which undergo an outflow driven by a Type Ia supernova (SN Ia). We detect hot X-ray gas with a temperature of kT {approx} 0.35 keV in NGC 4278, the component of which has a steeper surface brightness distribution than the stellar light. Within the central 50'' ({approx}3.9 kpc), the estimated gas mass is {approx}3 Multiplication-Sign 10{sup 7} M{sub Sun }, implying a gas mass fraction of {approx}0.06%. We demonstrate that the X-ray gas exhibits a bipolar morphology in the northeast-southwest direction, indicating that it may be outflowing from the galaxy. The mass and energy budget of the outflow can be maintained by evolved stars and SNe Ia, respectively. The X-ray gas in NGC 4697 has an average temperature of kT {approx} 0.3 keV and a significantly broader distribution than the stellar light. The total gas mass within 90'' ({approx}5.1 kpc) is {approx}2.1 Multiplication-Sign 10{sup 8} M{sub Sun }, hence the gas mass fraction is {approx}0.4%. Based on the distribution and physical parameters of the X-ray gas, we conclude that it is most likely in hydrostatic equilibrium, although a subsonic outflow may be present.

  12. The Diverse Hot Gas Content and Dynamics of Optically Similar Low-mass Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Bogdán, Ákos; David, Laurence P.; Jones, Christine; Forman, William R.; Kraft, Ralph P.

    2012-10-01

    The presence of hot X-ray-emitting gas is ubiquitous in massive early-type galaxies. However, much less is known about the content and physical status of the hot X-ray gas in low-mass ellipticals. In the present paper, we study the X-ray gas content of four low-mass elliptical galaxies using archival Chandra X-ray observations. The sample galaxies, NGC 821, NGC 3379, NGC 4278, and NGC 4697, have approximately identical K-band luminosities, and hence stellar masses, yet their X-ray appearance is strikingly different. We conclude that the unresolved emission in NGC 821 and NGC 3379 is built up from a multitude of faint compact objects, such as coronally active binaries and cataclysmic variables. Despite the non-detection of X-ray gas, these galaxies may host low density, and hence low luminosity, X-ray gas components, which undergo an outflow driven by a Type Ia supernova (SN Ia). We detect hot X-ray gas with a temperature of kT ~ 0.35 keV in NGC 4278, the component of which has a steeper surface brightness distribution than the stellar light. Within the central 50'' (~3.9 kpc), the estimated gas mass is ~3 × 107 M ⊙, implying a gas mass fraction of ~0.06%. We demonstrate that the X-ray gas exhibits a bipolar morphology in the northeast-southwest direction, indicating that it may be outflowing from the galaxy. The mass and energy budget of the outflow can be maintained by evolved stars and SNe Ia, respectively. The X-ray gas in NGC 4697 has an average temperature of kT ~ 0.3 keV and a significantly broader distribution than the stellar light. The total gas mass within 90'' (~5.1 kpc) is ~2.1 × 108 M ⊙, hence the gas mass fraction is ~0.4%. Based on the distribution and physical parameters of the X-ray gas, we conclude that it is most likely in hydrostatic equilibrium, although a subsonic outflow may be present.

  13. Studying the Structure and Dynamics of the Subcomponents of the Andromeda Galaxy

    NASA Astrophysics Data System (ADS)

    Lin, Jimmy; Mukherjee, Arin; Wang, Margaret; Guhathakurta, Puragra; Fardal, Mark A.; Sohn, S. Tony; Cunningham, Emily; Deason, Alis J.; Toloba, Elisa; Keoliya, Shruti; Van Der Marel, Roeland P.; Rockosi, Constance M.; HSTPROMO, HALO7D, SPLASH

    2016-01-01

    The Andromeda (M31) galaxy is the only large galaxy besides the Milky Way (MW) that is nearby enough to be dissected star by star, making it an excellent candidate for studying galaxy formation and evolution. A galaxy's evolutionary path is determined by factors such as its dark matter distribution, gas content, energy injection by supernovae and active nucleus, merger history, etc.. To constrain these physical processes, we studied the structure and dynamics M31 using very accurate proper motion (PM) measurements and exquisite photometry from three Hubble Space Telescope fields in the direction of the M31 galaxy. In order to exclude the MW contaminants from our data set, we used PM and photometric data to cuts define our M31 sample. We used this sample to analyze the motion of the subcomponents of M31 in the context of the state-of-the-art M31 model presented in van der Marel et al. 2012. We observed the relative PMs of three M31 subcomponents to gain unprecedented insight into the internal kinematics of M31. The PM differences we found were compared to a M31 model and provide input for refining the model. Our results serve as constraints for any dynamical formation model of the subcomponents of M31 and for any other large galaxy, allowing for better study and understanding of the dark matter contents and formation of the M31 galaxy.

  14. 52. Humbug Creek Diversion Dam showing original masonry structure at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. Humbug Creek Diversion Dam showing original masonry structure at right and concrete weir at left added later. Photographer James Eastwood, 1986. Source: Salt River Project. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  15. Structural Diversity and Close Interracial Relationships in College

    ERIC Educational Resources Information Center

    Bowman, Nicholas A.

    2012-01-01

    Recent legal and political actions have challenged the use of race-conscious college admissions policies. Earlier research offers mixed evidence about the link between an institution's racial/ethnic composition (i.e., structural diversity) and the formation of close interracial relationships, so the present study examines this topic directly for…

  16. Orbital structure and mass distribution in elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Kronawitter, Andi; Saglia, R. P.; Gerhard, Ortwin; Bender, Ralf

    2000-05-01

    We report on a homogeneous dynamical analysis of a sample of 21 round (17 E0/E1, 4 E2) elliptical galaxies. We present new kinematic data for eight of these galaxies and new photometry for one object. The remaining kinematic and photometric data and the required distance information are taken from the literature. The analysis uses non-parametric spherical models and takes into account line profile information as well as velocity dispersions. We present model fits to the kinematic data and the derived radial profiles of orbital anisotropy and B-band mass-to-light ratio, including confidence intervals. The circular velocity curves resulting from our model fits are all consistent with being flat outside R~ 0.3 R_e. Generally, the M/L ratio profiles show an outward increase, although models based on luminous matter are ruled out at 95% confidence only for three galaxies (NGC 2434, NGC 7507, NGC 7626). For NGC 1399, NGC 4472, NGC 4486, and NGC 4636, where X-ray observations are available, the mass profiles of the best fit models match the ones derived from the X-ray analysis. The best models for most galaxies are isotropic to slightly radially anisotropic, with typical beta <~0.3, in a few cases beta <~0 .5 at R_e/2. We discuss the generally small effects of flattening along the line-of-sight (the expected = 0.79 for this sample of luminous ellipticals) and of small embedded disks. Our results suggest that elliptical galaxies have surprisingly uniform dynamical properties.

  17. Addressing the Role of Conformational Diversity in Protein Structure Prediction

    PubMed Central

    Parisi, Gustavo; Fornasari, Maria Silvina

    2016-01-01

    Computational modeling of tertiary structures has become of standard use to study proteins that lack experimental characterization. Unfortunately, 3D structure prediction methods and model quality assessment programs often overlook that an ensemble of conformers in equilibrium populates the native state of proteins. In this work we collected sets of publicly available protein models and the corresponding target structures experimentally solved and studied how they describe the conformational diversity of the protein. For each protein, we assessed the quality of the models against known conformers by several standard measures and identified those models ranked best. We found that model rankings are defined by both the selected target conformer and the similarity measure used. 70% of the proteins in our datasets show that different models are structurally closest to different conformers of the same protein target. We observed that model building protocols such as template-based or ab initio approaches describe in similar ways the conformational diversity of the protein, although for template-based methods this description may depend on the sequence similarity between target and template sequences. Taken together, our results support the idea that protein structure modeling could help to identify members of the native ensemble, highlight the importance of considering conformational diversity in protein 3D quality evaluations and endorse the study of the variability of the native structure for a meaningful biological analysis. PMID:27159429

  18. Addressing the Role of Conformational Diversity in Protein Structure Prediction.

    PubMed

    Palopoli, Nicolas; Monzon, Alexander Miguel; Parisi, Gustavo; Fornasari, Maria Silvina

    2016-01-01

    Computational modeling of tertiary structures has become of standard use to study proteins that lack experimental characterization. Unfortunately, 3D structure prediction methods and model quality assessment programs often overlook that an ensemble of conformers in equilibrium populates the native state of proteins. In this work we collected sets of publicly available protein models and the corresponding target structures experimentally solved and studied how they describe the conformational diversity of the protein. For each protein, we assessed the quality of the models against known conformers by several standard measures and identified those models ranked best. We found that model rankings are defined by both the selected target conformer and the similarity measure used. 70% of the proteins in our datasets show that different models are structurally closest to different conformers of the same protein target. We observed that model building protocols such as template-based or ab initio approaches describe in similar ways the conformational diversity of the protein, although for template-based methods this description may depend on the sequence similarity between target and template sequences. Taken together, our results support the idea that protein structure modeling could help to identify members of the native ensemble, highlight the importance of considering conformational diversity in protein 3D quality evaluations and endorse the study of the variability of the native structure for a meaningful biological analysis. PMID:27159429

  19. Spectroscopic Studies of Starburst Galaxies; the Dynamical Structure of Blue Compact Dwarf Galaxy Haro 6

    NASA Astrophysics Data System (ADS)

    Chun, Mun-Suk; Moon, Honh-Kyu; Sung, Eon-Chang

    1995-06-01

    We carried out photometric and spectroscopic observations of the blue compact dwarf galaxy Haro 6 in the Virgo Cluster of Galaxies. The long-slit spectroscopy was employed at three position angles, ¥Õ = 0¡Æ, ¥Õ = 30¡Æ, and ¥Õ = 120¡Æwith CCD camera mounted on the Cassegrain Spectrograph. Based on the mean intrinsic axial ratio q0=0.3, we derived inclination i of the system as 44¡Æusing our composite V-band CCD image. Careful analysis on the velocity field of the system chows an asymptotically flat rotation curve with the maximum rotational velocity V(r)max reaches about 12 km/sec. The calculation of the dynamical mass of Haro 6 with a simple mass model is briefly discussed with emphasis on the mass to luminosity ratio. From the IRAS Point Source Catalogue, we derived dust-to-gas ratio which indicates relatively low dust content, thus tempting us to conjecture the youth of the system.

  20. Spin Alignments of Spiral Galaxies within the Large-scale Structure from SDSS DR7

    NASA Astrophysics Data System (ADS)

    Zhang, Youcai; Yang, Xiaohu; Wang, Huiyuan; Wang, Lei; Luo, Wentao; Mo, H. J.; van den Bosch, Frank C.

    2015-01-01

    Using a sample of spiral galaxies selected from the Sloan Digital Sky Survey Data Release 7 and Galaxy Zoo 2, we investigate the alignment of spin axes of spiral galaxies with their surrounding large-scale structure, which is characterized by the large-scale tidal field reconstructed from the data using galaxy groups above a certain mass threshold. We find that the spin axes only have weak tendencies to be aligned with (or perpendicular to) the intermediate (or minor) axis of the local tidal tensor. The signal is the strongest in a cluster environment where all three eigenvalues of the local tidal tensor are positive. Compared to the alignments between halo spins and the local tidal field obtained in N-body simulations, the above observational results are in best agreement with those for the spins of inner regions of halos, suggesting that the disk material traces the angular momentum of dark matter halos in the inner regions.

  1. SPIN ALIGNMENTS OF SPIRAL GALAXIES WITHIN THE LARGE-SCALE STRUCTURE FROM SDSS DR7

    SciTech Connect

    Zhang, Youcai; Yang, Xiaohu; Luo, Wentao; Wang, Huiyuan; Wang, Lei; Mo, H. J.; Van den Bosch, Frank C. E-mail: xyang@sjtu.edu.cn

    2015-01-01

    Using a sample of spiral galaxies selected from the Sloan Digital Sky Survey Data Release 7 and Galaxy Zoo 2, we investigate the alignment of spin axes of spiral galaxies with their surrounding large-scale structure, which is characterized by the large-scale tidal field reconstructed from the data using galaxy groups above a certain mass threshold. We find that the spin axes only have weak tendencies to be aligned with (or perpendicular to) the intermediate (or minor) axis of the local tidal tensor. The signal is the strongest in a cluster environment where all three eigenvalues of the local tidal tensor are positive. Compared to the alignments between halo spins and the local tidal field obtained in N-body simulations, the above observational results are in best agreement with those for the spins of inner regions of halos, suggesting that the disk material traces the angular momentum of dark matter halos in the inner regions.

  2. Genetic Diversity and Population Structure of Haemonchus contortus.

    PubMed

    Gilleard, J S; Redman, E

    2016-01-01

    Haemonchus contortus is one of the most successful and problematic livestock parasites worldwide. From its apparent evolutionary origins in sub-Saharan Africa, it is now found in small ruminants in almost all regions of the globe, and can infect a range of different domestic and wildlife artiodactyl hosts. It has a remarkably high propensity to develop resistance to anthelmintic drugs, making control increasingly difficult. The success of this parasite is, at least in part, due to its extremely high levels of genetic diversity that, in turn, provide a high adaptive capacity. Understanding this genetic diversity is important for many areas of research including anthelmintic resistance, epidemiology, control, drug/vaccine development and molecular diagnostics. In this article, we review the current knowledge of H. contortus genetic diversity and population structure for both field isolates and laboratory strains. We highlight the practical relevance of this knowledge with a particular emphasis on anthelmintic resistance research. PMID:27238002

  3. Structure and Formation of Elliptical and Spheroidal Galaxies

    NASA Astrophysics Data System (ADS)

    Kormendy, John; Fisher, David B.; Cornell, Mark E.; Bender, Ralf

    2009-05-01

    New surface photometry of all known elliptical galaxies in the Virgo cluster is combined with published data to derive composite profiles of brightness, ellipticity, position angle, isophote shape, and color over large radius ranges. These provide enough leverage to show that Sérsic log I vprop r 1/n functions fit the brightness profiles I(r) of nearly all ellipticals remarkably well over large dynamic ranges. Therefore, we can confidently identify departures from these profiles that are diagnostic of galaxy formation. Two kinds of departures are seen at small radii. All 10 of our ellipticals with total absolute magnitudes MVT <= -21.66 have cuspy cores—"missing light"—at small radii. Cores are well known and naturally scoured by binary black holes (BHs) formed in dissipationless ("dry") mergers. All 17 ellipticals with -21.54 <= MVT <= -15.53 do not have cores. We find a new distinct component in these galaxies: all coreless ellipticals in our sample have extra light at the center above the inward extrapolation of the outer Sérsic profile. In large ellipticals, the excess light is spatially resolved and resembles the central components predicted in numerical simulations of mergers of galaxies that contain gas. In the simulations, the gas dissipates, falls toward the center, undergoes a starburst, and builds a compact stellar component that, as in our observations, is distinct from the Sérsic-function main body of the elliptical. But ellipticals with extra light also contain supermassive BHs. We suggest that the starburst has swamped core scouring by binary BHs. That is, we interpret extra light components as a signature of formation in dissipative ("wet") mergers. Besides extra light, we find three new aspects to the ("E-E") dichotomy into two types of elliptical galaxies. Core galaxies are known to be slowly rotating, to have relatively anisotropic velocity distributions, and to have boxy isophotes. We show that they have Sérsic indices n > 4 uncorrelated

  4. The catalog of edge-on disk galaxies from SDSS. I. The catalog and the structural parameters of stellar disks

    SciTech Connect

    Bizyaev, D. V.; Kautsch, S. J.; Mosenkov, A. V.; Reshetnikov, V. P.; Sotnikova, N. Ya.; Yablokova, N. V.; Hillyer, R. W.

    2014-05-20

    We present a catalog of true edge-on disk galaxies automatically selected from the Seventh Data Release of the Sloan Digital Sky Survey (SDSS). A visual inspection of the g, r, and i images of about 15,000 galaxies allowed us to split the initial sample of edge-on galaxy candidates into 4768 (31.8% of the initial sample) genuine edge-on galaxies, 8350 (55.7%) non-edge-on galaxies, and 1865 (12.5%) edge-on galaxies not suitable for simple automatic analysis because these objects either show signs of interaction and warps, or nearby bright stars project on it. We added more candidate galaxies from RFGC, EFIGI, RC3, and Galaxy Zoo catalogs found in the SDSS footprints. Our final sample consists of 5747 genuine edge-on galaxies. We estimate the structural parameters of the stellar disks (the stellar disk thickness, radial scale length, and central surface brightness) in the galaxies by analyzing photometric profiles in each of the g, r, and i images. We also perform simplified three-dimensional modeling of the light distribution in the stellar disks of edge-on galaxies from our sample. Our large sample is intended to be used for studying scaling relations in the stellar disks and bulges and for estimating parameters of the thick disks in different types of galaxies via the image stacking. In this paper, we present the sample selection procedure and general description of the sample.

  5. The Structure of Dark Matter Halos in Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Burkert, A.

    1995-07-01

    Recent observations indicate that dark matter halos have flat central density profiles. Cosmological simulations with nonbaryonic dark matter, however, predict self-similar halos with central density cusps. This contradiction has lead to the conclusion that dark matter must be baryonic. Here it is shown that the dark matter halos of dwarf spiral galaxies represent a one-parameter family with self-similar density profiles. The observed global halo parameters are coupled with each other through simple scaling relations which can be explained by the standard cold dark matter model if one assumes that all the halos formed from density fluctuations with the same primordial amplitude. We find that the finite central halo densities correlate with the other global parameters. This result rules out scenarios where the flat halo cores formed subsequently through violent dynamical processes in the baryonic component. These cores instead provide important information on the origin and nature of dark matter in dwarf galaxies.

  6. The structure of cross-cultural musical diversity

    PubMed Central

    Rzeszutek, Tom; Savage, Patrick E.; Brown, Steven

    2012-01-01

    Human cultural traits, such as languages, musics, rituals and material objects, vary widely across cultures. However, the majority of comparative analyses of human cultural diversity focus on between-culture variation without consideration for within-culture variation. In contrast, biological approaches to genetic diversity, such as the analysis of molecular variance (AMOVA) framework, partition genetic diversity into both within- and between-population components. We attempt here for the first time to quantify both components of cultural diversity by applying the AMOVA model to music. By employing this approach with 421 traditional songs from 16 Austronesian-speaking populations, we show that the vast majority of musical variability is due to differences within populations rather than differences between. This demonstrates a striking parallel to the structure of genetic diversity in humans. A neighbour-net analysis of pairwise population musical divergence shows a large amount of reticulation, indicating the pervasive occurrence of borrowing and/or convergent evolution of musical features across populations. PMID:22072606

  7. LUMINOUS RED GALAXY HALO DENSITY FIELD RECONSTRUCTION AND APPLICATION TO LARGE-SCALE STRUCTURE MEASUREMENTS

    SciTech Connect

    Reid, Beth A.; Spergel, David N.; Bode, Paul E-mail: dns@astro.princeton.edu

    2009-09-01

    The nontrivial relationship between observations of galaxy positions in redshift space and the underlying matter field complicates our ability to determine the linear theory power spectrum and extract cosmological information from galaxy surveys. The Sloan Digital Sky Survey (SDSS) luminous red galaxy (LRG) catalog has the potential to place powerful constraints on cosmological parameters. LRGs are bright, highly biased tracers of large-scale structure. However, because they are highly biased, the nonlinear contribution of satellite galaxies to the galaxy power spectrum is large and fingers-of-God (FOGs) are significant. The combination of these effects leads to a {approx}10% correction in the underlying power spectrum at k = 0.1 h Mpc{sup -1} and {approx}40% correction at k = 0.2 h Mpc{sup -1} in the LRG P(k) analysis of Tegmark et al., thereby compromising the cosmological constraints when this potentially large correction is left as a free parameter. We propose an alternative approach to recovering the matter field from galaxy observations. Our approach is to use halos rather than galaxies to trace the underlying mass distribution. We identify FOGs and replace each FOG with a single halo object. This removes the nonlinear contribution of satellite galaxies, the one-halo term. We test our method on a large set of high-fidelity mock SDSS LRG catalogs and find that the power spectrum of the reconstructed halo density field deviates from the underlying matter power spectrum at the {<=}1% level for k {<=} 0.1 h Mpc{sup -1} and {<=}4% at k = 0.2 h Mpc{sup -1}. The reconstructed halo density field also removes the bias in the measurement of the redshift space distortion parameter {beta} induced by the FOG smearing of the linear redshift space distortions.

  8. Panchromatic modeling of structure and stellar population of early type galaxies

    NASA Astrophysics Data System (ADS)

    Shao, Zhengyi; Chen, Zhendong

    2015-08-01

    We introduce a new approach to model the structure and stellar population of early type galaxies (ETGs). In this method, the mass distribution of stellar components in the galaxy is assumed directly, instead of that used in previous studies, which is the surface brightness profile of a specific wave band. Thus, multiple wavebands photometric data, from optical to NIR, can be used simultaneously to determine model parameters, such as the Sersic index and the size of galaxy structure, age, metallicity and their radial gradients of stellar population. The PSF effects of different wavebands are also considered in the model prediction, with which compare the observational photometric profiles. Also, information from fiber spectrum of the central part of a galaxy is very easy to be taken into account during the fitting process. Moreover, the Bayesian evidence (BE) is involved in the method to assess different empirical models, and help us to decide, for individual ETGs, if an extra outer disk structure is necessary to be added. Primary results show that, for most of ETGs from SDSS, they have negative color gradients, which means their stellar population in central part are older or metal richer than that in outer part, and this gradient is significantly correlated to the total stellar mass of the galaxy, more massive ETGs have shallower gradients. Additionally, the scaling relation of ETGs, such as their fundamental plane, is well constrained by their stellar mass distributions rather than by surface brightness profiles.

  9. Tracing galaxy evolution by their present-day luminosity function

    NASA Astrophysics Data System (ADS)

    Tempel, Elmo

    2011-04-01

    Galaxies, which are complex objects containing up to several tens of billions stars, as well as gas and dust, are remarkable objects. The Universe contains a very diverse "zoo" of galaxies: there are galaxies with a discy shape and spiral structure, elliptical galaxies, and even galaxies, which show no sign of structure. This variety of galaxies leads to the basic question: how the galaxies form and evolve and which processes shape the structure of galaxies? Due to the complexity of galaxy formation and evolution, this question is still an unresolved puzzle and it is one of the biggest challenges in modern cosmology. The present thesis is based on large galaxy surveys and concentrates on the large-scale structure: how galaxy evolution is related to the surrounding large-scale environment of superclusters and voids. To study the evolution of galaxies, we use the luminosity function, which is in this respect one of the most fundamental of all cosmological observables. One of the principal results of the present study was the conclusion that the evolution of spiral galaxies is almost independent of the global environment, especially for blue and red spirals separately, showing that the formation of spiral galaxies has to be similar in all environments. Meanwhile, the luminosity function of elliptical galaxies depends strongly on the environment. This shows that the global environmental density is an important factor (via merging history) in the formation of elliptical galaxies. The results of the present study show clearly, that besides the local/group environment, the global (supercluster-void) environment plays also an important role in the formation and evolution of galaxies. Accounting for the role of global environment can help to solve several problems in the present picture of galaxy formation and evolution.

  10. Early Type Galaxies and Structural Parameters from ESO Public Survey KiDS

    NASA Astrophysics Data System (ADS)

    Roy, N.; Napolitano, N. R.; La Barbera, F.; Tortora, C.; Getman, F.; Radovich, M.; Capaccioli, M.

    The Kilo Degree survey (KiDS) is a large-scale optical imaging survey carried out with the VLT Survey Telescope (VST), which is the ideal tool for galaxy evolution studies. We expect to observe millions of galaxies for which we extract the structural parameters in four wavebands (u, g, r and i). This sample will represent the largest dataset with measured structural parameters up to a redshift z = 0. 5. In this paper we will introduce the sample, and describe the 2D fitting procedure using the 2DPHOT environment and the validation of the parameters with an external catalog.

  11. Structure of Disk-dominated Galaxies. II. Color Gradients and Stellar Population Models

    NASA Astrophysics Data System (ADS)

    MacArthur, Lauren A.; Courteau, Stéphane; Bell, Eric; Holtzman, Jon A.

    2004-06-01

    We investigate optical and near-IR color gradients in a sample of 172 low-inclination galaxies spanning Hubble types S0-Irr. The colors are compared with stellar population synthesis models from which luminosity-weighted average ages and metallicities are determined. We explore the effects of different underlying star formation histories and additional bursts of star formation. Our results are robust in a relative sense under the assumption that our galaxies shared a similar underlying star formation history and that no bursts involving more than ~10% of the galaxy mass have occurred in the past 1-2 Gyr. Because the observed gradients show radial structure, we measure ``inner'' and ``outer'' disk age and metallicity gradients. Trends in age and metallicity and their gradients are explored as a function of Hubble type, rotational velocity, total near-IR galaxy magnitude, central surface brightness, and scale length. We find strong correlations in age and metallicity with Hubble type, rotational velocity, total magnitude, and central surface brightness in the sense that earlier-type, faster rotating, more luminous, and higher surface brightness galaxies are older and more metal-rich, suggesting an early and more rapid star formation history for these galaxies. The increasing trends with rotational velocity and total magnitude level off for Vrot>~120kms-1 and MK<~-23 mag, respectively. This effect is stronger for metallicity (than age), which could reflect a threshold potential above which all metals are retained and thus metallicity saturates at the yield. Outer disk gradients are found to be weaker than the inner gradients as expected for a slower variation of the potential and surface brightness in the outer parts. We find that stronger age gradients are associated with weaker metallicity gradients. Trends in gradients with galaxy parameters are compared with model predictions: these trends do not agree with predictions of semianalytic models of hierarchical galaxy

  12. Recovering 3D structural properties of galaxies from SDSS-like photometry

    NASA Astrophysics Data System (ADS)

    Tempel, Elmo; Tamm, Antti; Kipper, Rain; Tenjes, Teeter

    2015-10-01

    Because of the 3D nature of galaxies, an algorithm for constructing spatial density distribution models of galaxies on the basis of galaxy images has many advantages over approximations of the surface density distribution. We present a method for deriving the spatial structure and overall parameters of galaxies from images and estimate its accuracy and derived parameter degeneracies on a sample of idealised model galaxies. The test galaxies consist of a disc-like component and a spheroidal component with varying proportions and properties. Both components are assumed to be axially symmetric and coplanar. We simulate these test galaxies as if they had been observed in the SDSS project through ugriz filters, thus gaining a set of realistically imperfect images of galaxies with known intrinsic properties. These artificial SDSS galaxies were thereafter remodelled by approximating the surface brightness distribution with a 2D projection of a bulge+disc spatial distribution model and the restored parameters were compared to the initial ones. Down to the r-band limiting magnitude of 18, errors in the restored integral luminosities and colour indices remain within 0.05 mag and errors in the luminosities of individual components within 0.2 mag. Accuracy of the restored bulge-to-disc luminosity ratio (B/D) is within 40% in most cases, and becomes worse for galaxies with low B/D, but the general balance between bulges and discs is not shifted systematically. Assuming that the intrinsic disc axial ratio is ≤ 0.3, then the inclination angles can be estimated with errors < 5° for most of the galaxies with B/D < 2 and with errors < 15° up to B/D = 6. Errors in the recovered sizes of the galactic components are below 10% in most cases. The axial ratios and the shape parameter N of Einasto's distribution (similar to the Sérsic index) are relatively inaccurate, but can provide statistical estimates for large samples. In general, models of disc components are more accurate than

  13. 25. DIVERSION STRUCTURE EAST OF FORMER BASIN F IN SECTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. DIVERSION STRUCTURE EAST OF FORMER BASIN F IN SECTION 26. - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  14. 26. DIVERSION STRUCTURE WITH FORMER BASIN F IN DISTANCE (SECTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. DIVERSION STRUCTURE WITH FORMER BASIN F IN DISTANCE (SECTION 26). - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  15. 8. GENERAL VIEW OF LARGE DIVERSION STRUCTURE ON LATERAL WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. GENERAL VIEW OF LARGE DIVERSION STRUCTURE ON LATERAL WEST OF LOWER DERBY LAKE (SECTION 2). - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  16. Structure and dynamics of star-forming galaxies across the history of the Universe using GRBs

    NASA Astrophysics Data System (ADS)

    Thöne, Christina; Fynbo, Johan; de Ugarte Postigo, Antonio

    2015-08-01

    Gamma-ray bursts are exploding massive stars and some of the most luminous explosions in the Universe. They can serve as powerful light houses that probe the structure and abundances of the dense ISM in their hosts at almost any redshift and not accessible by other types of observations, e.g. using quasars. Since 2009 our collaboration has collected UV to nIR medium-resolution spectra of over 70 GRB afterglows using the ESO/VLT X-shooter spectrograph. Our sample covers a redshift range from 0.06 to 6.3 allowing us to study the dynamics of the ISM in star-forming galaxies from the nearby Universe out to the epoch of reionization and for the first time in a statistically sound way. Absorption lines usually show a rich structure of different components due to galaxy dynamics, turbulences or in-/outflows and different ionization levels seem to arise from different regions in the host. Fine-structure lines some of which are uniquely observed in GRB hosts are excited in the dense regions close to the GRB site itself. For some host with z < 3 we can also simultaenously observe emission lines from the hot ISM, comparing the origin of hot and cold gas within the same galaxy. The large wavelength coverage of the sample gives us the unique opportunity to study the evolution of gas dynamics across most of the time galaxies have existed, how the gas structure changed over time and what is the importance and consistency of in- and ouflows. Here we will present the X-shooter GRB afterglow sample, our results on the study of absorption and emission line features and compare the observed structures with theoretical models of galaxies to get a unique insight on the distrubution and dynamics of the ISM in starforming galaxies at any redshift.

  17. GHOSTS: the age and structure of stellar halos around nearby disk galaxies

    NASA Astrophysics Data System (ADS)

    de Jong, Roelof S.; Bailin, Jeremy; Bell, Eric; Holwerda, Benne Willem; Monachesi, Antonela; Streich, David

    2015-08-01

    The stars in the halos around galaxies are thought to be for a significant fraction the result of tidally disrupted infalling smaller galaxies, an important process in the mass build up of galaxies. However, in recent year the realization has grown that a fraction of halo stars may have formed in situ or in the disk of the host galaxy.To understand the nature of stellar halos, the GHOSTS project has used the Hubble Space Telescope to observe the resolved stellar populations in the outskirts of 18 nearby massive galaxies, with a range of masses and seen from face-on to edge-on. From two filter observations (F814W and F606W) with both WFC3 and ACS, we map the different giant populations in these haloes: typically Asymptotic, Red, and He-burning Giants (AGB, RGB and HeB). By studying the distribution of these stellar populations, the GHOSTS project aims to characterize on a statistical basis the size, shape, age, amount of sub-structure, and chemical composition of stellar halos, thereby allowing us to constrain models of the hierarchical galaxy formation process.In this presentation we will in particular show the structural parameters of the observed stellar halos out to 70 kpc and present the rather small range in color gradients present in the RGB population indicative in small metallicity gradients in these halos. We also present the discovery of a surprisingly large population of AGB stars with ages <2 Gyr seen to ~20 kpc above the disks of many edge-on galaxies and speculations on the origin of these young populations at a location where no current star formation is seen.

  18. Structural diversity in a human antibody germline library

    PubMed Central

    Teplyakov, Alexey; Obmolova, Galina; Malia, Thomas J.; Luo, Jinquan; Muzammil, Salman; Sweet, Raymond; Almagro, Juan Carlos; Gilliland, Gary L.

    2016-01-01

    ABSTRACT To support antibody therapeutic development, the crystal structures of a set of 16 germline variants composed of 4 different kappa light chains paired with 4 different heavy chains have been determined. All four heavy chains of the antigen-binding fragments (Fabs) have the same complementarity-determining region (CDR) H3 that was reported in an earlier Fab structure. The structure analyses include comparisons of the overall structures, canonical structures of the CDRs and the VH:VL packing interactions. The CDR conformations for the most part are tightly clustered, especially for the ones with shorter lengths. The longer CDRs with tandem glycines or serines have more conformational diversity than the others. CDR H3, despite having the same amino acid sequence, exhibits the largest conformational diversity. About half of the structures have CDR H3 conformations similar to that of the parent; the others diverge significantly. One conclusion is that the CDR H3 conformations are influenced by both their amino acid sequence and their structural environment determined by the heavy and light chain pairing. The stem regions of 14 of the variant pairs are in the ‘kinked’ conformation, and only 2 are in the extended conformation. The packing of the VH and VL domains is consistent with our knowledge of antibody structure, and the tilt angles between these domains cover a range of 11 degrees. Two of 16 structures showed particularly large variations in the tilt angles when compared with the other pairings. The structures and their analyses provide a rich foundation for future antibody modeling and engineering efforts. PMID:27210805

  19. Structural diversity in a human antibody germline library.

    PubMed

    Teplyakov, Alexey; Obmolova, Galina; Malia, Thomas J; Luo, Jinquan; Muzammil, Salman; Sweet, Raymond; Almagro, Juan Carlos; Gilliland, Gary L

    2016-01-01

    To support antibody therapeutic development, the crystal structures of a set of 16 germline variants composed of 4 different kappa light chains paired with 4 different heavy chains have been determined. All four heavy chains of the antigen-binding fragments (Fabs) have the same complementarity-determining region (CDR) H3 that was reported in an earlier Fab structure. The structure analyses include comparisons of the overall structures, canonical structures of the CDRs and the VH:VL packing interactions. The CDR conformations for the most part are tightly clustered, especially for the ones with shorter lengths. The longer CDRs with tandem glycines or serines have more conformational diversity than the others. CDR H3, despite having the same amino acid sequence, exhibits the largest conformational diversity. About half of the structures have CDR H3 conformations similar to that of the parent; the others diverge significantly. One conclusion is that the CDR H3 conformations are influenced by both their amino acid sequence and their structural environment determined by the heavy and light chain pairing. The stem regions of 14 of the variant pairs are in the 'kinked' conformation, and only 2 are in the extended conformation. The packing of the VH and VL domains is consistent with our knowledge of antibody structure, and the tilt angles between these domains cover a range of 11 degrees. Two of 16 structures showed particularly large variations in the tilt angles when compared with the other pairings. The structures and their analyses provide a rich foundation for future antibody modeling and engineering efforts. PMID:27210805

  20. COS-GTO: QSO Absorbers, Galaxies and Large-scale Structures in the Local Universe.

    NASA Astrophysics Data System (ADS)

    Green, James

    2009-07-01

    This is a program to probe the large scale structure of baryons in the universe, including addressing questions of baryon fraction, physical conditions and relationships between absorbers and large-scale structures of galaxies. Besides these specific goals, this proposed GTO program also probes a large enough total path length in Ly alpha and OVI to add significantly to what STIS/FUSE has already observed. Several Galactic High Velocity Cloud Complexes also are probed by these sightlines, particularly the M Complex. The total path length of this proposed program for Ly alpha large-scale structure surveys is delta_z 5.5. We have selected a variety of targets to address these questions, under the following subcategories:1. Target 8 bright BL Lac objects to search for low contrast Ly alpha absorbers from the warm-hot interstellar medium {WHIM}. Science drivers: What are physical conditions and extent of warm-hot IGM in the current epoch? Can we discover metal-poor WHIM using very broad Ly alpha lines? What is the number density of such lines {dN/dz} and what is their relationship if any with tentative Chandra detections of even hotter gas?2. Ly alpha cloud sizes: The targets are a bright AGN pair which yield tangential distance separations of 100-500 kpc at z=0.01-0.05, where galaxy surveys are excellent. This pair has two filaments and two voids in this distance range. Science drivers: What are the characteristic sizes of Ly alpha absorbers, weak metal-line absorbers and absorbers in voids? Better size determinations will tighten current estimates of the baryon content of the photoionzed IGM .3. Probes of starburst outflows: The targets are bright AGN, <= 100 kpc in projection out of the minor axis of nearby starburst galaxies. Science drivers: Outflowing, unbound winds have been implicated as a primary mechanism to enrich the IGM in mass, metals and energy. But do starburst winds from massive galaxies escape the galaxy's gravitational potential? If so, what is the

  1. The Study of Clusters of Galaxies and Large Scale Structures

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Many research projects have been initiated and completed under support of this program. The results are summarized below. The work on the ROSAT Deep Survey has been successfully completed. A number of interesting results have been established within this joint MPE, Cal Tech, JHU, ST ScI, ESO collaboration. First, a very large fraction, 70-80 percent, of the X-ray background has been directly resolved into point sources. We have derived a new log N-log S for X-ray sources and have measured a source density of 970 sources per square degree at a limiting flux level. Care was taken in these studies to accurately model and measure the effects of sources confusion. This was possible because of our observing strategy which included both deep PSPC and HRI observations. No evidence of a population of narrow emission line galaxies has been established but some evidence for the evolution of low luminosity AGN (Seyfert galaxies) has been reported. The work on the ROSAT All Sky Survey Northern Cluster Survey has been substantially concluded but the publication of the list has been held up by the need to analyze newly re-calibrated data. This should result in publication over the next year. During the past year we have submitted a paper to the Astrophysical Journal which utilized a sample of clusters originally selected from the ROSAT All-sky survey at redshifts greater than 0.3. This sample was studied with ASCA to determine temperature and luminosity.

  2. Molecular diversity and tools for deciphering the methanogen community structure and diversity in freshwater sediments.

    PubMed

    Chaudhary, Prem Prashant; Brablcová, Lenka; Buriánková, Iva; Rulík, Martin

    2013-09-01

    Methanogenic archaeal communities existing in freshwater sediments are responsible for approximately 50 % of the total global emission of methane. This process contributes significantly to global warming and, hence, necessitates interventional control measures to limit its emission. Unfortunately, the diversity and functional interactions of methanogenic populations occurring in these habitats are yet to be fully characterized. Considering several disadvantages of conventional culture-based methodologies, in recent years, impetus is given to molecular biology approaches to determine the community structure of freshwater sedimentary methanogenic archaea. 16S rRNA and methyl coenzyme M reductase (mcrA) gene-based cloning techniques are the first choice for this purpose. In addition, electrophoresis-based (denaturing gradient gel electrophoresis, temperature gradient gel electrophoresis, and terminal restriction fragment length polymorphism) and quantitative real-time polymerase chain reaction techniques have also found extensive applications. These techniques are highly sensitive, rapid, and reliable as compared to traditional culture-dependent approaches. Molecular diversity studies revealed the dominance of the orders Methanomicrobiales and Methanosarcinales of methanogens in freshwater sediments. The present review discusses in detail the status of the diversity of methanogens and the molecular approaches applied in this area of research. PMID:23877581

  3. Lanthanide coordination polymers: Synthesis, diverse structure and luminescence properties

    SciTech Connect

    Song, Xue-Qin Lei, Yao-Kun; Wang, Xiao-Run; Zhao, Meng-Meng; Peng, Yun-Qiao; Cheng, Guo-Quan

    2014-10-15

    The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis([(2′-furfurylaminoformyl)phenoxyl]methyl)-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schläfli symbol 6{sup 3}, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversities indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of Eu{sup III}, Tb{sup III} and Dy{sup III} complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in Eu{sup III}, Tb{sup III} and Dy{sup III} complexes can be efficiently sensitized by the ligand. - Graphical abstract: We present herein six lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display diverse structures but also possess strong luminescence properties. - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit diverse structures. • The luminescent properties of Tb{sup III}, Eu{sup III} and Dy{sup III} complexes are discussed in detail.

  4. Differences in the Structural Properties and Star-formation Rates of Field and Cluster Galaxies at z~1

    NASA Astrophysics Data System (ADS)

    Allen, Rebecca J.; Kacprzak, Glenn G.; Glazebrook, Karl; Tran, Kim-Vy H.; Spitler, Lee R.; Straatman, Caroline M. S.; Cowley, Michael; Nanayakkara, Themiya

    2016-07-01

    We investigate the dependence of galaxy sizes and star formation rates (SFRs) on their environment using a mass-limited sample of quiescent and star-forming galaxies with log(M */{M}ȯ ) ≥ 9.5 at \\bar{z}=0.92 selected from the NEWFIRM medium-band Survey (NMBS). Using the Galaxy Environment Evolution Collaboration 2 spectroscopic cluster catalog and the accurate photometric redshifts from the NMBS, we select quiescent and star-forming cluster (\\bar{σ }=490 km s‑1) galaxies within two virial radius, R vir, intervals of 2 > R vir > 0.5 and R vir < 0.5. Galaxies residing outside of the 2 R vir of both the cluster centers and the additional candidate over-densities are defined as our field sample. Galaxy structural parameters are measured from the COSMOS legacy Hubble Space Telescope/ACS F814W image. The sizes and Sérsic indices of quiescent field and cluster galaxies have the same distribution regardless of R vir. However, cluster star-forming galaxies within 0.5 R vir have lower mass-normalized average sizes by 16+/- 7 % , and a higher fraction of Sérsic indices with n\\gt 1, than field star-forming galaxies. The average SFRs of star-forming cluster galaxies show a trend of decreasing SFR with clustocentric radius. The mass-normalized average SFR of cluster star-forming galaxies is a factor of 2{--}2.5 (7{--}9σ ) lower than that of star-forming galaxies in the field. While we find no significant dependence on environment for quiescent galaxies, the properties of star-forming galaxies are affected, which could be the result of environment acting on their gas content.

  5. Diversity, structure and convergent evolution of the global sponge microbiome.

    PubMed

    Thomas, Torsten; Moitinho-Silva, Lucas; Lurgi, Miguel; Björk, Johannes R; Easson, Cole; Astudillo-García, Carmen; Olson, Julie B; Erwin, Patrick M; López-Legentil, Susanna; Luter, Heidi; Chaves-Fonnegra, Andia; Costa, Rodrigo; Schupp, Peter J; Steindler, Laura; Erpenbeck, Dirk; Gilbert, Jack; Knight, Rob; Ackermann, Gail; Victor Lopez, Jose; Taylor, Michael W; Thacker, Robert W; Montoya, Jose M; Hentschel, Ute; Webster, Nicole S

    2016-01-01

    Sponges (phylum Porifera) are early-diverging metazoa renowned for establishing complex microbial symbioses. Here we present a global Porifera microbiome survey, set out to establish the ecological and evolutionary drivers of these host-microbe interactions. We show that sponges are a reservoir of exceptional microbial diversity and major contributors to the total microbial diversity of the world's oceans. Little commonality in species composition or structure is evident across the phylum, although symbiont communities are characterized by specialists and generalists rather than opportunists. Core sponge microbiomes are stable and characterized by generalist symbionts exhibiting amensal and/or commensal interactions. Symbionts that are phylogenetically unique to sponges do not disproportionally contribute to the core microbiome, and host phylogeny impacts complexity rather than composition of the symbiont community. Our findings support a model of independent assembly and evolution in symbiont communities across the entire host phylum, with convergent forces resulting in analogous community organization and interactions. PMID:27306690

  6. Diversity, structure and convergent evolution of the global sponge microbiome

    PubMed Central

    Thomas, Torsten; Moitinho-Silva, Lucas; Lurgi, Miguel; Björk, Johannes R.; Easson, Cole; Astudillo-García, Carmen; Olson, Julie B.; Erwin, Patrick M.; López-Legentil, Susanna; Luter, Heidi; Chaves-Fonnegra, Andia; Costa, Rodrigo; Schupp, Peter J.; Steindler, Laura; Erpenbeck, Dirk; Gilbert, Jack; Knight, Rob; Ackermann, Gail; Victor Lopez, Jose; Taylor, Michael W.; Thacker, Robert W.; Montoya, Jose M.; Hentschel, Ute; Webster, Nicole S.

    2016-01-01

    Sponges (phylum Porifera) are early-diverging metazoa renowned for establishing complex microbial symbioses. Here we present a global Porifera microbiome survey, set out to establish the ecological and evolutionary drivers of these host–microbe interactions. We show that sponges are a reservoir of exceptional microbial diversity and major contributors to the total microbial diversity of the world's oceans. Little commonality in species composition or structure is evident across the phylum, although symbiont communities are characterized by specialists and generalists rather than opportunists. Core sponge microbiomes are stable and characterized by generalist symbionts exhibiting amensal and/or commensal interactions. Symbionts that are phylogenetically unique to sponges do not disproportionally contribute to the core microbiome, and host phylogeny impacts complexity rather than composition of the symbiont community. Our findings support a model of independent assembly and evolution in symbiont communities across the entire host phylum, with convergent forces resulting in analogous community organization and interactions. PMID:27306690

  7. Beyond Ellipse(s): Accurately Modelling the Isophotal Structure of Galaxies with ISOFIT and CMODEL

    NASA Astrophysics Data System (ADS)

    Ciambur, B. C.

    2015-09-01

    This work introduces a new fitting formalism for isophotes that enables more accurate modeling of galaxies with non-elliptical shapes, such as disk galaxies viewed edge-on or galaxies with X-shaped/peanut bulges. Within this scheme, the angular parameter that defines quasi-elliptical isophotes is transformed from the commonly used, but inappropriate, polar coordinate to the “eccentric anomaly.” This provides a superior description of deviations from ellipticity, better capturing the true isophotal shape. Furthermore, this makes it possible to accurately recover both the surface brightness profile, using the correct azimuthally averaged isophote, and the two-dimensional model of any galaxy: the hitherto ubiquitous, but artificial, cross-like features in residual images are completely removed. The formalism has been implemented into the Image Reduction and Analysis Facility tasks Ellipse and Bmodel to create the new tasks “Isofit,” and “Cmodel.” The new tools are demonstrated here with application to five galaxies, chosen to be representative case-studies for several areas where this technique makes it possible to gain new scientific insight. Specifically: properly quantifying boxy/disky isophotes via the fourth harmonic order in edge-on galaxies, quantifying X-shaped/peanut bulges, higher-order Fourier moments for modeling bars in disks, and complex isophote shapes. Higher order (n > 4) harmonics now become meaningful and may correlate with structural properties, as boxyness/diskyness is known to do. This work also illustrates how the accurate construction, and subtraction, of a model from a galaxy image facilitates the identification and recovery of over-lapping sources such as globular clusters and the optical counterparts of X-ray sources.

  8. GASEOUS STRUCTURES IN BARRED GALAXIES: EFFECTS OF THE BAR STRENGTH

    SciTech Connect

    Kim, Woong-Tae; Seo, Woo-Young; Kim, Yonghwi

    2012-10-10

    Using hydrodynamic simulations, we investigate the physical properties of gaseous substructures in barred galaxies and their relationships with the bar strength. The gaseous medium is assumed to be isothermal and unmagnetized. The bar potential is modeled as a Ferrers prolate with index n. To explore situations with differing bar strength, we vary the bar mass f{sub bar} relative to the spheroidal component as well as its aspect ratio R. We derive expressions as functions of f{sub bar} and R for the bar strength Q{sub b} and the radius r(Q{sub b} ) where the maximum bar torque occurs. When applied to observations, these expressions suggest that bars in real galaxies are most likely to have f{sub bar} {approx} 0.25-0.50 and n {approx}< 1. Dust lanes approximately follow one of the x{sub 1}-orbits and tend to be straighter under a stronger and more elongated bar, but are insensitive to the presence of self-gravity. A nuclear ring of a conventional x{sub 2} type forms only when the bar is not so massive or elongated. The radius of an x{sub 2}-type ring is generally smaller than the inner Lindblad resonance, decreases systematically with increasing Q{sub b} , and is slightly larger when self-gravity is included. This is evidence that the ring position is not determined by the resonance, but instead by the amount of angular momentum loss at dust-lane shocks. Nuclear spirals exist only when the ring is of the x{sub 2} type and is sufficiently large in size. Unlike the other features, nuclear spirals are transient in that they start out being tightly wound and weak, and then, due to the nonlinear effect, unwind and become stronger until they turn into shocks, with an unwinding rate that is higher for larger Q{sub b} . The mass inflow rate to the galaxy center is found to be less than 0.01 M{sub Sun} yr{sup -1} for models with Q{sub b} {approx}< 0.2, while becoming larger than 0.1 M{sub Sun} yr{sup -1} when Q{sub b} {approx}> 0.2 and self-gravity is included.

  9. Entropic forces stabilize diverse emergent structures in colloidal membranes

    NASA Astrophysics Data System (ADS)

    Kang, Louis; Gibaud, Thomas; Dogic, Zvonimir; Lubensky, T. C.

    The depletion interaction mediated by non-adsorbing polymers promotes condensation and assembly of repulsive colloidal particles into diverse higher-order structures and materials. One example, with particularly rich emergent behaviors, is the formation of two-dimensional colloidal membranes from a suspension of filamentous $\\it{fd}$ viruses, which act as rods with effective repulsive interactions, and dextran, which acts as a condensing, depletion-inducing agent. Colloidal membranes exhibit chiral twist even when the constituent virus mixture lacks macroscopic chirality, change from a circular shape to a striking starfish shape upon changing the chirality of constituent rods, and partially coalesce via domain walls through which the viruses twist by $180^\\circ$. We formulate an entropically-motivated theory that can quantitatively explain these experimental structures and measurements, both previously published and newly performed, over a wide range of experimental conditions. Our results elucidate how entropy alone, manifested through the viruses as Frank elastic energy and through the depletants as an effective surface tension, drives the formation and behavior of these diverse structures. Our generalizable principles propose the existence of analogous effects in molecular membranes and can be exploited in the design of reconfigurable colloidal structures.

  10. Entropic forces stabilize diverse emergent structures in colloidal membranes.

    PubMed

    Kang, Louis; Gibaud, Thomas; Dogic, Zvonimir; Lubensky, T C

    2016-01-14

    The depletion interaction mediated by non-adsorbing polymers promotes condensation and assembly of repulsive colloidal particles into diverse higher-order structures and materials. One example, with particularly rich emergent behaviors, is the formation of two-dimensional colloidal membranes from a suspension of filamentous fd viruses, which act as rods with effective repulsive interactions, and dextran, which acts as a condensing, depletion-inducing agent. Colloidal membranes exhibit chiral twist even when the constituent virus mixture lacks macroscopic chirality, change from a circular shape to a striking starfish shape upon changing the chirality of constituent rods, and partially coalesce via domain walls through which the viruses twist by 180°. We formulate an entropically-motivated theory that can quantitatively explain these experimental structures and measurements, both previously published and newly performed, over a wide range of experimental conditions. Our results elucidate how entropy alone, manifested through the viruses as Frank elastic energy and through the depletants as an effective surface tension, drives the formation and behavior of these diverse structures. Our generalizable principles propose the existence of analogous effects in molecular membranes and can be exploited in the design of reconfigurable colloidal structures. PMID:26472139

  11. Plasmodium vivax Diversity and Population Structure across Four Continents.

    PubMed

    Koepfli, Cristian; Rodrigues, Priscila T; Antao, Tiago; Orjuela-Sánchez, Pamela; Van den Eede, Peter; Gamboa, Dionicia; van Hong, Nguyen; Bendezu, Jorge; Erhart, Annette; Barnadas, Céline; Ratsimbasoa, Arsène; Menard, Didier; Severini, Carlo; Menegon, Michela; Nour, Bakri Y M; Karunaweera, Nadira; Mueller, Ivo; Ferreira, Marcelo U; Felger, Ingrid

    2015-01-01

    Plasmodium vivax is the geographically most widespread human malaria parasite. To analyze patterns of microsatellite diversity and population structure across countries of different transmission intensity, genotyping data from 11 microsatellite markers was either generated or compiled from 841 isolates from four continents collected in 1999-2008. Diversity was highest in South-East Asia (mean allelic richness 10.0-12.8), intermediate in the South Pacific (8.1-9.9) Madagascar and Sudan (7.9-8.4), and lowest in South America and Central Asia (5.5-7.2). A reduced panel of only 3 markers was sufficient to identify approx. 90% of all haplotypes in South Pacific, African and SE-Asian populations, but only 60-80% in Latin American populations, suggesting that typing of 2-6 markers, depending on the level of endemicity, is sufficient for epidemiological studies. Clustering analysis showed distinct clusters in Peru and Brazil, but little sub-structuring was observed within Africa, SE-Asia or the South Pacific. Isolates from Uzbekistan were exceptional, as a near-clonal parasite population was observed that was clearly separated from all other populations (FST>0.2). Outside Central Asia FST values were highest (0.11-0.16) between South American and all other populations, and lowest (0.04-0.07) between populations from South-East Asia and the South Pacific. These comparisons between P. vivax populations from four continents indicated that not only transmission intensity, but also geographical isolation affect diversity and population structure. However, the high effective population size results in slow changes of these parameters. This persistency must be taken into account when assessing the impact of control programs on the genetic structure of parasite populations. PMID:26125189

  12. Plasmodium vivax Diversity and Population Structure across Four Continents

    PubMed Central

    Koepfli, Cristian; Rodrigues, Priscila T.; Antao, Tiago; Orjuela-Sánchez, Pamela; Van den Eede, Peter; Gamboa, Dionicia; van Hong, Nguyen; Bendezu, Jorge; Erhart, Annette; Barnadas, Céline; Ratsimbasoa, Arsène; Menard, Didier; Severini, Carlo; Menegon, Michela; Nour, Bakri Y. M.; Karunaweera, Nadira; Mueller, Ivo; Ferreira, Marcelo U.; Felger, Ingrid

    2015-01-01

    Plasmodium vivax is the geographically most widespread human malaria parasite. To analyze patterns of microsatellite diversity and population structure across countries of different transmission intensity, genotyping data from 11 microsatellite markers was either generated or compiled from 841 isolates from four continents collected in 1999–2008. Diversity was highest in South-East Asia (mean allelic richness 10.0–12.8), intermediate in the South Pacific (8.1–9.9) Madagascar and Sudan (7.9–8.4), and lowest in South America and Central Asia (5.5–7.2). A reduced panel of only 3 markers was sufficient to identify approx. 90% of all haplotypes in South Pacific, African and SE-Asian populations, but only 60–80% in Latin American populations, suggesting that typing of 2–6 markers, depending on the level of endemicity, is sufficient for epidemiological studies. Clustering analysis showed distinct clusters in Peru and Brazil, but little sub-structuring was observed within Africa, SE-Asia or the South Pacific. Isolates from Uzbekistan were exceptional, as a near-clonal parasite population was observed that was clearly separated from all other populations (FST>0.2). Outside Central Asia FST values were highest (0.11–0.16) between South American and all other populations, and lowest (0.04–0.07) between populations from South-East Asia and the South Pacific. These comparisons between P. vivax populations from four continents indicated that not only transmission intensity, but also geographical isolation affect diversity and population structure. However, the high effective population size results in slow changes of these parameters. This persistency must be taken into account when assessing the impact of control programs on the genetic structure of parasite populations. PMID:26125189

  13. An Open-Source Galaxy Redshift Survey Simulator for next-generation Large Scale Structure Surveys

    NASA Astrophysics Data System (ADS)

    Seijak, Uros

    Galaxy redshift surveys produce three-dimensional maps of the galaxy distribution. On large scales these maps trace the underlying matter fluctuations in a relatively simple manner, so that the properties of the primordial fluctuations along with the overall expansion history and growth of perturbations can be extracted. The BAO standard ruler method to measure the expansion history of the universe using galaxy redshift surveys is thought to be robust to observational artifacts and understood theoretically with high precision. These same surveys can offer a host of additional information, including a measurement of the growth rate of large scale structure through redshift space distortions, the possibility of measuring the sum of neutrino masses, tighter constraints on the expansion history through the Alcock-Paczynski effect, and constraints on the scale-dependence and non-Gaussianity of the primordial fluctuations. Extracting this broadband clustering information hinges on both our ability to minimize and subtract observational systematics to the observed galaxy power spectrum, and our ability to model the broadband behavior of the observed galaxy power spectrum with exquisite precision. Rapid development on both fronts is required to capitalize on WFIRST's data set. We propose to develop an open-source computational toolbox that will propel development in both areas by connecting large scale structure modeling and instrument and survey modeling with the statistical inference process. We will use the proposed simulator to both tailor perturbation theory and fully non-linear models of the broadband clustering of WFIRST galaxies and discover novel observables in the non-linear regime that are robust to observational systematics and able to distinguish between a wide range of spatial and dynamic biasing models for the WFIRST galaxy redshift survey sources. We have demonstrated the utility of this approach in a pilot study of the SDSS-III BOSS galaxies, in which we

  14. The structure and content of the galaxy and galactic gamma rays. [conferences

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Stecker, F. W.

    1976-01-01

    Papers are presented dealing with galactic structure drawing on all branches of galactic astronomy with emphasis on the implications of the new gamma ray observations. Topics discussed include: (1) results from the COS-B gamma ray satellite; (2) results from SAS-2 on gamma ray pulsar, Cygnus X-3, and maps of the galactic diffuse flux; (3) recent data from CO surveys of the galaxy; (4) high resolution radio surveys of external galaxies; (5) results on the galactic distribution of pulsars; and (6) theoretical work on galactic gamma ray emission.

  15. OPTICAL STRUCTURE AND EVOLUTION OF THE Arp 104 INTERACTING GALAXY SYSTEM

    SciTech Connect

    Gallagher, John S. III; Parker, Angela E-mail: parker@astro.indiana.ed

    2010-10-20

    Arp 104 is a pair of luminous interacting galaxies consisting of NGC 5216, an elliptical, and NGC 5218, a disturbed disk galaxy and joined by a stellar bridge. We obtained optical imaging to support photometric and color studies of the system. NGC 5216 lies on the red sequence, while the unusual distribution of stellar population properties in combination with intense central star formation in a dusty region result in NGC 5218 being a nearby example of an intermediate color (green valley) system. The stellar bridge has remarkably uniform optical surface brightness, with colors consistent with its stars coming from the outskirts of NGC 5218, but is relatively gas-poor while the northern tidal tail is rich in H I. While both galaxies contain shells, the shell structures in NGC 5218 are pronounced, and some appear to be associated with counter-rotating gas. This combination of features suggests that Arp 104 could be the product of distinct multiple interactions in a small galaxy group, possibly resulting from a hierarchical merging process, and likely leading to the birth of a relatively massive and isolated early-type galaxy.

  16. RED NUGGETS AT HIGH REDSHIFT: STRUCTURAL EVOLUTION OF QUIESCENT GALAXIES OVER 10 Gyr OF COSMIC HISTORY

    SciTech Connect

    Damjanov, Ivana; Abraham, Roberto G.; Carlberg, Raymond G.; Mentuch, Erin; Glazebrook, Karl; Caris, Evelyn; Green, Andrew W.; McCarthy, Patrick J.; Chen, Hsiao-Wen; Crampton, David; Murowinski, Richard; Joergensen, Inger; Roth, Kathy; Juneau, Stephanie; Marzke, Ronald O.; Savaglio, Sandra; Yan Haojing

    2011-10-01

    We present an analysis of the size growth seen in early-type galaxies over 10 Gyr of cosmic time. Our analysis is based on a homogeneous synthesis of published data from 16 spectroscopic surveys observed at similar spatial resolution, augmented by new measurements for galaxies in the Gemini Deep Deep Survey. In total, our sample contains structural data for 465 galaxies (mainly early-type) in the redshift range 0.2 < z < 2.7. The size evolution of passively evolving galaxies over this redshift range is gradual and continuous, with no evidence for an end or change to the process around z {approx} 1, as has been hinted at by some surveys which analyze subsets of the data in isolation. The size growth appears to be independent of stellar mass, with the mass-normalized half-light radius scaling with redshift as R{sub e} {proportional_to}(1 + z){sup -1.62{+-}0.34}. Surprisingly, this power law seems to be in good agreement with the recently reported continuous size evolution of UV-bright galaxies in the redshift range z {approx} 0.5-3.5. It is also in accordance with the predictions from recent theoretical models.

  17. Building disc structure and galaxy properties through angular momentum: The DARK SAGE semi-analytic model

    NASA Astrophysics Data System (ADS)

    Stevens, Adam R. H.; Croton, Darren J.; Mutch, Simon J.

    2016-06-01

    We present the new semi-analytic model of galaxy evolution, DARK SAGE, a heavily modified version of the publicly available SAGE code. The model is designed for detailed evolution of galactic discs. We evolve discs in a series of annuli with fixed specific angular momentum, which allows us to make predictions for the radial and angular-momentum structure of galaxies. Most physical processes, including all channels of star formation and associated feedback, are performed in these annuli. We present the surface density profiles of our model spiral galaxies, both as a function of radius and specific angular momentum, and find the discs naturally build a pseduobulge-like component. Our main results are focussed on predictions relating to the integrated mass-specific angular momentum relation of stellar discs. The model produces a distinct sequence between these properties in remarkable agreement with recent observational literature. We investigate the impact Toomre disc instabilities have on shaping this sequence and find they are crucial for regulating both the mass and spin of discs. Without instabilities, high-mass discs would be systematically deficient in specific angular momentum by a factor of ˜2.5, with increased scatter. Instabilities also appear to drive the direction in which the mass-spin sequence of spiral galaxy discs evolves. With them, we find galaxies of fixed mass have higher specific angular momentum at later epochs.

  18. Building disc structure and galaxy properties through angular momentum: the DARK SAGE semi-analytic model

    NASA Astrophysics Data System (ADS)

    Stevens, Adam R. H.; Croton, Darren J.; Mutch, Simon J.

    2016-09-01

    We present the new semi-analytic model of galaxy evolution, DARK SAGE, a heavily modified version of the publicly available SAGE code. The model is designed for detailed evolution of galactic discs. We evolve discs in a series of annuli with fixed specific angular momentum, which allows us to make predictions for the radial and angular-momentum structure of galaxies. Most physical processes, including all channels of star formation and associated feedback, are performed in these annuli. We present the surface density profiles of our model spiral galaxies, both as a function of radius and specific angular momentum, and find that the discs naturally build a pseudo-bulge-like component. Our main results are focused on predictions relating to the integrated mass-specific angular momentum relation of stellar discs. The model produces a distinct sequence between these properties in remarkable agreement with recent observational literature. We investigate the impact Toomre disc instabilities have on shaping this sequence and find they are crucial for regulating both the mass and spin of discs. Without instabilities, high-mass discs would be systematically deficient in specific angular momentum by a factor of ˜2.5, with increased scatter. Instabilities also appear to drive the direction in which the mass-spin sequence of spiral galaxy discs evolves. With them, we find galaxies of fixed mass have higher specific angular momentum at later epochs.

  19. The structure of the nearby universe traced by theIRAS galaxies

    NASA Technical Reports Server (NTRS)

    Yahil, Amos

    1993-01-01

    One of the most important discoveries of the Infrared Astronomical Satellite (IRAS) has been the detection of about 20,000 galaxies with 60 microns fluxes above 0.5 Jy. From the observational point of view, the IRAS galaxies are ideal tracers of density, since they are homogeneously detected over most of the sky, and their fluxes are unaffected by galactic extinction. The nearby universe was mapped by the IRAS galaxies to a distance of approximately 200 h(exp -1) Mpc for the absolute value of b less than 5 deg. The ability to map down to such low galactic latitudes has proven to be particularly imporant, since some of the most important nearby large-scale structures, such as the Great Attractor, the Perseus-Pisces region, and the Shapley concentration, all lie there. Two major results of the U.S. IRAS redshift survey are discussed.

  20. Galaxy evolution. Quasar quartet embedded in giant nebula reveals rare massive structure in distant universe.

    PubMed

    Hennawi, Joseph F; Prochaska, J Xavier; Cantalupo, Sebastiano; Arrigoni-Battaia, Fabrizio

    2015-05-15

    All galaxies once passed through a hyperluminous quasar phase powered by accretion onto a supermassive black hole. But because these episodes are brief, quasars are rare objects typically separated by cosmological distances. In a survey for Lyman-α emission at redshift z ≈ 2, we discovered a physical association of four quasars embedded in a giant nebula. Located within a substantial overdensity of galaxies, this system is probably the progenitor of a massive galaxy cluster. The chance probability of finding a quadruple quasar is estimated to be ∼10(-7), implying a physical connection between Lyman-α nebulae and the locations of rare protoclusters. Our findings imply that the most massive structures in the distant universe have a tremendous supply (≃10(11) solar masses) of cool dense (volume density ≃ 1 cm(-3)) gas, which is in conflict with current cosmological simulations. PMID:25977547

  1. Effects of Galaxy collisions on the structure and evolution of Galaxy clusters. I. Mass and luminosity functions and background light

    SciTech Connect

    Miller, G.E.

    1983-05-15

    The role of galaxy collisions in controlling the form of the galaxy mass and luminosity functions and in creating a diffuse background light is investigated by means of a direct computer simulation. Galaxy collisions are treated in a realistic manner, including both galaxy mergers and tidal encounters. A large number of theoretical studies of a galaxy collisions were consulted to formulate the basic input physics of collision cross sections. Despite this large number of studies, there remains considerable uncertainty in the effects of a collision on a galaxy due mainly to our lack of knowledge of the orbital distribution of matter in galaxies. To improve this situation, some methods of semiempirical calibration are suggested: for example, a survey of background light in clusters of different richness and morphological classes. If real galaxies are represented by galaxy models where the bulk of the matter is on radial, rather than circular, orbits, then tidal collisions are more damaging and there are a number of interesting effects: Repeated tidal encounters lead to galaxy mass and luminosity functions which are largely independent of model parameters and the initial galaxy mass function. It appears unlikely that the form of the average present-day luminosity function characteristic of both field and cluster galaxies is due to collisions, but certain observed deviations from the average found by Heiligman and Turner and by Dressler may be a signature of collisions, in particular a flat faint-end slope. The amount of luminous matter stripped from the galaxies in the simulations agrees with the amount of diffuse background light seen in the Coma Cluster.

  2. Detailed Decomposition of Galaxy Images II: Fitting Spiral Arms, Bars, and Non-axisymmetric Structures in GALFIT 3.0

    NASA Astrophysics Data System (ADS)

    Peng, Chien Y.; Ho, L. C.; Impey, C. D.; Rix, H. W.

    2007-12-01

    The technique of fitting galaxy light profiles with analytic functions (e.g. de Vaucouleurs, exponential), also known as parametric fitting, has been a useful tool for studying galaxy structure and evolution. It is often used to quantify global properties of galaxies such as luminosity, size, ellipticity, and profile shape in a self-consistent manner. It also allows one to deblend multiple components of a galaxy, e.g. bulge/disk/bar/AGN, or to separate overlapping galaxies in a rigorous and robust way. However, the traditional method of fitting galaxies relies on using ellipsoid models, which is sometimes criticized to argue in favor of non-parametric techniques. In this study, we show that two dimensional image fitting is not fundamentally restricted to using axisymmetric ellipsoid shapes. By breaking from axisymmetry parametrically through the use of Fourier modes, one can better quantify the degree of galaxy irregularity in an intuitive and well-motivated manner. We also introduce a technique that allows one to fit spiral structures in late-type galaxies through the use of coordinate rotation. By comparing with more realistic models now possible, we find that the traditional use of simple ellipsoid models is robust even on irregular and spiral galaxies, because single component fits are by nature large scale averages. However, when it comes to quantifying sub-components of a galaxy, sometimes it is necessary to model structures in detail, such as when performing bulge-to-disk decomposition of galaxies with strong spiral arms, or quantifying the symmetry due to bright (e.g. bulge) and faint (e.g. disk) galaxy sub-components separately. These new techniques are implemented in GALFIT 3.0 (http://www.ociw.edu/ peng/work/galfit/galfit.html ). CYP gratefully acknowledges support from the Plaskett Fellowship (NRC-HIA) and the Institute/Giacconi Fellowship (STScI) programs.

  3. The role of galaxy formation in the structure and dynamics of dark matter halos

    NASA Astrophysics Data System (ADS)

    Tonini, Chiara

    2009-02-01

    The structure and dynamics of dark matter halos, as predicted by the hierarchical clustering scenario, are at odds with the properties inferred from the observations at galactic scales. My Thesis addresses this problem by taking an evolutionary approach. I analysed in detail the many and different observational evidences of a discrepancy the predicted halo equilibrium state and the one inferred from the measurable properties of disk galaxies, as well as of the scaling relations existing between the angular momentum, geometry and mass distribution of the luminous and dark components, and realized that they all seem to point towards the same conclusion: the baryons hosted inside the halo, by collapsing and assembling to form the galaxy, perturb the halo equilibrium structure and made it evolve into new configurations. From the theoretical point of view, the behaviour of dark matter halos as collisionless systems of particles makes their equilibrium structure and mass distribution extremely sensitive to perturbations of their inner dynamics. The galaxy formation occurring inside the halos is a tremendous event, and the dynamical coupling between the baryons and the dark matter during the protogalaxy collapse represents a perturbation of the halo dynamical structure large enough to trigger a halo evolution, according to the relative mass and angular momentum of the two components. My conclusion is that the structure and dynamics of dark matter halos, as well as the origin of the connection between the halo and galaxy properties, are to be understood in in terms of a joint evolution of the baryonic and dark components, originating at the epoch of the collapse and formation of the galaxy.

  4. Bulge-disc decompositions and structural bimodality of Ursa Major cluster spiral galaxies

    NASA Astrophysics Data System (ADS)

    McDonald, Michael; Courteau, Stéphane; Tully, R. Brent

    2009-02-01

    We present bulge and disc (B/D) decompositions of existing K' surface brightness profiles for 65 Ursa Major (UMa) cluster spiral galaxies. This improves upon the disc-only fits of Tully et al. The 1996 disc fits were used by Tully & Verheijen for their discovery of the bimodality of structural parameters in the UMa cluster galaxies. It is shown that our new one-dimensional B/D decompositions yield disc structural parameters that differ only slightly from the basic fits of Tully et al. and evidence for structural bimodality of UMa galaxies is maintained. Our B/D software for the decomposition of one-dimensional surface brightness profiles of galaxies uses a non-linear minimization scheme to recover the best-fitting Sérsic bulge and the exponential disc while accounting for the possible presence of a compact nucleus and spiral arms and for the effects of seeing and disc truncations. In agreement with Tully & Verheijen, we find that the distribution of near-infrared disc central surface brightnesses is bimodal with an F-test confidence of 80 per cent. There is also strong evidence for a local minimum in the luminosity function at . A connection between the brightness bimodality and a dynamical bimodality, based on new HI linewidths, is identified. The B/D parameters are presented in Table 1.

  5. The vertical disk structure of the edge-on spiral galaxy NGC 3079

    NASA Technical Reports Server (NTRS)

    Veilleux, S.; Bland-Hawthorn, Jonathan; Cecil, G.; Tully, R. B.

    1993-01-01

    NGC 3079 is an edge-on SB(s)c galaxy at a redshift of 1225 km/s relative to the Local Group. Earlier researchers found a spectacular 'figure-eight' radio structure aligned along the minor axis of the galaxy, centered on the nucleus, and extending 3 kpc above and below the plane. The geometry of this structure and the evidence of unusually high nuclear gas velocities suggest that a wind-type outflow from the nucleus is taking place. The disk of NGC 3079 is also remarkable: it is extremely rich in H 2 regions and is the only unambiguous example of a galaxy outside M31 and our own Galaxy to exhibit 'Heiles-like' shells. Other researchers have also identified a nebulosity with a ragged X-shaped morphology formed by a system of lumpy filaments with individual lengths of 3 - 5 kpc. They suggest that this material is ambient halo gas entrained into the boundary layers of the nuclear outflow. The complex structure of the line emission in NGC 3079 makes this object an ideal target for an imaging spectroscopic study. The present paper reports the preliminary results of such a study.

  6. Structural Diversity of Self-Assembled Iridescent Arthropod Biophotonic Nanostructures

    NASA Astrophysics Data System (ADS)

    Saranathan, Vinod Kumar; Prum, Richard O.

    2015-03-01

    Many organisms, especially arthropods, produce vivid interference colors using diverse mesoscopic (100-350 nm) integumentary biophotonic nanostructures that are increasingly being investigated for technological applications. Despite a century of interest, we lack precise structural knowledge of many biophotonic nanostructures and mechanisms controlling their development, when such knowledge can open novel biomimetic routes to facilely self-assemble tunable, multi-functional materials. Here, we use synchrotron small angle X-ray scattering and electron microscopy to characterize the photonic nanostructure of 140 iridescent integumentary scales and setae from 127 species of terrestrial arthropods in 85 genera from 5 orders. We report a rich nanostructural diversity, including triply-periodic bicontinuous networks, close-packed spheres, inverse columnar, perforated lamellar, and disordered sponge-like morphologies, commonly observed as stable phases of amphiphilic surfactants, block copolymer, and lyotropic lipid-water systems. Diverse arthropod lineages appear to have independently evolved to utilize the self-assembly of infolding bilayer membranes to develop biophotonic nanostructures that span the phase-space of amphiphilic morphologies, but at optical length scales.

  7. 11. CONTINUATION OF LATERAL LEAVING THE DIVERSION STRUCTURE WEST OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. CONTINUATION OF LATERAL LEAVING THE DIVERSION STRUCTURE WEST OF LOWER DERBY LAKE (SECTION 2), SHOWING MEASURING GAUGE. - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  8. 27. DIVERSION STRUCTURE WITH CONCRETE SIDEWALLS AND CONCRETE CHANNEL BEYOND, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. DIVERSION STRUCTURE WITH CONCRETE SIDEWALLS AND CONCRETE CHANNEL BEYOND, A SHORT DISTANCE WEST OF D STREET ABOUT ONE-QUARTER MILE SOUTH OF 9TH AVENUE (SECTION 26). - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  9. Peach genetic resources: diversity, population structure and linkage disequilibrium

    PubMed Central

    2013-01-01

    Background Peach (Prunus persica (L.) Batsch) is one of the most important model fruits in the Rosaceae family. Native to the west of China, where peach has been domesticated for more than 4,000 years, its cultivation spread from China to Persia, Mediterranean countries and to America. Chinese peach has had a major impact on international peach breeding programs due to its high genetic diversity. In this research, we used 48 highly polymorphic SSRs, distributed over the peach genome, to investigate the difference in genetic diversity, and linkage disequilibrium (LD) among Chinese cultivars, and North American and European cultivars, and the evolution of current peach cultivars. Results In total, 588 alleles were obtained with 48 SSRs on 653 peach accessions, giving an average of 12.25 alleles per locus. In general, the average value of observed heterozygosity (0.47) was lower than the expected heterozygosity (0.60). The separate analysis of groups of accessions according to their origin or reproductive strategies showed greater variability in Oriental cultivars, mainly due to the high level of heterozygosity in Chinese landraces. Genetic distance analysis clustered the cultivars into two main groups: one included four wild related Prunus, and the other included most of the Oriental and Occidental landraces and breeding cultivars. STRUCTURE analysis assigned 469 accessions to three subpopulations: Oriental (234), Occidental (174), and Landraces (61). Nested STRUCTURE analysis divided the Oriental subpopulation into two different subpopulations: ‘Yu Lu’ and ‘Hakuho’. The Occidental breeding subpopulation was also subdivided into nectarine and peach subpopulations. Linkage disequilibrium (LD) analysis in each of these subpopulations showed that the percentage of linked (r2 > 0.1) intra-chromosome comparisons ranged between 14% and 47%. LD decayed faster in Oriental (1,196 Kbp) than in Occidental (2,687 Kbp) samples. In the ‘Yu Lu’ subpopulation there

  10. Large-Scale Structure Formation: From the First Non-linear Objects to Massive Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Planelles, S.; Schleicher, D. R. G.; Bykov, A. M.

    2015-05-01

    The large-scale structure of the Universe formed from initially small perturbations in the cosmic density field, leading to galaxy clusters with up to 1015 M⊙ at the present day. Here, we review the formation of structures in the Universe, considering the first primordial galaxies and the most massive galaxy clusters as extreme cases of structure formation where fundamental processes such as gravity, turbulence, cooling and feedback are particularly relevant. The first non-linear objects in the Universe formed in dark matter halos with 105-108 M⊙ at redshifts 10-30, leading to the first stars and massive black holes. At later stages, larger scales became non-linear, leading to the formation of galaxy clusters, the most massive objects in the Universe. We describe here their formation via gravitational processes, including the self-similar scaling relations, as well as the observed deviations from such self-similarity and the related non-gravitational physics (cooling, stellar feedback, AGN). While on intermediate cluster scales the self-similar model is in good agreement with the observations, deviations from such self-similarity are apparent in the core regions, where numerical simulations do not reproduce the current observational results. The latter indicates that the interaction of different feedback processes may not be correctly accounted for in current simulations. Both in the most massive clusters of galaxies as well as during the formation of the first objects in the Universe, turbulent structures and shock waves appear to be common, suggesting them to be ubiquitous in the non-linear regime.

  11. Population structure and genetic diversity of moose in Alaska.

    PubMed

    Schmidt, Jennifer I; Hundertmark, Kris J; Bowyer, R Terry; McCracken, Kevin G

    2009-01-01

    Moose (Alces alces) are highly mobile mammals that occur across arboreal regions of North America, Europe, and Asia. Alaskan moose (Alces alces gigas) range across much of Alaska and are primary herbivore consumers, exerting a prominent influence on ecosystem structure and functioning. Increased knowledge gained from population genetics provides insights into their population dynamics, history, and dispersal of these unique large herbivores and can aid in conservation efforts. We examined the genetic diversity and population structure of moose (n = 141) with 8 polymorphic microsatellites from 6 regions spanning much of Alaska. Expected heterozygosity was moderate (H(E) = 0.483-0.612), and private alleles ranged from 0 to 6. Both F(ST) and R(ST) indicated significant population structure (P < 0.001) with F(ST) < 0.109 and R(ST) < 0.125. Results of analyses from STRUCTURE indicated 2 prominent population groups, a mix of moose from the Yakutat and Tetlin regions versus all other moose, with slight substructure observed among the second population. Estimates of dispersal differed between analytical approaches, indicating a high level of historical or current gene flow. Mantel tests indicated that isolation-by-distance partially explained observed structure among moose populations (R(2) = 0.45, P < 0.01). Finally, there was no evidence of bottlenecks either at the population level or overall. We conclude that weak population structure occurs among moose in Alaska with population expansion from interior Alaska westward toward the coast. PMID:18836148

  12. Morphology and large-scale structure within the Horologium-Reticulum supercluster of galaxies

    NASA Astrophysics Data System (ADS)

    Fleenor, Matthew Clay

    We have undertaken a comprehensive spectroscopic survey of the Horologium-Reticulum supercluster (HRS) of galaxies. With a concentration on the intercluster regions, our goal is to resolve the "cosmic web" of filaments, voids, and sheets within the HRS and to examine the interrelationship between them. What are the constituents of the HRS? What can be understood about the formation of such a behemoth from these current constituents? More locally, are there small-scale imprints of the larger, surrounding environment, and can we relate the two with any confidence? What is the relationship between the HRS and the other superclusters in the nearby universe? These are the questions driving our inquiry. To answer them, we have obtained over 2500 galaxy redshifts in the direction of the intercluster regions in the HRS. Specifically, we have developed a sample of galaxies with a limiting brightness of bJ < 17.5, which samples the galaxy luminosity function down to one magnitude below M* at the mean redshift of the HRS, z¯ ≈ 0.06. Exclusively, these intercluster redshifts were obtained with the six-degree field (6dF), multi-fiber spectrograph at the Anglo-Australian Observatory. In conjunction with the wide-field, 1.2m UK Schmidt, 6dF is the ideal supercluster observatory. Because it deploys the 150 fiber buttons over a 6-degree field, we are able to obtain coherent information over large areas of the sky, as is the case with a supercluster. In addition, we have obtained a complete sample of mean cluster redshifts and velocity dispersions for Abell clusters in the HRS using the Australian National University/2.3m, primarily. For most of the clusters, more than 10 galaxies were observed, and a reliable mean cluster redshift is determined. Furthermore, we have a near complete sample of bJ < 18.6 galaxies over a 4° x 4° region that encompasses several HRS clusters. With these datasets, we are able to "piece" together various structures over a large range of scales. We

  13. Sufficient observables for large-scale structure in galaxy surveys

    NASA Astrophysics Data System (ADS)

    Carron, J.; Szapudi, I.

    2014-03-01

    Beyond the linear regime, the power spectrum and higher order moments of the matter field no longer capture all cosmological information encoded in density fluctuations. While non-linear transforms have been proposed to extract this information lost to traditional methods, up to now, the way to generalize these techniques to discrete processes was unclear; ad hoc extensions had some success. We pointed out in Carron and Szapudi's paper that the logarithmic transform approximates extremely well the optimal `sufficient statistics', observables that extract all information from the (continuous) matter field. Building on these results, we generalize optimal transforms to discrete galaxy fields. We focus our calculations on the Poisson sampling of an underlying lognormal density field. We solve and test the one-point case in detail, and sketch out the sufficient observables for the multipoint case. Moreover, we present an accurate approximation to the sufficient observables in terms of the mean and spectrum of a non-linearly transformed field. We find that the corresponding optimal non-linear transformation is directly related to the maximum a posteriori Bayesian reconstruction of the underlying continuous field with a lognormal prior as put forward in the paper of Kitaura et al.. Thus, simple recipes for realizing the sufficient observables can be built on previously proposed algorithms that have been successfully implemented and tested in simulations.

  14. Characterizing the Small Scale Structure in Clusters of Galaxies

    NASA Technical Reports Server (NTRS)

    Forman, William R.

    2001-01-01

    We studied galaxy clusters Abell 119, Abell 754, and Abell 1750, using data from the ASCA and ROSAT satellites. In addition, we completed the paper "Merging Binary Clusters". In this paper we study three prominent bi-modal X-ray clusters: A3528, A1750 and A3395. Since the sub-clusters in these systems have projected separations of 0.93, 1.00 and 0.67 Mpc respectively, we examine their X-ray and optical observations to investigate the dynamics and possible merging of these sub-clusters. Using data taken with ROSAT and ASCA, we analyze the temperature and surface brightness distributions. We also analyze the velocity distributions of the three clusters using new measurements supplemented with previously published data. We examined both the overall cluster properties as well as the two sub-cluster elements in each. These results were then applied to the determination of the overall cluster masses, that demonstrate excellent consistency between the various methods used. While the characteristic parameters of the sub-clusters are typical of isolated objects, our temperature results for the regions between the two sub-clusters clearly confirm the presence of merger activity that is suggested by the surface brightness distributions. These three clusters represent a progression of equal-sized sub-cluster mergers, starting from initial contact to immediately before first core passage.

  15. Structural basis of diverse membrane target recognitions by ankyrins

    PubMed Central

    Wang, Chao; Wei, Zhiyi; Chen, Keyu; Ye, Fei; Yu, Cong; Bennett, Vann; Zhang, Mingjie

    2014-01-01

    Ankyrin adaptors together with their spectrin partners coordinate diverse ion channels and cell adhesion molecules within plasma membrane domains and thereby promote physiological activities including fast signaling in the heart and nervous system. Ankyrins specifically bind to numerous membrane targets through their 24 ankyrin repeats (ANK repeats), although the mechanism for the facile and independent evolution of these interactions has not been resolved. Here we report the structures of ANK repeats in complex with an inhibitory segment from the C-terminal regulatory domain and with a sodium channel Nav1.2 peptide, respectively, showing that the extended, extremely conserved inner groove spanning the entire ANK repeat solenoid contains multiple target binding sites capable of accommodating target proteins with very diverse sequences via combinatorial usage of these sites. These structures establish a framework for understanding the evolution of ankyrins' membrane targets, with implications for other proteins containing extended ANK repeat domains. DOI: http://dx.doi.org/10.7554/eLife.04353.001 PMID:25383926

  16. Evolution of Diversity in Spatially Structured Escherichia coli Populations▿

    PubMed Central

    Ponciano, José Miguel; La, Hyun-Joon; Joyce, Paul; Forney, Larry J.

    2009-01-01

    The stochastic Ricker population model was used to investigate the generation and maintenance of genetic diversity in a bacterial population grown in a spatially structured environment. In particular, we showed that Escherichia coli undergoes dramatic genetic diversification when grown as a biofilm. Using a novel biofilm entrapment method, we retrieved 64 clones from each of six different depths of a mature biofilm, and after subculturing for ∼30 generations, we measured their growth kinetics in three different media. We fit a stochastic Ricker population growth model to the recorded growth curves. The growth kinetics of clonal lineages descendant from cells sampled at different biofilm depths varied as a function of both the depth in the biofilm and the growth medium used. We concluded that differences in the growth dynamics of clones were heritable and arose during adaptive evolution under local conditions in a spatially heterogeneous environment. We postulate that under nutrient-limited conditions, selective sweeps would be protracted and would be insufficient to purge less-fit variants, a phenomenon that would allow the coexistence of genetically distinct clones. These findings contribute to the current understanding of biofilm ecology and complement current hypotheses for the maintenance and generation of microbial diversity in spatially structured environments. PMID:19648364

  17. Structure, Function and Diversity of the Healthy Human Microbiome

    PubMed Central

    2012-01-01

    Studies of the human microbiome have revealed that even healthy individuals differ remarkably in the microbes that occupy habitats such as the gut, skin, and vagina. Much of this diversity remains unexplained, although diet, environment, host genetics, and early microbial exposure have all been implicated. Accordingly, to characterize the ecology of human-associated microbial communities, the Human Microbiome Project has analyzed the largest cohort and set of distinct, clinically relevant body habitats to date. We found the diversity and abundance of each habitat’s signature microbes to vary widely even among healthy subjects, with strong niche specialization both within and among individuals. The project encountered an estimated 81–99% of the genera, enzyme families, and community configurations occupied by the healthy Western microbiome. Metagenomic carriage of metabolic pathways was stable among individuals despite variation in community structure, and ethnic/racial background proved to be one of the strongest associations of both pathways and microbes with clinical metadata. These results thus delineate the range of structural and functional configurations normal in the microbial communities of a healthy population, enabling future characterization of the epidemiology, ecology, and translational applications of the human microbiome. PMID:22699609

  18. Using asteroseismology to probe the structure and evolution of the Galaxy

    NASA Astrophysics Data System (ADS)

    Stello, Dennis

    2015-08-01

    Recent space missions have transformed our ability to use asteroseismology on vast numbers of stars. This advance has opened up for exploration of the structure and evolution of the Galaxy using oscillating red giant stars as distant tracers of stellar populations including the halo, the bulge and the thin and thick disks. Asteroseismology provides a powerful way to obtain precise estimates of stellar bulk properties such as radius, mass, and age. The radius, and hence distance, places a star accurately in the Galaxy, the mass reveals the mass function and, in combination with composition, provide ages for red giants. Initial results from the CoRoT and Kepler missions have demonstrated the enormous potential there is in the marriage between asteroseismology and contemporary Galactic Archaeology based on single-epoch spectroscopy, photometry, and parallax measurements. The scope for this research received a significant boost last year on several fronts. The re-purposed Kepler telescope, K2, started observing tens of thousands of red giants along the ecliptic covering all main constituents of the Galaxy, and in a few years time NASA's TESS mission will stars observing up to 1 mio red giants full sky. Finally, ESA's decision to fund PLATO guaranties that high quality seismic measurements will continue to flow beyond the nextdecade. In this talk I will give an overview of how seismology can aid the study of the structure and evolution of the Galaxy. I will include the most recent results that we have obtained with our K2 Galactic Archaeology Program.

  19. The Monte Carlo Milky Way: reverse engineering the dense gas structure of the Galaxy with ATLASGAL

    NASA Astrophysics Data System (ADS)

    Figura, Charles C.; Urquhart, James S.

    2016-01-01

    The APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) is the most senstive sub-millimetre survey of the inner Galaxy, covering 420 square degrees of the Galactic plane at a wavelength of 870 um. As with nearly any survey, however, ATLASGAL presents an incomplete view of the Milky Way, as it is biased by observational limitations which can distort our view of both the structure and distribution of the dense molecular gas.In order to better understand the structure of matter in the Galaxy, we have used Monte Carlo methods to simulate the distribution of dense gas from a grid of input models. By taking account of the observational limitations of the survey, we are able to compare the output from these models with the results obtained from the observations and determine the most likely distribution of dense gas. We investigate a number of spiral arm models, and discuss the results in the context of their role in massive star formation in the Galaxy.

  20. Structural adaptations to diverse fighting styles in sexually selected weapons

    PubMed Central

    McCullough, Erin L.; Tobalske, Bret W.; Emlen, Douglas J.

    2014-01-01

    The shapes of sexually selected weapons differ widely among species, but the drivers of this diversity remain poorly understood. Existing explanations suggest weapon shapes reflect structural adaptations to different fighting styles, yet explicit tests of this hypothesis are lacking. We constructed finite element models of the horns of different rhinoceros beetle species to test whether functional specializations for increased performance under species-specific fighting styles could have contributed to the diversification of weapon form. We find that horns are both stronger and stiffer in response to species-typical fighting loads and that they perform more poorly under atypical fighting loads, which suggests weapons are structurally adapted to meet the functional demands of fighting. Our research establishes a critical link between weapon form and function, revealing one way male–male competition can drive the diversification of animal weapons. PMID:25201949

  1. MAJOR STRUCTURES OF THE INNER GALAXY DELINEATED BY 6.7 GHz METHANOL MASERS

    SciTech Connect

    Green, J. A.; Caswell, J. L.; McClure-Griffiths, N. M.; Breen, S. L.; Voronkov, M. A.; Avison, A.; Fuller, G. A.; Gray, M. D.; Burton, M. G.; Ellingsen, S. P.; Pestalozzi, M.

    2011-05-20

    We explore the longitude-velocity distribution of 6.7 GHz methanol masers in the context of the inner structure of our Galaxy. We analyze the correlation in velocities within this distribution and identify density enhancements indicating large-scale regions of enhanced star formation. These are interpreted as the starting points of the spiral arms and the interaction of the Galactic bar with the 3 kpc arms. The methanol masers support the presence of a long thin bar with a 45{sup 0} orientation. Signatures of the full 3 kpc arm structure are seen, including a prominent tangent at approximately -22{sup 0} Galactic longitude. We compare this distribution with existing models of the gas dynamics of our Galaxy. The 3 kpc arm structure appears likely to correspond to the radius of corotation resonance of the bar, with the bar on its inner surface and the starting points of the spiral arms on its outer surface.

  2. Galaxy masses

    NASA Astrophysics Data System (ADS)

    Courteau, Stéphane; Cappellari, Michele; de Jong, Roelof S.; Dutton, Aaron A.; Emsellem, Eric; Hoekstra, Henk; Koopmans, L. V. E.; Mamon, Gary A.; Maraston, Claudia; Treu, Tommaso; Widrow, Lawrence M.

    2014-01-01

    Galaxy masses play a fundamental role in our understanding of structure formation models. This review addresses the variety and reliability of mass estimators that pertain to stars, gas, and dark matter. The different sections on masses from stellar populations, dynamical masses of gas-rich and gas-poor galaxies, with some attention paid to our Milky Way, and masses from weak and strong lensing methods all provide review material on galaxy masses in a self-consistent manner.

  3. Kinematical evidence for secular evolution in Spitzer Survey of Stellar Structure in Galaxies (S4G) spirals

    NASA Astrophysics Data System (ADS)

    Erroz-Ferrer, Santiago; Knapen, Johan H.; Font, Joan; Beckman, John E.

    2015-03-01

    We present a study of the kinematics of a sample of isolated spiral galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S4G). We use Hα Fabry-Perot data from the GHαFaS instrument at the William Herschel Telescope (WHT) in La Palma, complemented with images at 3.6 microns, in the R band and in the Hα filter. The resulting data cubes and velocity field maps allow a complete study of the kinematics of a galaxy, including in-depth investigations of the rotation curve, velocity moment maps, velocity residual maps, gradient maps and position-velocity (PV) diagrams. We find clear evidence of the secular evolution processes going on in these galaxies, such as asymmetries in the velocity field in the bar zone, and non-circular motions, probably in response to the potential of the structural components of the galaxies, or to past or present interactions.

  4. Morphological parameters of a Spitzer survey of stellar structure in galaxies

    SciTech Connect

    Holwerda, B. W.; Muñoz-Mateos, J.-C.; Sheth, K.; Kim, T.; Meidt, S.; Mizusawa, T.; Hinz, J. L.; Zaritsky, D.; Regan, M. W.; Gil de Paz, A.; Menéndez-Delmestre, K.; Seibert, M.; Ho, L. C.; Gadotti, D. A.; Erroz-Ferrer, S. E-mail: benne.holwerda@gmail.com [Instituto de Astrofísica de Canarias, Vía Láctea s and others

    2014-01-20

    The morphology of galaxies can be quantified to some degree using a set of scale-invariant parameters. Concentration (C), asymmetry (A), smoothness (S), the Gini index (G), the relative contribution of the brightest pixels to the second-order moment of the flux (M {sub 20}), ellipticity (E), and the Gini index of the second-order moment (G{sub M} ) have all been applied to morphologically classify galaxies at various wavelengths. Here, we present a catalog of these parameters for the Spitzer Survey of stellar structure in Galaxies, a volume-limited, near-infrared (NIR) imaging survey of nearby galaxies using the 3.6 and 4.5 μm channels of the Infrared Array Camera on board the Spitzer Space Telescope. Our goal is to provide a reference catalog of NIR quantified morphology for high-redshift studies and galaxy evolution models with enough detail to resolve stellar mass morphology. We explore where normal, non-interacting galaxies—those typically found on the Hubble tuning fork—lie in this parameter space and show that there is a tight relation between concentration (C {sub 82}) and M {sub 20} for normal galaxies. M {sub 20} can be used to classify galaxies into earlier and later types (i.e., to separate spirals from irregulars). Several criteria using these parameters exist to select systems with a disturbed morphology, i.e., those that appear to be undergoing a tidal interaction. We examine the applicability of these criteria to Spitzer NIR imaging. We find that four relations, based on the parameters A and S, G and M {sub 20}, G{sub M} , C, and M {sub 20}, respectively, select outliers in morphological parameter space, but each selects different subsets of galaxies. Two criteria (G{sub M} > 0.6, G > –0.115 × M {sub 20} + 0.384) seem most appropriate to identify possible mergers and the merger fraction in NIR surveys. We find no strong relation between lopsidedness and most of these morphological parameters, except for a weak dependence of lopsidedness on

  5. The Effect of Large-Scale Structure on the Formation of Disk Galaxies : Specific Angular Momentum Point of View

    NASA Astrophysics Data System (ADS)

    Kim, Ji Hoon

    2015-01-01

    We investigate the correlation between the environment parameters and central surface brightness of disk galaxies in order to study the effect of the large-scale structure on the formation of disk galaxies. In the standard galaxy formation picture, galaxy discs form out of primordial gas due to density fluctuation while conserving its specific angular momentum. The specific angular momentum of the pre-collapse gas is generally assumed to be equal to that of the dark matter, which is acquired by the tidal interactions with the surrounding matter distribution at its proto-halo stage. The difference of specific angular momentum of host dark matter halos is the favored origin for the difference between low surface brightness galaxies (LSBGs) and high surface brightness galaxies (HSBGs) which results in the different evolutionary paths. We utilize broadband photometry data from Simard et al. (2011) to extract the environment parameters and properties of individual galaxies. We calculate central surface brightness (μ0) for 1,123,718 galaxies based on absolute magnitude of model disk and exponential disk scale lengths in g'- and r'- bands. We convert g'- and r'-band central surface brightnesses into B-band central surface brightness (μ0,B) using conversion from Smith et al. (2002). We classify disk galaxies with μ0,B ≥ 22.5 mag arcsec-2 as LSBGs while ones with μ0,B < 22.7 mag arcsec-2 as HSBGs.Then we compute a surface galaxy number density estimated from the fifth nearest neighbour galaxies (Σ5). We are presenting a preliminary result based on our sample selection process and discussing the future prospect for the studies of disk galaxy formation with current and future facilities.

  6. Diverse Galaxies: Clumpy Regions In The UVUDF at 0.5 ≤ z ≤ 1.5

    NASA Astrophysics Data System (ADS)

    Soto, Emmaris; de Mello, Duilia F.; Teplitz, Harry I.; Gardner, Jonathan P.; Bond, Nicholas A.; Rafelski, Marc; Ravindranath, Swara; Scarlata, Claudia; Codoreanu, Alex; Koekemoer, Anton M.; Kurczynski, Peter; Uvudf Team

    2015-01-01

    We present an investigation of clumpy galaxies using the deepest ultraviolet data in the Hubble Ultra Deep Field (HUDF) taken with Wide Field Camera 3 UVIS detector. We use 3 new post-flashed UV images taken with the F225W, F275W, and F336W filters. Here we present an analysis of all galaxies in the 0.5 to 1.5 redshift range. These galaxies show a variety of properties, with objects having just a single clump to galaxies littered with clumps. We perform an optical morphological study of ultraviolet-detected galaxies using a visual classification scheme similar to that employed by the Hubble CANDELS survey team. We find that the majority of the objects that are clumpy in the ultraviolet have optical morphologies that are disks, followed by irregulars. We measure galaxy luminosities in the rest-frame UV, clump sizes, and luminosities for each clump in 7 passbands from the UV to the optical. We find that the majority of these UV bright clumpy galaxies are classified as Scd and starburst spectral types and have clump sizes between 0.7 to 1.9 kpc. We quantify the contribution of the clumps to the global star formation rate of the galaxy.

  7. The evolution of galaxies at constant number density: a less biased view of star formation, quenching, and structural formation

    NASA Astrophysics Data System (ADS)

    Ownsworth, Jamie R.; Conselice, Christopher J.; Mundy, Carl J.; Mortlock, Alice; Hartley, William G.; Duncan, Kenneth; Almaini, Omar

    2016-09-01

    Due to significant galaxy contamination and impurity in stellar mass selected samples (up to 95 per cent from z = 0-3), we examine the star formation history, quenching time-scales, and structural evolution of galaxies using a constant number density selection with data from the United Kingdom Infra-Red Deep Sky Survey Ultra-Deep Survey field. Using this methodology, we investigate the evolution of galaxies at a variety of number densities from z = 0-3. We find that samples chosen at number densities ranging from 3 × 10-4 to 10-5 galaxies Mpc-3 (corresponding to z ˜ 0.5 stellar masses of M* = 1010.95-11.6 M0) have a star-forming blue fraction of ˜50 per cent at z ˜ 2.5, which evolves to a nearly 100 per cent quenched red and dead population by z ˜ 1. We also see evidence for number density downsizing, such that the galaxies selected at the lowest densities (highest masses) become a homogeneous red population before those at higher number densities. Examining the evolution of the colours for these systems furthermore shows that the formation redshift of galaxies selected at these number densities is zform > 3. The structural evolution through size and Sérsic index fits reveal that while there remains evolution in terms of galaxies becoming larger and more concentrated in stellar mass at lower redshifts, the magnitude of the change is significantly smaller than for a mass-selected sample. We also find that changes in size and structure continues at z < 1, and is coupled strongly to passivity evolution. We conclude that galaxy structure is driving the quenching of galaxies, such that galaxies become concentrated before they become passive.

  8. The origin of CDR H3 structural diversity

    PubMed Central

    Weitzner, Brian D.; Dunbrack, Roland L.; Gray, Jeffrey J.

    2014-01-01

    Antibody CDR H3 loops are critical for adaptive immunological functions. Although the other five CDR loops adopt predictable canonical structures, H3 conformations have proven unclassifiable, other than an unusual C-terminal “kink” present in most antibodies. To determine why the majority of H3 loops are kinked and to learn whether non-antibody proteins have loop structures similar to H3, we searched a set of 15,679 high-quality non-antibody structures for regions geometrically similar to the residues immediately surrounding the loop. By incorporating the kink into our search, we identified 1,030 H3-like loops from 632 protein families. Some protein families, including PDZ domains, appear to use the identified region for recognition and binding. Our results suggest the kink is conserved in the immunoglobulin heavy chain fold because it disrupts the β-strand pairing at the base of the loop. Thus, the kink is a critical driver of the observed structural diversity in CDR H3. PMID:25579815

  9. DETERMINING THE NATURE OF THE EXTENDED H I STRUCTURE AROUND LITTLE THINGS DWARF GALAXY NGC 1569

    SciTech Connect

    Johnson, Megan

    2013-06-15

    This work presents an extended, neutral hydrogen emission map around Magellanic-type dwarf irregular galaxy (dIm) NGC 1569. In the spring of 2010, the Robert C. Byrd Green Bank Telescope was used to map a 9 Degree-Sign Multiplication-Sign 2 Degree-Sign region in H I line emission that includes NGC 1569 and IC 342 as well as two other dwarf galaxies. The primary objective for these observations was to search for structures potentially connecting NGC 1569 with IC 342 group members in order to trace previous interactions and thus, provide an explanation for the starburst and peculiar kinematics prevalent in NGC 1569. A large, half-degree diameter H I cloud was detected that shares the same position and velocity as NGC 1569. Also, two long structures were discovered that are reminiscent of intergalactic filaments extending out in a V-shaped manner from NGC 1569 toward UGCA 92, a nearby dwarf galaxy. These filamentary structures extend for about 1. Degree-Sign 5, which is 77 kpc at NGC 1569. There is a continuous velocity succession with the 0. Degree-Sign 5 H I cloud, filaments, and main body of the galaxy. The 0. Degree-Sign 5 H I cloud and filamentary structures may be foreground Milky Way, but are suggestive as possible remnants of an interaction between NGC 1569 and UGCA 92. The data also show two tidal tails extending from UGCA 86 and IC 342, respectively. These structures may be part of a continuous H I bridge but more data are needed to determine if this is the case.

  10. Polarimetric consequences of large-scale structure in the distribution of galaxies and quasars

    NASA Astrophysics Data System (ADS)

    Silant'ev, N. A.; Gnedin, Y. N.; Piotrovich, M. Yu.; Natsvlishvili, T. M.; Buliga, S. D.

    2010-12-01

    The problem of inhomogeneities in the distribution of galaxies and quasars over cosmological distances (cell structure) has been discussed in many papers. Here, in particular, we wish to draw attention to the polarimetric consequences of this structure. We discuss in detail the possibility of a large-scale rotation of the mean position angle of the observed polarization over the scale of the cellular structure. We mainly consider rotation mechanisms associated with polarized radiation from magnetized accretion disks near quasars and black holes. In that case the possible correlation of magnetic fields on cosmological scales will show up as a rotation of the mean position angle ranging from 0 to 45 degrees. Correlations in nonspherical formations of galaxies and quasars over cosmological distances also lead to rotation in the mean position angle over these distances. In principle, these two rotation mechanisms can, together, produce an arbitrary rotation of the mean position angle over distances corresponding to the inhomogeneous structure in the distribution of galaxies and quasars.

  11. Phylogeography, genetic structure, and diversity in the dhole (Cuon alpinus).

    PubMed

    Iyengar, A; Babu, V N; Hedges, S; Venkataraman, A B; Maclean, N; Morin, P A

    2005-07-01

    The Asiatic wild dog or dhole was once very widely distributed across Asia but now has a very fragmented range. In this first genetic study of this little-known species, we obtained information on genetic diversity, phylogeography, and social structure using both mitochondrial control region sequencing and microsatellite genotyping of noninvasive faecal samples from wild populations, as well as from museum and captive samples. A pattern largely consistent with isolation by distance across the Asian mainland was observed, with no clear subspecies distinctions. However, two major phylogeographical groupings were found across the mainland, one extending from South, Central, and North India (south of the Ganges) into Myanmar, and the other extending from India north of the Ganges into northeastern India, Myanmar, Thailand and the Malaysian Peninsula. We propose a scenario involving glaciation events that could explain this pattern. The origin of the dhole populations in Sumatra and Java is enigmatic and requires further study. Very low levels of genetic diversity were observed among wild dholes from Baluran National Park in Java, Indonesia, but in contrast, high levels were observed in Mudumalai Wildlife Sanctuary in South India. PMID:15969714

  12. Black Holes and the Central Structure of Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Lauer, Tod R.

    Central massive black holes appear to have a strong role in determining the central structure of elliptical galaxies. The existence of cores in the more luminous ellipticals may be understood as the merger endpoint of two less-luminous galaxies, each harboring a massive black hole. As the two black holes spiral together at the center of the merger product, stars would be ejected from this region, creating a break in the stellar density profile and the shallow cusp in surface brightness characteristic of a core. Further, the resulting binary or merged black hole would preserve the core over subsequent mergers or cannibalism events by disrupting any incoming dense stellar system that would otherwise fill in the core. The effects of black holes are also strongly favored to explain central ``double-nuclei,'' such as that seen in M31, and a recently discovered class of ``hollow galaxies,'' which have local minima in their central stellar density profiles. In short, any discussion of the origin of galaxy morphology must include the ubiquitous presence of massive black holes.

  13. The structure and dynamics of the AC114 galaxy cluster revisited

    NASA Astrophysics Data System (ADS)

    Proust, Dominique; Yegorova, Irina; Saviane, Ivo; Ivanov, Valentin D.; Bresolin, Fabio; Salzer, John J.; Capelato, Hugo V.

    2015-10-01

    We present a dynamical analysis of the galaxy cluster AC114 based on a catalogue of 524 velocities. Of these, 169 (32 per cent) are newly obtained at European Southern Observatory (Chile) with the Very Large Telescope and the VIsible MultiObject spectrograph. Data on individual galaxies are presented and the accuracy of the measured velocities is discussed. Dynamical properties of the cluster are derived. We obtain an improved mean redshift value z = 0.31665 ± 0.0008 and velocity dispersion σ = 1893^{+73}_{-82} km s^{-1}. A large velocity dispersion within the core radius and the shape of the infall pattern suggests that this part of the cluster is in a radial phase of relaxation with a very elongated radial filament spanning 12 000 km s-1. A radial foreground structure is detected within the central 0.5 h-1 Mpc radius, recognizable as a redshift group at the same central redshift value. We analyse the colour distribution for this archetype Butcher-Oemler galaxy cluster and identify the separate red and blue galaxy sequences. The latter subset contains 44 per cent of confirmed members of the cluster, reaching magnitudes as faint as Rf= 21.1 (1.0 mag fainter than previous studies). We derive a mass M200 = (4.3 ± 0.7) × 1015 M⊙ h-1. In a subsequent paper, we will utilize the spectral data presented here to explore the mass-metallicity relation for this intermediate redshift cluster.

  14. Extragalactic archeology with the GHOSTS Survey. I. Age-resolved disk structure of nearby low-mass galaxies

    NASA Astrophysics Data System (ADS)

    Streich, David; de Jong, Roelof S.; Bailin, Jeremy; Bell, Eric F.; Holwerda, Benne W.; Minchev, Ivan; Monachesi, Antonela; Radburn-Smith, David J.

    2016-01-01

    Aims: We study the individual evolution histories of three nearby low-mass edge-on galaxies (IC 5052, NGC 4244, and NGC 5023). Methods: Using resolved stellar populations, we constructed star count density maps for populations of different ages and analyzed the change of structural parameters with stellar age within each galaxy. Results: We do not detect a separate thick disk in any of the three galaxies, even though our observations cover a wider range in equivalent surface brightness than any integrated light study. While scale heights increase with age, each population can be well described by a single disk. Two of the galaxies contain a very weak additional component, which we identify as the faint halo. The mass of these faint halos is lower than 1% of the mass of the disk. The three galaxies show low vertical heating rates, which are much lower than the heating rate of the Milky Way. This indicates that heating agents, such as giant molecular clouds and spiral structure, are weak in low-mass galaxies. All populations in the three galaxies exhibit no or only little flaring. While this finding is consistent with previous integrated light studies, it poses strong constraints on galaxy simulations, where strong flaring is often found as a result of interactions or radial migration.

  15. Genetic Diversity and Population Structure of Theileria annulata in Oman

    PubMed Central

    Al-Hamidhi, Salama; H. Tageldin, Mohammed.; Weir, William; Al-Fahdi, Amira; Johnson, Eugene H.; Bobade, Patrick; Alqamashoui, Badar; Beja-Pereira, Albano; Thompson, Joanne; Kinnaird, Jane; Shiels, Brian; Tait, Andy; Babiker, Hamza

    2015-01-01

    Background Theileriosis, caused by a number of species within the genus Theileria, is a common disease of livestock in Oman. It is a major constraint to the development of the livestock industry due to a high rate of morbidity and mortality in both cattle and sheep. Since little is currently known about the genetic diversity of the parasites causing theileriosis in Oman, the present study was designed to address this issue with specific regard to T. annulata in cattle. Methods Blood samples were collected from cattle from four geographically distinct regions in Oman for genetic analysis of the Theileria annulata population. Ten genetic markers (micro- and mini-satellites) representing all four chromosomes of T. annulata were applied to these samples using a combination of PCR amplification and fragment analysis. The resultant genetic data was analysed to provide a first insight into the structure of the T. annulata population in Oman. Results We applied ten micro- and mini-satellite markers to a total of 310 samples obtained from different regions (174 [56%] from Dhofar, 68 [22%] from Dhira, 44 [14.5%] from Batinah and 24 [8%] from Sharqia). A high degree of allelic diversity was observed among the four parasite populations. Expected heterozygosity for each site ranged from 0.816 to 0.854. A high multiplicity of infection was observed in individual hosts, with an average of 3.3 to 3.4 alleles per locus, in samples derived from Batinah, Dhofar and Sharqia regions. In samples from Dhira region, an average of 2.9 alleles per locus was observed. Mild but statistically significant linkage disequilibrium between pairs of markers was observed in populations from three of the four regions. In contrast, when the analysis was performed at farm level, no significant linkage disequilibrium was observed. Finally, no significant genetic differentiation was seen between the four populations, with most pair-wise FST values being less than 0.03. Slightly higher FST values (GST

  16. THICK DISKS OF EDGE-ON GALAXIES SEEN THROUGH THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G): LAIR OF MISSING BARYONS?

    SciTech Connect

    Comeron, Sebastien; Elmegreen, Bruce G.; Knapen, Johan H.; Salo, Heikki; Laine, Jarkko; Laurikainen, Eija; Athanassoula, E.; Bosma, Albert; Hinz, Joannah L.; De Paz, Armando Gil; Menendez-Delmestre, KarIn; Seibert, Mark; Ho, Luis C.; Elmegreen, Debra M.; Gadotti, Dimitri A.

    2011-11-01

    Most, if not all, disk galaxies have a thin (classical) disk and a thick disk. In most models thick disks are thought to be a necessary consequence of the disk formation and/or evolution of the galaxy. We present the results of a study of the thick disk properties in a sample of carefully selected edge-on galaxies with types ranging from T = 3 to T = 8. We fitted one-dimensional luminosity profiles with physically motivated functions-the solutions of two stellar and one gaseous isothermal coupled disks in equilibrium-which are likely to yield more accurate results than other functions used in previous studies. The images used for the fits come from the Spitzer Survey of Stellar Structure in Galaxies (S{sup 4}G). We found that thick disks are on average more massive than previously reported, mostly due to the selected fitting function. Typically, the thin and thick disks have similar masses. We also found that thick disks do not flare significantly within the observed range in galactocentric radii and that the ratio of thick-to-thin disk scale heights is higher for galaxies of earlier types. Our results tend to favor an in situ origin for most of the stars in the thick disk. In addition, the thick disk may contain a significant amount of stars coming from satellites accreted after the initial buildup of the galaxy and an extra fraction of stars coming from the secular heating of the thin disk by its own overdensities. Assigning thick disk light to the thin disk component may lead to an underestimate of the overall stellar mass in galaxies because of different mass-to-light ratios in the two disk components. On the basis of our new results, we estimate that disk stellar masses are between 10% and 50% higher than previously thought and we suggest that thick disks are a reservoir of 'local missing baryons'.

  17. BREAKS IN THIN AND THICK DISKS OF EDGE-ON GALAXIES IMAGED IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G)

    SciTech Connect

    Comeron, Sebastien; Salo, Heikki; Laurikainen, Eija; Laine, Jarkko; Elmegreen, Bruce G.; Athanassoula, E.; Bosma, Albert; Knapen, Johan H.; Gadotti, Dimitri A.; Sheth, Kartik; Munoz-Mateos, Juan Carlos; Kim, Taehyun; Hinz, Joannah L.; Regan, Michael W.; Gil de Paz, Armando; Menendez-Delmestre, Karin; Seibert, Mark; Ho, Luis C.; Mizusawa, Trisha; Holwerda, Benne

    2012-11-10

    Breaks in the radial luminosity profiles of galaxies have until now been mostly studied averaged over disks. Here, we study separately breaks in thin and thick disks in 70 edge-on galaxies using imaging from the Spitzer Survey of Stellar Structure in Galaxies. We built luminosity profiles of the thin and thick disks parallel to midplanes and we found that thin disks often truncate (77%). Thick disks truncate less often (31%), but when they do, their break radius is comparable with that in the thin disk. This suggests either two different truncation mechanisms-one of dynamical origin affecting both disks simultaneously and another one only affecting the thin disk-or a single mechanism that creates a truncation in one disk or in both depending on some galaxy property. Thin disks apparently antitruncate in around 40% of galaxies. However, in many cases, these antitruncations are an artifact caused by the superposition of a thin disk and a thick disk, with the latter having a longer scale length. We estimate the real thin disk antitruncation fraction to be less than 15%. We found that the ratio of the thick and thin stellar disk mass is roughly constant (0.2 < M{sub T} /M{sub t} < 0.7) for circular velocities v{sub c} > 120 km s{sup -1}, but becomes much larger at smaller velocities. We hypothesize that this is due to a combination of a high efficiency of supernova feedback and a slower dynamical evolution in lower-mass galaxies causing stellar thin disks to be younger and less massive than in higher-mass galaxies.

  18. Molecular clouds and the large-scale structure of the galaxy

    NASA Technical Reports Server (NTRS)

    Thaddeus, Patrick; Stacy, J. Gregory

    1990-01-01

    The application of molecular radio astronomy to the study of the large-scale structure of the Galaxy is reviewed and the distribution and characteristic properties of the Galactic population of Giant Molecular Clouds (GMCs), derived primarily from analysis of the Columbia CO survey, and their relation to tracers of Population 1 and major spiral features are described. The properties of the local molecular interstellar gas are summarized. The CO observing programs currently underway with the Center for Astrophysics 1.2 m radio telescope are described, with an emphasis on projects relevant to future comparison with high-energy gamma-ray observations. Several areas are discussed in which high-energy gamma-ray observations by the EGRET (Energetic Gamma-Ray Experiment Telescope) experiment aboard the Gamma Ray Observatory will directly complement radio studies of the Milky Way, with the prospect of significant progress on fundamental issues related to the structure and content of the Galaxy.

  19. The parsec-scale structure and evolution of the nearby Fanaroff-Riley type II radio galaxy Pictor A

    NASA Technical Reports Server (NTRS)

    Tingay, S. J.; Jauncey, D. L.; Reynolds, J. E.; Tzioumis, A. K.; McCulloch, P. M.; Ellingsen, S. P.; Costa, M. E.; Lovell, J. E. J.; Preston, R. A.; Simkin, S. M.

    2000-01-01

    We present very long baseline interferometry (VLBI) images of the core emission from a nearby bright FR II radio galaxy, Pictor A, revealing its parsec-scale jet structure and evolution for the first time.

  20. Sponge derived bromotyrosines: structural diversity through natural combinatorial chemistry.

    PubMed

    Niemann, Hendrik; Marmann, Andreas; Lin, Wenhan; Proksch, Peter

    2015-01-01

    Sponge derived bromotyrosines are a multifaceted class of marine bioactive compounds that are important for the chemical defense of sponges but also for drug discovery programs as well as for technical applications in the field of antifouling constituents. These compounds, which are mainly accumulated by Verongid sponges, exhibit a diverse range of bioactivities including antibiotic, cytotoxic and antifouling effects. In spite of the simple biogenetic building blocks, which consist only of brominated tyrosine and tyramine units, an impressive diversity of different compounds is obtained through different linkages between these precursors and through structural modifications of the side chains and/or aromatic rings resembling strategies that are known from combinatorial chemistry. As examples for bioactive, structurally divergent bromotyrosines psammaplin A, Aplysina alkaloids featuring aerothionin, aeroplysinin-1 and the dienone, and the bastadins, including the synthetically derived hemibastadin congeners, have been selected for this review. Whereas all of these natural products are believed to be involved in the chemical defense of sponges, some of them may also be of particular relevance to drug discovery due to their interaction with specific molecular targets in eukaryotic cells. These targets involve important enzymes and receptors, such as histone deacetylases (HDAC) and DNA methyltransferases (DNMT), which are inhibited by psammaplin A, as well as ryanodine receptors that are targeted by bastadine type compounds. The hemibastadins such as the synthetically derived dibromohemibastadin are of particular interest due to their antifouling activity. For the latter, a phenoloxidase which catalyzes the bioglue formation needed for firm attachment of fouling organisms to a given substrate was identified as a molecular target. The Aplysina alkaloids finally provide a vivid example for dynamic wound induced bioconversions of natural products that generate highly

  1. Lanthanide coordination polymers: Synthesis, diverse structure and luminescence properties

    NASA Astrophysics Data System (ADS)

    Song, Xue-Qin; Lei, Yao-Kun; Wang, Xiao-Run; Zhao, Meng-Meng; Peng, Yun-Qiao; Cheng, Guo-Quan

    2014-10-01

    The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis{[(2‧-furfurylaminoformyl)phenoxyl]methyl}-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schläfli symbol 63, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversities indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of EuIII, TbIII and DyIII complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in EuIII, TbIII and DyIII complexes can be efficiently sensitized by the ligand.

  2. Structural basis for resistance to diverse classes of NAMPT inhibitors.

    PubMed

    Wang, Weiru; Elkins, Kristi; Oh, Angela; Ho, Yen-Ching; Wu, Jiansheng; Li, Hong; Xiao, Yang; Kwong, Mandy; Coons, Mary; Brillantes, Bobby; Cheng, Eric; Crocker, Lisa; Dragovich, Peter S; Sampath, Deepak; Zheng, Xiaozhang; Bair, Kenneth W; O'Brien, Thomas; Belmont, Lisa D

    2014-01-01

    Inhibiting NAD biosynthesis by blocking the function of nicotinamide phosphoribosyl transferase (NAMPT) is an attractive therapeutic strategy for targeting tumor metabolism. However, the development of drug resistance commonly limits the efficacy of cancer therapeutics. This study identifies mutations in NAMPT that confer resistance to a novel NAMPT inhibitor, GNE-618, in cell culture and in vivo, thus demonstrating that the cytotoxicity of GNE-618 is on target. We determine the crystal structures of six NAMPT mutants in the apo form and in complex with various inhibitors and use cellular, biochemical and structural data to elucidate two resistance mechanisms. One is the surprising finding of allosteric modulation by mutation of residue Ser165, resulting in unwinding of an α-helix that binds the NAMPT substrate 5-phosphoribosyl-1-pyrophosphate (PRPP). The other mechanism is orthosteric blocking of inhibitor binding by mutations of Gly217. Furthermore, by evaluating a panel of diverse small molecule inhibitors, we unravel inhibitor structure activity relationships on the mutant enzymes. These results provide valuable insights into the design of next generation NAMPT inhibitors that offer improved therapeutic potential by evading certain mechanisms of resistance. PMID:25285661

  3. Diverse plasma populations and structures in Jupiter's magnetotail.

    PubMed

    McComas, D J; Allegrini, F; Bagenal, F; Crary, F; Ebert, R W; Elliott, H; Stern, A; Valek, P

    2007-10-12

    Jupiter's magnetotail is the largest cohesive structure in the solar system and marks the loss of vast numbers of heavy ions from the Jupiter system. The New Horizons spacecraft traversed the magnetotail to distances exceeding 2500 jovian radii (R(J)) and revealed a remarkable diversity of plasma populations and structures throughout its length. Ions evolve from a hot plasma disk distribution at approximately 100 R(J) to slower, persistent flows down the tail that become increasingly variable in flux and mean energy. The plasma is highly structured-exhibiting sharp breaks, smooth variations, and apparent plasmoids-and contains ions from both Io and Jupiter's ionosphere with intense bursts of H(+) and H(+)(3). Quasi-periodic changes were seen in flux at approximately 450 and approximately 1500 R(J) with a 10-hour period. Other variations in flow speed at approximately 600 to 1000 R(J) with a 3- to 4-day period may be attributable to plasmoids moving down the tail. PMID:17932282

  4. The Spitzer Survey of Stellar Structure in Galaxies (S4G): Stellar Masses, Sizes, and Radial Profiles for 2352 Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Muñoz-Mateos, Juan Carlos; Sheth, Kartik; Regan, Michael; Kim, Taehyun; Laine, Jarkko; Erroz-Ferrer, Santiago; Gil de Paz, Armando; Comeron, Sebastien; Hinz, Joannah; Laurikainen, Eija; Salo, Heikki; Athanassoula, E.; Bosma, Albert; Bouquin, Alexandre Y. K.; Schinnerer, Eva; Ho, Luis; Zaritsky, Dennis; Gadotti, Dimitri A.; Madore, Barry; Holwerda, Benne; Menéndez-Delmestre, Karín; Knapen, Johan H.; Meidt, Sharon; Querejeta, Miguel; Mizusawa, Trisha; Seibert, Mark; Laine, Seppo; Courtois, Helene

    2015-07-01

    The Spitzer Survey of Stellar Structure in Galaxies is a volume, magnitude, and size-limited survey of 2352 nearby galaxies with deep imaging at 3.6 and 4.5 μm. In this paper, we describe our surface photometry pipeline and showcase the associated data products that we have released to the community. We also identify the physical mechanisms leading to different levels of central stellar mass concentration for galaxies with the same total stellar mass. Finally, we derive the local stellar mass-size relation at 3.6 μm for galaxies of different morphologies. Our radial profiles reach stellar mass surface densities below ˜ 1 {M}⊙ {{pc}}-2. Given the negligible impact of dust and the almost constant mass-to-light ratio at these wavelengths, these profiles constitute an accurate inventory of the radial distribution of stellar mass in nearby galaxies. From these profiles we have also derived global properties such as asymptotic magnitudes (and the corresponding stellar masses), isophotal sizes and shapes, and concentration indices. These and other data products from our various pipelines (science-ready mosaics, object masks, 2D image decompositions, and stellar mass maps) can be publicly accessed at IRSA (http://irsa.ipac.caltech.edu/data/SPITZER/S4G/).

  5. THE ADVANCED CAMERA FOR SURVEYS GENERAL CATALOG: STRUCTURAL PARAMETERS FOR APPROXIMATELY HALF A MILLION GALAXIES

    SciTech Connect

    Griffith, Roger L.; Kirkpatrick, J. Davy; Cooper, Michael C.; Newman, Jeffrey A.; Moustakas, Leonidas A.; Stern, Daniel; Comerford, Julia M.; Davis, Marc; Lotz, Jennifer M.; Koekemoer, Anton M.; Barden, Marco; Conselice, Christopher J.; Capak, Peter L.; Scoville, Nick; Sheth, Kartik; Shopbell, Patrick; Faber, S. M.; Koo, David C.; Willmer, Christopher N. A.; and others

    2012-05-01

    We present the Advanced Camera for Surveys General Catalog (ACS-GC), a photometric and morphological database using publicly available data obtained with the Advanced Camera for Surveys (ACS) instrument on the Hubble Space Telescope. The goal of the ACS-GC database is to provide a large statistical sample of galaxies with reliable structural and distance measurements to probe the evolution of galaxies over a wide range of look-back times. The ACS-GC includes approximately 470,000 astronomical sources (stars + galaxies) derived from the AEGIS, COSMOS, GEMS, and GOODS surveys. GALAPAGOS was used to construct photometric (SEXTRACTOR) and morphological (GALFIT) catalogs. The analysis assumes a single Sersic model for each object to derive quantitative structural parameters. We include publicly available redshifts from the DEEP2, COMBO-17, TKRS, PEARS, ACES, CFHTLS, and zCOSMOS surveys to supply redshifts (spectroscopic and photometric) for a considerable fraction ({approx}74%) of the imaging sample. The ACS-GC includes color postage stamps, GALFIT residual images, and photometry, structural parameters, and redshifts combined into a single catalog.

  6. The Structure of Nearby Nuclear Star Clusters in Late-Type Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Carson, Daniel; Barth, A. J.; Ho, L. C.; Greene, J. E.; Seth, A.; Cappellari, M.; Neumayer, N.

    2013-01-01

    Hubble Space Telescope imaging surveys have shown that most late-type, bulgeless spiral galaxies contain compact nuclear star clusters. To examine the structure and stellar content of these objects in detail, we have obtained HST WFC3 images of a sample of 10 spiral galaxies containing bright nuclear star clusters, most at distances of less than 5 Mpc. Each galaxy was observed in seven filters spanning the near-UV to near-IR. GALFIT was used to fit parametric models to the surface brightness distribution of each cluster. In most cases, a single Sersic model provides an adequate description of the cluster structure, although some clusters required 2 Sersic components, and one object (NGC 4395) requires an additional pointlike component to represent the active nucleus. This poster will present the measured cluster properties including magnitudes, Sersic indices, effective radii, and surface brightness profiles. The structural parameters measured from these HST images will be used as input to future dynamical models in order to determine cluster masses and to constrain the possible presence of intermediate-mass black holes within the clusters.

  7. Cosmological N-body Simulation of Galaxy and Large-Scale Structure Formation: The Gravity Frontier

    NASA Astrophysics Data System (ADS)

    Klypin, Anatoly

    2015-04-01

    One of the first N-body simulations done almost 50 years ago had only 200 self-gravitating particles. Even this first baby step made substantial impact on understanding how astronomical objects should form. Now powerful supercomputers and new algorithms allow astronomers produce N-body simulations that employ up to a trillion dark matter particles and produce vital theoretical predictions regarding formation, evolution, structure and statistics of objects ranging from dwarf galaxies to clusters and superclusters of galaxies. With only gravity involved in these theoretical models, one would naively expect that by now we should know everything we need about N-body dynamics of cosmological fluctuations. Not the case. It appears that the Universe was not cooperative and gave us divergencies in the initial conditions generated during the Inflation epoch and subsequent expansion of the Universe - the infinite phase-space density and divergent density fluctuations. Ever increasing observational demands on statistics and accuracy of theoretical predictions is another driving force for more realistic and larger N-body simulations. Large current and new planned observational projects such as BOSS, eBOSS, Euclid, LSST will bring information on spatial distribution, motion, and properties of millions of galaxies at different redshifts. Direct simulations of evolution of gas and formation of stars for millions of forming galaxies will not be available for years leaving astronomers with the only option - to develop methods to combine large N-body simulations with models of galaxy formation to produce accurate theoretical predictions. I will discuss the current status of the field and directions of its development.

  8. Probing the Absorption Structures in Seyfert Galaxies with X-ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Gelbord, J.

    2001-12-01

    The paradigm of the unified model for Seyfert galaxies has had many successes in explaining the range of phenomena observed in active galaxies. However, the structures invoked in this scenario have been difficult to observe due to their limited sizes and due to contaminating flux from other regions. As a result, some of these structures, notably the putative obscuring torus, are poorly constrained. The difficulty in isolating the emission from the central regions can be mitigated (but not eliminated!) by focusing upon high-energy radiation, which is dominated by direct and reprocessed radiation from the nuclear region. We have drawn upon the large number of X-ray spectra available in the ASCA archive in order to study the distribution of properties in a large sample of high-energy observations. Furthermore, by uniformly processing the data ourselves, we minimize systematic effects. One asset of X-rays is that they provide a sensitive probe of absorbers in the line of sight toward the central region, because photoelectric absorption cuts off the continuum at low energies. In the ASCA bandpass column densities of ~1021-23 cm-2 can be measured. This is an interesting range of densities because it allows us to distinguish between absorption in a torus or possibly a warped accretion disk (where column densities are expected to be high) and absorption taking place at larger scales in the host galaxy (where column densities are expected to be closer to Galactic values of 1020-21 cm-2). This data is then compared to data from other wavebands. Published radio studies (e.g.: Nagar & Wilson 1999, Kinney et al. 2000) have put constraints on the orientations of the accretion systems in Seyfert galaxies. We combine these and the X-ray measurements for the ~50 sources in these studies which have ASCA data in order to constrain the various possible absorption structures and test the unification scenario.

  9. Genetic diversity, structure, and breed relationships in Iberian cattle.

    PubMed

    Martín-Burriel, I; Rodellar, C; Cañón, J; Cortés, O; Dunner, S; Landi, V; Martínez-Martínez, A; Gama, L T; Ginja, C; Penedo, M C T; Sanz, A; Zaragoza, P; Delgado, J V

    2011-04-01

    In Iberia there are 51 officially recognized cattle breeds of which 15 are found in Portugal and 38 in Spain. We present here a comprehensive analysis of the genetic diversity and structure of Iberian cattle. Forty of these breeds were genotyped with 19 highly polymorphic microsatellite markers. Asturiana de los Valles displayed the greatest allelic diversity and Mallorquina the least. Unbiased heterozygosity values ranged from 0.596 to 0.787. The network based on Reynolds distances was star-shaped with few pairs of interrelated breeds and a clear cluster of 4 breeds (Alistana/Arouquesa/Marinhoa/Mirandesa). The analysis of the genetic structure of Iberian cattle indicated that the most probable number of population clusters included in the study would be 36. Distance results were supported by the STRUCTURE software indicating a relatively recent origin or possible crossbreeding or both between pairs or small groups of breeds. Five clusters included 2 different breeds (Betizu/Pirenaica, Morucha/Avileña, Parda de Montaña/Bruna de los Pirineos, Barrosã/Cachena, and Toro de Lidia/Brava de Lide), 3 breeds (Berrenda en Negro, Negra Andaluza, and Mertolenga) were divided in 2 independent clusters each, and 2 breeds were considered admixed (Asturiana de los Valles and Berrenda en Colorado). Individual assignation to breeds was not possible in the 2 admixed breeds and the pair Parda de Montaña/Bruna de los Pirineos. The relationship between Iberian cattle reflects their geographical origin rather than their morphotypes. Exceptions to this geographic clustering are most probably a consequence of crossbreeding with foreign breeds. The relative genetic isolation within their geographical origin, the consequent genetic drift, the adaptation to specific environment and production systems, and the influence of African and European cattle have contributed to the current genetic status of Iberian cattle, which are grouped according to their geographical origin. The greater

  10. Jatropha curcas L. Root Structure and Growth in Diverse Soils

    PubMed Central

    Valdés-Rodríguez, Ofelia Andrea; Sánchez-Sánchez, Odilón; Pérez-Vázquez, Arturo; Caplan, Joshua S.; Danjon, Frédéric

    2013-01-01

    Unlike most biofuel species, Jatropha curcas has promise for use in marginal lands, but it may serve an additional role by stabilizing soils. We evaluated the growth and structural responsiveness of young J. curcas plants to diverse soil conditions. Soils included a sand, a sandy-loam, and a clay-loam from eastern Mexico. Growth and structural parameters were analyzed for shoots and roots, although the focus was the plasticity of the primary root system architecture (the taproot and four lateral roots). The sandy soil reduced the growth of both shoot and root systems significantly more than sandy-loam or clay-loam soils; there was particularly high plasticity in root and shoot thickness, as well as shoot length. However, the architecture of the primary root system did not vary with soil type; the departure of the primary root system from an index of perfect symmetry was 14 ± 5% (mean ± standard deviation). Although J. curcas developed more extensively in the sandy-loam and clay-loam soils than in sandy soil, it maintained a consistent root to shoot ratio and root system architecture across all types of soil. This strong genetic determination would make the species useful for soil stabilization purposes, even while being cultivated primarily for seed oil. PMID:23844412

  11. Glycoconjugates from parasitic helminths: structure diversity and immunobiological implications.

    PubMed

    Khoo, K H; Dell, A

    2001-01-01

    We have provided an account of the progress we and others have made over the last decade on the structural characterization of glycans from parasitic helminths. We hope to have illustrated a few principles and patterns governing helminth glycosylation, as well as the experimental approaches adopted and their associated strengths and limitations. Schistosomes remain the best studied systems but are still punctuated with gaps of knowledge. An important theme developed here is the regulated developmental stage-specific expression of various glycan epitopes and their interplay with immediate host environments for successful parasitism. It is anticipated that more novel or unusual structures will continuously be uncovered in the future and that despite many difficulties, current analytical techniques should be well up to meet the challenge in at least elucidating the major or key glycoconjugates from each of the diverse range of worms. The bottle neck will in fact reside in finding suitable experimental models to test their putative immunobiological functions from which the intricate host-parasite interactions can be delineated and rational vaccine design be achieved. The glycobiology of parasitic helminths is an area waiting to be more fully explored and the rewards should be sweet. PMID:14533799

  12. Structural and Functional Diversity of Estrogen Receptor Ligands

    PubMed Central

    Farooq, Amjad

    2015-01-01

    Estrogen receptors, comprised of ERα and ERβ isoforms in mammals, act as ligand-modulated transcription factors and orchestrate a plethora of cellular functions from sexual development and reproduction to metabolic homeostasis. Herein, I revisit the structural basis of the binding of ERα to DNA and estradiol in light of the recent discoveries and emerging trends in the field of nuclear receptors. A particular emphasis of this review is on the chemical and structural diversity of an ever-increasing repertoire of physiological, environmental and synthetic ligands of estrogen receptors that ultimately modulate their interactions with cognate DNA located within the promoters of estrogen-responsive genes. In particular, modulation of estrogen receptors by small molecule ligands represents an important therapeutic goal toward the treatment of a wide variety of human pathologies including breast cancer, cardiovascular disease, osteoporosis and obesity. Collectively, this article provides an overview of a wide array of small organic and inorganic molecules that can fine-tune the physiological function of estrogen receptors, thereby bearing a direct impact on human health and disease. PMID:25866274

  13. Jatropha curcas L. root structure and growth in diverse soils.

    PubMed

    Valdés-Rodríguez, Ofelia Andrea; Sánchez-Sánchez, Odilón; Pérez-Vázquez, Arturo; Caplan, Joshua S; Danjon, Frédéric

    2013-01-01

    Unlike most biofuel species, Jatropha curcas has promise for use in marginal lands, but it may serve an additional role by stabilizing soils. We evaluated the growth and structural responsiveness of young J. curcas plants to diverse soil conditions. Soils included a sand, a sandy-loam, and a clay-loam from eastern Mexico. Growth and structural parameters were analyzed for shoots and roots, although the focus was the plasticity of the primary root system architecture (the taproot and four lateral roots). The sandy soil reduced the growth of both shoot and root systems significantly more than sandy-loam or clay-loam soils; there was particularly high plasticity in root and shoot thickness, as well as shoot length. However, the architecture of the primary root system did not vary with soil type; the departure of the primary root system from an index of perfect symmetry was 14 ± 5% (mean ± standard deviation). Although J. curcas developed more extensively in the sandy-loam and clay-loam soils than in sandy soil, it maintained a consistent root to shoot ratio and root system architecture across all types of soil. This strong genetic determination would make the species useful for soil stabilization purposes, even while being cultivated primarily for seed oil. PMID:23844412

  14. TIGHT CORRELATIONS BETWEEN MASSIVE GALAXY STRUCTURAL PROPERTIES AND DYNAMICS: THE MASS FUNDAMENTAL PLANE WAS IN PLACE BY z ∼ 2

    SciTech Connect

    Bezanson, Rachel; Van Dokkum, Pieter G.; Leja, Joel; Van de Sande, Jesse; Franx, Marijn; Kriek, Mariska

    2013-12-20

    The fundamental plane (FP) is an empirical relation between the size, surface brightness, and velocity dispersion of early-type galaxies. This relation has been studied extensively for early-type galaxies in the local universe to constrain galaxy formation mechanisms. The evolution of the zero point of this plane has been extended to high redshifts to study the luminosity evolution of massive galaxies, under the assumption of structural homology. In this work, we assess this assumption by replacing surface brightness with stellar mass density and present the evolution of the ''mass FP'' for massive, quiescent galaxies since z ∼ 2. By accounting for stellar populations, we thereby isolate and trace structural and dynamical evolution. Despite the observed dramatic evolution in the sizes and morphologies of massive galaxies since z ∼ 3, we find that quiescent galaxies lie on the mass FP out to z ∼ 2. In contrast with ∼1.4 dex evolution in the luminosity FP, average residuals from the z ∼ 0 mass FP are less than ∼0.15 dex since z ∼ 2. Assuming the Hyde and Bernardi mass FP slope, we find that this minimal offset scales as (1 + z){sup –0.095} {sup ±} {sup 0.043}. This result lends credence to previous studies that derived luminosity evolution from the FP. Therefore, despite their compact sizes and suggestions that massive galaxies are more disk-like at z ∼ 2, the relationship between their dynamics and structural properties are consistent with local early-type galaxies. Finally, we find no strong evidence for a tilt of the mass FP relative to the virial plane, but emphasize the need for full models including selection biases to fully investigate this issue.

  15. Isotopic Diversity Indices: How Sensitive to Food Web Structure?

    PubMed Central

    Brind'Amour, Anik; Dubois, Stanislas F.

    2013-01-01

    Recently revisited, the concept of niche ecology has lead to the formalisation of functional and trophic niches using stable isotope ratios. Isotopic diversity indices (IDI) derived from a set of measures assessing the dispersion/distribution of points in the δ-space were recently suggested and increasingly used in the literature. However, three main critics emerge from the use of these IDI: 1) they fail to account for the isotopic sources overlap, 2) some indices are highly sensitive to the number of species and/or the presence of rare species, and 3) the lack of standardization prevents any spatial and temporal comparisons. Using simulations we investigated the ability of six commonly used IDI to discriminate among different trophic food web structures, with a focus on the first two critics. We tested the sensitivity of the IDI to five food web structures along a gradient of sources overlap, varying from two distinct food chains with differentiated sources to two superimposed food chains sharing two sources. For each of the food web structure we varied the number of species (from 10 to 100 species) and the type of species feeding behaviour (i.e. random or selective feeding). Values of IDI were generally larger in food webs with distinct basal sources and tended to decrease as the superimposition of the food chains increased. This was more pronounced when species displayed food preferences in comparison to food webs where species fed randomly on any prey. The number of species composing the food web also had strong effects on the metrics, including those that were supposedly less sensitive to small sample size. In all cases, computing IDI on food webs with low numbers of species always increases the uncertainty of the metrics. A threshold of ∼20 species was detected above which several metrics can be safely used. PMID:24391910

  16. Isotopic diversity indices: how sensitive to food web structure?

    PubMed

    Brind'Amour, Anik; Dubois, Stanislas F

    2013-01-01

    Recently revisited, the concept of niche ecology has lead to the formalisation of functional and trophic niches using stable isotope ratios. Isotopic diversity indices (IDI) derived from a set of measures assessing the dispersion/distribution of points in the δ-space were recently suggested and increasingly used in the literature. However, three main critics emerge from the use of these IDI: 1) they fail to account for the isotopic sources overlap, 2) some indices are highly sensitive to the number of species and/or the presence of rare species, and 3) the lack of standardization prevents any spatial and temporal comparisons. Using simulations we investigated the ability of six commonly used IDI to discriminate among different trophic food web structures, with a focus on the first two critics. We tested the sensitivity of the IDI to five food web structures along a gradient of sources overlap, varying from two distinct food chains with differentiated sources to two superimposed food chains sharing two sources. For each of the food web structure we varied the number of species (from 10 to 100 species) and the type of species feeding behaviour (i.e. random or selective feeding). Values of IDI were generally larger in food webs with distinct basal sources and tended to decrease as the superimposition of the food chains increased. This was more pronounced when species displayed food preferences in comparison to food webs where species fed randomly on any prey. The number of species composing the food web also had strong effects on the metrics, including those that were supposedly less sensitive to small sample size. In all cases, computing IDI on food webs with low numbers of species always increases the uncertainty of the metrics. A threshold of ~20 species was detected above which several metrics can be safely used. PMID:24391910

  17. Connecting Star Formation Quenching with Galaxy Structure and Supermassive Black Holes through Gravitational Heating of Cooling Flows

    NASA Astrophysics Data System (ADS)

    Guo, Fulai

    2014-12-01

    Recent observations suggested that star formation quenching in galaxies is related to galaxy structure. Here we propose a new mechanism to explain the physical origin of this correlation. We assume that while quenching is maintained in quiescent galaxies by a feedback mechanism, cooling flows in the hot halo gas can still develop intermittently. We study cooling flows in a large suite of around 90 hydrodynamic simulations of an isolated galaxy group, and find that the flow development depends significantly on the gravitational potential well in the central galaxy. If the galaxy's gravity is not strong enough, cooling flows result in a central cooling catastrophe, supplying cold gas and feeding star formation to galactic bulges. When the bulge grows prominent enough, compressional heating starts to offset radiative cooling and maintains cooling flows in a long-term hot mode without producing a cooling catastrophe. Our model thus describes a self-limited growth channel for galaxy bulges and naturally explains the connection between quenching and bulge prominence. In particular, we explicitly demonstrate that M*/R_eff1.5 is a good structural predictor of quenching. We further find that the gravity from the central supermassive black hole also affects the bimodal fate of cooling flows, and we predict a more general quenching predictor to be M_bh1.6M*/R_eff1.5, which may be tested in future observational studies.

  18. CONNECTING STAR FORMATION QUENCHING WITH GALAXY STRUCTURE AND SUPERMASSIVE BLACK HOLES THROUGH GRAVITATIONAL HEATING OF COOLING FLOWS

    SciTech Connect

    Guo, Fulai

    2014-12-20

    Recent observations suggested that star formation quenching in galaxies is related to galaxy structure. Here we propose a new mechanism to explain the physical origin of this correlation. We assume that while quenching is maintained in quiescent galaxies by a feedback mechanism, cooling flows in the hot halo gas can still develop intermittently. We study cooling flows in a large suite of around 90 hydrodynamic simulations of an isolated galaxy group, and find that the flow development depends significantly on the gravitational potential well in the central galaxy. If the galaxy's gravity is not strong enough, cooling flows result in a central cooling catastrophe, supplying cold gas and feeding star formation to galactic bulges. When the bulge grows prominent enough, compressional heating starts to offset radiative cooling and maintains cooling flows in a long-term hot mode without producing a cooling catastrophe. Our model thus describes a self-limited growth channel for galaxy bulges and naturally explains the connection between quenching and bulge prominence. In particular, we explicitly demonstrate that M{sub ∗}/R{sub eff}{sup 1.5} is a good structural predictor of quenching. We further find that the gravity from the central supermassive black hole also affects the bimodal fate of cooling flows, and we predict a more general quenching predictor to be M{sub bh}{sup 1.6}M{sub ∗}/R{sub eff}{sup 1.5}, which may be tested in future observational studies.

  19. An assessment of the impact of water impoundment and diversion structures on vegetation in Southern Arizona

    NASA Technical Reports Server (NTRS)

    Conn, J. S.; Mouat, D. A.; Clark, R. B.

    1975-01-01

    High-altitude color infrared photography was used to survey existing conditions, both upstream and downstream, from nineteen diversion structures in Southern Arizona to determine their effect upon vegetation health, vigor, and cover. A diversion structure is defined as a man/made feature constructed to control storm runoff. The results are used to determine the policy for future structure design.

  20. KILOPARSEC-SCALE RADIO STRUCTURES IN NARROW-LINE SEYFERT 1 GALAXIES

    SciTech Connect

    Doi, Akihiro; Kino, Motoki; Nagira, Hiroshi; Kawakatu, Nozomu; Nagai, Hiroshi; Asada, Keiichi

    2012-11-20

    We report the finding of kiloparsec (kpc)-scale radio structures in three radio-loud narrow-line Seyfert 1 (NLS1) galaxies from the Faint Images of the Radio Sky at Twenty-centimeters of the Very Large Array, which increases the number of known radio-loud NLS1s with kpc-scale structures to six, including two {gamma}-ray-emitting NLS1s (PMN J0948+0022 and 1H 0323+342) detected by the Fermi Gamma-ray Space Telescope. The detection rate of extended radio emissions in NLS1s is lower than that in broad-line active galactic nuclei (AGNs) with a statistical significance. We found both core-dominated (blazar-like) and lobe-dominated (radio-galaxy-like) radio structures in these six NLS1s, which can be understood in the framework of the unified scheme of radio-loud AGNs that considers radio galaxies as non-beamed parent populations of blazars. Five of the six NLS1s have (1) extended radio luminosities suggesting jet kinetic powers of {approx}> 10{sup 44} erg s{sup -1}, which is sufficient to make jets escape from hosts' dense environments; (2) black holes of {approx}> 10{sup 7} M {sub Sun }, which can generate the necessary jet powers from near-Eddington mass accretion; and (3) two-sided radio structures at kpc scales, requiring expansion rates of {approx}0.01c-0.3c and kinematic ages of {approx}> 10{sup 7} years. On the other hand, most typical NLS1s would be driven by black holes of {approx}< 10{sup 7} M {sub Sun} in a limited lifetime of {approx}10{sup 7} years. Hence, the kpc-scale radio structures may originate in a small window of opportunity during the final stage of the NLS1 phase just before growing into broad-line AGNs.

  1. STRUCTURE IN THE 3D GALAXY DISTRIBUTION. II. VOIDS AND WATERSHEDS OF LOCAL MAXIMA AND MINIMA

    SciTech Connect

    Way, M. J.; Gazis, P. R.; Scargle, Jeffrey D. E-mail: PGazis@sbcglobal.net

    2015-01-20

    The major uncertainties in studies of the multi-scale structure of the universe arise not from observational errors but from the variety of legitimate definitions and detection methods for individual structures. To facilitate the study of these methodological dependencies, we have carried out 12 different analyses defining structures in various ways. This has been done in a purely geometrical way by utilizing the HOP algorithm as a unique parameter-free method of assigning groups of galaxies to local density maxima or minima. From three density estimation techniques (smoothing kernels, Bayesian blocks, and self-organizing maps) applied to three data sets (the Sloan Digital Sky Survey Data Release 7, the Millennium simulation, and randomly distributed points) we tabulate information that can be used to construct catalogs of structures connected to local density maxima and minima. We also introduce a void finder that utilizes a method to assemble Delaunay tetrahedra into connected structures and characterizes regions empty of galaxies in the source catalog.

  2. HI content and other structural properties of galaxies in the Virgo cluster from the Arecibo Legacy Fast ALFA Survey

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Giovanelli, R.; Haynes, M. P.; Fabello, S.; Fumagalli, M.; Kent, B. R.; Koopmann, R. A.; Brosch, N.; Hoffman, G. L.; Salzer, J. J.; Boselli, A.

    2008-04-01

    We report the results of an HI blind survey of 80 deg2 of the Virgo cluster, based on the 08° ≤ δ ≤ 16° strip of ALFALFA, the Arecibo Legacy Fast ALFA Survey. 187 HI sources of high significance are found providing a complete census of HI sources in this region of the Virgo cluster (-1000galaxies from the Virgo Cluster Catalogue (Binggeli et al. 1985, AJ, 90, 1681), all but 8 with late-type galaxies. Ten sources are not associated with optical galaxies and were found to correspond to tidally-disrupted systems (see Kent et al. 2007, ApJ, 665, L15; and Haynes et al. 2007, ApJ, 665, L19). The remaining 21 (11%) are associated with galaxies that are not listed in the Virgo Cluster Catalogue. For all sources with an optical counterpart in the Sloan Digital Sky Survey, we analyzed i-band SDSS plates to measure optical structural parameters. We find that in the Virgo cluster: i) HI inhabits galaxies that are structurally similar to ordinary late-type galaxies; ii) their HI content can be predicted from their optical luminosity; iii) low surface brightness galaxies have low optical luminosity and contain small quantities of neutral hydrogen; iv) low surface brightness, massive Malin1 type galaxies are comfortably rare objects (less than 0.5%); v) there are no “dark-galaxies” with HI masses M_HI ≥ 107.5 ˜ 8~M_⊙; vi) less than 1% of early-type galaxies contain neutral hydrogen with M_HI ≥ 107.5 ˜ 8~M_⊙ (di Serego Alighieri et al. 2007, A&A, 474, 851).

  3. Structure and diversity of Mexican axolotl lambda light chains.

    PubMed

    André, S; Guillet, F; Charlemagne, J; Fellah, J S

    2000-11-01

    We report here the structure of cDNA clones encoding axolotl light chains of the lambda type. A single IGLC gene and eight different potential IGLV genes belonging to four different families were detected. The axolotl Cgamma domain has several residues or stretches of residues that are typically conserved in mammalian, avian, and Xenopus Cgamma, but the KATLVCL stretch, which is well conserved in the Cgamma and T-cell receptor Cbeta domains of many vertebrate species, is not well conserved. All axolotl Vgamma sequences closely match several human and Xenopus Vgamma-like sequences and, although the axolotl Cgamma and Vgamma sequences are very like their tetrapod homologues, they are not closely related to nontetrapod L chains. Southern blot experiments suggested the presence of a single IGLC gene and of a limited number of IGLV genes, and analysis of IGLV-J junctions clearly indicated that at least three of the IGLJ segments can associate with IGLV1, IGLV2, or IGLV3 subgroup genes. The overall diversity of the axolotl Vgamma CDR3 junctions seems to be of the same order as that of mammalian Vgamma chains. However, a single IGLV4 segment was found among the 45 cDNAs analyzed. This suggests that the axolotl IGL locus may have a canonical tandem structure, like the mammalian IGK or IGH loci. Immunofluorescence, immunoblotting, and microsequencing experiments strongly suggested that most, if not all L chains are of the gamma type. This may explain in part the poor humoral response of the axolotl. PMID:11132150

  4. The kinematics and spiral structure of the Galaxy from the neutral hydrogen

    NASA Astrophysics Data System (ADS)

    Petrovskaya, I. V.

    The kinematical and structural characteristics of the Galaxy are investigated using the whole 21-cm line profile of the neutral hydrogen emission. The concerted rotation curve and the spiral arms parameters are obtained. The Galaxy is found to have four armes with the pitch angle i = 14^circ in the region R >= 0.6R_0 and the gaseous ring when 0.4 < R / R_0 < 0.6. The Sun is between the arms. Comparing the rotation laws of the neutral and ionised gas subsystems we found the distance of the Sun to the Galactic centre R_0 = 7.5 plus or minus 1.0 kpk. The rotation velocity has a signature with the depression approximatedly 20 km/s near R = R_0. The velocity jump may be connected with giant vortices near corotation region. The parameters of the anticyclonic motion in that region are investigated. Our method of interpretation of the 21 cm profile gives the possibility to investigate z-dependance of the velocity field. To solve this problem for the inner region of the Galaxy (R

  5. Distinctive 21-cm structures of the first stars, galaxies and quasars

    NASA Astrophysics Data System (ADS)

    Yajima, Hidenobu; Li, Yuexing

    2014-12-01

    Observations of the redshifted 21-cm line with forthcoming radio telescopes promise to transform our understanding of the cosmic reionization. To unravel the underlying physical process, we investigate the 21-cm structures of three different ionizing sources - Population (Pop) III stars, the first galaxies and the first quasars - by using radiative transfer simulations that include both ionization of neutral hydrogen and resonant scattering of Lyα photons. We find that Pop III stars and quasars produce a smooth transition from an ionized and hot state to a neutral and cold state, because of their hard spectral energy distribution with abundant ionizing photons, in contrast to the sharp transition in galaxies. Furthermore, Lyα scattering plays a dominant role in producing the 21-cm signal because it determines the relation between hydrogen spin temperature and gas kinetic temperature. This effect, also called Wouthuysen-Field coupling, depends strongly on the ionizing source. It is strongest around galaxies, where the spin temperature is highly coupled to that of the gas, resulting in extended absorption troughs in the 21-cm brightness temperature. However, in the case of Pop III stars, the 21-cm signal shows both emission and absorption regions around a small H II bubble. For quasars, a large emission region in the 21-cm signal is produced, and the absorption region decreases as the size of the H II bubble becomes large due to the limited travelling time of photons. We predict that future surveys from large radio arrays, such as the Murchison Widefield Array, the Low Frequency Array and the Square Kilometre Array, might be able to detect the 21-cm signals of primordial galaxies and quasars, but possibly not those of Pop III stars, because of their small angular diameters.

  6. MAPPING THE CLUMPY STRUCTURES WITHIN SUBMILLIMETER GALAXIES USING LASER-GUIDE STAR ADAPTIVE OPTICS SPECTROSCOPY

    SciTech Connect

    Menendez-Delmestre, Karin; Goncalves, Thiago S.; Blain, Andrew W.; Swinbank, Mark; Smail, Ian; Ivison, Rob J.; Chapman, Scott C.

    2013-04-20

    We present the first integral-field spectroscopic observations of high-redshift submillimeter-selected galaxies (SMGs) using Laser-Guide Star Adaptive Optics. We target H{alpha} emission of three SMGs at redshifts z {approx} 1.4-2.4 with the OH-Suppressing Infrared Imaging Spectrograph on Keck. The spatially resolved spectroscopy of these galaxies reveals unresolved broad-H{alpha} line regions (FWHM >1000 km s{sup -1}) likely associated with an active galactic nucleus (AGN) and regions of diffuse star formation traced by narrow-line H{alpha} emission (FWHM {approx}< 500 km s{sup -1}) dominated by multiple H{alpha}-bright stellar clumps, each contributing 1%-30% of the total clump-integrated H{alpha} emission. We find that these SMGs host high star formation rate surface densities, similar to local extreme sources, such as circumnuclear starbursts and luminous infrared galaxies. However, in contrast to these local environments, SMGs appear to be undergoing such intense activity on significantly larger spatial scales as revealed by extended H{alpha} emission over 4-16 kpc. H{alpha} kinematics show no evidence of ordered global motion as would be found in a disk, but rather large velocity offsets ({approx}few Multiplication-Sign 100 km s{sup -1}) between the distinct stellar clumps. Together with the asymmetric distribution of the stellar clumps around the AGN in these objects, it is unlikely that we are unveiling a clumpy disk structure as has been suggested in other high-redshift populations of star-forming galaxies. The SMG clumps in this sample may correspond to remnants of originally independent gas-rich systems that are in the process of merging, hence triggering the ultraluminous SMG phase.

  7. Unveiling the structure of barred galaxies at 3.6 μm with the Spitzer survey of stellar structure in galaxies (S{sup 4}G). I. Disk breaks

    SciTech Connect

    Kim, Taehyun; Lee, Myung Gyoon; Gadotti, Dimitri A.; Muñoz-Mateos, Juan-Carlos; Sheth, Kartik; Madore, Barry F.; Ho, Luis C.; Elmegreen, Bruce; Knapen, Johan H.; Cisternas, Mauricio; Erroz-Ferrer, Santiago; Zaritsky, Dennis; Comerón, Sébastien; Laurikainen, Eija; Salo, Heikki; Holwerda, Benne; Hinz, Joannah L.; Buta, Ron; and others

    2014-02-20

    We have performed two-dimensional multicomponent decomposition of 144 local barred spiral galaxies using 3.6 μm images from the Spitzer Survey of Stellar Structure in Galaxies. Our model fit includes up to four components (bulge, disk, bar, and a point source) and, most importantly, takes into account disk breaks. We find that ignoring the disk break and using a single disk scale length in the model fit for Type II (down-bending) disk galaxies can lead to differences of 40% in the disk scale length, 10% in bulge-to-total luminosity ratio (B/T), and 25% in bar-to-total luminosity ratios. We find that for galaxies with B/T ≥ 0.1, the break radius to bar radius, r {sub br}/R {sub bar}, varies between 1 and 3, but as a function of B/T the ratio remains roughly constant. This suggests that in bulge-dominated galaxies the disk break is likely related to the outer Lindblad resonance of the bar and thus moves outward as the bar grows. For galaxies with small bulges, B/T < 0.1, r {sub br}/R {sub bar} spans a wide range from 1 to 6. This suggests that the mechanism that produces the break in these galaxies may be different from that in galaxies with more massive bulges. Consistent with previous studies, we conclude that disk breaks in galaxies with small bulges may originate from bar resonances that may be also coupled with the spiral arms, or be related to star formation thresholds.

  8. Dissecting simulated disc galaxies - I. The structure of mono-age populations

    NASA Astrophysics Data System (ADS)

    Martig, Marie; Minchev, Ivan; Flynn, Chris

    2014-08-01

    We study seven simulated disc galaxies, three with a quiescent merger history, and four with mergers in their last 9 Gyr of evolution. We compare their structure at z = 0 by decomposing them into `mono-age populations' (MAPs) of stars within 500 Myr age bins. All studied galaxies undergo a phase of merging activity at high redshift, so that stars older than 9 Gyr are found in a centrally concentrated component, while younger stars are mostly found in discs. We find that most MAPs have simple exponential radial and vertical density profiles, with a scaleheight that typically increases with age. Because a large range of merger histories can create populations with simple structures, this suggests that the simplicity of the structure of mono-abundance populations observed in the Milky Way by Bovy et al. is not necessarily a direct indicator of a quiescent history for the Milky Way. Similarly, the anticorrelation between scalelength and scaleheight does not necessarily imply a merger-free history. However, mergers produce discontinuities between thin and thick disc components, and jumps in the age-velocity relation. The absence of a structural discontinuity between thin and thick disc observed in the Milky Way would seem to be a good indicator that no merger with a mass ratio larger than 1:15-1:10 occurred in the last 9 Gyr. Mergers at higher redshift might nevertheless be necessary to produce the thickest, hottest components of the Milky Way's disc.

  9. The Halo Masses and Galaxy Environments of Hyperluminous QSOs at z ~= 2.7 in the Keck Baryonic Structure Survey

    NASA Astrophysics Data System (ADS)

    Trainor, Ryan F.; Steidel, Charles C.

    2012-06-01

    We present an analysis of the galaxy distribution surrounding 15 of the most luminous (gsim 1014 L ⊙ M1450 ~= -30) QSOs in the sky with z ~= 2.7. Our data are drawn from the Keck Baryonic Structure Survey, which has been optimized to examine the small-scale interplay between galaxies and the intergalactic medium during the peak of the galaxy formation era at z ~ 2-3. In this work, we use the positions and spectroscopic redshifts of 1558 galaxies that lie within ~3' (4.2 h -1 comoving Mpc cMpc) of the hyperluminous QSO (HLQSO) sight line in 1 of 15 independent survey fields, together with new measurements of the HLQSO systemic redshifts. By combining the spatial and redshift distributions, we measure the galaxy-HLQSO cross-correlation function, the galaxy-galaxy autocorrelation function, and the characteristic scale of galaxy overdensities surrounding the sites of exceedingly rare, extremely rapid, black hole accretion. On average, the HLQSOs lie within significant galaxy overdensities, characterized by a velocity dispersion σ v ~= 200 km s-1 and a transverse angular scale of ~25'' (~200 physical kpc). We argue that such scales are expected for small groups with log (M h/M ⊙) ~= 13. The galaxy-HLQSO cross-correlation function has a best-fit correlation length r GQ 0 = (7.3 ± 1.3) h -1 cMpc, while the galaxy autocorrelation measured from the spectroscopic galaxy sample in the same fields has r GG 0 = (6.0 ± 0.5) h -1 cMpc. Based on a comparison with simulations evaluated at z ~ 2.6, these values imply that a typical galaxy lives in a host halo with log (M h/M ⊙) = 11.9 ± 0.1, while HLQSOs inhabit host halos of log (M h/M ⊙) = 12.3 ± 0.5. In spite of the extremely large black hole masses implied by their observed luminosities [log (M BH/M ⊙) >~ 9.7], it appears that HLQSOs do not require environments very different from their much less luminous QSO counterparts. Evidently, the exceedingly low space density of HLQSOs (lsim 10-9 cMpc-3) results from a one

  10. Galaxy Assembly and the Evolution of Structure over the First Third of Cosmic Time - I

    NASA Astrophysics Data System (ADS)

    Faber, Sandra

    2010-09-01

    The Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey {CANDELS}is designed to document the |*|rst third of galactic evolution from z =8 to 1.5 via deep imaging of more than 250,000 galaxies with WFC3/IRand ACS. It will also find the first Type Ia SNe beyond z > 1.5 andestablish their accuracy as standard candles for cosmology. Fivepremier multi-wavelength sky regions are selected from the SpitzerExtragalactic Deep Survey {SEDS} to provide complementary IRAC imagingdata down to 26.5 AB mag, a unique resource for stellar masses at allredshifts. The use of |*|ve widely separated |*|elds mitigates cosmicvariance and yields statistically robust and complete samples ofgalaxies down to 10^9 solar masses out to z 8.The program merges two originally separate MCT proposals. The Faberprogram incorporates a |*|Wide|*| imaging survey in three separate fieldsto 2 orbit depth over 0.2 sq. degrees, plus a |*|Deep|*| imaging surveyto 12 orbit depth in the two GOODS regions over 0.04 sq. degrees.In combination with ultra-deep imaging from the Hubble Ultradeep Fieldprogram {GO 11563}, the result is a three-tiered strategy that ef|*|cientlysamples both bright/rare and faint/common extragalactic objects. TheFerguson program adds an extensive high-redshift Type Ia SNe search,plus ultraviolet "daytime" UVIS exposures in GOODS-N to exploit theCVZ opportunity in that field.This program, GO 12064, is part of the Wide mosaic survey, which has thefollowing field centers and sizes: Field ID RA{2000} Dec{2000} WFC3 Dim. PA on sky UDS 02 17 38 -05 12 02 4x11 270 COSMOS 10 00 31 +02 24 00 4x11 180 EGS 14 19 31 +52 54 10 3x15 41 Science highlights from the Wide program: * Underlying structural properties of galaxies as revealed by WFC3-IR images sensitive to older stars {beyond the 4000-A break} and less affected by dust than ACS. A key redshift is z 2, where star-formation peaks, QSOs are most abundant, and where restframe B-band is still accessible to WFC3. Sample questions include

  11. Cosmic Structure and Galaxy Evolution through Intensity Mapping of Molecular Gas

    NASA Astrophysics Data System (ADS)

    Bower, Geoffrey C.; Keating, Garrett K.; Marrone, Daniel P.; YT Lee Array Team, SZA Team

    2016-01-01

    The origin and evolution of structure in the Universe is one of the major challenges of observational astronomy. How does baryonic structure trace the underlying dark matter? How have galaxies evolved to produce the present day Universe? A multi-wavelength, multi-tool approach is necessary to provide the complete story of the evolution of structure in the Universe. Intensity mapping, which relies on the ability to detect many objects at once through their integrated emission rather than direct detection of individual objects, is a critical part of this mosaic. In particular, our understanding of the molecular gas component of massive galaxies is being revolutionized by ALMA and EVLA but the population of smaller, star-forming galaxies, which provide the bulk of star formation cannot be individually probed by these instruments.In this talk, I will summarize two intensity mapping experiments to detect molecular gas through the carbon monoxide (CO) rotational transition. We have completed sensitive observations with the Sunyaev-Zel'dovic Array (SZA) telescope at a wavelength of 1 cm that are sensitive to emission at redshifts 2.3 to 3.3. The SZA experiments sets strong limits on models for the CO emission and demonstrates the ability to reject foregrounds and telescope systematics in very deep integrations. I also describe the development of an intensity mapping capability for the Y.T. Lee Array, a 13-element interferometer located on Mauna Loa. In its first phase, this project focuses on detection of CO at redshifts 2.4 - 3.0 with detection via power spectrum and cross-correlation with other surveys. The project includes a major technical upgrade, a new digital correlator and IF electronics component to be deployed in 2015/2016. The Y.T. Lee Array observations will be more sensitive and extend to larger angular scales than the SZA observations.

  12. From Globular Clusters to Tidal Dwarfs: Structure Formation in the Tidal Tails of Merging Galaxies

    NASA Astrophysics Data System (ADS)

    Knierman, Karen A.; Gallagher, Sarah C.; Charlton, Jane C.; Hunsberger, Sally D.; Whitmore, Bradley; Kundu, Arunav; Hibbard, J. E.; Zaritsky, Dennis

    2003-09-01

    Using V and I images obtained with the Wide Field Planetary Camera 2 (WFPC2) of the Hubble Space Telescope, we investigate compact stellar structures within tidal tails. Six regions of tidal debris in the four classic ``Toomre sequence'' mergers: NGC 4038/39 (``Antennae''), NGC 3256, NGC 3921, and NGC 7252 (``Atoms for Peace'') have been studied in order to explore how the star formation depends on the local and global physical conditions. These mergers sample a range of stages in the evolutionary sequence and tails with and without embedded tidal dwarf galaxies. The six tails are found to contain a variety of stellar structures, with sizes ranging from those of globular clusters up to those of dwarf galaxies. From V and I WFPC2 images, we measure the luminosities and colors of the star clusters. NGC 3256 is found to have a large population of blue clusters (0.2<~V-I<~0.9), particularly in its western tail, similar to those found in the inner region of the merger. In contrast, NGC 4038/39 has no clusters in the observed region of the tail, only less luminous point sources likely to be individual stars. NGC 3921 and NGC 7252 have small populations of clusters along their tails. A significant cluster population is clearly associated with the prominent tidal dwarf candidates in the eastern and western tails of NGC 7252. The cluster-rich western tail of NGC 3256 is not distinguished from the others by its dynamical age or by its total H I mass. However, the mergers that have few clusters in the tail all have tidal dwarf galaxies, while NGC 3256 does not have prominent tidal dwarfs. We speculate that star formation in tidal tails may manifest itself either in small structures like clusters along the tail or in large structures such as dwarf galaxies, but not in both. Also, NGC 3256 has the highest star formation rate of the four mergers studied, which may contribute to the high number of star clusters in its tidal tails. Based in part on observations obtained with the

  13. A long-term space astrophysics research program: An x-ray perspective of the components and structure of galaxies

    NASA Technical Reports Server (NTRS)

    Fabbiano, G.

    1995-01-01

    X-ray studies of galaxies by the Smithsonian Astrophysical Observatory (SAO) and MIT are described. Activities at SAO include ROSAT PSPC x-ray data reduction and analysis pipeline; x-ray sources in nearby Sc galaxies; optical, x-ray, and radio study of ongoing galactic merger; a radio, far infrared, optical, and x-ray study of the Sc galaxy NGC247; and a multiparametric analysis of the Einstein sample of early-type galaxies. Activities at MIT included continued analysis of observations with ROSAT and ASCA, and continued development of new approaches to spectral analysis with ASCA and AXAF. Also, a new method for characterizing structure in galactic clusters was developed and applied to ROSAT images of a large sample of clusters. An appendix contains preprints generated by the research.

  14. GalaxyRefineComplex: Refinement of protein-protein complex model structures driven by interface repacking

    PubMed Central

    Heo, Lim; Lee, Hasup; Seok, Chaok

    2016-01-01

    Protein-protein docking methods have been widely used to gain an atomic-level understanding of protein interactions. However, docking methods that employ low-resolution energy functions are popular because of computational efficiency. Low-resolution docking tends to generate protein complex structures that are not fully optimized. GalaxyRefineComplex takes such low-resolution docking structures and refines them to improve model accuracy in terms of both interface contact and inter-protein orientation. This refinement method allows flexibility at the protein interface and in the overall docking structure to capture conformational changes that occur upon binding. Symmetric refinement is also provided for symmetric homo-complexes. This method was validated by refining models produced by available docking programs, including ZDOCK and M-ZDOCK, and was successfully applied to CAPRI targets in a blind fashion. An example of using the refinement method with an existing docking method for ligand binding mode prediction of a drug target is also presented. A web server that implements the method is freely available at http://galaxy.seoklab.org/refinecomplex. PMID:27535582

  15. Dark energy and the structure of the Coma cluster of galaxies

    NASA Astrophysics Data System (ADS)

    Chernin, A. D.; Bisnovatyi-Kogan, G. S.; Teerikorpi, P.; Valtonen, M. J.; Byrd, G. G.; Merafina, M.

    2013-05-01

    Context. We consider the Coma cluster of galaxies as a gravitationally bound physical system embedded in the perfectly uniform static dark energy background as implied by ΛCDM cosmology. Aims: We ask if the density of dark energy is high enough to affect the structure of a large and rich cluster of galaxies. Methods: We base our work on recent observational data on the Coma cluster, and apply our theory of local dynamical effects of dark energy, including the zero-gravity radius RZG of the local force field as the key parameter. Results: 1) Three masses are defined that characterize the structure of a regular cluster: the matter mass MM, the dark-energy effective mass MDE (<0), and the gravitating mass MG (=MM + MDE). 2) A new matter-density profile is suggested that reproduces the observational data well for the Coma cluster in the radius range from 1.4 Mpc to 14 Mpc and takes the dark energy background into account. 3) Using this profile, we calculate upper limits for the total size of the Coma cluster, R ≤ RZG ≈ 20 Mpc, and its total matter mass, MM ≲ MM(RZG) = 6.2 × 1015 M⊙. Conclusions: The dark energy antigravity affects the structure of the Coma cluster strongly at large radii R ≳ 14 Mpc and should be considered when its total mass is derived.

  16. GalaxyRefineComplex: Refinement of protein-protein complex model structures driven by interface repacking.

    PubMed

    Heo, Lim; Lee, Hasup; Seok, Chaok

    2016-01-01

    Protein-protein docking methods have been widely used to gain an atomic-level understanding of protein interactions. However, docking methods that employ low-resolution energy functions are popular because of computational efficiency. Low-resolution docking tends to generate protein complex structures that are not fully optimized. GalaxyRefineComplex takes such low-resolution docking structures and refines them to improve model accuracy in terms of both interface contact and inter-protein orientation. This refinement method allows flexibility at the protein interface and in the overall docking structure to capture conformational changes that occur upon binding. Symmetric refinement is also provided for symmetric homo-complexes. This method was validated by refining models produced by available docking programs, including ZDOCK and M-ZDOCK, and was successfully applied to CAPRI targets in a blind fashion. An example of using the refinement method with an existing docking method for ligand binding mode prediction of a drug target is also presented. A web server that implements the method is freely available at http://galaxy.seoklab.org/refinecomplex. PMID:27535582

  17. One ring to encompass them all: a giant stellar structure that surrounds the Galaxy

    NASA Astrophysics Data System (ADS)

    Ibata, R. A.; Irwin, M. J.; Lewis, G. F.; Ferguson, A. M. N.; Tanvir, N.

    2003-04-01

    We present evidence that the curious stellar population found by the Sloan Digital Sky Survey in the Galactic anticentre direction extends to other distant fields that skirt the plane of the Milky Way. New data, taken with the Isaac Newton Telescope Wide Field Camera, show a similar population, narrowly aligned along the line of sight, but with a galactocentric distance that changes from ~15 to ~20 kpc (over ~100° on the sky). Despite being narrowly concentrated along the line of sight, the structure is fairly extended vertically out of the plane of the disc, with a vertical scaleheight of 0.75 +/- 0.04 kpc. This finding suggests that the outer rim of the Galaxy ends in a low surface brightness stellar ring. Presently available data do not allow us to ascertain the origin of the structure. One possibility is that it is the wraith of a satellite galaxy devoured long ago by the Milky Way, although our favoured interpretation is that it is a perturbation of the disc, possibly the result of ancient warps. Assuming that the ring is smooth and axisymmetric, the total stellar mass in the structure may amount to ~2 × 108 Msolar up to~109 Msolar.

  18. Evaluation of GalaxyDock Based on the Community Structure-Activity Resource 2013 and 2014 Benchmark Studies.

    PubMed

    Shin, Woong-Hee; Lee, Gyu Rie; Seok, Chaok

    2016-06-27

    We analyze the results of the GalaxyDock protein-ligand docking program in the two recent experiments of Community Structure-Activity Resource (CSAR), CSAR 2013 and 2014. GalaxyDock performs global optimization of a modified AutoDock3 energy function by employing the conformational space annealing method. The energy function of GalaxyDock is quite sensitive to atomic clashes. Such energy functions can be effective for sampling physically correct conformations but may not be effective for scoring when conformations are not fully optimized. In phase 1 of CSAR 2013, we successfully selected all four true binders of digoxigenin along with three false positives. However, the energy values were rather high due to insufficient optimization of the conformations docked to homology models. A posteriori relaxation of the model complex structures by GalaxyRefine improved the docking energy values and differentiated the true binders from the false positives better. In the scoring test of CSAR 2013 phase 2, we selected the best poses for each of the two targets. The results of CSAR 2013 phase 3 suggested that an improved method for generating initial conformations for GalaxyDock is necessary for targets involving bulky ligands. Finally, combining existing binding information with GalaxyDock energy-based optimization may be needed for more accurate binding affinity prediction. PMID:26583962

  19. Structural and Functional Diversity of Acidic Scorpion Potassium Channel Toxins

    PubMed Central

    He, Ya-Wen; Pan, Na; Ding, Jiu-Ping; Cao, Zhi-Jian; Liu, Mai-Li; Li, Wen-Xin; Yi, Hong; Jiang, Ling; Wu, Ying-Liang

    2012-01-01

    Background Although the basic scorpion K+ channel toxins (KTxs) are well-known pharmacological tools and potential drug candidates, characterization the acidic KTxs still has the great significance for their potential selectivity towards different K+ channel subtypes. Unfortunately, research on the acidic KTxs has been ignored for several years and progressed slowly. Principal Findings Here, we describe the identification of nine new acidic KTxs by cDNA cloning and bioinformatic analyses. Seven of these toxins belong to three new α-KTx subfamilies (α-KTx28, α-KTx29, and α-KTx30), and two are new members of the known κ-KTx2 subfamily. ImKTx104 containing three disulfide bridges, the first member of the α-KTx28 subfamily, has a low sequence homology with other known KTxs, and its NMR structure suggests ImKTx104 adopts a modified cystine-stabilized α-helix-loop-β-sheet (CS-α/β) fold motif that has no apparent α-helixs and β-sheets, but still stabilized by three disulfide bridges. These newly described acidic KTxs exhibit differential pharmacological effects on potassium channels. Acidic scorpion toxin ImKTx104 was the first peptide inhibitor found to affect KCNQ1 channel, which is insensitive to the basic KTxs and is strongly associated with human cardiac abnormalities. ImKTx104 selectively inhibited KCNQ1 channel with a Kd of 11.69 µM, but was less effective against the basic KTxs-sensitive potassium channels. In addition to the ImKTx104 toxin, HeTx204 peptide, containing a cystine-stabilized α-helix-loop-helix (CS-α/α) fold scaffold motif, blocked both Kv1.3 and KCNQ1 channels. StKTx23 toxin, with a cystine-stabilized α-helix-loop-β-sheet (CS-α/β) fold motif, could inhibit Kv1.3 channel, but not the KCNQ1 channel. Conclusions/Significance These findings characterize the structural and functional diversity of acidic KTxs, and could accelerate the development and clinical use of acidic KTxs as pharmacological tools and potential drugs. PMID

  20. Heterometallic europium disiloxanediolates: synthesis, structural diversity, and photoluminescence properties.

    PubMed

    Rausch, Janek; Lorenz, Volker; Hrib, Cristian G; Frettlöh, Vanessa; Adlung, Matthias; Wickleder, Claudia; Hilfert, Liane; Jones, Peter G; Edelmann, Frank T

    2014-11-01

    This contribution presents a full account of a structurally diverse class of heterometallic europium disiloxanediolates. The synthetic protocol involves in situ metalation of (HO)SiPh2OSiPh2(OH) (1) with either (n)BuLi or KN(SiMe3)2 followed by treatment with EuCl3 in suitable solvents such as 1,2-dimethoxyethane (DME) or tetrahydrofuran (THF). Reaction of EuCl3 with 2 equiv of (LiO)SiPh2OSiPh2(OLi) in DME afforded the Eu(III) bis(disiloxanediolate) "ate" complex [{(Ph2SiO)2O}2{Li(DME)}3]EuCl2 (2), which upon attempted reduction with Zn gave the tris(disiloxanediolate) [{(Ph2SiO)2O}3{Li(DME)}3]Eu (3). Treatment of EuCl3 with (LiO)SiPh2OSiPh2(OLi) in a molar ratio of 1:2 yielded both the ate complex [{(Ph2SiO)2O}3Li{Li(THF)2}{Li(THF)}]EuCl·Li(THF)3 (4) and the LiCl-free europium(III) complex [{(Ph2SiO)2O}2{Li(THF)2}2]EuCl (5). Compound 5 was found to exhibit a brilliant red triboluminescence. When (KO)SiPh2OSiPh2(OK) was used as starting material in a 3:1 reaction with EuCl3, the Eu(III) tris(disiloxanediolate) [{(Ph2SiO)2O}3{K(DME)}3]Eu (6) was isolated. Attempted ligand transfer between 5 and (DAD(Dipp))2Ba(DME) (DAD(Dipp) = N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene) afforded the unique mixed-valent Eu(III)/Eu(II) disiloxanediolate cluster [(Ph2SiO)2O]6Eu(II)4Eu(III)2Li4O2Cl2 (7). All new complexes were structurally characterized by X-ray diffraction. Photoluminescence studies were carried out for complex 5 showing an excellent color quality, due to the strong (5)D0→(7)F2 transition, but a weak antenna effect. PMID:25330143

  1. Beyond spheroids and discs: classifications of CANDELS galaxy structure at 1.4 < z < 2 via principal component analysis

    NASA Astrophysics Data System (ADS)

    Peth, Michael A.; Lotz, Jennifer M.; Freeman, Peter E.; McPartland, Conor; Mortazavi, S. Alireza; Snyder, Gregory F.; Barro, Guillermo; Grogin, Norman A.; Guo, Yicheng; Hemmati, Shoubaneh; Kartaltepe, Jeyhan S.; Kocevski, Dale D.; Koekemoer, Anton M.; McIntosh, Daniel H.; Nayyeri, Hooshang; Papovich, Casey; Primack, Joel R.; Simons, Raymond C.

    2016-05-01

    Important but rare and subtle processes driving galaxy morphology and star formation may be missed by traditional spiral, elliptical, irregular or Sérsic bulge/disc classifications. To overcome this limitation, we use a principal component analysis (PCA) of non-parametric morphological indicators (concentration, asymmetry, Gini coefficient, M20, multimode, intensity and deviation) measured at rest-frame B band (corresponding to HST/WFC3 F125W at 1.4 1010 M⊙) galaxy morphologies. PCA quantifies the correlations between these morphological indicators and determines the relative importance of each. The first three principal components (PCs) capture ˜75 per cent of the variance inherent to our sample. We interpret the first PC as bulge strength, the second PC as dominated by concentration and the third PC as dominated by asymmetry. Both PC1 and PC2 correlate with the visual appearance of a central bulge and predict galaxy quiescence. PC1 is a better predictor of quenching than stellar mass, as good as other structural indicators (Sérsic-n or compactness). We divide the PCA results into groups using an agglomerative hierarchical clustering method. Unlike Sérsic, this classification scheme separates compact galaxies from larger, smooth protoelliptical systems, and star-forming disc-dominated clumpy galaxies from star-forming bulge-dominated asymmetric galaxies. Distinguishing between these galaxy structural types in a quantitative manner is an important step towards understanding the connections between morphology, galaxy assembly and star formation.

  2. THE IMPACT OF BARYON PHYSICS ON THE STRUCTURE OF HIGH-REDSHIFT GALAXIES

    SciTech Connect

    Zemp, Marcel; Gnedin, Oleg Y.; Gnedin, Nickolay Y.; Kravtsov, Andrey V.

    2012-03-20

    We study the detailed structure of galaxies at redshifts z {>=} 2 using cosmological simulations with improved modeling of the interstellar medium and star formation. The simulations follow the formation and dissociation of molecular hydrogen and include star formation only in cold molecular gas. The molecular gas is more concentrated toward the center of galaxies than the atomic gas, and as a consequence, the resulting stellar distribution is very compact. For halos with total mass above 10{sup 11} M{sub Sun }, the median half-mass radius of the stellar disks is 0.8 kpc at z Almost-Equal-To 3. The vertical structure of the molecular disk is much thinner than that of the atomic neutral gas. Relative to the non-radiative run, the inner regions of the dark matter halo change shape from prolate to mildly oblate and align with the stellar disk. However, we do not find evidence for a significant fast-rotating 'dark disk' of dark matter around the stellar disk. The outer halo regions retain the orientation acquired during accretion and mergers and are significantly misaligned with the inner regions. The radial profile of the dark matter halo contracts in response to baryon dissipation, establishing an approximately isothermal profile throughout most of the halo. This effect can be accurately described by a modified model of halo contraction. The angular momentum of a fixed amount of inner dark matter is approximately conserved over time, while in the dissipationless case most of it is transferred outward during mergers. The conservation of the dark matter angular momentum provides supporting evidence for the validity of the halo contraction model in a hierarchical galaxy formation process.

  3. Structure of the Galactic Bulge: Is the Milky Way a Double-barred Galaxy?

    NASA Astrophysics Data System (ADS)

    Nishiyama, Shogo; Nagata, Tetsuya; IRSF/SIRIUS Team

    2006-12-01

    Using the data of the IRSF/SIRIUS infrared survey along the Galactic plane (| l | <= 10.°5 at b = +1°), we find a distinct structure, which is probably a secondary bar, inside the primary bar of our Galaxy. The apparent magnitude peak of Bulge red clump stars changes continuously from KS ~ 13.5 (l = -10°) to KS ~ 12.3 (l = +10°), and this can be explained by the bar structure of the Galactic Bulge. However, the apparent magnitude changes by only ~ 0.1 mag over the central 8°, and this indicates that there is a distinct structure inside the primary bar. In the process of the distance derivation, we have used the infrared extinction law in the J, H, and KS bands toward the Galactic center newly determined from our survey.

  4. Structure Diversity, Synthesis, and Biological Activity of Cyathane Diterpenoids in Higher Fungi.

    PubMed

    Tang, Hao-Yu; Yin, Xia; Zhang, Cheng-Chen; Jia, Qian; Gao, Jin-Ming

    2015-01-01

    Cyathane diterpenoids, occurring exclusively in higher basidiomycete (mushrooms), represent a structurally diverse class of natural products based on a characteristic 5-6-7 tricyclic carbon scaffold, including 105 members reported to date. These compounds show a diverse range of biological activities, such as antimicrobial, anti-MRSA, agonistic toward the kappa-opioid receptor, antiinflammatory, anti-proliferative and nerve growth factor (NGF)-like properties. The present review focuses on the structure diversity, structure elucidation and biological studies of these compounds, including mechanisms of actions and structure-activity relationships (SARs). In addition, new progress in chemical synthesis of cyathane diterpenoids is discussed. PMID:25994862

  5. Prochlorococcus: the structure and function of collective diversity.

    PubMed

    Biller, Steven J; Berube, Paul M; Lindell, Debbie; Chisholm, Sallie W

    2015-01-01

    The marine cyanobacterium Prochlorococcus is the smallest and most abundant photosynthetic organism on Earth. In this Review, we summarize our understanding of the diversity of this remarkable phototroph and describe its role in ocean ecosystems. We discuss the importance of interactions of Prochlorococcus with the physical environment, with phages and with heterotrophs in shaping the ecology and evolution of this group. In light of recent studies, we have come to view Prochlorococcus as a 'federation' of diverse cells that sustains its broad distribution, stability and abundance in the oceans via extensive genomic and phenotypic diversity. Thus, it is proving to be a useful model system for elucidating the forces that shape microbial populations and ecosystems. PMID:25435307

  6. Genetic diversity and structure in two protected Posidonia oceanica meadows.

    PubMed

    Micheli, Carla; D'Esposito, Daniela; Belmonte, Alessandro; Peirano, Andrea; Valiante, Luigi Maria; Procaccini, Gabriele

    2015-08-01

    Posidonia oceanica meadows growing along the west Mediterranean coastline are under continuous anthropogenic pressure. The way meadow health correlates with genetic and genotypic diversity in P. oceanica, is still under debate. Here we report a microsatellite analysis of two P. oceanica meadows living in protected areas of the Ligurian (Monterosso al Mare, MPA of "Cinque Terre") and central Tyrrhenian Sea (Santa Marinella, regional Site of Community Importance). Both meadows were recently classified as "disturbed", according to shoot density and other phenological parameters. Between the two meadows, Santa Marinella showed higher genetic diversity, while clear genetic substructure was present in both sites, reflecting high spatial heterogeneity. The present study suggests that genetic diversity does not match unequivocally with shoot density and leaf morphology and that small scale intra-meadow heterogeneity is an important factor to consider for establishing the relation between genetic/genotypic variability and health of natural seagrass meadows. PMID:26164681

  7. VII Zw 403: H I STRUCTURE IN A BLUE COMPACT DWARF GALAXY

    SciTech Connect

    Simpson, Caroline E.; Ashley, Trisha; Hunter, Deidre A.; Nordgren, Tyler E.; Brinks, Elias; Elmegreen, Bruce G.; Lynds, Roger; O'Neil, Earl J.; McIntyre, Vince J.; Oestlin, Goeran; Westpfahl, David J.; Wilcots, Eric M.

    2011-09-15

    We present optical (UBVJ), ultraviolet (FUV, NUV), and high-resolution atomic hydrogen (H I) observations of the nearby blue compact dwarf (BCD), VII Zw 403. We find that VII Zw 403 has a relatively high H I mass-to-light ratio for a BCD. The rotation velocity is nominally 10-15 km s{sup -1}, but rises to {approx}20 km s{sup -1} after correction for the {approx}8-10 km s{sup -1} random motions present in the gas. The velocity field is complex, including a variation in the position angle of the major axis going from the northeast to the southwest parts of the galaxy. Our high-resolution H I maps reveal structure in the central gas, including a large, low-density H I depression or hole between the southern and northern halves of the galaxy, coincident with an unresolved X-ray source. Although interactions have been proposed as the triggering mechanism for the vigorous star formation occurring in BCDs, VII Zw 403 does not seem to have been tidally triggered by an external interaction, as we have found no nearby possible perturbers. It also does not appear to fall in the set of galaxies that exhibit a strong central mass density concentration, as its optical scale length is large in comparison to similar systems. However, there are some features that are compatible with an accretion event: optical/H I axis misalignment, a change in position angle of the kinematic axis, and a complex velocity field.

  8. Horizon Run 4 Simulation: Coupled Evolution of Galaxies and Large-Scale Structures of the Universe

    NASA Astrophysics Data System (ADS)

    Kim, Juhan; Park, Changbom; L'Huillier, Benjamin; Hong, Sungwook E.

    2015-08-01

    The Horizon Run 4 is a cosmological N-body simulation designed for the study of coupled evolution between galaxies and large-scale structures of the Universe, and for the test of galaxy formation models. Using 6300^3 gravitating particles in a cubic box of L_{box} = 3150 h^{-1} Mpc, we build a dense forest of halo merger trees to trace the halo merger history with a halo mass resolution scale down to M_s = 2.7 × 10^{11} h^{-1} M_⊙. We build a set of particle and halo data, which can serve as testbeds for comparison of cosmological models and gravitational theories with observations. We find that the FoF halo mass function shows a substantial deviation from the universal form with tangible redshift evolution of amplitude and shape. At higher redshifts, the amplitude of the mass function is lower, and the functional form is shifted toward larger values of ln (1/σ). We also find that the baryonic acoustic oscillation feature in the two-point correlation funct-ion of mock galaxies becomes broader with a peak position moving to smaller scales and the peak amplitude decreasing for increasing directional cosine mu compared to the linear predictions. From the halo merger trees built from halo data at 75 redshifts, we measure the half-mass epoch of halos and find that less massive halos tend to reach half of their current mass at higher redshifts. Simulation outputs including snapshot data, past lightcone space data, and halo merger data are available at http://sdss.kias.re.kr/astro/Horizon-Run4

  9. Structure and dynamics of elliptical galaxies; Proceedings of the IAU Symposium, Institute for Advanced Study, Princeton, NJ, May 27-31, 1986

    NASA Astrophysics Data System (ADS)

    de Zeeuw, Pieter Timotheus

    Various papers on the structure and dynamics of elliptical galaxies (EGs) are presented. The topics addressed include: cores of early-type galaxies, isophote shapes, distribution of light in the outer regions, stellar kinematics of EGs, manifold of EGs, properties of cD galaxies, compact EGs, dust and gas, ionized gas in EGs, properties of EGs with dust lanes, cold ISM in EGs, X-rays from EGs, star formation in cooling flows, mass distributions in EGs at large radii, line strength gradients in early-type galaxies, and population synthesis of composite systems. Also considered are: intrinsic shapes of EGs, orbits, dynamics in the centers of triaxial EGs, shells and potential wells of EGs, methods and models for spherical galaxies, dynamical models for axisymmetric and triaxial galaxies, N-body simulations of EGs, stability of EGs, formation and secular evolution of EGs, dissipationless formation of EGs, and dissipation and the formation of galaxies.

  10. Genetic diversity and population structure of cucumber (Cucumis sativus L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding genetic variation in germplasm collection is essential for the conservation and their efficient use in plant breeding. Cucumber is an important vegetable crop worldwide. Previous studies revealed a low genetic diversity in cucumber, but detailed insights into the crop’s genetic structu...

  11. Catalogue of the morphological features in the Spitzer Survey of Stellar Structure in Galaxies (S4G)

    NASA Astrophysics Data System (ADS)

    Herrera-Endoqui, M.; Díaz-García, S.; Laurikainen, E.; Salo, H.

    2015-10-01

    Context. A catalogue of the features for the complete Spitzer Survey of Stellar Structure in Galaxies (S4G), including 2352 nearby galaxies, is presented. The measurements are made using 3.6 μm images, largely tracing the old stellar population; at this wavelength the effects of dust are also minimal. The measured features are the sizes, ellipticities, and orientations of bars, rings, ringlenses, and lenses. Measured in a similar manner are also barlenses (lens-like structures embedded in the bars), which are not lenses in the usual sense, being rather the more face-on counterparts of the boxy/peanut structures in the edge-on view. In addition, pitch angles of spiral arm segments are measured for those galaxies where they can be reliably traced. More than one pitch angle may appear for a single galaxy. All measurements are made in a human-supervised manner so that attention is paid to each galaxy. Aims: We create a catalogue of morphological features in the complete S4G. Methods: We used isophotal analysis, unsharp masking, and fitting ellipses to measured structures. Results: We find that the sizes of the inner rings and lenses normalized to barlength correlate with the galaxy mass: the normalized sizes increase toward the less massive galaxies; it has been suggested that this is related to the larger dark matter content in the bar region in these systems. Bars in the low mass galaxies are also less concentrated, likely to be connected to the mass cut-off in the appearance of the nuclear rings and lenses. We also show observational evidence that barlenses indeed form part of the bar, and that a large fraction of the inner lenses in the non-barred galaxies could be former barlenses in which the thin outer bar component has dissolved. Full Tables 2 and 3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/582/A86

  12. VizieR Online Data Catalog: Galaxy structural parameters from 3.6um images (Kim+, 2014)

    NASA Astrophysics Data System (ADS)

    Kim, T.; Gadotti, D. A.; Sheth, K.; Athanassoula, E.; Bosma, A.; Lee, M. G.; Madore, B. F.; Elmegreen, B.; Knapen, J. H.; Zaritsky, D.; Ho, L. C.; Comeron, S.; Holwerda, B.; Hinz, J. L.; Munoz-Mateos, J.-C.; Cisternas, M.; Erroz-Ferrer, S.; Buta, R.; Laurikainen, E.; Salo, H.; Laine, J.; Menendez-Delmestre, K.; Regan, M. W.; de Swardt, B.; Gil de, Paz A.; Seibert, M.; Mizusawa, T.

    2016-03-01

    We select our samples from the Spitzer Survey of Stellar Structure in Galaxies (S4G; Sheth et al. 2010, cat. J/PASP/122/1397). We chose galaxies that had already been processed by the first three S4G pipelines (Pipelines 1, 2, and 3; Sheth et al. 2010, cat. J/PASP/122/1397) at the moment of this study (2011 November). In brief, Pipeline processes images and provides science-ready images. Pipeline 2 prepares mask images (to exclude foreground and background objects) for further analysis, and Pipeline 3 derives surface brightness profiles and total magnitudes using IRAF ellipse fits. We excluded highly inclined (b/a<0.5), significantly disturbed, very faint, or irregular galaxies. Galaxies were also discarded if their images are unsuitable for decomposition due to contamination such as a bright foreground star or significant stray light from stars in the IRAC scattering zones. Then we chose barred galaxies from all Hubble types from S0 to Sdm using the numerical Hubble types from Hyperleda (Paturel et al. 2003, cat. VII/237, VII/238). The assessment of the presence of a bar was done visually by K. Sheth, T. Kim, and B. de Swardt. Later, we also confirmed the presence of a bar by checking the mid-infrared classification (Buta et al. 2010, cat. J/ApJS/190/147; Buta et al. 2015, cat. J/ApJS/217/32). A total of 144 barred galaxies were selected that satisfy our criteria, and we list our sample in Table1 with basic information. Table2 presents the measures of structural parameters for all galaxies in the sample obtained from the 2D model fit with BUDDA (BUlge/disk Decomposition Analysis, de Souza et al., 2004ApJS..153..411D; Gadotti, 2008MNRAS.384..420G) code. (2 data files).

  13. Strong Evidence for the Density-wave Theory of Spiral Structure in Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Pour-Imani, Hamed; Kennefick, Daniel; Kennefick, Julia; Davis, Benjamin L.; Shields, Douglas W.; Shameer Abdeen, Mohamed

    2016-08-01

    The density-wave theory of galactic spiral-arm structure makes a striking prediction that the pitch angle of spiral arms should vary with the wavelength of the galaxy’s image. The reason is that stars are born in the density wave but move out of it as they age. They move ahead of the density wave inside the co-rotation radius, and fall behind outside of it, resulting in a tighter pitch angle at wavelengths that image stars (optical and near-infrared) than those that are associated with star formation (far-infrared and ultraviolet). In this study we combined large sample size with wide range of wavelengths, from the ultraviolet to the infrared to investigate this issue. For each galaxy we used an optical wavelength image (B-band: 445 nm) and images from the Spitzer Space Telescope at two infrared wavelengths (infrared: 3.6 and 8.0 μm) and we measured the pitch angle with the 2DFFT and Spirality codes. We find that the B-band and 3.6 μm images have smaller pitch angles than the infrared 8.0 μm image in all cases, in agreement with the prediction of density-wave theory. We also used images in the ultraviolet from Galaxy Evolution Explorer, whose pitch angles agreed with the measurements made at 8 μm.

  14. The internal structure and external feeding of the most massive protoclusters in the Galaxy

    NASA Astrophysics Data System (ADS)

    Ginsburg, Adam

    2015-08-01

    The most massive star clusters forming today go through a phase during which massive, luminous stars coexist with their birth molecular cloud. These clusters collect their mass from a surrounding region much larger than the final cluster size, and therefore their final mass is not set until their parent cloud is completely destroyed. The conditions at these early stages are crucial for determining the initial mass function and cluster structure. I will discuss a comparitive study of two of the most active cluster-forming regions in the Galaxy today, W51 and Sgr B2. In W51, two separate clusters of massive stars have formed within ~5 pc of each other, and both clusters are still accreting from their parent cloud. We observe the kinematics of the mostmassive stars in the central clusters and compare the luminosity and dynamically derived masses. In W51, the clusters are presently failing to disrupt their parent clouds, but supernovae will probably eventually remove the gas. In Sgr B2, the massive clusters are driving powerful bubbles, but the gas remains hot and molecular. Some of these bubbles may be driven by supernovae, making Sgr B2 the only region in our Galaxy where supernova feedback fails to halt star formation. The failure of different feedback mechanisms has important implications for the timescale of star formation, setting a lower limit that is in tension with the short single-burst models that fit more evolved young massive clusters.

  15. Structure of Dark Matter and Baryons in AMIBA SZE Galaxy Clusters (II)

    NASA Astrophysics Data System (ADS)

    Ho, Paul

    2010-01-01

    We propose deep BR_cz' imaging with Suprime-Cam of several hot X-ray (> 8 keV) clusters of galaxies for which Sunyaev-Zel'dovich effect (SZE) observations are underway at 3mm with the Array for Microwave Background Anisotropy (AMiBA) and superb resolution HST/ACS strong lensing (SL) data are readily available. Joint weak lensing (WL), SL, multicolor imaging, and SZE observations, combined with archival X-ray data, will probe in a model-independent manner the structure of dark matter, member galaxies, and the hot cluster gas in rich cluster environments. Our targets are composed of a class of the most massive clusters at moderate redshifts (0.2 <~ z <~ 0.7), allowing us to derive reliable WL shape measurements and thus accurate mass profiles out to the cluster virial radius. Our proposal aims to (1) map out the mass distribution in clusters via WL techniques, and compare with the distributions of hot and cold baryonic components, (2) make an accurate determination of the cluster mass profile from a joint WL+SL analysis, (3) derive cluster gas-mass fraction profiles free from the hydrostatic equilibrium assumption, and (4) examine directly the cluster mass vs. SZE observable relation, which will provide an important basis for cosmological tests with upcoming blind SZE surveys.

  16. GRAND DESIGN AND FLOCCULENT SPIRALS IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G)

    SciTech Connect

    Elmegreen, Debra Meloy; Yau, Andrew; Elmegreen, Bruce G.; Athanassoula, E.; Bosma, Albert; Helou, George; Sheth, Kartik; Ho, Luis C.; Madore, Barry F.; Menendez-Delmestre, KarIn; Gadotti, Dimitri A.; Knapen, Johan H.; Laurikainen, Eija; Salo, Heikki; Meidt, Sharon E.; Regan, Michael W.; Zaritsky, Dennis; Aravena, Manuel

    2011-08-10

    Spiral arm properties of 46 galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S{sup 4}G) were measured at 3.6 {mu}m, where extinction is small and the old stars dominate. The sample includes flocculent, multiple arm, and grand design types with a wide range of Hubble and bar types. We find that most optically flocculent galaxies are also flocculent in the mid-IR because of star formation uncorrelated with stellar density waves, whereas multiple arm and grand design galaxies have underlying stellar waves. Arm-interarm contrasts increase from flocculent to multiple arm to grand design galaxies and with later Hubble types. Structure can be traced further out in the disk than in previous surveys. Some spirals peak at mid-radius while others continuously rise or fall, depending on Hubble and bar type. We find evidence for regular and symmetric modulations of the arm strength in NGC 4321. Bars tend to be long, high amplitude, and flat-profiled in early-type spirals, with arm contrasts that decrease with radius beyond the end of the bar, and they tend to be short, low amplitude, and exponential-profiled in late Hubble types, with arm contrasts that are constant or increase with radius. Longer bars tend to have larger amplitudes and stronger arms.

  17. "No. 182. Grand Valley Diversion Dam. June, 1917. R.B.D." Structures ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "No. 182. Grand Valley Diversion Dam. June, 1917. R.B.D." Structures on the west side of the river below the dam are three bunkhouses, a mess hall, hospital, doctor's residence, engineer's residence, and outbuildings." - Grand Valley Diversion Dam, Half a mile north of intersection of I-70 & Colorado State Route 65, Cameo, Mesa County, CO

  18. Genetic diversity and population structure of cowpea (Vigna unguiculata L. Walp)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genetic diversity of cowpea was analyzed and the population structure was estimated in a diverse set of 768 cultivated cowpea genotypes from USDA GRIN cowpea collection, originally collected from 56 countries worldwide. Genotyping by sequencing was used to discover single nucleotide polymorphism...

  19. HOT X-RAY CORONAE AROUND MASSIVE SPIRAL GALAXIES: A UNIQUE PROBE OF STRUCTURE FORMATION MODELS

    SciTech Connect

    Bogdan, Akos; Forman, William R.; Vogelsberger, Mark; Sijacki, Debora; Mazzotta, Pasquale; Kraft, Ralph P.; Jones, Christine; David, Laurence P.; Bourdin, Herve; Gilfanov, Marat; Churazov, Eugene

    2013-08-01

    Luminous X-ray gas coronae in the dark matter halos of massive spiral galaxies are a fundamental prediction of structure formation models, yet only a few such coronae have been detected so far. In this paper, we study the hot X-ray coronae beyond the optical disks of two 'normal' massive spirals, NGC 1961 and NGC 6753. Based on XMM-Newton X-ray observations, hot gaseous emission is detected to {approx}60 kpc-well beyond their optical radii. The hot gas has a best-fit temperature of kT {approx} 0.6 keV and an abundance of {approx}0.1 Solar, and exhibits a fairly uniform distribution, suggesting that the quasi-static gas resides in hydrostatic equilibrium in the potential well of the galaxies. The bolometric luminosity of the gas in the (0.05-0.15)r{sub 200} region (r{sub 200} is the virial radius) is {approx}6 Multiplication-Sign 10{sup 40} erg s{sup -1} for both galaxies. The baryon mass fractions of NGC 1961 and NGC 6753 are f{sub b,NGC1961} {approx} 0.11 and f{sub b,NGC6753} {approx} 0.09, which values fall short of the cosmic baryon fraction. The hot coronae around NGC 1961 and NGC 6753 offer an excellent basis to probe structure formation simulations. To this end, the observations are confronted with the moving mesh code AREPO and the smoothed particle hydrodynamics code GADGET. Although neither model gives a perfect description, the observed luminosities, gas masses, and abundances favor the AREPO code. Moreover, the shape and the normalization of the observed density profiles are better reproduced by AREPO within {approx}0.5r{sub 200}. However, neither model incorporates efficient feedback from supermassive black holes or supernovae, which could alter the simulated properties of the X-ray coronae. With the further advance of numerical models, the present observations will be essential in constraining the feedback effects in structure formation simulations.

  20. COS-GTO: QSO Absorbers, Galaxies and Large-scale Structures in the Local Universe Part 2

    NASA Astrophysics Data System (ADS)

    Green, James

    2010-09-01

    This is a program to probe the large scale structure of baryons in the universe, including addressing questions of baryon fraction, physical conditions and relationships between absorbers and large-scale structures of galaxies. Besides these specific goals, this proposed GTO program also probes a large enough total path length in Ly alpha and OVI to add significantly to what STIS/FUSE has already observed. Several Galactic High Velocity Cloud Complexes also are probed by these sightlines, particularly the M Complex. The total path length of this proposed program for Ly alpha large-scale structure surveys is delta_z 5.5. We have selected a variety of targets to address these questions, under the following subcategories:1. Target 8 bright BL Lac objects to search for low contrast Ly alpha absorbers from the warm-hot interstellar medium {WHIM}. Science drivers: What are physical conditions and extent of warm-hot IGM in the current epoch? Can we discover metal-poor WHIM using very broad Ly alpha lines? What is the number density of such lines {dN/dz} and what is their relationship if any with tentative Chandra detections of even hotter gas?2. Ly alpha cloud sizes: The targets are a bright AGN pair which yield tangential distance separations of 100-500 kpc at z=0.01-0.05, where galaxy surveys are excellent. This pair has two filaments and two voids in this distance range. Science drivers: What are the characteristic sizes of Ly alpha absorbers, weak metal-line absorbers and absorbers in voids? Better size determinations will tighten current estimates of the baryon content of the photoionzed IGM .3. Probes of starburst outflows: The targets are bright AGN, <= 100 kpc in projection out of the minor axis of nearby starburst galaxies. Science drivers: Outflowing, unbound winds have been implicated as a primary mechanism to enrich the IGM in mass, metals and energy. But do starburst winds from massive galaxies escape the galaxy's gravitational potential? If so, what is the

  1. Structural Diversity of Eukaryotic Membrane Cytochrome P450s*

    PubMed Central

    Johnson, Eric F.; Stout, C. David

    2013-01-01

    X-ray crystal structures are available for 29 eukaryotic microsomal, chloroplast, or mitochondrial cytochrome P450s, including two non-monooxygenase P450s. These structures provide a basis for understanding structure-function relations that underlie their distinct catalytic activities. Moreover, structural plasticity has been characterized for individual P450s that aids in understanding substrate binding in P450s that mediate drug clearance. PMID:23632020

  2. Microsatellite diversity and genetic structure among common bean (Phaseolus vulgaris L.) landraces in Brazil, a secondary center of diversity

    PubMed Central

    Burle, Marília Lobo; Fonseca, Jaime Roberto; Kami, James A.

    2010-01-01

    Brazil is the largest producer and consumer of common bean (Phaseolus vulgaris L.), which is the most important source of human dietary protein in that country. This study assessed the genetic diversity and the structure of a sample of 279 geo-referenced common bean landraces from Brazil, using molecular markers. Sixty-seven microsatellite markers spread over the 11 linkage groups of the common bean genome, as well as Phaseolin, PvTFL1y, APA and four SCAR markers were used. As expected, the sample showed lower genetic diversity compared to the diversity in the primary center of diversification. Andean and Mesoamerican gene pools were both present but the latter gene pool was four times more frequent than the former. The two gene pools could be clearly distinguished; limited admixture was observed between these groups. The Mesoamerican group consisted of two sub-populations, with a high level of admixture between them leading to a large proportion of stabilized hybrids not observed in the centers of domestication. Thus, Brazil can be considered a secondary center of diversification of common bean. A high degree of genome-wide multilocus associations even among unlinked loci was observed, confirming the high level of structure in the sample and suggesting that association mapping should be conducted in separate Andean and Mesoamerican Brazilian samples. Electronic supplementary material The online version of this article (doi:10.1007/s00122-010-1350-5) contains supplementary material, which is available to authorized users. PMID:20502861

  3. Relationships between adaptive and neutral genetic diversity and ecological structure and functioning: a meta-analysis

    PubMed Central

    Whitlock, Raj

    2014-01-01

    Understanding the effects of intraspecific genetic diversity on the structure and functioning of ecological communities is a fundamentally important part of evolutionary ecology and may also have conservation relevance in identifying the situations in which genetic diversity coincides with species-level diversity.Early studies within this field documented positive relationships between genetic diversity and ecological structure, but recent studies have challenged these findings. Conceptual synthesis has been hampered because studies have used different measures of intraspecific variation (phenotypically adaptive vs. neutral) and have considered different measures of ecological structure in different ecological and spatial contexts. The aim of this study is to strengthen conceptual understanding by providing an empirical synthesis quantifying the relationship between genetic diversity and ecological structure.Here, I present a meta-analysis of the relationship between genetic diversity within plant populations and the structure and functioning of associated ecological communities (including 423 effect sizes from 70 studies). I used Bayesian meta-analyses to examine (i) the strength and direction of this relationship, (ii) the extent to which phenotypically adaptive and neutral (molecular) measures of diversity differ in their association with ecological structure and (iii) variation in outcomes among different measures of ecological structure and in different ecological contexts.Effect sizes measuring the relationship between adaptive diversity (genotypic richness) and both community- and ecosystem-level ecological responses were small, but significantly positive. These associations were supported by genetic effects on species richness and productivity, respectively.There was no overall association between neutral genetic diversity and measures of ecological structure, but a positive correlation was observed under a limited set of demographic conditions. These

  4. Long-lived Spiral Structure for Galaxies with Intermediate-size Bulges

    NASA Astrophysics Data System (ADS)

    Saha, Kanak; Elmegreen, Bruce

    2016-08-01

    Spiral structure in disk galaxies is modeled with nine collisionless N-body simulations including live disks, halos, and bulges with a range of masses. Two of these simulations make long-lasting and strong two-arm spiral wave modes that last for ∼5 Gyr with constant pattern speed. These two had a light stellar disk and the largest values of the Toomre Q parameter in the inner region at the time the spirals formed, suggesting the presence of a Q-barrier to wave propagation resulting from the bulge. The relative bulge mass in these cases is about 10%. Models with weak two-arm spirals had pattern speeds that followed the radial dependence of the Inner Lindblad Resonance.

  5. The structure and evolution of X-ray clusters of galaxies

    NASA Technical Reports Server (NTRS)

    Jones, C.

    1979-01-01

    The structure of clusters is described from observations at the Einstein Observatory. It was concluded that the nature of the X-ray emission is complex and varies from broad and highly clumped to smooth and centrally peaked. The clusters whose emission is clumped tend to be rich in spirals and to have X-ray temperatures in the few kilovolt range and low velocity dispersions. The smooth centrally peaked clusters are spiral poor, and have higher temperatures and larger velocity dispersions. For many of the clusters, the emission is irregular and cannot be described by the simple, spherically symmetric models for a hot isothermal or adiabatic gas. For these clusters, the low density, intracluster gas is influenced by the potential of individual bright galaxies.

  6. Long-lived Spiral Structure for Galaxies with Intermediate-size Bulges

    NASA Astrophysics Data System (ADS)

    Saha, Kanak; Elmegreen, Bruce

    2016-08-01

    Spiral structure in disk galaxies is modeled with nine collisionless N-body simulations including live disks, halos, and bulges with a range of masses. Two of these simulations make long-lasting and strong two-arm spiral wave modes that last for ˜5 Gyr with constant pattern speed. These two had a light stellar disk and the largest values of the Toomre Q parameter in the inner region at the time the spirals formed, suggesting the presence of a Q-barrier to wave propagation resulting from the bulge. The relative bulge mass in these cases is about 10%. Models with weak two-arm spirals had pattern speeds that followed the radial dependence of the Inner Lindblad Resonance.

  7. Spiral-like structure in the core of nearby galaxy clusters

    SciTech Connect

    Lagana, Tatiana F.; Andrade-Santos, Felipe; Lima Neto, Gastao B.

    2010-07-15

    Not surprisingly, with the very high angular resolution of the Chandra telescope, results revealed fairly complex structures in cluster cores to be more common than expected. In particular, understanding the nature of spiral-like features at the center of some clusters is the major motivation of this work. We present results from Chandra deep observations of 15 nearby galaxy clusters (0.01

  8. Constraints on a possible variation of the fine structure constant from galaxy cluster data

    NASA Astrophysics Data System (ADS)

    Holanda, R. F. L.; Landau, S. J.; Alcaniz, J. S.; Sánchez G., I. E.; Busti, V. C.

    2016-05-01

    We propose a new method to probe a possible time evolution of the fine structure constant α from X-ray and Sunyaev-Zel'dovich measurements of the gas mass fraction (fgas) in galaxy clusters. Taking into account a direct relation between variations of α and violations of the distance-duality relation, we discuss constraints on α for a class of dilaton runaway models. Although not yet competitive with bounds from high-z quasar absorption systems, our constraints, considering a sample of 29 measurements of fgas, in the redshift interval 0.14 < z < 0.89, provide an independent estimate of α variation at low and intermediate redshifts. Furthermore, current and planned surveys will provide a larger amount of data and thus allow to improve the limits on α variation obtained in the present analysis.

  9. The structure of the broad-line region in the Seyfert galaxy Markarian 590

    NASA Technical Reports Server (NTRS)

    Peterson, Bradley M.; Ali, Babar; Horne, Keith; Bertram, Ray; Lame, Nancy J.; Pogge, Richard W.; Wagner, R. M.

    1993-01-01

    We have undertaken a nine-month study of continuum and emission-line variability in the Seyfert galaxy Mrk 590 in order to determine the structure of the broad-line region. The H-beta variations are found to lag behind those of the optical continuum by about 19 days. We apply a maximum entropy method to solve for the transfer function which relates the line and continuum variability. This analysis suggests that there is a deficit of emission-line response due to gas along the line of sight to the continuum source, as in the case of NGC 5548, although these data do not allow us to reject with confidence models with significant line-of-sight response. We also show that the H-beta line variability is apparently confined to the core of the emission line, as suggested previously by Ferland, Korista, and Peterson (1990).

  10. Broad-line region structure and kinematics in the radio galaxy 3C 120

    NASA Astrophysics Data System (ADS)

    Kollatschny, W.; Ulbrich, K.; Zetzl, M.; Kaspi, S.; Haas, M.

    2014-06-01

    Context. Broad emission lines originate in the surroundings of supermassive black holes in the centers of active galactic nuclei (AGN). These broad-line emitting regions are spatially unresolved even for the nearest AGN. The origin and geometry of broad-line region (BLR) gas and their connection with geometrically thin or thick accretion disks is of fundamental importance for the understanding of AGN activity. Aims: One method to investigate the extent, structure, and kinematics of the BLR is to study the continuum and line profile variability in AGN. We selected the radio-loud Seyfert 1 galaxy 3C 120 as a target for this study. Methods: We took spectra with a high signal-to-noise ratio of 3C 120 with the 9.2 m Hobby-Eberly Telescope between Sept. 2008 and March 2009. In parallel, we photometrically monitored the continuum flux at the Wise observatory. We analyzed the continuum and line profile variations in detail (1D and 2D reverberation mapping) and modeled the geometry of the line-emitting regions based on the line profiles. Results: We show that the BLR in 3C 120 is stratified with respect to the distance of the line-emitting regions from the center with respect to the line widths (FWHM) of the rms profiles and with respect to the variability amplitude of the emission lines. The emission line wings of Hα and Hβ respond much faster than their central region. This is explained by accretion disk models. In addition, these lines show a stronger response in the red wings. However, the velocity-delay maps of the helium lines show a stronger response in the blue wing. Furthermore, the He ii λ4686 line responds faster in the blue wing in contradiction to observations made one and a half years later when the galaxy was in a lower state. The faster response in the blue wing is an indication for central outflow motions when this galaxy was in a bright state during our observations. The vertical BLR structure in 3C 120 coincides with that of other AGN. We confirm the

  11. WAXS studies of the structural diversity of hemoglobin in solution.

    SciTech Connect

    Makowski, L.; Bardhan, J.; Gore, D.; Lal, J.; Mandava, S.; Park, S.; Rodi, D. J.; Ho, N. T.; Ho, C.; Fischetti, R. F.

    2011-01-01

    Specific ligation states of hemoglobin are, when crystallized, capable of taking on multiple quaternary structures. The relationship between these structures, captured in crystal lattices, and hemoglobin structure in solution remains uncertain. Wide-angle X-ray solution scattering (WAXS) is a sensitive probe of protein structure in solution that can distinguish among similar structures and has the potential to contribute to these issues. We used WAXS to assess the relationships among the structures of human and bovine hemoglobins in different liganded forms in solution. WAXS data readily distinguished among the various forms of hemoglobins. WAXS patterns confirm some of the relationships among hemoglobin structures that have been defined through crystallography and NMR and extend others. For instance, methemoglobin A in solution is, as expected, nearly indistinguishable from HbCO A. Interestingly, for bovine hemoglobin, the differences between deoxy-Hb, methemoglobin and HbCO are smaller than the corresponding differences in human hemoglobin. WAXS data were also used to assess the spatial extent of structural fluctuations of various hemoglobins in solution. Dynamics has been implicated in allosteric control of hemoglobin, and increased dynamics has been associated with lowered oxygen affinity. Consistent with that notion, WAXS patterns indicate that deoxy-Hb A exhibits substantially larger structural fluctuations than HbCO A. Comparisons between the observed WAXS patterns and those predicted on the basis of atomic coordinate sets suggest that the structures of Hb in different liganded forms exhibit clear differences from known crystal structure.

  12. Structure Analysis Uncovers a Highly Diverse but Structurally Conserved Effector Family in Phytopathogenic Fungi

    PubMed Central

    Gracy, Jérome; Fournier, Elisabeth; Kroj, Thomas; Padilla, André

    2015-01-01

    Phytopathogenic ascomycete fungi possess huge effector repertoires that are dominated by hundreds of sequence-unrelated small secreted proteins. The molecular function of these effectors and the evolutionary mechanisms that generate this tremendous number of singleton genes are largely unknown. To get a deeper understanding of fungal effectors, we determined by NMR spectroscopy the 3-dimensional structures of the Magnaporthe oryzae effectors AVR1-CO39 and AVR-Pia. Despite a lack of sequence similarity, both proteins have very similar 6 β-sandwich structures that are stabilized in both cases by a disulfide bridge between 2 conserved cysteins located in similar positions of the proteins. Structural similarity searches revealed that AvrPiz-t, another effector from M. oryzae, and ToxB, an effector of the wheat tan spot pathogen Pyrenophora tritici-repentis have the same structures suggesting the existence of a family of sequence-unrelated but structurally conserved fungal effectors that we named MAX-effectors (Magnaporthe Avrs and ToxB like). Structure-informed pattern searches strengthened this hypothesis by identifying MAX-effector candidates in a broad range of ascomycete phytopathogens. Strong expansion of the MAX-effector family was detected in M. oryzae and M. grisea where they seem to be particularly important since they account for 5–10% of the effector repertoire and 50% of the cloned avirulence effectors. Expression analysis indicated that the majority of M. oryzae MAX-effectors are expressed specifically during early infection suggesting important functions during biotrophic host colonization. We hypothesize that the scenario observed for MAX-effectors can serve as a paradigm for ascomycete effector diversity and that the enormous number of sequence-unrelated ascomycete effectors may in fact belong to a restricted set of structurally conserved effector families. PMID:26506000

  13. THE ZURICH ENVIRONMENTAL STUDY OF GALAXIES IN GROUPS ALONG THE COSMIC WEB. III. GALAXY PHOTOMETRIC MEASUREMENTS AND THE SPATIALLY RESOLVED COLOR PROPERTIES OF EARLY- AND LATE-TYPE SATELLITES IN DIVERSE ENVIRONMENTS

    SciTech Connect

    Cibinel, A.; Carollo, C. M.; Lilly, S. J.; Miniati, F.; Pipino, A.; Cameron, E.; Peng, Y.; Rudick, C. S.; Bonoli, S.; Silverman, J. D.; Van Gorkom, J. H.; Finoguenov, A.; Norberg, P. E-mail: marcella@phys.ethz.ch

    2013-11-10

    We present photometric measurements for the galaxies—and when possible their bulges and disks—in the 0.05 < z < 0.0585 groups of the Zurich Environmental Study (ZENS); these measurements include (B – I) colors, color gradients and maps, color dispersions, as well as stellar masses and star formation rates. The ZENS galaxies are classified into quenched, moderately star-forming, and strongly star-forming using a combination of spectral features and far-UV-to-optical colors; this approach optimally distinguishes quenched systems from dust-reddened star-forming galaxies. The latter contribute up to 50% to the (B – I) 'red sequence' at ∼10{sup 10} M{sub ☉}. At fixed morphological or spectral type, we find that galaxy stellar masses are largely independent of environment, and especially of halo mass. As a first utilization of our photometric database, we study, at fixed stellar mass and Hubble type, how (B – I) colors, color gradients, and color dispersion of disk satellites depend on group mass M{sub GROUP}, group-centric distance R/R{sub 200}, and large-scale structure overdensity δ{sub LSS}. The strongest environmental trend is found for disk-dominated satellites with M{sub GROUP} and R/R{sub 200}. At M ∼< 10{sup 10} M{sub ☉}, disk-dominated satellites are redder in the inner regions of the groups than in the outer parts. At M ∼> 10{sup 10} M{sub ☉}, these satellites have shallower color gradients in higher mass groups and in the cores of groups compared with lower mass groups and the outskirts of groups. Stellar population analyses and semi-analytic models suggest that disk-dominated satellites undergo quenching of star formation in their outer disks, on timescales τ{sub quench} ∼ 2 Gyr, as they progressively move inside the group potential.

  14. The Zurich Environmental Study of Galaxies in Groups along the Cosmic Web. III. Galaxy Photometric Measurements and the Spatially Resolved Color Properties of Early- and Late-type Satellites in Diverse Environments

    NASA Astrophysics Data System (ADS)

    Cibinel, A.; Carollo, C. M.; Lilly, S. J.; Bonoli, S.; Miniati, F.; Pipino, A.; Silverman, J. D.; van Gorkom, J. H.; Cameron, E.; Finoguenov, A.; Norberg, P.; Peng, Y.; Rudick, C. S.

    2013-11-01

    We present photometric measurements for the galaxies—and when possible their bulges and disks—in the 0.05 < z < 0.0585 groups of the Zurich Environmental Study (ZENS); these measurements include (B - I) colors, color gradients and maps, color dispersions, as well as stellar masses and star formation rates. The ZENS galaxies are classified into quenched, moderately star-forming, and strongly star-forming using a combination of spectral features and far-UV-to-optical colors; this approach optimally distinguishes quenched systems from dust-reddened star-forming galaxies. The latter contribute up to 50% to the (B - I) "red sequence" at ~1010 M ⊙. At fixed morphological or spectral type, we find that galaxy stellar masses are largely independent of environment, and especially of halo mass. As a first utilization of our photometric database, we study, at fixed stellar mass and Hubble type, how (B - I) colors, color gradients, and color dispersion of disk satellites depend on group mass M GROUP, group-centric distance R/R 200, and large-scale structure overdensity δLSS. The strongest environmental trend is found for disk-dominated satellites with M GROUP and R/R 200. At M <~ 1010 M ⊙, disk-dominated satellites are redder in the inner regions of the groups than in the outer parts. At M >~ 1010 M ⊙, these satellites have shallower color gradients in higher mass groups and in the cores of groups compared with lower mass groups and the outskirts of groups. Stellar population analyses and semi-analytic models suggest that disk-dominated satellites undergo quenching of star formation in their outer disks, on timescales τquench ~ 2 Gyr, as they progressively move inside the group potential. Based on observations collected at the European Southern Observatory, La Silla Chile. Program ID 177.A-0680.

  15. Global-, local-, and intermediate-scale structures in prototype spiral galaxies

    NASA Technical Reports Server (NTRS)

    Roberts, William W., Jr.

    1993-01-01

    The relationship between galactic spiral structure and the matter in the underlying disk constitutes one of the central problems in galactic dynamics. In Bertin et al. (1989), disk matter characterized by a low-dispersive speed is shown to be capable of playing a key role in the generation of large-scale spiral structure. In Roberts et al. (1992), this self-gravitating, low-dispersion disk matter is shown to be capable of playing an essential role in the formation of structure on local and intermediate scales. Both in computed cases where large-scale spiral structure is present and in those where it is not, the same dominant physical processes and fundamental dynamical mechanisms are active on local scales. The new perception, in which large-scale and small-scale phenomena operate somewhat independently as evidenced in the computational studies, permits a range of flocculent, multiarmed, and grand design spiral types to be simulated. In particular, grand design galaxies with ragged appearances exhibiting spurs, arm branchings, and interarm bridges in addition to the major spiral arms, similar to those often observed, can be generated.

  16. Large-scale power spectrum and structures from the ENEAR galaxy peculiar velocity catalogue

    NASA Astrophysics Data System (ADS)

    Zaroubi, S.; Bernardi, M.; da Costa, L. N.; Hoffman, Y.; Alonso, M. V.; Wegner, G.; Willmer, C. N. A.; Pellegrini, P. S.

    2001-09-01

    We estimate the mass density fluctuations power spectrum (PS) on large scales by applying a maximum likelihood technique to the peculiar velocity data of the recently completed redshift-distance survey of early-type galaxies (hereafter ENEAR). Parametric cold dark matter (CDM)-like models for the PS are assumed, and the best-fitting parameters are determined by maximizing the probability of the model given the measured peculiar velocities of the galaxies, their distances and estimated errors. The method has been applied to CDM models with and without COBE normalization. The general results are in agreement with the high-amplitude power spectra found from similar analyses of other independent all-sky catalogue of peculiar velocity data such as MARK III and SFI, in spite of the differences in the way these samples were selected, the fact that they probe different regions of space and galaxy distances are computed using different distance relations. For example, at k=0.1hMpc-1 the power spectrum value is P(k)Ω1.2=(6.5+/-3)×103(h- 1Mpc)3 and η8≡σ8Ω0.6=1.1- 0.35+0.2 the quoted uncertainties refer to 3σ error level. We also find that, for ΛCDM and OCDM COBE-normalized models, the best-fitting parameters are confined by a contour approximately defined by Ωh1.3=0.377+/-0.08 and Ωh0.88=0.517+/-0.083 respectively. Γ-shape models, free of COBE normalization, result in the weak constraint of Γ>=0.17 and in the rather stringent constraint of η8=1.0+/-0.25. All quoted uncertainties refer to 3σ confidence level (c.l.). The calculated PS has been used as a prior for Wiener reconstruction of the density field at different resolutions and the three-dimensional velocity field within a volume of radius ~80h-1Mpc. All major structures in the nearby Universe are recovered and are well matched to those predicted from all-sky redshift surveys. The robustness of these features has been tested with constrained realizations (CR). Analysis of the reconstructed three

  17. Exploring Optically Compact Dwarf Galaxies for Kinematic Structures and Extended HI Halos

    NASA Astrophysics Data System (ADS)

    Most, Hans; Cannon, J. M.; Salzer, J. J.; Rosenberg, J. L.

    2012-01-01

    We present Very Large Array H I spectral line and optical imaging of eight optically compact (optical radii <1 kpc), star-forming dwarf galaxies. These galaxies were chosen because of their optically compact stellar distributions, faint blue magnitudes, ongoing star formation, and relative proximity. The sample includes ADBS 113845+2008, which was found to have an HI halo that extends nearly 40 optical scale lengths from the stellar body (Cannon et al. 2009). Using this larger sample, we are working to discern if the "giant gas disk" dwarf galaxy is common or rare. We are also exploring the kinematics and dark matter contents of each of the sample galaxies.

  18. Protein structure prediction enhanced with evolutionary diversity : SPEED.

    SciTech Connect

    DeBartolo, J.; Hocky, G.; Wilde, M.; Xu, J.; Freed, K. F.; Sosnick, T. R.; Univ. of Chicago; Toyota Technological Inst. at Chicago

    2010-03-01

    For naturally occurring proteins, similar sequence implies similar structure. Consequently, multiple sequence alignments (MSAs) often are used in template-based modeling of protein structure and have been incorporated into fragment-based assembly methods. Our previous homology-free structure prediction study introduced an algorithm that mimics the folding pathway by coupling the formation of secondary and tertiary structure. Moves in the Monte Carlo procedure involve only a change in a single pair of {phi},{psi} backbone dihedral angles that are obtained from a Protein Data Bank-based distribution appropriate for each amino acid, conditional on the type and conformation of the flanking residues. We improve this method by using MSAs to enrich the sampling distribution, but in a manner that does not require structural knowledge of any protein sequence (i.e., not homologous fragment insertion). In combination with other tools, including clustering and refinement, the accuracies of the predicted secondary and tertiary structures are substantially improved and a global and position-resolved measure of confidence is introduced for the accuracy of the predictions. Performance of the method in the Critical Assessment of Structure Prediction (CASP8) is discussed.

  19. MID-INFRARED GALAXY MORPHOLOGY FROM THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G): THE IMPRINT OF THE DE VAUCOULEURS REVISED HUBBLE-SANDAGE CLASSIFICATION SYSTEM AT 3.6 {mu}m

    SciTech Connect

    Buta, Ronald J.; Sheth, Kartik; Aravena, Manuel; Hinz, Joannah L.; Gil de Paz, Armando; Munoz-Mateos, Juan-Carlos; Laurikainen, Eija; Salo, Heikki; Gadotti, Dimitri A.; Athanassoula, E.; Bosma, Albert; Elmegreen, Debra M.; Masters, Karen L.; Comeron, Sebastien

    2010-09-15

    Spitzer Space Telescope Infrared Array Camera imaging provides an opportunity to study all known morphological types of galaxies in the mid-IR at a depth significantly better than ground-based near-infrared and optical images. The goal of this study is to examine the imprint of the de Vaucouleurs classification volume in the 3.6 {mu}m band, which is the best Spitzer waveband for galactic stellar mass morphology owing to its depth and its reddening-free sensitivity mainly to older stars. For this purpose, we have prepared classification images for 207 galaxies from the Spitzer archive, most of which are formally part of the Spitzer Survey of Stellar Structure in Galaxies (S{sup 4}G), a Spitzer post-cryogenic ('warm') mission Exploration Science Legacy Program survey of 2331 galaxies closer than 40 Mpc. For the purposes of morphology, the galaxies are interpreted as if the images are blue light, the historical waveband for classical galaxy classification studies. We find that 3.6 {mu}m classifications are well correlated with blue-light classifications, to the point where the essential features of many galaxies look very similar in the two very different wavelength regimes. Drastic differences are found only for the most dusty galaxies. Consistent with a previous study by Eskridge et al., the main difference between blue-light and mid-IR types is an {approx}1 stage interval difference for S0/a to Sbc or Sc galaxies, which tend to appear 'earlier' in type at 3.6 {mu}m due to the slightly increased prominence of the bulge, the reduced effects of extinction, and the reduced (but not completely eliminated) effect of the extreme population I stellar component. We present an atlas of all of the 207 galaxies analyzed here and bring attention to special features or galaxy types, such as nuclear rings, pseudobulges, flocculent spiral galaxies, I0 galaxies, double-stage and double-variety galaxies, and outer rings, that are particularly distinctive in the mid-IR.

  20. DISSECTING EARLY-TYPE DWARF GALAXIES INTO THEIR MULTIPLE COMPONENTS

    SciTech Connect

    Janz, J.; Laurikainen, E.; Salo, H.; Lisker, T.; Peletier, R. F.; Den Brok, M.; Niemi, S.-M.; Toloba, E.; Hensler, G.

    2012-02-15

    Early-type dwarf galaxies, once believed to be simple systems, have recently been shown to exhibit an intriguing diversity in structure and stellar content. To analyze this further, we started the SMAKCED project (Stellar content, MAss and Kinematics of Cluster Early-type Dwarfs, http://www.smakced.net) and obtained deep H-band images for 101 early-type dwarf galaxies in the Virgo Cluster in a brightness range of -19 mag {<=} M{sub r} {<=} -16 mag, typically reaching a signal-to-noise ratio of 1 per pixel of {approx}0.''25 at surface brightnesses {approx}22.5 mag arcsec{sup -2} in the H band. Here we present the first results of decomposing their two-dimensional light distributions. This is the first study dedicated to early-type dwarf galaxies using the two-dimensional multi-component decomposition approach, which has been proven to be important for giant galaxies. Armed with this new technique, we find more structural components than previous studies: only a quarter of the galaxies fall into the simplest group, namely, those represented by a single Sersic function, optionally with a nucleus. Furthermore, we find a bar fraction of 18%. We also detect a similar fraction of lenses which appear as shallow structures with sharp outer edges. Galaxies with bars and lenses are found to be more concentrated toward the Virgo galaxy center than the other sample galaxies.

  1. The physical structure of radio galaxies explored with three-dimensional simulations

    NASA Astrophysics Data System (ADS)

    Donohoe, Justin; Smith, Michael D.

    2016-05-01

    We present a large systematic study of hydrodynamic simulations of supersonic adiabatic jets in three dimensions to provide a definitive set of results on exploring jet density, Mach number and precession angle as variables. We restrict the set-up to non-relativistic pressure-equilibrium flows into a homogeneous environment. We first focus on the distribution and evolution of physical parameters associated with radio galaxies. We find that the jet density has limited influence on the structure for a given jet Mach number. The speed of advance varies by a small factor for jet densities between 0.1 and 0.0001 of the ambient density while the cocoon and cavity evolution change from narrow pressure balanced to wide overpressure as the ratio falls. We also find that the fraction of energy transferred to the ambient medium increases with decreasing jet-ambient density ratio, reaching ≈80 per cent. This energy is predominantly in thermal energy with almost all the remainder in ambient kinetic form. The total energy remaining in the lobe is typically under 5 per cent. We find that radio galaxies with wide transverse cocoons can be generated through slow precession at low Mach numbers. We explore a slow precession model in which the jet direction changes very slowly relative to the jet flow dynamical time. This reveals two separated bow shocks propagating into the ambient medium, one associated with the entire lobe expansion and the other with the immediate impact zone. The lobes generated are generally consistent with observations, displaying straight jets but asymmetric lobes.

  2. Structural parameters and blue stragglers in Sagittarius dwarf spheroidal galaxy globular clusters

    NASA Astrophysics Data System (ADS)

    Salinas, Ricardo; Jílková, Lucie; Carraro, Giovanni; Catelan, Márcio; Amigo, Pía.

    2012-04-01

    We present BV photometry of four Sagittarius dwarf spheroidal galaxy globular clusters: Arp 2, NGC 5634, Palomar 12 and Terzan 8, obtained with the Danish Telescope at ESO La Silla. We measure the structural parameters of the clusters using a King profile fitting, obtaining the first reliable measurements of the tidal radius of Arp 2 and Terzan 8. These two clusters are remarkably extended and with low concentrations; with a concentration of only c= 0.41 ± 0.02, Terzan 8 is less concentrated than any cluster in our Galaxy. Blue stragglers are identified in the four clusters, and their spatial distribution is compared to those of horizontal branch and red giant branch stars. The blue straggler properties do not provide evidence of mass segregation in Terzan 8, while Arp 2 probably shares the same status, although with less confidence. In the case of NGC 5634 and Palomar 12, blue stragglers are significantly less populous, and their analysis suggests that the two clusters have probably undergone mass segregation. References: (1) Peterson (1976); (2) Kron, Hewitt & Wasserman (1984); (3) Chernoff & Djorgovski (1989); (4) Trager, Djorgovski & King (1993); (5) Trager et al. (1995); (6) Rosenberg et al. (1998); (7) Mackey & Gilmore (2003b); (8) McLaughlin & van der Marel (2005) and (9) Carballo-Bello et al. (2012).

  3. EVIDENCE OF QUASI-LINEAR SUPER-STRUCTURES IN THE COSMIC MICROWAVE BACKGROUND AND GALAXY DISTRIBUTION

    SciTech Connect

    Inoue, Kaiki Taro; Sakai, Nobuyuki; Tomita, Kenji

    2010-11-20

    Recent measurements of hot and cold spots on the cosmic microwave background (CMB) sky suggest the presence of super-structures on (>100 h {sup -1} Mpc) scales. We develop a new formalism to estimate the expected amplitude of temperature fluctuations due to the integrated Sachs-Wolfe (ISW) effect from prominent quasi-linear structures. Applying the developed tools to the observed ISW signals from voids and clusters in catalogs of galaxies at redshifts z < 1, we find that they indeed imply a presence of quasi-linear super-structures with a comoving radius of 100 {approx} 300 h {sup -1} Mpc and a density contrast |{delta}| {approx} O(0.1). We also find that the observed ISW signals are at odds with the concordant {Lambda} cold dark matter model that predicts Gaussian primordial perturbations at {approx}>3{sigma} level. We confirm that the mean temperature around the CMB cold spot in the southern Galactic hemisphere filtered by a compensating top-hat filter deviates from the mean value at {approx}3{sigma} level, implying that a quasi-linear supervoid or an underdensity region surrounded by a massive wall may reside at low redshifts z < 0.3 and the actual angular size (16{sup 0}-17{sup 0}) may be larger than the apparent size (4{sup 0}-10{sup 0}) discussed in literature. Possible solutions are briefly discussed.

  4. Formation of S0 galaxies through mergers. Bulge-disc structural coupling resulting from major mergers

    NASA Astrophysics Data System (ADS)

    Querejeta, M.; Eliche-Moral, M. C.; Tapia, T.; Borlaff, A.; Rodríguez-Pérez, C.; Zamorano, J.; Gallego, J.

    2015-01-01

    Context. Observations reveal a strong structural coupling between bulge and disc in S0 galaxies, which seems difficult to explain if they have formed from supposedly catastrophic events such as major mergers. Aims: We face this question by quantifying the bulge-disc coupling in dissipative simulations of major and minor mergers that result in realistic S0s. Methods: We have studied the dissipative N-body binary merger simulations from the GalMer database that give rise to realistic, relaxed E/S0 and S0 remnants (67 major and 29 minor mergers). We simulate surface brightness profiles of these S0-like remnants in the K band, mimicking typical observational conditions, to perform bulge-disc decompositions analogous to those carried out in real S0s. Additional components have been included when needed. The global bulge-disc structure of these remnants has been compared with real data. Results: The S0-like remnants distribute in the B/T - re - hd parameter space consistently with real bright S0s, where B/T is the bulge-to-total luminosity ratio, re is the bulge effective radius, and hd is the disc scalelength. Major mergers can rebuild a bulge-disc coupling in the remnants after having destroyed the structures of the progenitors, whereas minor mergers directly preserve them. Remnants exhibit B/T and re/hd spanning a wide range of values, and their distribution is consistent with observations. Many remnants have bulge Sérsic indices ranging 1 structures in less than ~3 Gyr. The bulge-disc coupling and the presence of pseudobulges in real S0s cannot be used as an argument against the possible major-merger origin of these galaxies. Table 3 is available in electronic form at http://www.aanda.org

  5. A New Outer Galaxy Molecular Cloud Catalog: Applications to Galactic Structure

    NASA Astrophysics Data System (ADS)

    Kerton, C. R.; Brunt, C. M.; Pomerleau, C.

    2001-12-01

    We have generated a new molecular cloud catalog from a reprocessed version of the Five College Radio Astronomy (FCRAO) Observatory Outer Galaxy Survey (OGS) of 12CO (J=1--0) emission. The catalog has been used to develop a technique that uses the observed angular size-linewidth relation (ASLWR) as a distance indicator to molecular cloud ensembles. The new technique is a promising means to map out the large-scale structure of our Galaxy using the new high spatial dynamic range CO surveys currently available. The catalog was created using a two-stage object-identification algorithm. We first identified contiguous emission structures of a specified minimum number of pixels above a specified temperature threshold. Each structure so defined was then examined and localized emission enhancements within each structure were identified as separate objects. The resulting cloud catalog, contains basic data on 14595 objects. From the OGS we identified twenty-three cloud ensembles. For each, bisector fits to angular size vs. linewidth plots were made. The fits vary in a systematic way that allows a calibration of the fit parameters with distance to be made. Our derived distances to the ensembles are consistent with the distance to the Perseus Arm, and the accurate radial velocity measurements available from the same data are in accord with the known non-circular motions at the location of the Perseus Arm. The ASLWR method was also successfully applied to data from the Boston University/FCRAO Galactic Ring Survey (GRS) of 13CO(J=1--0) emission. Based upon our experience with the GRS and OGS, the ASLWR technique should be usable in any data set with sufficient spatial dynamic range to allow it to be properly calibrated. C.P. participated in this study through the Women in Engineering and Science (WES) program of NRC Canada. The Dominion Radio Astrophysical Observatory is a National Facility operated by the National Research Council. The Canadian Galactic Plane Survey is a Canadian

  6. Kdo2-lipid A: structural diversity and impact on immunopharmacology

    PubMed Central

    Wang, Xiaoyuan; Quinn, Peter J; Yan, Aixin

    2015-01-01

    3-deoxy-d-manno-octulosonic acid-lipid A (Kdo2-lipid A) is the essential component of lipopolysaccharide in most Gram-negative bacteria and the minimal structural component to sustain bacterial viability. It serves as the active component of lipopolysaccharide to stimulate potent host immune responses through the complex of Toll-like-receptor 4 (TLR4) and myeloid differentiation protein 2. The entire biosynthetic pathway of Escherichia coli Kdo2-lipid A has been elucidated and the nine enzymes of the pathway are shared by most Gram-negative bacteria, indicating conserved Kdo2-lipid A structure across different species. Yet many bacteria can modify the structure of their Kdo2-lipid A which serves as a strategy to modulate bacterial virulence and adapt to different growth environments as well as to avoid recognition by the mammalian innate immune systems. Key enzymes and receptors involved in Kdo2-lipid A biosynthesis, structural modification and its interaction with the TLR4 pathway represent a clear opportunity for immunopharmacological exploitation. These include the development of novel antibiotics targeting key biosynthetic enzymes and utilization of structurally modified Kdo2-lipid A or correspondingly engineered live bacteria as vaccines and adjuvants. Kdo2-lipid A/TLR4 antagonists can also be applied in anti-inflammatory interventions. This review summarizes recent knowledge on both the fundamental processes of Kdo2-lipid A biosynthesis, structural modification and immune stimulation, and applied research on pharmacological exploitations of these processes for therapeutic development. PMID:24838025

  7. The Impact of Spatial Structure on Viral Genomic Diversity Generated during Adaptation to Thermal Stress

    PubMed Central

    Ally, Dilara; Wiss, Valorie R.; Deckert, Gail E.; Green, Danielle; Roychoudhury, Pavitra; Wichman, Holly A.; Brown, Celeste J.; Krone, Stephen M.

    2014-01-01

    Background Most clinical and natural microbial communities live and evolve in spatially structured environments. When changes in environmental conditions trigger evolutionary responses, spatial structure can impact the types of adaptive response and the extent to which they spread. In particular, localized competition in a spatial landscape can lead to the emergence of a larger number of different adaptive trajectories than would be found in well-mixed populations. Our goal was to determine how two levels of spatial structure affect genomic diversity in a population and how this diversity is manifested spatially. Methodology/Principal Findings We serially transferred bacteriophage populations growing at high temperatures (40°C) on agar plates for 550 generations at two levels of spatial structure. The level of spatial structure was determined by whether the physical locations of the phage subsamples were preserved or disrupted at each passage to fresh bacterial host populations. When spatial structure of the phage populations was preserved, there was significantly greater diversity on a global scale with restricted and patchy distribution. When spatial structure was disrupted with passaging to fresh hosts, beneficial mutants were spread across the entire plate. This resulted in reduced diversity, possibly due to clonal interference as the most fit mutants entered into competition on a global scale. Almost all substitutions present at the end of the adaptation in the populations with disrupted spatial structure were also present in the populations with structure preserved. Conclusions/Significance Our results are consistent with the patchy nature of the spread of adaptive mutants in a spatial landscape. Spatial structure enhances diversity and slows fixation of beneficial mutants. This added diversity could be beneficial in fluctuating environments. We also connect observed substitutions and their effects on fitness to aspects of phage biology, and we provide

  8. Host Galaxies of Luminous Quasars: Structural Properties and the Fundamental Plane

    NASA Astrophysics Data System (ADS)

    Wolf, Marsha J.; Sheinis, Andrew I.

    2008-10-01

    We present stellar velocity dispersion measurements in the host galaxies of ten luminous quasars (MV < -23) using the Ca H&K lines in off-nuclear spectra. We combine these data with effective radii and magnitudes from the literature to place the host galaxies on the fundamental plane (FP) where their properties are compared with other types of galaxies. We find that the radio-loud (RL) QSO hosts have similar properties to massive elliptical galaxies, while the radio-quiet (RQ) hosts are more similar to intermediate-mass galaxies. The RL hosts lie at the upper extreme of the FP due to their large velocity dispersions (langσ*rang = 321 km s-1), low surface brightness (langμ e (r)rang = 20.8 mag arcsec-2), and large effective radii (langRe rang = 11.4 kpc), and have langM *rang = 1.5 × 1012 M sun and langM/Lrang = 12.4. In contrast, properties of the RQ hosts are langσ*rang = 241 km s-1, langM *rang = 4.4 × 1011 M sun, and M/L ~ 5.3. The distinction between these galaxies occurs at σ*~ 300 km s-1, Re ~ 6 kpc, and corresponding M * ~ 5.9 ± 3.5 × 1011 M sun. Our data support previous results that Palomar-Green QSOs are related to gas-rich galaxy mergers that form intermediate-mass galaxies, while RL QSOs reside in massive early-type galaxies, most of which also show signs of recent mergers or interactions. Previous authors have drawn these conclusions by using estimates of the black hole mass and inferring host galaxy properties from that, while here we have relied purely on directly measured host galaxy properties.

  9. Galaxy morphologies in the era of big-data surveys

    NASA Astrophysics Data System (ADS)

    Huertas-Company, M.

    Galaxy morphology is a first-order descriptor of a galaxy and a useful proxy to identify physical processes. The 100 years old Hubble fork describes the structural diversity of galaxies in the local universe. Unveiling the origins of this galaxy zoology is a key challenge in galaxy evolution. In this review talk, I first summarized some key advances in our understanding of the morphological evolution of galaxies from z ~ 0 to z ~ 3, thank you in particular to the SDSS and HST legacies. In the second part, I focused on the classification techniques. With the emergence in the last years of large surveys the samples of study have increased by several orders of magnitude going from a few tens to several millions of objects. This trend will clearly continue in the next decade with coming surveys/missions such as EUCLID and WFIRST. While galaxy classification is still a required step in any survey, visual inspection of galaxies is becoming prohibitively time-consuming. Under these circumstances, the techniques used to estimate galaxy morphologies need to be updated.

  10. Presentation of a structurally diverse and commercially available drug data set for correlation and benchmarking studies.

    PubMed

    Sköld, Christian; Winiwarter, Susanne; Wernevik, Johan; Bergström, Fredrik; Engström, Leif; Allen, Ruth; Box, Karl; Comer, John; Mole, Jon; Hallberg, Anders; Lennernäs, Hans; Lundstedt, Torbjörn; Ungell, Anna-Lena; Karlén, Anders

    2006-11-16

    A multivariate analysis of drugs on the Swedish market was the basis for the selection of a small, physicochemically diverse set of 24 drug compounds. Factors such as structural diversity, commercial availability, price, and a suitable analytical technique for quantification were considered in the selection. Lipophilicity, pKa, solubility, and permeability across human Caco-2 cell monolayers were measured for the compiled data set. The results show that, by use of a physicochemically diverse data set, experimental responses over a wide range were obtained. The paper also shows how experimental difficulties due to the diversity of the data set can be overcome. We anticipate that this data set can serve as a benchmark set for validation of new experimental techniques or in silico models. It can also be used as a diverse starting data set for the development of new computational models. PMID:17154497

  11. Structural basis for diversity in the SAM clan of riboswitches

    PubMed Central

    Trausch, Jeremiah J.; Xu, Zhenjiang; Edwards, Andrea L.; Reyes, Francis E.; Ross, Phillip E.; Knight, Rob; Batey, Robert T.

    2014-01-01

    In bacteria, sulfur metabolism is regulated in part by seven known families of riboswitches that bind S-adenosyl-l-methionine (SAM). Direct binding of SAM to these mRNA regulatory elements governs a downstream secondary structural switch that communicates with the transcriptional and/or translational expression machinery. The most widely distributed SAM-binding riboswitches belong to the SAM clan, comprising three families that share a common SAM-binding core but differ radically in their peripheral architecture. Although the structure of the SAM-I member of this clan has been extensively studied, how the alternative peripheral architecture of the other families supports the common SAM-binding core remains unknown. We have therefore solved the X-ray structure of a member of the SAM-I/IV family containing the alternative “PK-2” subdomain shared with the SAM-IV family. This structure reveals that this subdomain forms extensive interactions with the helix housing the SAM-binding pocket, including a highly unusual mode of helix packing in which two helices pack in a perpendicular fashion. Biochemical and genetic analysis of this RNA reveals that SAM binding induces many of these interactions, including stabilization of a pseudoknot that is part of the regulatory switch. Despite strong structural similarity between the cores of SAM-I and SAM-I/IV members, a phylogenetic analysis of sequences does not indicate that they derive from a common ancestor. PMID:24753586

  12. Structural Diversity of DNA-Coated Particle Assemblies

    NASA Astrophysics Data System (ADS)

    Starr, Francis W.

    2012-02-01

    Custom designed nanoparticles (NP) or colloids with specific recognition offer the possibility to control the phase behavior and structure of particle assemblies for a range of applications. One approach to realize these new materials is by attaching DNA to a core particle; the hybridization of double-stranded DNA between particles results in the spontaneous assembly of higher-order structures. Control of the assembled state can be achieved by adjusting several parameters, including sequence selectivity, DNA link orientation, DNA length and flexibility, and the balance between the length of links and non-specific repulsive interactions. I will discuss the results of a coarse-grained molecular model for DNA-linked nanoparticles that helps to rationalize experimental findings and demonstrate new routes to control the assembled structure. We examine how the number and orientation of strands affects the structure, phase behavior, and dynamics. We show that it is possible to realize unusual phase diagrams with many thermodynamically distinct phases, both amorphous and crystal. We further examine the parameters that control the pathways of assembly, which are critical to avoid kinetic bottlenecks. Finally, we discuss strategies to create highly anisoptropic structures using both isotropic and anisotropic core units.

  13. Structural diversity in hybrid organic-inorganic lead iodide materials.

    PubMed

    Weber, Oliver J; Marshall, Kayleigh L; Dyson, Lewis M; Weller, Mark T

    2015-12-01

    The structural chemistry of hybrid organic-inorganic lead iodide materials has become of increasing significance for energy applications since the discovery and development of perovskite solar cells based on methylammonium lead iodide. Seven new hybrid lead iodide compounds have been synthesized and structurally characterized using single-crystal X-ray diffraction. The lead iodide units in materials templated with bipyridyl, 1,2-bis(4-pyridyl)ethane, 1,2-di(4-pyridyl)ethylene and imidazole adopt one-dimensional chain structures, while crystallization from solutions containing piperazinium cations generates a salt containing isolated [PbI6](4-) octahedral anions. Templating with 4-chlorobenzylammonium lead iodide adopts the well known two-dimensional layered perovskite structure with vertex shared sheets of composition [PbI4](2-) separated by double layers of organic cations. The relationships between the various structures determined, their compositions, stability and hydrogen bonding between the protonated amine and the iodide ions of the PbI6 octahedra are described. PMID:26634723

  14. Structural diversity in dinickel(II) complexes of thiosemicarbazones

    NASA Astrophysics Data System (ADS)

    Naik, Anil D.; Annigeri, Satish M.; Gangadharmath, Umesh B.; Revankar, Vidyanand K.; Mahale, Vinayak B.

    2002-10-01

    2,6-Diformyl- p-cresol serves as a starting point for the generation of multidentate N/O/S chelating agents. Condensation with 4-(X-phenyl) thiosemicarbazide yields the pentadentate ligand having SNONS donor sequences, capable of holding two metal ions in close proximity. The ligands behave as mono/di/tri basic depending on the pH of the medium. Stereochemical diversity in the reaction product of such ligands with nickel(II) chloride at different pH is observed. Sterically demanding substituted ligands in association with various exogenous bridges dictate the geometry and coordination number of such complexes. The compounds were investigated by elemental analysis, molar conductivities, electronic spectra, IR, NMR, FAB mass spectra, TG-DTG, magnetic susceptibility measurements. Varieties of geometries such as square planar, square pyramidal, octahedral and square planar-square pyramidal are observed. Cryomagnetic data for the complexes (79-296 K) can be reproduced by an equation based on the Heisenberg model ( H=-2 JS1S2, S1= S2=1). The singlet-triplet splitting, J varies systematically with the coordination geometry about the Ni 2(SNONS) core, with the hydroxo bridged complex exhibiting the greatest degree of antiferromagnetic coupling. The coupling is somewhat weaker for the chloro-bridged complexes. None of the complexes have shown any appreciable antimicrobial activity.

  15. Impact of metal pollution on fungal diversity and community structures.

    PubMed

    Op De Beeck, Michiel; Lievens, Bart; Busschaert, Pieter; Rineau, Francois; Smits, Mark; Vangronsveld, Jaco; Colpaert, Jan V

    2015-06-01

    The impact of metal pollution on plant communities has been studied extensively in the past, but little is known about the effects of metal pollution on fungal communities that occur in metal-polluted soils. Metal-tolerant ecotypes of the ectomycorrhizal fungus Suillus luteus are frequently found in pioneer pine forests in the Campine region in Belgium on metal-polluted soils. We hypothesized that metal pollution would play an important role in shaping below-ground fungal communities that occur in these soils and that Suillus luteus would be a dominant player. To test these hypotheses, the fungal communities in a young pine plantation in soil polluted with zinc, and cadmium were studied using 454 amplicon pyrosequencing. Results show that zinc, cadmium and soil organic matter content were strongly correlated with the fungal community composition, but no effects on fungal diversity were observed. As hypothesized, S. luteus was found to be a dominant member of the studied fungal communities. However, other dominant fungal species, such as Sistotrema sp., Wilcoxina mikolae and Cadophora finlandica were found as well. Their presence in metal-polluted sites is discussed. PMID:24947496

  16. Diverse Family Structures and the Care of Older Persons.

    PubMed

    Roberto, Karen A; Blieszner, Rosemary

    2015-09-01

    Demographic and social trends lead to a variety of micro-level and internal structural contexts that influence caregiving in families with older members. The results of macro-level changes have received little focused attention in the aging literature, where much of the caregiving research has addressed issues within the context of traditional family structure. Yet the conventional nuclear family model is increasingly uncommon as new, pluralistic models of family life are emerging in contemporary society. The majority of elder care is provided by relatives, albeit with varying patterns of involvement and responsibility across family structures. Both conventional and pluralistic families face challenges in meeting the care needs of their oldest members, leaving some older adults at risk of having unmet needs. Additional research on family risk and resilience related to the care of older relatives is warranted, particularly with respect to pluralistic models of family life. PMID:26300190

  17. GALAXY STRUCTURE AND MODE OF STAR FORMATION IN THE SFR-MASS PLANE FROM z {approx} 2.5 TO z {approx} 0.1

    SciTech Connect

    Wuyts, Stijn; Foerster Schreiber, Natascha M.; Magnelli, Benjamin; Genzel, Reinhard; Lutz, Dieter; Berta, Stefano; Gracia-Carpio, Javier; Nordon, Raanan; Van der Wel, Arjen; Guo, Yicheng; Aussel, Herve; Le Floc'h, Emeric; Hathi, Nimish P.; Huang, Kuang-Han; Koekemoer, Anton M.; Lee, Kyoung-Soo; and others

    2011-12-01

    We analyze the dependence of galaxy structure (size and Sersic index) and mode of star formation ({Sigma}{sub SFR} and SFR{sub IR}/SFR{sub UV}) on the position of galaxies in the star formation rate (SFR) versus mass diagram. Our sample comprises roughly 640,000 galaxies at z {approx} 0.1, 130,000 galaxies at z {approx} 1, and 36,000 galaxies at z {approx} 2. Structural measurements for all but the z {approx} 0.1 galaxies are based on Hubble Space Telescope imaging, and SFRs are derived using a Herschel-calibrated ladder of SFR indicators. We find that a correlation between the structure and stellar population of galaxies (i.e., a 'Hubble sequence') is already in place since at least z {approx} 2.5. At all epochs, typical star-forming galaxies on the main sequence are well approximated by exponential disks, while the profiles of quiescent galaxies are better described by de Vaucouleurs profiles. In the upper envelope of the main sequence, the relation between the SFR and Sersic index reverses, suggesting a rapid buildup of the central mass concentration in these starbursting outliers. We observe quiescent, moderately and highly star-forming systems to co-exist over an order of magnitude or more in stellar mass. At each mass and redshift, galaxies on the main sequence have the largest size. The rate of size growth correlates with specific SFR, and so does {Sigma}{sub SFR} at each redshift. A simple model using an empirically determined star formation law and metallicity scaling, in combination with an assumed geometry for dust and stars, is able to relate the observed {Sigma}{sub SFR} and SFR{sub IR}/SFR{sub UV}, provided a more patchy dust geometry is assumed for high-redshift galaxies.

  18. "Presumed fair: Ironic effects of organizational diversity structures": Correction to Kaiser et al. (2013).

    PubMed

    2016-06-01

    Reports an error in "Presumed fair: Ironic effects of organizational diversity structures" by Cheryl R. Kaiser, Brenda Major, Ines Jurcevic, Tessa L. Dover, Laura M. Brady and Jenessa R. Shapiro (Journal of Personality and Social Psychology, 2013[Mar], Vol 104[3], 504-519). In the article, a raw data merging error in one racial discrimination claim condition from Experiment 6 inadvertently resulted in data analyses on an inaccurate data set. When the error was discovered by the authors and corrected, all analyses reported in Experiment 6 for claim validity, seriousness of the claim, and support for the claimant were inaccurate and none were statistically significant. The conclusions should be altered to indicate that participants with management experience who reflected on their own workplace diversity policies did not show the predicted effects. The literature review, remaining five studies, and remaining conclusions in the article are unaffected by this error. Experiment 6 should also report that 26.4% (not 26.4.7%) of participants had a graduate degree and eight participants (not 8%) did not provide educational data. Experiment 5 should have referred to the claim validity measure as a six-item measure ( .92) rather than a five-item measure; analyses on claim validity are accurate in text. Table 2's note should have said standard errors, not standard deviations. (The following abstract of the original article appeared in record 2012-31077-001.) This research tests the hypothesis that the presence (vs. absence) of organizational diversity structures causes high-status group members (Whites, men) to perceive organizations with diversity structures as procedurally fairer environments for underrepresented groups (racial minorities, women), even when it is clear that underrepresented groups have been unfairly disadvantaged within these organizations. Furthermore, this illusory sense of fairness derived from the mere presence of diversity structures causes high

  19. Convergent structural responses of tropical forests to diverse disturbance regimes.

    PubMed

    Kellner, James R; Asner, Gregory P

    2009-09-01

    Size frequency distributions of canopy gaps are a hallmark of forest dynamics. But it remains unknown whether legacies of forest disturbance are influencing vertical size structure of landscapes, or space-filling in the canopy volume. We used data from LiDAR remote sensing to quantify distributions of canopy height and sizes of 434,501 canopy gaps in five tropical rain forest landscapes in Costa Rica and Hawaii. The sites represented a wide range of variation in structure and natural disturbance history, from canopy gap dynamics in lowland Costa Rica and Hawaii, to stages and types of stand-level dieback on upland Mauna Kea and Kohala volcanoes. Large differences in vertical canopy structure characterized these five tropical rain forest landscapes, some of which were related to known disturbance events. Although there were quantitative differences in the values of scaling exponents within and among sites, size frequency distributions of canopy gaps followed power laws at all sites and in all canopy height classes. Scaling relationships in gap size at different heights in the canopy were qualitatively similar at all sites, revealing a remarkable similarity despite clearly defined differences in species composition and modes of prevailing disturbance. These findings indicate that power-law gap-size frequency distributions are ubiquitous features of these five tropical rain forest landscapes, and suggest that mechanisms of forest disturbance may be secondary to other processes in determining vertical and horizontal size structure in canopies. PMID:19614757

  20. Structural Evolution of Early-type Galaxies to z = 2.5 in CANDELS

    NASA Astrophysics Data System (ADS)

    Chang, Yu-Yen; van der Wel, Arjen; Rix, Hans-Walter; Holden, Bradford; Bell, Eric F.; McGrath, Elizabeth J.; Wuyts, Stijn; Häussler, Boris; Barden, Marco; Faber, S. M.; Mozena, Mark; Ferguson, Henry C.; Guo, Yicheng; Galametz, Audrey; Grogin, Norman A.; Kocevski, Dale D.; Koekemoer, Anton M.; Dekel, Avishai; Huang, Kuang-Han; Hathi, Nimish P.; Donley, Jennifer

    2013-08-01

    Projected axis ratio measurements of 880 early-type galaxies at redshifts 1 < z < 2.5 selected from CANDELS are used to reconstruct and model their intrinsic shapes. The sample is selected on the basis of multiple rest-frame colors to reflect low star-formation activity. We demonstrate that these galaxies as an ensemble are dust-poor and transparent and therefore likely have smooth light profiles, similar to visually classified early-type galaxies. Similar to their present-day counterparts, the z > 1 early-type galaxies show a variety of intrinsic shapes; even at a fixed mass, the projected axis ratio distributions cannot be explained by the random projection of a set of galaxies with very similar intrinsic shapes. However, a two-population model for the intrinsic shapes, consisting of a triaxial, fairly round population, combined with a flat (c/a ~ 0.3) oblate population, adequately describes the projected axis ratio distributions of both present-day and z > 1 early-type galaxies. We find that the proportion of oblate versus triaxial galaxies depends both on the galaxies' stellar mass, and—at a given mass—on redshift. For present-day and z < 1 early-type galaxies the oblate fraction strongly depends on galaxy mass. At z > 1, this trend is much weaker over the mass range explored here (1010 < M */M ⊙ < 1011), because the oblate fraction among massive (M * ~ 1011 M ⊙) was much higher in the past: 0.59 ± 0.10 at z > 1, compared to 0.20 ± 0.02 at z ~ 0.1. When combined with previous findings that the number density and sizes of early-type galaxies substantially increase over the same redshift range, this can be explained by the gradual emergence of merger-produced elliptical galaxies, at the expense of the destruction of pre-existing disks that were common among their high-redshift progenitors. In contrast, the oblate fraction among low-mass early-type galaxies (log (M */M ⊙) < 10.5) increased toward the present, from z = 0 to 0.38 ± 0.11 at z > 1 to 0

  1. IRAS galaxies and the large-scale structure in the CfA slice

    SciTech Connect

    Babul, A.; Postman, M. Space Telescope Science Institute, Baltimore, MD )

    1990-08-01

    The spatial distributions of the IRAS and the optical galaxies in the first CfA slice are compared. The IRAS galaxies are generally less clustered than optical ones, but their distribution is essentially identical to that of late-type optical galaxies. The discrepancy between the clustering properties of the IRAS and optical samples in the CfA slice region is found to be entirely due to the paucity of IRAS galaxies in the core of the Coma cluster. The spatial distributions of the IRAS and the optical galaxies, both late and early types, outside the dense core of the Coma cluster are entirely consistent with each other. This conflicts with the prediction of the linear biasing scenario. 39 refs.

  2. IRAS galaxies and the large-scale structure in the CfA slice

    NASA Technical Reports Server (NTRS)

    Babul, Arif; Postman, Marc

    1990-01-01

    The spatial distributions of the IRAS and the optical galaxies in the first CfA slice are compared. The IRAS galaxies are generally less clustered than optical ones, but their distribution is essentially identical to that of late-type optical galaxies. The discrepancy between the clustering properties of the IRAS and optical samples in the CfA slice region is found to be entirely due to the paucity of IRAS galaxies in the core of the Coma cluster. The spatial distributions of the IRAS and the optical galaxies, both late and early types, outside the dense core of the Coma cluster are entirely consistent with each other. This conflicts with the prediction of the linear biasing scenario.

  3. Global mammal beta diversity shows parallel assemblage structure in similar but isolated environments.

    PubMed

    Penone, Caterina; Weinstein, Ben G; Graham, Catherine H; Brooks, Thomas M; Rondinini, Carlo; Hedges, S Blair; Davidson, Ana D; Costa, Gabriel C

    2016-08-31

    The taxonomic, phylogenetic and trait dimensions of beta diversity each provide us unique insights into the importance of historical isolation and environmental conditions in shaping global diversity. These three dimensions should, in general, be positively correlated. However, if similar environmental conditions filter species with similar trait values, then assemblages located in similar environmental conditions, but separated by large dispersal barriers, may show high taxonomic, high phylogenetic, but low trait beta diversity. Conversely, we expect lower phylogenetic diversity, but higher trait biodiversity among assemblages that are connected but are in differing environmental conditions. We calculated all pairwise comparisons of approximately 110 × 110 km grid cells across the globe for more than 5000 mammal species (approx. 70 million comparisons). We considered realms as units representing geographical distance and historical isolation and biomes as units with similar environmental conditions. While beta diversity dimensions were generally correlated, we highlight geographical regions of decoupling among beta diversity dimensions. Our analysis shows that assemblages from tropical forests in different realms had low trait dissimilarity while phylogenetic beta diversity was significantly higher than expected, suggesting potential convergent evolution. Low trait beta diversity was surprisingly not found between isolated deserts, despite harsh environmental conditions. Overall, our results provide evidence for parallel assemblage structure of mammal assemblages driven by environmental conditions at a global scale. PMID:27559061

  4. Genetic diversity, structure and differentiation in cultivated walnut (juglans regia l.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An analysis of genetic structure and differentiation in cultivated walnut (Juglans regia) using 15 microsatellite loci revealed a considerable amount of genetic variation with a mild genetic structure indicating five genetic groups corresponding to the centers of diversity within the home range of w...

  5. Star Formation Quenching in High-redshift Large-scale Structure: Post-starburst Galaxies in the Cl 1604 Supercluster at z ~ 0.9

    NASA Astrophysics Data System (ADS)

    Wu, Po-Feng; Gal, Roy R.; Lemaux, Brian C.; Kocevski, Dale D.; Lubin, Lori M.; Rumbaugh, Nicholas; Squires, Gordon K.

    2014-09-01

    The Cl 1604 supercluster at z ~ 0.9 is one of the most extensively studied high-redshift large-scale structures, with more than 500 spectroscopically confirmed members. It consists of eight clusters and groups, with members numbering from a dozen to nearly a hundred, providing a broad range of environments for investigating the large-scale environmental effects on galaxy evolution. Here we examine the properties of 48 post-starburst galaxies in Cl 1604, comparing them to other galaxy populations in the same supercluster. Incorporating photometry from ground-based optical and near-infrared imaging, along with Spitzer mid-infrared observations, we derive stellar masses for all Cl 1604 members. The colors and stellar masses of the K+A galaxies support the idea that they are progenitors of red sequence galaxies. Their morphologies, residual star formation rates, and spatial distributions suggest that galaxy mergers may be the principal mechanism producing post-starburst galaxies. Interaction between galaxies and the dense intracluster medium (ICM) is also effective, but only in the cores of dynamically evolved clusters. The prevalence of post-starburst galaxies in clusters correlates with the dynamical state of the host cluster, as both galaxy mergers and the dense ICM produce post-starburst galaxies. We also investigate the incompleteness and contamination of K+A samples selected by means of Hδ and [O II] equivalent widths. K+A samples may be up to ~50% incomplete due to the presence of LINERs/Seyferts, and up to ~30% of K+A galaxies could have substantial star formation activity.

  6. Star formation quenching in high-redshift large-scale structure: post-starburst galaxies in the Cl 1604 supercluster at z ∼ 0.9

    SciTech Connect

    Wu, Po-Feng; Gal, Roy R.; Lemaux, Brian C.; Kocevski, Dale D.; Lubin, Lori M.; Rumbaugh, Nicholas; Squires, Gordon K.

    2014-09-01

    The Cl 1604 supercluster at z ∼ 0.9 is one of the most extensively studied high-redshift large-scale structures, with more than 500 spectroscopically confirmed members. It consists of eight clusters and groups, with members numbering from a dozen to nearly a hundred, providing a broad range of environments for investigating the large-scale environmental effects on galaxy evolution. Here we examine the properties of 48 post-starburst galaxies in Cl 1604, comparing them to other galaxy populations in the same supercluster. Incorporating photometry from ground-based optical and near-infrared imaging, along with Spitzer mid-infrared observations, we derive stellar masses for all Cl 1604 members. The colors and stellar masses of the K+A galaxies support the idea that they are progenitors of red sequence galaxies. Their morphologies, residual star formation rates, and spatial distributions suggest that galaxy mergers may be the principal mechanism producing post-starburst galaxies. Interaction between galaxies and the dense intracluster medium (ICM) is also effective, but only in the cores of dynamically evolved clusters. The prevalence of post-starburst galaxies in clusters correlates with the dynamical state of the host cluster, as both galaxy mergers and the dense ICM produce post-starburst galaxies. We also investigate the incompleteness and contamination of K+A samples selected by means of Hδ and [O II] equivalent widths. K+A samples may be up to ∼50% incomplete due to the presence of LINERs/Seyferts, and up to ∼30% of K+A galaxies could have substantial star formation activity.

  7. Star-forming complexes and the spiral structure of our Galaxy

    NASA Astrophysics Data System (ADS)

    Russeil, D.

    2003-01-01

    We have carried out a multiwavelength study of the plane of our Galaxy in order to establish a star-forming-complex catalogue which is as complete as possible. Features observed include Hα , H109alpha , CO, the radio continuum and absorption lines. For each complex we have determined the position, the systemic velocity, the kinematic distance and, when possible, the stellar distance and the corresponding uncertainties. All of these parameters were determined as homogeneously as possible, in particular all the stellar distances have been (re)calculated with the same calibration and the kinematic distances with the same mean Galactic rotation curve. Through the complexes with stellar distance determination, a rotation curve has been fitted. It is in good agreement with the one of Brand & Blitz (1993). We also investigated the residual velocities relative to the circular rotation model. We find that departures exist over large areas of the arms, with different values from one arm to another. From our data and in good agreement with previous studies, the Galactic warp is observed. It does not seem correlated with the departures from circular rotation. Finally, as segment-like features are noted from the complexes' distribution, we tried to find if they are indicative of a larger underlying structure. Then, we attempted to interpret the complexes' distribution in terms of spiral structure by fitting models with two, three and four logarithmic spiral arms. The four-arm model seems more appropriate to represent the grand design of our Galaxy. In this model the Norma arm and the external arm appear as being the two extremities of a single arm called the Norma-Cygnus arm. The new data and fitted model confirm the four-segment model of Georgelin & Georgelin (1976), clarifying the arms' design and extension and doubling their known length. Based on observations collected at the European Southern Observatory. Tables 1 and 3 (table1.ps and table3.txt) are available in

  8. Quantifying the (X/peanut)-shaped structure in edge-on disc galaxies: length, strength, and nested peanuts

    NASA Astrophysics Data System (ADS)

    Ciambur, Bogdan C.; Graham, Alister W.

    2016-06-01

    X-shaped or peanut-shaped (X/P) bulges are observed in more than 40 per cent of (nearly) edge-on disc galaxies, though to date a robust method to quantify them is lacking. Using Fourier harmonics to describe the deviation of galaxy isophotes from ellipses, we demonstrate with a sample of 11 such galaxies (including NGC 128) that the sixth Fourier component (B6) carries physical meaning by tracing this X/P structure. We introduce five quantitative diagnostics based on the radial B6 profile, namely: its `peak' amplitude (Πmax); the (projected major-axis) `length' where this peak occurs (RΠ, max); its vertical `height' above the disc plane (zΠ, max); a measure of the B6 profile's integrated `strength' (SΠ); and the B6 peak `width' (WΠ). We also introduce different `classes' of B6 profile shape. Furthermore, we convincingly detect and measure the properties of multiple (nested) X/P structures in individual galaxies which additionally display the signatures of multiple bars in their surface brightness profiles, thus consolidating further the scenario in which peanuts are associated with bars. We reveal that the peanut parameter space (`length', `strength' and `height') for real galaxies is not randomly populated, but the three metrics are inter-correlated (both in kpc and disc scalelength h). Additionally, the X/P `length' and `strength' appear to correlate with (vrot/σ⋆), lending further support to the notion that peanuts `know' about the galactic disc in which they reside. Such constraints are important for numerical simulations, as they provide a direct link between peanuts and their host disc. Our diagnostics reveal a spectrum of X/P properties and could provide a means of distinguishing between different peanut formation scenarios discussed in the literature. Moreover, nested peanuts, as remnants of bar buckling events, can provide insights into the disc and bar instability history.

  9. The inner structure of ΛCDM haloes - II. Halo mass profiles and low surface brightness galaxy rotation curves

    NASA Astrophysics Data System (ADS)

    Hayashi, E.; Navarro, J. F.; Power, C.; Jenkins, A.; Frenk, C. S.; White, S. D. M.; Springel, V.; Stadel, J.; Quinn, T. R.

    2004-12-01

    We use a set of high-resolution cosmological N-body simulations to investigate the inner mass profile of galaxy-sized cold dark matter (CDM) haloes. These simulations extend the numerical convergence study presented in Paper I of this series, and demonstrate that the mass profile of CDM galaxy haloes can be robustly estimated beyond a minimum converged radius of order rconv~ 1h-1 kpc in our highest-resolution runs. The density profiles of simulated haloes become progressively shallower from the virial radius inwards, and show no sign of approaching a well-defined power law near the centre. At rconv, the density profile is steeper than expected from the formula proposed by Navarro, Frenk & White, which has a ρ~r-1 cusp, but significantly shallower than the steeply divergent ρ~r-1.5 cusp proposed by Moore et al. We perform a direct comparison of the spherically averaged dark matter circular velocity profiles with Hα rotation curves of a sample of low surface brightness (LSB) galaxies. We find that most galaxies in the sample (about 70 per cent) have rotation curves that are consistent with the structure of CDM haloes. Of the remainder, 20 per cent have rotation curves which cannot be fit by any smooth fitting function with few free parameters, and 10 per cent are inconsistent with CDM haloes. However, the latter consist mostly of rotation curves that do not extend to large enough radii to accurately determine their shapes and maximum velocities. We conclude that the inner structure of CDM haloes is not manifestly inconsistent with the rotation curves of LSB galaxies.

  10. Euphorbesulins A-P, Structurally Diverse Diterpenoids from Euphorbia esula.

    PubMed

    Zhou, Bin; Wu, Yan; Dalal, Seema; Cassera, Maria B; Yue, Jian-Min

    2016-08-26

    Aqueous ethanol extracts of powdered twigs of Euphorbia esula afforded 16 new diterpenoids, named euphorbesulins A-P. These euphorbesulins included presegetane (1-3), jatrophane (4-14), paraliane (15), and isopimarane (16) diterpenoids as well as six known analogues. Compounds 1-3 represent a rare type of presegetane diterpenoid. Their structures were determined by analysis of the spectroscopic data, and the absolute configuration of 1 was established by X-ray crystallography. Diterpenoid 7 showed low nanomolar antimalarial activity, while the remaining compounds showed only moderate or no antimalarial activity. PMID:27447736

  11. Diversity and spatial distribution of surname structure in South Korea

    NASA Astrophysics Data System (ADS)

    Kwon, Okyu; Son, Woo-Sik

    2015-11-01

    We studied the population structure of South Korea by using the distributions of surnames for all 246 administrative regions. Every 4,177 surnames are distinguished by their bon-gwan which indicates the place of their family clans. Using Fisher's Alpha, we found that the level of inbreeding increases as the distance from the capital Seoul increases. We introduced the Shannon index to measure the level of spatial diffusion for each surname population, and the geographical clusters based on similarities of the surname compositions among the regions show almost exact agreement with those at the administrative districts.

  12. The Diverse Structures and Functions of Surfactant Proteins.

    PubMed

    Schor, Marieke; Reid, Jack L; MacPhee, Cait E; Stanley-Wall, Nicola R

    2016-07-01

    Surface tension at liquid-air interfaces is a major barrier that needs to be surmounted by a wide range of organisms; surfactant and interfacially active proteins have evolved for this purpose. Although these proteins are essential for a variety of biological processes, our understanding of how they elicit their function has been limited. However, with the recent determination of high-resolution 3D structures of several examples, we have gained insight into the distinct shapes and mechanisms that have evolved to confer interfacial activity. It is now a matter of harnessing this information, and these systems, for biotechnological purposes. PMID:27242193

  13. LYα FOREST TOMOGRAPHY FROM BACKGROUND GALAXIES: THE FIRST MEGAPARSEC-RESOLUTION LARGE-SCALE STRUCTURE MAP AT z > 2

    SciTech Connect

    Lee, Khee-Gan; Hennawi, Joseph F.; Eilers, Anna-Christina; Stark, Casey; White, Martin; Prochaska, J. Xavier; Schlegel, David J.; Arinyo-i-Prats, Andreu; Suzuki, Nao; Croft, Rupert A. C.; Caputi, Karina I.; Cassata, Paolo; Ilbert, Olivier; Le Brun, Vincent; Le Fèvre, Olivier; Garilli, Bianca; Koekemoer, Anton M.; Maccagni, Dario; Nugent, Peter; and others

    2014-11-01

    We present the first observations of foreground Lyα forest absorption from high-redshift galaxies, targeting 24 star-forming galaxies (SFGs) with z ∼ 2.3-2.8 within a 5' × 14' region of the COSMOS field. The transverse sightline separation is ∼2 h {sup –1} Mpc comoving, allowing us to create a tomographic reconstruction of the three-dimensional (3D) Lyα forest absorption field over the redshift range 2.20 ≤ z ≤ 2.45. The resulting map covers 6 h {sup –1} Mpc × 14 h {sup –1} Mpc in the transverse plane and 230 h {sup –1} Mpc along the line of sight with a spatial resolution of ≈3.5 h {sup –1} Mpc, and is the first high-fidelity map of a large-scale structure on ∼Mpc scales at z > 2. Our map reveals significant structures with ≳ 10 h {sup –1} Mpc extent, including several spanning the entire transverse breadth, providing qualitative evidence for the filamentary structures predicted to exist in the high-redshift cosmic web. Simulated reconstructions with the same sightline sampling, spectral resolution, and signal-to-noise ratio recover the salient structures present in the underlying 3D absorption fields. Using data from other surveys, we identified 18 galaxies with known redshifts coeval with our map volume, enabling a direct comparison with our tomographic map. This shows that galaxies preferentially occupy high-density regions, in qualitative agreement with the same comparison applied to simulations. Our results establish the feasibility of the CLAMATO survey, which aims to obtain Lyα forest spectra for ∼1000 SFGs over ∼1 deg{sup 2} of the COSMOS field, in order to map out the intergalactic medium large-scale structure at (z) ∼ 2.3 over a large volume (100 h {sup –1} Mpc){sup 3}.

  14. H I Structure and Topology of the Galaxy Revealed by the I-GALFA H I 21-cm Line Survey

    NASA Astrophysics Data System (ADS)

    Koo, Bon-Chul; Park, G.; Cho, W.; Gibson, S. J.; Kang, J.; Douglas, K. A.; Peek, J. E. G.; Korpela, E. J.; Heiles, C. E.

    2011-05-01

    The I-GALFA survey mapping all the H I in the inner Galactic disk visible to the Arecibo 305m telescope within 10 degrees of the Galactic plane (longitudes of 32 to 77 degrees at b = 0) completed observations in 2009 September and will soon be made publicly available. The high (3.4 arcmin) resolution and tremendous sensitivity of the survey offer a great opportunity to observe the fine details of H I both in the inner and in the far outer Galaxy. The reduced HI column density maps show that the HI structure is highly filamentary and clumpy, pervaded by shell-like structures, vertical filaments, and small clumps. By inspecting individual maps, we have found 36 shell candidates of angular sizes ranging from 0.4 to 12 degrees, half of which appear to be expanding. In order to characterize the filamentary/clumpy morphology of the HI structure, we have carried out statistical analyses of selected areas representing the spiral arms in the inner and outer Galaxy. Genus statistics that can distinguish the ``meatball'' and ``swiss-cheese'' topologies show that the HI topology is clump-like in most regions. The two-dimensional Fourier analysis further shows the HI structures are filamentary and mainly parallel to the plane in the outer Galaxy. We also examine the level-crossing statistics, the results of which are described in detail in an accompanying poster by Park et al.

  15. SDSS-III Baryon Oscillation Spectroscopic Survey data release 12: Galaxy target selection and large-scale structure catalogues

    SciTech Connect

    Reid, Beth; Ho, Shirley; Padmanabhan, Nikhil; Percival, Will J.; Tinker, Jeremy; Tojeiro, Rito; White, Marin; Daniel J. Einstein; Maraston, Claudia; Ross, Ashley J.; Sanchez, Ariel G.; Schlegel, David; Sheldon, Erin; Strauss, Michael A.; Thomas, Daniel; Wake, David; Beutler, Florian; Bizyaev, Dmitry; Bolton, Adam S.; Brownstein, Joel R.; Chuang, Chia -Hsun; Dawson, Kyle; Harding, Paul; Kitaura, Francisco -Shu; Leauthaud, Alexie; Masters, Karen; McBride, Cameron K.; More, Surhud; Olmstead, Matthew D.; Oravetz, Daniel; Nuza, Sebastian E.; Pan, Kaike; Parejko, John; Pforr, Janine; Prada, Francisco; Rodriguez-Torres, Sergio; Salazar-Albornoz, Salvador; Samushia, Lado; Schneider, Donald P.; Scoccola, Claudia G.; Simmons, Audrey; Vargas-Magana, Mariana

    2015-11-17

    The Baryon Oscillation Spectroscopic Survey (BOSS), part of the Sloan Digital Sky Survey (SDSS) III project, has provided the largest survey of galaxy redshifts available to date, in terms of both the number of galaxy redshifts measured by a single survey, and the effective cosmological volume covered. Key to analysing the clustering of these data to provide cosmological measurements is understanding the detailed properties of this sample. Potential issues include variations in the target catalogue caused by changes either in the targeting algorithm or properties of the data used, the pattern of spectroscopic observations, the spatial distribution of targets for which redshifts were not obtained, and variations in the target sky density due to observational systematics. We document here the target selection algorithms used to create the galaxy samples that comprise BOSS. We also present the algorithms used to create large-scale structure catalogues for the final Data Release (DR12) samples and the associated random catalogues that quantify the survey mask. The algorithms are an evolution of those used by the BOSS team to construct catalogues from earlier data, and have been designed to accurately quantify the galaxy sample. Furthermore, the code used, designated mksample, is released with this paper.

  16. SDSS-III Baryon Oscillation Spectroscopic Survey data release 12: Galaxy target selection and large-scale structure catalogues

    DOE PAGESBeta

    Reid, Beth; Ho, Shirley; Padmanabhan, Nikhil; Percival, Will J.; Tinker, Jeremy; Tojeiro, Rito; White, Marin; Daniel J. Einstein; Maraston, Claudia; Ross, Ashley J.; et al

    2015-11-17

    The Baryon Oscillation Spectroscopic Survey (BOSS), part of the Sloan Digital Sky Survey (SDSS) III project, has provided the largest survey of galaxy redshifts available to date, in terms of both the number of galaxy redshifts measured by a single survey, and the effective cosmological volume covered. Key to analysing the clustering of these data to provide cosmological measurements is understanding the detailed properties of this sample. Potential issues include variations in the target catalogue caused by changes either in the targeting algorithm or properties of the data used, the pattern of spectroscopic observations, the spatial distribution of targets formore » which redshifts were not obtained, and variations in the target sky density due to observational systematics. We document here the target selection algorithms used to create the galaxy samples that comprise BOSS. We also present the algorithms used to create large-scale structure catalogues for the final Data Release (DR12) samples and the associated random catalogues that quantify the survey mask. The algorithms are an evolution of those used by the BOSS team to construct catalogues from earlier data, and have been designed to accurately quantify the galaxy sample. Furthermore, the code used, designated mksample, is released with this paper.« less

  17. An analysis of the temperature structure of galaxy clusters by means of the thermal Sunyaev-Zel'dovich effect

    NASA Astrophysics Data System (ADS)

    Prokhorov, D. A.; Dubois, Y.; Nagataki, S.

    2010-12-01

    Context. Measurements of the Sunyaev-Zel'dovich (hereafter SZ) effect distortion of the cosmic microwave background provide us with an independent method to derive the gas temperature of galaxy clusters. In merging galaxy clusters the gas distribution is inhomogeneous and, therefore, the method of temperature measuring based on the SZ effect should be more relevant than that based on an X-ray emission analysis. Aims: We study a method for measuring the gas temperature in merging clusters by means of the SZ effect. Methods: Our calculations of intensity maps of the SZ effect include relativistic corrections considered within the framework of the Wright formalism and utilize a cosmological numerical simulation of a merging galaxy cluster evolved with its baryon physics. Results: We found that the gas temperature in merging clusters can be inferred from the ratio of the SZ intensity at a low frequency (128 GHz) to that at a high frequency (369 GHz). This SZ intensity ratio permits us to reveal prominent features of the temperature structure caused by violent merger shock waves. Therefore, measurements of the ratio of the SZ intensities are a promising tool for measuring the gas temperature in merging galaxy clusters.

  18. SDSS-III Baryon Oscillation Spectroscopic Survey Data Release 12: galaxy target selection and large-scale structure catalogues

    NASA Astrophysics Data System (ADS)

    Reid, Beth; Ho, Shirley; Padmanabhan, Nikhil; Percival, Will J.; Tinker, Jeremy; Tojeiro, Rita; White, Martin; Eisenstein, Daniel J.; Maraston, Claudia; Ross, Ashley J.; Sánchez, Ariel G.; Schlegel, David; Sheldon, Erin; Strauss, Michael A.; Thomas, Daniel; Wake, David; Beutler, Florian; Bizyaev, Dmitry; Bolton, Adam S.; Brownstein, Joel R.; Chuang, Chia-Hsun; Dawson, Kyle; Harding, Paul; Kitaura, Francisco-Shu; Leauthaud, Alexie; Masters, Karen; McBride, Cameron K.; More, Surhud; Olmstead, Matthew D.; Oravetz, Daniel; Nuza, Sebastián E.; Pan, Kaike; Parejko, John; Pforr, Janine; Prada, Francisco; Rodríguez-Torres, Sergio; Salazar-Albornoz, Salvador; Samushia, Lado; Schneider, Donald P.; Scóccola, Claudia G.; Simmons, Audrey; Vargas-Magana, Mariana

    2016-01-01

    The Baryon Oscillation Spectroscopic Survey (BOSS), part of the Sloan Digital Sky Survey (SDSS) III project, has provided the largest survey of galaxy redshifts available to date, in terms of both the number of galaxy redshifts measured by a single survey, and the effective cosmological volume covered. Key to analysing the clustering of these data to provide cosmological measurements is understanding the detailed properties of this sample. Potential issues include variations in the target catalogue caused by changes either in the targeting algorithm or properties of the data used, the pattern of spectroscopic observations, the spatial distribution of targets for which redshifts were not obtained, and variations in the target sky density due to observational systematics. We document here the target selection algorithms used to create the galaxy samples that comprise BOSS. We also present the algorithms used to create large-scale structure catalogues for the final Data Release (DR12) samples and the associated random catalogues that quantify the survey mask. The algorithms are an evolution of those used by the BOSS team to construct catalogues from earlier data, and have been designed to accurately quantify the galaxy sample. The code used, designated MKSAMPLE, is released with this paper.

  19. IR Fine-Structure Line Signatures of Central Dust-Bounded Nebulae in Luminous Infrared Galaxies

    NASA Technical Reports Server (NTRS)

    Fischer, J.; Allen, R.; Dudley, C. C.; Satyapal, S.; Luhman, M.; Wolfire, M.; Smith, H. A.

    2004-01-01

    To date, the only far-infrared spectroscopic observations of ultraluminous infrared galaxies have been obtained with the European Space Agency s Infrared Space Observatory Long Wavelength Spectrometer. The spectra of these galaxies are characterized by molecular absorption lines and weak emission lines from photodissociation regions (PDRs), but no far-infrared (greater than 40 microns) lines from ionized regions have been detected. ESA s Herschel Space Observatory, slated for launch in 2007, will likely be able to detect these lines in samples of local and moderate redshift ultra luminous galaxies and to enable measurement of the ionization parameters, the slope of the ionizing continuum, and densities present in the ionized regions of these galaxies. The higher spatial resolution of proposed observatories discussed in this workshop will enable isolation of the central regions of local galaxies and detection of these lines in high-redshift galaxies for study of the evolution of galaxies. Here we discuss evidence for the e.ects of absorption by dust within ionized regions and present the spectroscopic signatures predicted by photoionization modeling of dust-bounded regions.

  20. A study of the structure and kinematics of the narrow-line region in Seyfert galaxies

    SciTech Connect

    Veilleux, S.

    1989-01-01

    The results of a high resolution study of the narrow emission line profiles of 16 Seyfert galaxies are presented. It is shown that the line profile parameters published in earlier low resolution studies are sometimes strongly influenced by resolution effects. In spite of these important systematic errors, many of the results derived from low resolution data are confirmed in the high resolution data. The narrow line profiles of Seyfert galaxies have a stronger base relative to core than a Gaussian. Most of the emission lines present a blueward asymmetry in the lower portion of their profile. In some galaxies, the line widths and/or line asymmetries are correlated with the ionization potential and/or critical density of the lines. There is a weak correlation between the line asymmetry and the dust content of the narrow line region (NLR). The large scatter in this relation, the absence of a similar correlation in Seyfert 1 to 1.5 galaxies, and the presence of a blue asymmetry in galaxies with dustfree line-emitting regions suggest that dust obscuration is not the only mechanism responsible for the line asymmetry in active galaxies. An optically-thick disk close to the nucleus is proposed as the other source of line asymmetry. An important result is that the host galaxy is probably playing a role in the kinematics of some of the gas in the NLR. A multicomponent model of the NLR is proposed to explain these results.

  1. Integrative phenomics reveals insight into the structure of phenotypic diversity in budding yeast

    PubMed Central

    Skelly, Daniel A.; Merrihew, Gennifer E.; Riffle, Michael; Connelly, Caitlin F.; Kerr, Emily O.; Johansson, Marnie; Jaschob, Daniel; Graczyk, Beth; Shulman, Nicholas J.; Wakefield, Jon; Cooper, Sara J.; Fields, Stanley; Noble, William S.; Muller, Eric G.D.; Davis, Trisha N.; Dunham, Maitreya J.; MacCoss, Michael J.; Akey, Joshua M.

    2013-01-01

    To better understand the quantitative characteristics and structure of phenotypic diversity, we measured over 14,000 transcript, protein, metabolite, and morphological traits in 22 genetically diverse strains of Saccharomyces cerevisiae. More than 50% of all measured traits varied significantly across strains [false discovery rate (FDR) = 5%]. The structure of phenotypic correlations is complex, with 85% of all traits significantly correlated with at least one other phenotype (median = 6, maximum = 328). We show how high-dimensional molecular phenomics data sets can be leveraged to accurately predict phenotypic variation between strains, often with greater precision than afforded by DNA sequence information alone. These results provide new insights into the spectrum and structure of phenotypic diversity and the characteristics influencing the ability to accurately predict phenotypes. PMID:23720455

  2. Structural Diversity and Function of Xyloglucan Sidechain Substituents.

    PubMed

    Schultink, Alex; Liu, Lifeng; Zhu, Lei; Pauly, Markus

    2014-01-01

    Xyloglucan (XyG) is a hemicellulose found in the cell walls of all land plants including early-divergent groups such as liverworts, hornworts and mosses. The basic structure of XyG, a xylosylated glucan, is similar in all of these plants but additional substituents can vary depending on plant family, tissue, and developmental stage. A comprehensive list of known XyG sidechain substituents is assembled including their occurrence within plant families, thereby providing insight into the evolutionary origin of the various sidechains. Recent advances in DNA sequencing have enabled comparative genomics approaches for the identification of XyG biosynthetic enzymes in Arabidopsis thaliana as well as in non-model plant species. Characterization of these biosynthetic genes not only allows the determination of their substrate specificity but also provides insights into the function of the various substituents in plant growth and development. PMID:27135518

  3. Structural Diversity and Function of Xyloglucan Sidechain Substituents

    PubMed Central

    Schultink, Alex; Liu, Lifeng; Zhu, Lei; Pauly, Markus

    2014-01-01

    Xyloglucan (XyG) is a hemicellulose found in the cell walls of all land plants including early-divergent groups such as liverworts, hornworts and mosses. The basic structure of XyG, a xylosylated glucan, is similar in all of these plants but additional substituents can vary depending on plant family, tissue, and developmental stage. A comprehensive list of known XyG sidechain substituents is assembled including their occurrence within plant families, thereby providing insight into the evolutionary origin of the various sidechains. Recent advances in DNA sequencing have enabled comparative genomics approaches for the identification of XyG biosynthetic enzymes in Arabidopsis thaliana as well as in non-model plant species. Characterization of these biosynthetic genes not only allows the determination of their substrate specificity but also provides insights into the function of the various substituents in plant growth and development. PMID:27135518

  4. Radio Galaxies.

    ERIC Educational Resources Information Center

    Downes, Ann

    1986-01-01

    Provides background information on radio galaxies. Topic areas addressed include: what produces the radio emission; radio telescopes; locating radio galaxies; how distances to radio galaxies are found; physics of radio galaxies; computer simulations of radio galaxies; and the evolution of radio galaxies with cosmic time. (JN)

  5. How similar is the stellar structure of low-mass late-type galaxies to that of early-type dwarfs?

    NASA Astrophysics Data System (ADS)

    Janz, J.; Laurikainen, E.; Laine, J.; Salo, H.; Lisker, T.

    2016-09-01

    We analyse structural decompositions of 500 late-type galaxies (Hubble T-type ≥6) from the Spitzer Survey of Stellar Structure in Galaxies (S4G; Salo et al.), spanning stellar mass range of about 107 to a few times 1010 M⊙. Their decomposition parameters are compared with those of the early-type dwarfs in the Virgo cluster from Janz et al. They have morphological similarities, including the fact that the fraction of simple one-component galaxies in both samples increases towards lower galaxy masses. We find that in the late-type two-component galaxies both the inner and outer structures are by a factor of 2 larger than in the early-type dwarfs, for the same stellar mass of the component. While dividing the late-type galaxies to low- and high-density environmental bins, it is noticeable that both the inner and outer components of late types in the high local density galaxies are smaller, and lie closer in size to those of the early-type dwarfs. This suggests that, although structural differences between the late- and early-type dwarfs are observed, environmental processes can plausibly transform their sizes sufficiently, thus linking them evolutionarily.

  6. Scale-dependence of processes structuring dung beetle metacommunities using functional diversity and community deconstruction approaches.

    PubMed

    Silva, Pedro Giovâni da; Hernández, Malva Isabel Medina

    2015-01-01

    Community structure is driven by mechanisms linked to environmental, spatial and temporal processes, which have been successfully addressed using metacommunity framework. The relative importance of processes shaping community structure can be identified using several different approaches. Two approaches that are increasingly being used are functional diversity and community deconstruction. Functional diversity is measured using various indices that incorporate distinct community attributes. Community deconstruction is a way to disentangle species responses to ecological processes by grouping species with similar traits. We used these two approaches to determine whether they are improvements over traditional measures (e.g., species composition, abundance, biomass) for identification of the main processes driving dung beetle (Scarabaeinae) community structure in a fragmented mainland-island landscape in southern Brazilian Atlantic Forest. We sampled five sites in each of four large forest areas, two on the mainland and two on the island. Sampling was performed in 2012 and 2013. We collected abundance and biomass data from 100 sampling points distributed over 20 sampling sites. We studied environmental, spatial and temporal effects on dung beetle community across three spatial scales, i.e., between sites, between areas and mainland-island. The γ-diversity based on species abundance was mainly attributed to β-diversity as a consequence of the increase in mean α- and β-diversity between areas. Variation partitioning on abundance, biomass and functional diversity showed scale-dependence of processes structuring dung beetle metacommunities. We identified two major groups of responses among 17 functional groups. In general, environmental filters were important at both local and regional scales. Spatial factors were important at the intermediate scale. Our study supports the notion of scale-dependence of environmental, spatial and temporal processes in the distribution

  7. Scale-Dependence of Processes Structuring Dung Beetle Metacommunities Using Functional Diversity and Community Deconstruction Approaches

    PubMed Central

    da Silva, Pedro Giovâni; Hernández, Malva Isabel Medina

    2015-01-01

    Community structure is driven by mechanisms linked to environmental, spatial and temporal processes, which have been successfully addressed using metacommunity framework. The relative importance of processes shaping community structure can be identified using several different approaches. Two approaches that are increasingly being used are functional diversity and community deconstruction. Functional diversity is measured using various indices that incorporate distinct community attributes. Community deconstruction is a way to disentangle species responses to ecological processes by grouping species with similar traits. We used these two approaches to determine whether they are improvements over traditional measures (e.g., species composition, abundance, biomass) for identification of the main processes driving dung beetle (Scarabaeinae) community structure in a fragmented mainland-island landscape in southern Brazilian Atlantic Forest. We sampled five sites in each of four large forest areas, two on the mainland and two on the island. Sampling was performed in 2012 and 2013. We collected abundance and biomass data from 100 sampling points distributed over 20 sampling sites. We studied environmental, spatial and temporal effects on dung beetle community across three spatial scales, i.e., between sites, between areas and mainland-island. The γ-diversity based on species abundance was mainly attributed to β-diversity as a consequence of the increase in mean α- and β-diversity between areas. Variation partitioning on abundance, biomass and functional diversity showed scale-dependence of processes structuring dung beetle metacommunities. We identified two major groups of responses among 17 functional groups. In general, environmental filters were important at both local and regional scales. Spatial factors were important at the intermediate scale. Our study supports the notion of scale-dependence of environmental, spatial and temporal processes in the distribution

  8. Characterizing Croatian Wheat Germplasm Diversity and Structure in a European Context by DArT Markers

    PubMed Central

    Novoselović, Dario; Bentley, Alison R.; Šimek, Ruđer; Dvojković, Krešimir; Sorrells, Mark E.; Gosman, Nicolas; Horsnell, Richard; Drezner, Georg; Šatović, Zlatko

    2016-01-01

    Narrowing the genetic base available for future genetic progress is a major concern to plant breeders. In order to avoid this, strategies to characterize and protect genetic diversity in regional breeding pools are required. In this study, 89 winter wheat cultivars released in Croatia between 1936 and 2006 were genotyped using 1,229 DArT (diversity array technology) markers to assess the diversity and population structure. In order to place Croatian breeding pool (CBP) in a European context, Croatian wheat cultivars were compared to 523 European cultivars from seven countries using a total of 166 common DArT markers. The results show higher genetic diversity in the wheat breeding pool from Central Europe (CE) as compared to that from Northern and Western European (NWE) countries. The most of the genetic diversity was attributable to the differences among cultivars within countries. When the geographical criterion (CE vs. NWE) was applied, highly significant difference between regions was obtained that accounted for 16.19% of the total variance, revealing that the CBP represents genetic variation not currently captured in elite European wheat. The current study emphasizes the important contribution made by plant breeders to maintaining wheat genetic diversity and suggests that regional breeding is essential to the maintenance of this diversity. The usefulness of open-access wheat datasets is also highlighted. PMID:26941756

  9. Characterizing Croatian Wheat Germplasm Diversity and Structure in a European Context by DArT Markers.

    PubMed

    Novoselović, Dario; Bentley, Alison R; Šimek, Ruđer; Dvojković, Krešimir; Sorrells, Mark E; Gosman, Nicolas; Horsnell, Richard; Drezner, Georg; Šatović, Zlatko

    2016-01-01

    Narrowing the genetic base available for future genetic progress is a major concern to plant breeders. In order to avoid this, strategies to characterize and protect genetic diversity in regional breeding pools are required. In this study, 89 winter wheat cultivars released in Croatia between 1936 and 2006 were genotyped using 1,229 DArT (diversity array technology) markers to assess the diversity and population structure. In order to place Croatian breeding pool (CBP) in a European context, Croatian wheat cultivars were compared to 523 European cultivars from seven countries using a total of 166 common DArT markers. The results show higher genetic diversity in the wheat breeding pool from Central Europe (CE) as compared to that from Northern and Western European (NWE) countries. The most of the genetic diversity was attributable to the differences among cultivars within countries. When the geographical criterion (CE vs. NWE) was applied, highly significant difference between regions was obtained that accounted for 16.19% of the total variance, revealing that the CBP represents genetic variation not currently captured in elite European wheat. The current study emphasizes the important contribution made by plant breeders to maintaining wheat genetic diversity and suggests that regional breeding is essential to the maintenance of this diversity. The usefulness of open-access wheat datasets is also highlighted. PMID:26941756

  10. Nematode community structure and diversity pattern in sandy beaches of Qingdao, China

    NASA Astrophysics Data System (ADS)

    Hua, Er; Mu, Fanghong; Zhang, Zhinan; Yang, Shichao; Zhang, Ting; Li, Jia

    2016-02-01

    We investigated the diversity and structure of free-living marine nematode communities at three sandy beaches representing typical intertidal environments of a temperate zone in Qingdao, Shandong Province, China. Average nematode abundance ranged from 1006 to 2170 ind. 10 cm-2, and a total of 34 nematode genera were recorded, of which only 8 were common in all the studied beaches. Pielou's evenness and Shannon-Wiener diversity index were the lowest at the second beach where nematode abundance was the highest. The highest species diversity index coincided with the lowest nematode abundance at Shilaoren beach. Sediment median grain size, sorting coefficient, and chlorophyll-a content were essential for differentiation in nematode abundance and species diversity, whereas taxonomic diversity of nematode was homogeneous across the three beaches. In 0-20 cm sediment profile, nematode abundance declined abruptly with depth, whereas nematode diversity changed gently with obvious difference in 16-20 cm layer. Sediment granulometry and chlorophyll- a content were the two foremost factors which influenced the vertical distribution pattern of nematode generic diversity. Non-selective deposit feeders constituted the most dominant trophic group, followed by epistratum feeders. Bathylaimus (family: Tripyloididae) dominated at the second and Yangkou beach, while Theristus (family: Xyalidae) prevailed at Shilaoren beach. Omnivores and predators became important at Shilaoren beach because of the high proportion of Enoplolaimus. Even though, nematode community of the studied beaches did not differ significantly from each other.

  11. International Conference: Milky Way Surveys: The Structure and Evolution of Our Galaxy

    NASA Technical Reports Server (NTRS)

    Clemens, Dan

    2004-01-01

    We were granted NASA support for partial sponsorship of an international conference on Galactic science, held June 15-17, 2003 and hosted by the Institute for Astrophysical Research at Boston University. This conference, entitled 'Milky Way Surveys: The Structure and Evolution of Our Galaxy' drew some 125 scientific experts, researchers, and graduate students to Boston to: (1) Present large area survey plans and findings; (2) Discuss important remaining questions and puzzles in Galactic science; and (3) To inform and excite students and researchers about the potential for using large area survey databases to address key Galactic science questions. An international Scientific Organizing Committee for this conference crafted a tightly packed two-day conference designed to highlight many recent and upcoming large area surveys (including 2MASS, SDSS, MSX, VLA-HI, GRS, and SIRTF/GLIMPSE) and current theoretical understandings and questions. By bringing together experts in the conduct of Galactic surveys and leading theorists, new ways of attacking long-standing scientific questions were encouraged. The titles of most of the talks and posters presented are attached to the end of this report.

  12. Diversity in the Strength and Structure of Unruptured Cerebral Aneurysms

    PubMed Central

    Robertson, Anne M.; Duan, Xinjie; Aziz, Khaled M.; Hill, Michael R.; Watkins, Simon C.; Cebral, Juan R.

    2015-01-01

    Intracranial aneurysms are pathological enlargements of brain arteries that are believed to arise from progressive wall degeneration and remodeling. Earlier work using classical histological approaches identified variability in cerebral aneurysm mural content, ranging from layered walls with intact endothelium and aligned smooth muscle cells, to thin, hypocellular walls. Here, we take advantage of recent advances in multiphoton microscopy, to provide novel results for collagen fiber architecture in 15 human aneurysm domes without staining or fixation as well as in 12 control cerebral arteries. For all aneurysm samples, the elastic lamina was absent and the abluminal collagen fibers had similar diameters to control arteries. In contrast, the collagen fibers on the luminal side showed great variability in both diameter and architecture ranging from dense fiber layers to sparse fiber constructs suggestive of ineffective remodeling efforts. The mechanical integrity of eight aneurysm samples was assessed using uniaxial experiments, revealing two sub-classes (i) vulnerable unruptured aneurysms (low failure stress and failure pressure), and (ii) strong unruptured aneurysms (high failure stress and failure pressure). These results suggest a need to refine the end-point of risk assessment studies that currently do not distinguish risk levels among unruptured aneurysms. We propose that a measure of wall integrity that identifies this vulnerable wall subpopulation will be useful for interpreting future biological and structural data. PMID:25632891

  13. Experimental warming effects on the bacterial community structure and diversity

    NASA Astrophysics Data System (ADS)

    Kim, W.; Han, S.; Adams, J.; Son, Y.

    2014-12-01

    The objective of this study is to investigate the responses of soil bacterial community to future temperature increase by conducting open-field warming experiment. We conducted an open-field experimental warming system using infra-red heater in 2011 and regulated the temperature of warmed plots by 3oC higher than that of control plots constantly. The seeds of Pinus densiflora, Abies holophylla, Abies koreana, Betula costata, Quercus variabilis, Fraxinus rhynchophylla, and Zelkova serrata were planted in each 1 m × 1 m plot (n=3) in April, 2012. We collected soil samples from the rhizosphere of 7 tree species. DNA was extracted and PCR-amplified for the bacterial 16S gene targeting V1-V3 region. The paired-end sequencing was performed at Beijing Genome Institute (BGI, Hong Kong, China) using 2× 100 bp Hiseq2000 (Illumina). This study aimed to answer the following prediction/hypothesis: 1) Experimental warming will change the structure of soil bacterial community, 2) There will be distinct 'indicator group' which response to warming treatment relatively more sensitive than other groups. 3) Warming treatment will enhance the microbial activity in terms of soil respiration. 4) The rhizoplane bacterial communities for each of 7 tree species will show different response pattern to warming treatment. Since the sequence data does not arrive before the submission deadline, therefore, we would like to present the results and discussions on December 2014, AGU Fall Meeting.

  14. Structural Diversity and Biological Activities of Indole Diketopiperazine Alkaloids from Fungi.

    PubMed

    Ma, Yang-Min; Liang, Xi-Ai; Kong, Yang; Jia, Bin

    2016-09-01

    Indole diketopiperazine alkaloids are secondary metabolites of microorganisms that are widely distributed in filamentous fungi, especially in the genera Aspergillus and Penicillium of the phylum Ascomycota or sac fungi. These alkaloids represent a group of natural products characterized by diversity in both chemical structures and biological activities. This review aims to summarize 166 indole diketopiperazine alkaloids from fungi published from 1944 to mid-2015. The emphasis is on diverse chemical structures within these alkaloids and their relevant biological activities. The aim is to assess which of these compounds merit further study for purposes of drug development. PMID:27538469

  15. The near-infrared structure of the barred galaxy NGC 253 from VISTA⋆

    NASA Astrophysics Data System (ADS)

    Iodice, E.; Arnaboldi, M.; Rejkuba, M.; Neeser, M. J.; Greggio, L.; Gonzalez, O. A.; Irwin, M.; Emerson, J. P.

    2014-07-01

    Context. The presence of a bar affects the distribution and dynamics of a stellar disk at all scales, from a fraction of a kpc in the inner central region to tens of kpc at the disk's edge. The quantitative study of the disk response to a bar can be hampered by the presence of dust, which is common in late type spirals. Aims: We want to quantify the structures in the stellar disk of the barred Sc galaxy NGC 253 located in the Sculptor group, at 3.47 Mpc distance. Methods: We use J and Ks band images acquired with the VISTA telescope as part of the Science Verification. The wide field of view and the high angular resolution of this survey facility allow the mapping of the large and small scale structure of the stellar disk in NGC 253. We use unsharp masking and two dimensional modelling of the smooth light distribution in the disk to identify and measure the sub-structures induced by the bar in the stellar disk of NGC 253. We build azimuthally-averaged profiles in the J and Ks bands to measure the radial surface brightness profile of the central bulge, bar and disk. Results: Moving outward from the galaxy center, we find a nuclear ring within the bright 1 kpc diameter nucleus, then a bar, a ring with 2.9 kpc radius, and spiral arms in the outer disk. From the Ks image we obtain a new measure of the de-projected length of the bar of 2.5 kpc. The bar's strength, as derived from the curvature of the dust lanes in the J-Ks image, is typical of weak bars with Δα = 25 degree/kpc. From the de-projected length of the bar, we establish the co-rotation radius (RCR = 3 kpc) and bar pattern speed (Ωb = 61.3 km s-1 kpc-1), which provides the connection between the high frequency structures in the disk and the orbital resonances induced by the bar. The nuclear ring is located at the Inner Lindblad resonance. The second ring (at 2.9 kpc) does not have a resonant origin, but it could be a merger remnant or a transient structure formed during an intermediate stage of the bar

  16. Hα Velocity Mapping of Ultraluminous Infrared Galaxies

    NASA Astrophysics Data System (ADS)

    Mihos, J. Christopher; Bothun, Gregory D.

    1998-06-01

    We use imaging Fabry-Pérot observations to explore the dynamical conditions in four southern ultraluminous (LIR >~ 1012 L⊙) infrared galaxies. These galaxies all show morphological and kinematic features indicative of a major merger, but they span a wide range of inferred dynamical ages: the youngest system is just past the first encounter, while the oldest has already merged into a single object. This diversity in dynamical states indicates that ultraluminous activity is not confined solely to late-stage mergers. The Hα emission is more spatially concentrated in the later stage mergers, in agreement with models that show that mergers drive gas inward toward the nucleus, but high luminosities are achieved even in young interactions where the Hα is quite extended. Our data indicate that physical details other than the dynamical phase--such as the internal structure or gas content of the galaxies--can play a strong role in determining the luminosity evolution of merging galaxies. We also find evidence for massive star-forming complexes at large radius in the tidal debris, which reaffirms the notion that some dwarf galaxies may be spawned during the merger of more massive disk galaxies.

  17. Hα Velocity Mapping of Ultraluminous Infrared Galaxies

    NASA Astrophysics Data System (ADS)

    Mihos, C.; Bothun, G.

    1997-12-01

    We use imaging Fabry-Perot observations to explore the dynamical conditions in four southern ultraluminous (LIR > 10(12) Lsun) infrared galaxies. These galaxies all show morphological and kinematic features indicative of a major merger, but span a wide range of inferred dynamical ages: the youngest system is just past the first encounter, while the oldest has already merged into a single object. This diversity in dynamical states indicates that ultraluminous activity is not confined solely to late-stage mergers. The Hα emission is more spatially concentrated in the later stage mergers, in agreement with models which show that mergers drive gas inwards towards the nucleus, but high luminosities are achieved even in young interactions where the Hα is quite extended. Our data indicate that physical details other than the dynamical phase -- such as the internal structure or gas content of the galaxies -- can play a strong role in determining the luminosity evolution of merging galaxies. We also find evidence for massive star-forming complexes at large radius in the tidal debris, reaffirming the notion that some dwarf galaxies may be spawned during the merger of more massive disk galaxies.

  18. Cyanobacterial Two-Component Proteins: Structure, Diversity, Distribution, and Evolution†

    PubMed Central

    Ashby, Mark K.; Houmard, Jean

    2006-01-01

    A survey of the already characterized and potential two-component protein sequences that exist in the nine complete and seven partially annotated cyanobacterial genome sequences available (as of May 2005) showed that the cyanobacteria possess a much larger repertoire of such proteins than most other bacteria. By analysis of the domain structure of the 1,171 potential histidine kinases, response regulators, and hybrid kinases, many various arrangements of about thirty different modules could be distinguished. The number of two-component proteins is related in part to genome size but also to the variety of physiological properties and ecophysiologies of the different strains. Groups of orthologues were defined, only a few of which have representatives with known physiological functions. Based on comparisons with the proposed phylogenetic relationships between the strains, the orthology groups show that (i) a few genes, some of them clustered on the genome, have been conserved by all species, suggesting their very ancient origin and an essential role for the corresponding proteins, and (ii) duplications, fusions, gene losses, insertions, and deletions, as well as domain shuffling, occurred during evolution, leading to the extant repertoire. These mechanisms are put in perspective with the different genetic properties that cyanobacteria have to achieve genome plasticity. This review is designed to serve as a basis for orienting further research aimed at defining the most ancient regulatory mechanisms and understanding how evolution worked to select and keep the most appropriate systems for cyanobacteria to develop in the quite different environments that they have successfully colonized. PMID:16760311

  19. Radio structures of Seyfert galaxies. VII - Extension of a distance-limited sample

    NASA Technical Reports Server (NTRS)

    Ulvestad, James S.; Wilson, Andrew S.

    1989-01-01

    The VLA has been used at 6 and 20 cm to observe 27 Seyfert galaxies with recessional velocities less than 4600 km/s that had not been mapped previously. The sample shows weak trends for Seyfert 2 galaxies to have more luminous and larger radio sources than Seyfert 1 galaxies. A 20 cm radio luminosity function is constructed for each Seyfert type and shown to be fairly flat for powers betwen 10 to the 20th and 10 to the 23rd W/Hz. About 10 percent of the galaxies in the present sample may have flat-spectrum components contributing a substantial amount of their total flux density at centimeter wavelengths.

  20. The structure and content of the galaxy and galactic gamma rays

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E. (Editor); Stecker, F. W. (Editor)

    1977-01-01

    Gamma radiation investigations by COS-B and SAS-2 satellite are reported. Data from CO surveys of the galaxy and the galactic distribution of pulsars are analyzed. Theories of galactic gamma ray emission are explored.

  1. THE STRUCTURE OF MASSIVE QUIESCENT GALAXIES AT Z {approx} 3 IN THE CANDELS-COSMOS FIELD

    SciTech Connect

    Fan Lulu; Chen Yang; Pan Zhizheng; Lv Xuanyi; Li Jinrong; Lin Lin; Kong Xu; Fang Guanwen

    2013-07-10

    In this Letter, we use a two-color (J - L) versus (V - J) selection criterion to search massive quiescent galaxy (QG) candidates at 2.5 {<=} z {<=} 4.0 in the CANDELS-COSMOS field. We construct an H{sub F160W}-selected catalog and complement it with public auxiliary data. We finally obtain 19 passive VJL-selected (hereafter pVJL) galaxies as the possible massive QG candidates at z {approx} 3 by several constrains. We find the sizes of our pVJL galaxies are on average three to four times smaller than those of local early-type galaxies (ETGs) with analogous stellar mass. The compact size of these z {approx} 3 galaxies can be modeled by assuming their formation at z{sub form} {approx} 4-6 according to the dissipative collapse of baryons. Up to z < 4, the mass-normalized size evolution can be described by r{sub e} {proportional_to}(1 + z){sup -1.0}. Low Sersic index and axis ratio, with median values n {approx}1.5 and b/a {approx} 0.65, respectively, indicate that most of the pVJL galaxies are disk-dominated. Despite large uncertainty, the inner region of the median mass profile of our pVJL galaxies is similar to those of QGs at 0.5 < z < 2.5 and local ETGs. It indicates that local massive ETGs have been formed according to an inside-out scenario: the compact galaxies at high redshift make up the cores of local massive ETGs and then build up the outskirts according to dissipationless minor mergers.

  2. Response of rocky invertebrate diversity, structure and function to the vertical layering of vegetation

    NASA Astrophysics Data System (ADS)

    Bustamante, María; Tajadura, Javier; Gorostiaga, José María; Saiz-Salinas, José Ignacio

    2014-06-01

    Macroalgae comprise a prominent part of the rocky benthos where many invertebrates develop, and are believed to be undergoing severe declines worldwide. In order to investigate how the vegetation structure (crustose, basal and canopy layers) contributes to the diversity, structure and function of benthic invertebrates, a total of 31 subtidal transects were sampled along the northeast Atlantic coast of Spain. Significant positive relationships were found between the canopy layer and faunal abundance, taxonomic diversity and functional group diversity. Canopy forming algae were also related to epiphytic invertebrates, medium size forms, colonial strategy and suspensivores. By contrast, basal algae showed negative relationships with all variables tested except for detritivores. Multivariate multiple regression analyses (DISTLM) point to crustose as well as canopy layers as the best link between seaweeds and invertebrate assemblage structure. A close relationship was found between taxonomic and functional diversities. In general, low levels of taxonomic redundancy were detected for functional groups correlated with vegetation structure. A conceptual model based on the results is proposed, describing distinct stages of invertebrate assemblages in relation to the vertical structure of vegetation.

  3. Structural Evolution of Early-type Galaxies to z=2.5 in CANDELS

    NASA Astrophysics Data System (ADS)

    Chang, Yu-Yen; van der Wel, A.; Rix, H.; CANDELS Collaboration

    2014-01-01

    Projected axis ratio measurements of 880 early-type galaxies at redshifts 1 < z < 2.5 selected from CANDELS are used to reconstruct and model their intrinsic shapes. The sample is selected on the basis of multiple rest-frame colors to reflect low star-formation activity. Similar to their present-day counterparts, the z > 1 early-type galaxies show a variety of intrinsic shapes; even at a fixed mass, the projected axis ratio distributions cannot be explained by the random projection of a set of galaxies with very similar intrinsic shapes. However, a two-population model for the intrinsic shapes, consisting of a triaxial, fairly round population, combined with a flat (c/a ~ 0.3) oblate population, adequately describes the projected axis ratio distributions of both present-day and z > 1 early-type galaxies. However, the oblate fraction among massive (M* ~ 10^11 Msun) objects was much higher in the past: 0.59 ± 0.10 at z > 1, compared to 0.20 ± 0.02 at z ~ 0.1. When combined with previous findings that the number density and sizes of early-type galaxies substantially increase over the same redshift range, this can be explained by the gradual emergence of merger-produced elliptical galaxies, at the expense of the destruction of pre-existing disks that were common among their high-redshift progenitors.

  4. Two spectroscopically confirmed galaxy structures at z = 0.61 and 0.74 in the CFHTLS Deep 3 field

    NASA Astrophysics Data System (ADS)

    Adami, C.; Cypriano, E. S.; Durret, F.; Le Brun, V.; Lima Neto, G. B.; Martinet, N.; Perez, F.; Rouze, B.; Sodré, L.

    2015-03-01

    Context. Galaxy evolution is known to depend on environment since it differs in clusters and in the field, but studies are sometimes limited to the relatively nearby Universe (z < 0.5). It is still necessary to increase our knowledge of cluster galaxy properties above z = 0.5. Aims: In a previous paper we have detected several cluster candidates at z> 0.5 as part of a systematic search for clusters in the Canada France Hawaii Telescope Legacy Survey by applying the Adami & MAzure Cluster FInder (AMACFI), based on photometric redshifts. We focus here on two of them, located in the Deep 3 (hereafter D3) field: D3-6 and D3-43. Methods: We have obtained spectroscopy with Gemini/GMOS instrument and measured redshifts for 23 and 14 galaxies in the two structures. These redshifts were combined with those available in the literature. A dynamical and a weak lensing analysis were also performed, together with the study of X-ray Chandra archive data. Results: Cluster D3-6 is found to be a single structure of eight spectroscopically confirmed members at an average redshift z = 0.607, with a velocity dispersion of 423 km s-1. It appears to be a relatively low-mass cluster. D3-43-S3 has 46 spectroscopically confirmed members at an average redshift z = 0.739. The cluster can be decomposed into two main substructures, having a velocity dispersion of about 600 and 350 km s-1. An explanation of the fact that D3-43-S3 is detected through weak lensing (only marginally, at the ~3σ level) but not in X-rays could be that the two substructures are just beginning to merge more or less along the line of sight. We also show that D3-6 and D3-43-S3 have similar global galaxy luminosity functions, stellar mass functions, and star formation rate (SFR) distributions. The only differences are that D3-6 exhibits a lack of faint early-type galaxies, a deficit of extremely high stellar mass galaxies compared to D3-43-S3, and an excess of very high SFR galaxies. Conclusions: This study shows the

  5. Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Miller, Christopher J. Miller

    2012-03-01

    of galaxy clusters will be at locations of the peaks in the true underlying (mostly) dark matter density field. Kaiser (1984) [19] called this the high-peak model, which we demonstrate in Figure 16.1. We show a two-dimensional representation of a density field created by summing plane-waves with a predetermined power and with random wave-vector directions. In the left panel, we plot only the largest modes, where we see the density peaks (black) and valleys (white) in the combined field. In the right panel, we allow for smaller modes. You can see that the highest density peaks in the left panel contain smaller-scale, but still high-density peaks. These are the locations of future galaxy clusters. The bottom panel shows just these cluster-scale peaks. As you can see, the peaks themselves are clustered, and instead of just one large high-density peak in the original density field (see the left panel), the smaller modes show that six peaks are "born" within the broader, underlying large-scale density modes. This exemplifies the "bias" or amplified structure that is traced by galaxy clusters [19]. Clusters are rare, easy to find, and their member galaxies provide good distance estimates. In combination with their amplified clustering signal described above, galaxy clusters are considered an efficient and precise tracer of the large-scale matter density field in the Universe. Galaxy clusters can also be used to measure the baryon content of the Universe [43]. They can be used to identify gravitational lenses [38] and map the distribution of matter in clusters. The number and spatial distribution of galaxy clusters can be used to constrain cosmological parameters, like the fraction of the energy density in the Universe due to matter (Omega_matter) or the variation in the density field on fixed physical scales (sigma_8) [26,33]. The individual clusters act as “Island Universes” and as such are laboratories here we can study the evolution of the properties of the cluster

  6. MULTIPLE SHOCK STRUCTURES IN A RADIO-SELECTED CLUSTER OF GALAXIES

    SciTech Connect

    Brown, S.; Duesterhoeft, J.; Rudnick, L.

    2011-01-20

    We present a new radio-selected cluster of galaxies, 0217+70, using observations from the Very Large Array and archival optical and X-ray data. The new cluster is one of only seven known that has candidate double peripheral radio relics, and the second of those with a giant radio halo (GRH), as well. It also contains unusual diffuse radio filaments interior to the peripheral relics and a clumpy, elongated X-ray structure. All of these indicate a very actively evolving system, with ongoing accretion and merger activity, illuminating a network of shocks, such as those first seen in numerical simulations. The peripheral relics are most easily understood as outgoing spherical merger shocks with large variations in brightness along them, likely reflecting the inhomogeneities in the shocks' magnetic fields. The interior filaments could be projections of substructures from the sheet-like peripheral shocks or they might be separate structures due to multiple accretion events. ROSAT images show large-scale diffuse X-ray emission coincident with the GRH and additional patchy diffuse emission that suggests a recent merger event. This uniquely rich set of radio shocks and halo offer the possibility, with deeper X-ray and optical data and higher resolution radio observations, of testing the models of how shocks and turbulence couple to the relativistic plasma. The cluster 0217+70 is also overluminous in the radio compared with the empirical radio-X-ray correlation for clusters-the third example of such a system. This new population of diffuse radio emission opens up the possibility of probing low-mass cluster mergers with upcoming deep radio continuum surveys.

  7. AN H{alpha} NUCLEAR SPIRAL STRUCTURE IN THE E0 ACTIVE GALAXY Arp 102B

    SciTech Connect

    Fathi, Kambiz; Axon, David J.; Kharb, Preeti; Robinson, Andrew; Storchi-Bergmann, Thaisa; Marconi, Alessandro; Maciejewski, Witold; Capetti, Alessandro E-mail: djasps@rit.edu E-mail: pxksps@cis.rit.edu E-mail: marconi@arcetri.astro.it E-mail: capetti@to.astro.it

    2011-08-01

    We report the discovery of a two-armed mini-spiral structure within the inner kiloparsec of the E0 LINER/Seyfert 1 galaxy Arp 102B. The arms are observed in H{alpha} emission and located east and west of the nucleus, extending up to {approx}1 kpc from it. We use narrow-band imaging from the Hubble Space Telescope Advanced Camera for Surveys, in combination with archival Very Large Array radio images at 3.6 and 6 cm to investigate the origin of the nuclear spiral. From the H{alpha} luminosity of the spiral, we obtain an ionized gas mass of the order of 10{sup 6} solar masses. One possibility is that the nuclear spiral represents a gas inflow triggered by a recent accretion event which has replenished the accretion disk, giving rise to the double-peaked emission-line profiles characteristic of Arp 102B. However, the radio images show a one-sided curved jet which correlates with the eastern spiral arm observed in the H{alpha} image. A published milliarcsecond radio image also shows a one-sided structure at position angle {approx}40{sup 0}, approximately aligned with the inner part of the eastern spiral arm. The absence of a radio counterpart to the western spiral arm is tentatively interpreted as indicating that the jet is relativistic, with an estimated speed of 0.45c. Estimates of the jet kinetic energy and the ionizing luminosity of the active nucleus indicate that both are capable of ionizing the gas along the spiral arms. We conclude that, although the gas in the nuclear region may have originated in an accretion event, the mini spiral is most likely the result of a jet-cloud interaction rather than an inflowing stream.

  8. The DEEP Groth Strip Survey. II. Hubble Space Telescope Structural Parameters of Galaxies in the Groth Strip

    NASA Astrophysics Data System (ADS)

    Simard, Luc; Willmer, Christopher N. A.; Vogt, Nicole P.; Sarajedini, Vicki L.; Phillips, Andrew C.; Weiner, Benjamin J.; Koo, David C.; Im, Myungshin; Illingworth, Garth D.; Faber, S. M.

    2002-09-01

    The quantitative morphological classification of distant galaxies is essential to the understanding of the evolution of galaxies over the history of the universe. This paper presents Hubble Space Telescope WFPC2 F606W and F814W photometric structural parameters for 7450 galaxies in the ``Groth Strip.'' These parameters are based on a two-dimensional bulge+disk surface brightness model and were obtained using an automated reduction and analysis pipeline described in detail here. A first set of fits was performed separately in each bandpass, and a second set of fits was performed simultaneously on both bandpasses. The information produced by these two types of fits can be used to explore different science goals. Systematic and random fitting errors in all structural parameters as well as bulge and disk colors are carefully characterized through extensive sets of simulations. The results of these simulations are given in catalogs similar to the real science catalogs so that both real and simulated measurements can be sampled according to the same selection criteria to show biases and errors in the science data subset of interest. The effects of asymmetric structures on the recovered bulge+disk fitting parameters are also explored through simulations. The full multidimensional photometric survey selection function of the Groth Strip is also computed. This selection function, coupled to bias maps from simulations, provides a complete and objective reproduction of the observational limits, and these limits can be applied to theoretical predictions from galaxy evolution models for direct comparisons with the data. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by AURA, Inc., under contract with NASA.

  9. THE RESOLVED STRUCTURE AND DYNAMICS OF AN ISOLATED DWARF GALAXY: A VLT AND KECK SPECTROSCOPIC SURVEY OF WLM

    SciTech Connect

    Leaman, Ryan; Venn, Kim A.; Mendel, J. Trevor; Brooks, Alyson M.; Cole, Andrew A.; Ibata, Rodrigo A.; Irwin, Mike J.; McConnachie, Alan W.; Tolstoy, Eline

    2012-05-01

    We present spectroscopic data for 180 red giant branch (RGB) stars in the isolated dwarf irregular galaxy Wolf-Lundmark-Mellote (WLM). Observations of the calcium II triplet lines in spectra of RGB stars covering the entire galaxy were obtained with FORS2 at the Very Large Telescope and DEIMOS on Keck II, allowing us to derive velocities, metallicities, and ages for the stars. With accompanying photometric and radio data we have measured the structural parameters of the stellar and gaseous populations over the full galaxy. The stellar populations show an intrinsically thick configuration with 0.39 {<=} q{sub 0} {<=} 0.57. The stellar rotation in WLM is measured to be 17 {+-} 1 km s{sup -1}; however, the ratio of rotation to pressure support for the stars is V/{sigma} {approx} 1, in contrast to the gas, whose ratio is seven times larger. This, along with the structural data and alignment of the kinematic and photometric axes, suggests we are viewing WLM as a highly inclined oblate spheroid. Stellar rotation curves, corrected for asymmetric drift, are used to compute a dynamical mass of (4.3 {+-} 0.3) Multiplication-Sign 10{sup 8} M{sub Sun} at the half-light radius (r{sub h} = 1656 {+-} 49 pc). The stellar velocity dispersion increases with stellar age in a manner consistent with giant molecular cloud and substructure interactions producing the heating in WLM. Coupled with WLM's isolation, this suggests that the extended vertical structure of its stellar and gaseous components and increase in stellar velocity dispersion with age are due to internal feedback, rather than tidally driven evolution. These represent some of the first observational results from an isolated Local Group dwarf galaxy that can offer important constraints on how strongly internal feedback and secular processes modulate star formation and dynamical evolution in low-mass isolated objects.

  10. The Study of Active Galactic Nuclei and Galaxy Structure Using SDSS Spectroscopy

    NASA Astrophysics Data System (ADS)

    Roig, Benjamin

    Two distinct projects involving spectroscopic data from the Sloan Digital Sky Survey are presented. Data from both the Legacy (SDSS-II) and BOSS (SDSS-III) surveys are used to study stellar populations and active galactic nuclei in old, red galaxies. In the first project, we infer stellar metallicity and abundance ratio gradients for a sample of red galaxies in the Sloan Digital Sky Survey (SDSS) Main galaxy sample. Because this sample does not have multiple spectra at various radii in a single galaxy, we measure these gradients statistically. This method is possible because for a fixed aperture size and a varying redshift range, the aperture will cover different physical sizes on each galaxy dependent on redshift. We stack galaxy spectra in relatively narrow redshift bins and calculate several absorption line indices in projected annuli by differencing spectra in neighboring redshift bins. After determining the line indices, we use stellar population modeling from the EZ_Ages software to calculate ages, metallicities, and abundance ratios within each annulus. Our data covers the central regions of these galaxies, out to slightly higher than 1 Re. We find detectable gradients in metallicity and relatively shallow gradients in abundance ratios, similar to results found for direct measurements of individual galaxies. We compare this data to previous observations and find general agreement, and then briefly to several theoretical studies simulating galaxy evolution models to see what the metallicity gradients and abundance ratios imply about the evolutionary track of these red galaxies. This project also involves developing a code framework to verify this method, with potential more generally applicable future uses. For the second project, we examine the sample of luminous galaxies in the Baryon Oscillation Spectroscopic Survey (BOSS). We find a potentially new observational class of AGN, one with strong and broad MgII 2799A line emission, but very weak emission in

  11. THE GEMINI/HST CLUSTER PROJECT: STRUCTURAL AND PHOTOMETRIC PROPERTIES OF GALAXIES IN THREE z = 0.28-0.89 CLUSTERS

    SciTech Connect

    Chiboucas, Kristin; Joergensen, Inger; Barr, Jordi; Collobert, Maela; Davies, Roger; Flint, Kathleen E-mail: ijorgensen@gemini.edu E-mail: maela.collobert@gmail.com E-mail: kflint@nationalpostdoc.org

    2009-10-01

    We present the data processing and analysis techniques we are using to determine the structural and photometric properties of galaxies in our Gemini/HST Galaxy Cluster Project sample. The goal of this study is to understand cluster galaxy evolution in terms of scaling relations and structural properties of cluster galaxies at redshifts 0.15 < z < 1.0. To derive parameters such as total magnitude, half-light radius, effective surface brightness, and Sersic n, we fit r {sup 1/4} law and Sersic function two-dimensional surface brightness profiles to each of the galaxies in our sample. Using simulated galaxies, we test how the assumed profile affects the derived parameters and how the uncertainties affect our Fundamental Plane results. We find that while fitting galaxies that have Sersic index n < 4 with r {sup 1/4} law profiles systematically overestimates the galaxy radius and flux, the combination of profile parameters that enter the Fundamental Plane has uncertainties that are small. Average systematic offsets and associated random uncertainties in magnitude and log r{sub e} for n>2 galaxies fitted with r {sup 1/4} law profiles are -0.1 {+-} 0.3 and 0.1 {+-} 0.2, respectively. The combination of effective radius and surface brightness, log r{sub e} - {beta}log (I) {sub e}, that enters the Fundamental Plane produces offsets smaller than -0.02 {+-} 0.10. This systematic error is insignificant and independent of galaxy magnitude or size. A catalog of photometry and surface brightness profile parameters is presented for three of the clusters in our sample, RX J0142.0+2131, RX J0152.7-1357, and RX J1226.9+3332 at redshifts 0.28, 0.83, and 0.89, respectively.

  12. Does the habitat structure control the distribution and diversity of the Odonatofauna?

    PubMed

    Souza, A M; Fogaça, F N O; Cunico, A M; Higuti, J

    2015-08-01

    The statement that the habitat complexity and structure govern the abundance and diversity of biological communities has been widely investigated. In this context, we assumed the hypothesis of habitat heterogeneity, that is, the higher habitat complexity leads to greater diversity of Odonata. In addition, we analyzed the influence of habitat structure on the distribution of this community, and evaluated the effects of abiotic variables. Odonata larvae were collected with sieves and by electrofishing in ten neotropical streams belonging to the Pirapó River basin. Forty species of Odonata were registered, which were distributed in eight families, Libellulidae stood out with the highest richness. The high gamma diversity and distribution of Odonata were associated with habitat heterogeneity in these streams. However, the abiotic variables also seem to affect the distribution of Odonata species, in view of the impact of the land use in the vicinity of streams. PMID:26421772

  13. Combining Galaxy-Galaxy Lensing and Galaxy Clustering

    SciTech Connect

    Park, Youngsoo; Krause, Elisabeth; Dodelson, Scott; Jain, Bhuvnesh; Amara, Adam; Becker, Matt; Bridle, Sarah; Clampitt, Joseph; Crocce, Martin; Honscheid, Klaus; Gaztanaga, Enrique; Sanchez, Carles; Wechsler, Risa

    2015-01-01

    Combining galaxy-galaxy lensing and galaxy clustering is a promising method for inferring the growth rate of large scale structure, a quantity that will shed light on the mechanism driving the acceleration of the Universe. The Dark Energy Survey (DES) is a prime candidate for such an analysis, with its measurements of both the distribution of galaxies on the sky and the tangential shears of background galaxies induced by these foreground lenses. By constructing an end-to-end analysis that combines large-scale galaxy clustering and small-scale galaxy-galaxy lensing, we also forecast the potential of a combined probes analysis on DES datasets. In particular, we develop a practical approach to a DES combined probes analysis by jointly modeling the assumptions and systematics affecting the different components of the data vector, employing a shared halo model, HOD parametrization, photometric redshift errors, and shear measurement errors. Furthermore, we study the effect of external priors on different subsets of these parameters. We conclude that DES data will provide powerful constraints on the evolution of structure growth in the universe, conservatively/ optimistically constraining the growth function to 8%/4.9% with its first-year data covering 1000 square degrees, and to 4%/2.3% with its full five-year data covering 5000 square degrees.

  14. Star Formation, Structure and Evolution of Galaxies in Loose Groups: The Environmental Connection

    NASA Astrophysics Data System (ADS)

    Marcum, Pamela Marie

    1994-01-01

    Galaxies seldom live in isolation. Rather, they reside in multi-galaxy systems (clusters, loose groups, compact groups) spanning a large range in kinematical properties. This thesis investigates the relationship between environment and properties of galaxies belonging to loose groups. The galactic properties which we consider are morphology, near infrared colors, Ha surface brightness (proportional to star formation rate), Ha emission equivalent width (sensitive to the star formation history), color gradients light distribution profiles, and luminosity functions. Recent N-body simulations predict that transitory compact configurations, each typically consisting of approx. 2 to 5 galaxies, are created continuously during collapse of a loose group. Given this model, a loose group is expected to acquire an increasing number of merger remnants and peculiar galaxies as that group evolves dynamically. This thesis investigates the possible observational consequences of group evolution by comparing two samples of galaxy groups: (1) groups that contain galaxies listed in the 'Atlas of Peculiar Galaxies', which either have obvious disturbed morphologies and/or are likely to be involved in an interaction with a close neighboring group member(s), and (2) a control sample containing members having 'normal' galaxy properties. The thesis consists of 3 papers: the first paper describes observations and data analysis for the near infrared (JHK) imaging, taken with the Kitt Peak SQIID detector at the 1.3 meter telescope. Near infrared contours, aperture photometry, and results based on the near infrared colors are presented. The second paper provides a description of the data analysis for the R and H(alpha) CCD images, taken with the Case Western Reserve University Burrell Schmidt telescope at Kitt Peak. The morphology of the star forming regions are shown by displaying H(alpha) maps overlaid with R band contours. Near infrared H(alpha) band and optical R band surface brightness

  15. Genetic Diversity and Spatial Genetic Structure of the Grassland Perennial Saxifraga granulata along Two River Systems

    PubMed Central

    van der Meer, Sascha; Jacquemyn, Hans

    2015-01-01

    Due to changes in land use, the natural habitats of an increasing number of plant species have become more and more fragmented. In landscapes that consist of patches of suitable habitat, the frequency and extent of long-distance seed dispersal can be expected to be an important factor determining local genetic diversity and regional population structure of the remaining populations. In plant species that are restricted to riparian habitats, rivers can be expected to have a strong impact on the dynamics and spatial genetic structure of populations as they may enable long-distance seed dispersal and thus maintain gene flow between fragmented populations. In this study, we used polymorphic microsatellite markers to investigate the genetic diversity and the spatial genetic structure of 28 populations of Saxifraga granulata along two rivers in central Belgium. We hypothesized that rivers might be essential for gene flow among increasingly isolated populations of this species. Genetic diversity was high (HS = 0.68), which to a certain extent can be explained by the octoploid nature of S. granulata in the study area. Populations along the Dijle and Demer rivers were also highly differentiated (G”ST = 0.269 and 0.164 and DEST = 0.190 and 0.124, respectively) and showed significant isolation-by-distance, indicating moderate levels of gene flow primarily between populations that are geographically close to each other. Along the river Demer population genetic diversity was higher upstream than downstream, suggesting that seed dispersal via the water was not the primary mode of dispersal. Overall, these results indicate that despite increasing fragmentation populations along both rivers were highly genetically diverse. The high ploidy level and longevity of S. granulata have most likely buffered negative effects of fragmentation on genetic diversity and the spatial genetic structure of populations in riparian grasslands. PMID:26079603

  16. Considering Future Potential Regarding Structural Diversity in Selection of Forest Reserves.

    PubMed

    Lundström, Johanna; Öhman, Karin; Rönnqvist, Mikael; Gustafsson, Lena

    2016-01-01

    A rich structural diversity in forests promotes biodiversity. Forests are dynamic and therefore it is crucial to consider future structural potential when selecting reserves, to make robust conservation decisions. We analyzed forests in boreal Sweden based on 17,599 National Forest Inventory (NFI) plots with the main aim to understand how effectiveness of reserves depends on the time dimension in the selection process, specifically by considering future structural diversity. In the study both the economic value and future values of 15 structural variables were simulated during a 100 year period. To get a net present structural value (NPSV), a single value covering both current and future values, we used four discounting alternatives: (1) only considering present values, (2) giving equal importance to values in each of the 100 years within the planning horizon, (3) applying an annual discount rate considering the risk that values could be lost, and (4) only considering the values in year 100. The four alternatives were evaluated in a reserve selection model under budget-constrained and area-constrained selections. When selecting young forests higher structural richness could be reached at a quarter of the cost over almost twice the area in a budget-constrained selection compared to an area-constrained selection. Our results point to the importance of considering future structural diversity in the selection of forest reserves and not as is done currently to base the selection on existing values. Targeting future values increases structural diversity and implies a relatively lower cost. Further, our results show that a re-orientation from old to young forests would imply savings while offering a more extensive reserve network with high structural qualities in the future. However, caution must be raised against a drastic reorientation of the current old-forest strategy since remnants of ancient forests will need to be prioritized due to their role for disturbance

  17. Considering Future Potential Regarding Structural Diversity in Selection of Forest Reserves

    PubMed Central

    Lundström, Johanna; Öhman, Karin; Rönnqvist, Mikael; Gustafsson, Lena

    2016-01-01

    A rich structural diversity in forests promotes biodiversity. Forests are dynamic and therefore it is crucial to consider future structural potential when selecting reserves, to make robust conservation decisions. We analyzed forests in boreal Sweden based on 17,599 National Forest Inventory (NFI) plots with the main aim to understand how effectiveness of reserves depends on the time dimension in the selection process, specifically by considering future structural diversity. In the study both the economic value and future values of 15 structural variables were simulated during a 100 year period. To get a net present structural value (NPSV), a single value covering both current and future values, we used four discounting alternatives: (1) only considering present values, (2) giving equal importance to values in each of the 100 years within the planning horizon, (3) applying an annual discount rate considering the risk that values could be lost, and (4) only considering the values in year 100. The four alternatives were evaluated in a reserve selection model under budget-constrained and area-constrained selections. When selecting young forests higher structural richness could be reached at a quarter of the cost over almost twice the area in a budget-constrained selection compared to an area-constrained selection. Our results point to the importance of considering future structural diversity in the selection of forest reserves and not as is done currently to base the selection on existing values. Targeting future values increases structural diversity and implies a relatively lower cost. Further, our results show that a re-orientation from old to young forests would imply savings while offering a more extensive reserve network with high structural qualities in the future. However, caution must be raised against a drastic reorientation of the current old-forest strategy since remnants of ancient forests will need to be prioritized due to their role for disturbance

  18. Whirlpool Galaxy

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Scientists are seeing unprecedented detail of the spiral arms and dust clouds in the nearby Whirlpool galaxy, thanks to a new Hubble Space Telescope image, available at http://www.jpl.nasa.gov/pictures/wfpc/wfpc.html. The image uses data collected January 15 and 24, 1995, and July 21, 1999, by Hubble's Wide Field and Planetary Camera 2, designed and built by JPL. Using the image, a research group led by Dr. Nick Scoville of the California Institute of Technology, Pasadena, clearly defined the structure of the galaxy's cold dust clouds and hot hydrogen, and they linked star clusters within the galaxy to their parent dust clouds.

    The Whirlpool galaxy is one of the most photogenic galaxies. This celestial beauty is easily seen and photographed with smaller telescopes and studied extensively from large ground- and space-based observatories. The new composite image shows visible starlight and light from the emission of glowing hydrogen, which is associated with the most luminous young stars in the spiral arms.

    The galaxy is having a close encounter with a nearby companion galaxy, NGC 5195, just off the upper edge of the image. The companion's gravitational pull is triggering star formation in the main galaxy, lit up by numerous clusters of young and energetic stars in brilliant detail. Luminous clusters are highlighted in red by their associated emission from glowing hydrogen gas.

    This image was composed by the Hubble Heritage Team from Hubble archive data and was superimposed onto data taken by Dr. Travis Rector of the National Optical Astronomy Observatory at the .9-meter (35-inch) telescope at the National Science Foundation's Kitt Peak National Observatory, Tucson, Ariz. Scoville's team includes M. Polletta of the University of Geneva, Switzerland; S. Ewald and S. Stolovy of Caltech; and R. Thompson and M. Rieke of the University of Arizona, Tucson.

    The Space Telescope Science Institute, Baltimore, Md., manages space operations for the Hubble Space

  19. STRUCTURAL EVOLUTION OF EARLY-TYPE GALAXIES TO z = 2.5 IN CANDELS

    SciTech Connect

    Chang, Yu-Yen; Van der Wel, Arjen; Rix, Hans-Walter; Holden, Bradford; Faber, S. M.; Mozena, Mark; Guo Yicheng; Kocevski, Dale D.; McGrath, Elizabeth J.; Wuyts, Stijn; Haeussler, Boris; Barden, Marco; Ferguson, Henry C.; Grogin, Norman A.; Koekemoer, Anton M.; Huang, Kuang-Han; Galametz, Audrey; Dekel, Avishai; Hathi, Nimish P.; and others

    2013-08-20

    Projected axis ratio measurements of 880 early-type galaxies at redshifts 1 < z < 2.5 selected from CANDELS are used to reconstruct and model their intrinsic shapes. The sample is selected on the basis of multiple rest-frame colors to reflect low star-formation activity. We demonstrate that these galaxies as an ensemble are dust-poor and transparent and therefore likely have smooth light profiles, similar to visually classified early-type galaxies. Similar to their present-day counterparts, the z > 1 early-type galaxies show a variety of intrinsic shapes; even at a fixed mass, the projected axis ratio distributions cannot be explained by the random projection of a set of galaxies with very similar intrinsic shapes. However, a two-population model for the intrinsic shapes, consisting of a triaxial, fairly round population, combined with a flat (c/a {approx} 0.3) oblate population, adequately describes the projected axis ratio distributions of both present-day and z > 1 early-type galaxies. We find that the proportion of oblate versus triaxial galaxies depends both on the galaxies' stellar mass, and-at a given mass-on redshift. For present-day and z < 1 early-type galaxies the oblate fraction strongly depends on galaxy mass. At z > 1, this trend is much weaker over the mass range explored here (10{sup 10} < M{sub *}/M{sub Sun} < 10{sup 11}), because the oblate fraction among massive (M{sub *} {approx} 10{sup 11} M{sub Sun }) was much higher in the past: 0.59 {+-} 0.10 at z > 1, compared to 0.20 {+-} 0.02 at z {approx} 0.1. When combined with previous findings that the number density and sizes of early-type galaxies substantially increase over the same redshift range, this can be explained by the gradual emergence of merger-produced elliptical galaxies, at the expense of the destruction of pre-existing disks that were common among their high-redshift progenitors. In contrast, the oblate fraction among low-mass early-type galaxies (log (M{sub *}/M{sub Sun }) < 10

  20. Genetic diversity, population structure, and formulation of a core collection of 1,197 Citrullus accessions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There has been continuing interests in breeding of watermelon for economic benefits, but information on the scope and utilization of genetic variations in this genus (Citrullus) is still limited. We evaluated the genetic diversity and population structure of 1,197 watermelon collections, which belon...

  1. The Diverse Social and Economic Structure of Nonmetropolitan America. Rural Development Research Report No. 49.

    ERIC Educational Resources Information Center

    Bender, Lloyd D.; And Others

    Effective rural development planning depends on facts and analysis based, not on rural averages, but on the diverse social and economic structure of rural America. Programs tailored to particular types of rural economies may be more effective than generalized programs. Because of their unique characteristics, government policies and economic…

  2. Population genetic structure and genetic diversity of soybean aphids from USA, Korea and Japan

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Following its recent invasion of North America, the soybean aphid (Aphis glycines Matsumura) has become the number one insect pest of soybean (Glycine max L. Merr.) in the north central states of USA. Very little is known about the population genetic structure and genetic diversity of the soybean ap...

  3. Microbial community structure and diversity as indicators for evaluating soil quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This review addresses two critical questions regarding soil quality: (1) which soil microbial properties, in particular diversity and community structure, most effectively characterize soil quality and should be used as indicators, and (2) how can soil quality assessed by such indicators be improved...

  4. Diverse Narrative Structures in Contemporary Picturebooks: Opportunities for Children's Meaning-Making

    ERIC Educational Resources Information Center

    Pantaleo, Sylvia; Sipe, Lawrence R.

    2012-01-01

    In this article, the authors situate their discussion of diverse narrative structures in the context of oral storytelling practices and postmodern picturebooks. They focus on three contemporary picturebooks: "Don't Read This Book!" (Lewis, 2009), "Abe Lincoln Crosses a Creek: A Tall Thin Tale" (Hopkins, 2008), and "The Stinky Cheese Man and Other…

  5. Structure of Vocational Interests for Diverse Groups on the 2005 Strong Interest Inventory

    ERIC Educational Resources Information Center

    Kantamneni, Neeta; Fouad, Nadya

    2011-01-01

    This study was designed to examine the structure of vocational interests in a diverse sample of individuals who completed the 2005 revision of the Strong Interest Inventory. We examined the fit of three racial/ethnic groups (African American, Caucasian, and Latino/a), both genders, and three levels of professional status (GRS participant, student,…

  6. Population structure and genetic diversity of Sclerotinia minor from peanut research plots in Oklahoma

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sclerotinia minor is the causal agent of Sclerotinia blight, a disease that significantly reduces peanut (Arachis hypogea) productivity. This study analyzed the diversity and population structure of 164 S. minor isolates from Oklahoma. Isolates were obtained from infected stems of peanut plants fr...

  7. Interracial Friendship and Structural Diversity: Trends for Greek, Religious, and Ethnic Student Organizations

    ERIC Educational Resources Information Center

    Park, Julie J.; Kim, Young K.

    2013-01-01

    This article examines how peer interactions in college organizations (Greek, ethnic, and religious) affect interracial friendships, including whether peer interaction in student organizations mediates the relationship between structural diversity and interracial friendship. Involvement in ethnic student organizations was non-significant;…

  8. Genetic diversity and population structure in the tomato-like nightshades Solanum lycopersicoides and S. sitiens

    PubMed Central

    Albrecht, Elena; Escobar, Miguel; Chetelat, Roger T.

    2010-01-01

    Background and Aims Two closely related, wild tomato-like nightshade species, Solanum lycopersicoides and Solanum sitiens, inhabit a small area within the Atacama Desert region of Peru and Chile. Each species possesses unique traits, including abiotic and biotic stress tolerances, and can be hybridized with cultivated tomato. Conservation and utilization of these tomato relatives would benefit from an understanding of genetic diversity and relationships within and between populations. Methods Levels of genetic diversity and population genetic structure were investigated by genotyping representative accessions of each species with a set of simple sequence repeat (SSR) and allozyme markers. Key Results As expected for self-incompatible species, populations of S. lycopersicoides and S. sitiens were relatively diverse, but contained less diversity than the wild tomato Solanum chilense, a related allogamous species native to this region. Populations of S. lycopersicoides were slightly more diverse than populations of S. sitiens according to SSRs, but the opposite trend was found with allozymes. A higher coefficient of inbreeding was noted in S. sitiens. A pattern of isolation by distance was evident in both species, consistent with the highly fragmented nature of the populations in situ. The populations of each taxon showed strong geographical structure, with evidence for three major groups, corresponding to the northern, central and southern elements of their respective distributions. Conclusions This information should be useful for optimizing regeneration strategies, for sampling of the populations for genes of interest, and for guiding future in situ conservation efforts. PMID:20154348

  9. Genetic diversity and structure of the threatened species Sinopodophyllum hexandrum (Royle) Ying.

    PubMed

    Liu, W; Wang, J; Yin, D X; Yang, M; Wang, P; Han, Q S; Ma, Q Q; Liu, J J; Wang, J X

    2016-01-01

    Sinopodophyllum hexandrum is an important medicinal plant that has been listed as an endangered species, making the conservation of its genetic diversity a priority. Therefore, the genetic diversity and population structure of S. hexandrum was investigated through inter-simple sequence repeat analysis of eight natural populations. Eleven selected primers generated 141 discernible fragments. The percentage of polymorphic bands was 37.59% at the species level, and 7.66-24.32% at the population level. Genetic diversity of S. hexandrum was low within populations (average HE = 0.0366), but higher at the species level (HE = 0.0963). Clear structure and high genetic differentiation were detected between populations using unweighted pair groups mean arithmetic and principle coordinate analysis. Clustering approaches clustered the eight sampled populations into three major groups, and AMOVA confirmed there to be significant variation between populations (63.27%). Genetic differentiation may have arisen through limited gene flow (Nm = 0.3317) in this species. Isolation by distance among populations was determined by comparing genetic distance versus geographical distance using the Mantel test. The results revealed no correlation between spatial pattern and geographic location. Given the low within-population genetic diversity, high differentiation among populations, and the increasing anthropogenic pressure on this species, in situ conservation measures, in addition to sampling and ex situ preservation, are recommended to preserve S. hexandrum populations and to retain their genetic diversity. PMID:27323174

  10. Population Structure and Genetic Diversity of Native and Invasive Populations of Solanum rostratum (Solanaceae)

    PubMed Central

    Zhao, Jiali; Solís-Montero, Lislie; Lou, Anru; Vallejo-Marín, Mario

    2013-01-01

    Aims We investigate native and introduced populations of Solanum rostratum, an annual, self-compatible plant that has been introduced around the globe. This study is the first to compare the genetic diversity of Solanum rostratum between native and introduced populations. We aim to (1) determine the level of genetic diversity across the studied regions; (2) explore the likely origins of invasive populations in China; and (3) investigate whether there is the evidence of multiple introductions into China. Methods We genotyped 329 individuals at 10 microsatellite loci to determine the levels of genetic diversity and to investigate population structure of native and introduced populations of S. rostratum. We studied five populations in each of three regions across two continents: Mexico, the U.S.A. and China. Important Findings We found the highest genetic diversity among Mexican populations of S. rostratum. Genetic diversity was significantly lower in Chinese and U.S.A. populations, but we found no regional difference in inbreeding coefficients (FIS) or population differentiation (FST). Population structure analyses indicate that Chinese and U.S.A. populations are more closely related to each other than to sampled Mexican populations, revealing that introduced populations in China share an origin with the sampled U.S.A. populations. The distinctiveness between some introduced populations indicates multiple introductions of S. rostratum into China. PMID:24224008

  11. Genetic structure and diversity among maize inbred lines as inferred from DNA microsatellites.

    PubMed Central

    Liu, Kejun; Goodman, Major; Muse, Spencer; Smith, J Stephen; Buckler, Ed; Doebley, John

    2003-01-01

    Two hundred and sixty maize inbred lines, representative of the genetic diversity among essentially all public lines of importance to temperate breeding and many important tropical and subtropical lines, were assayed for polymorphism at 94 microsatellite loci. The 2039 alleles identified served as raw data for estimating genetic structure and diversity. A model-based clustering analysis placed the inbred lines in five clusters that correspond to major breeding groups plus a set of lines showing evidence of mixed origins. A "phylogenetic" tree was constructed to further assess the genetic structure of maize inbreds, showing good agreement with the pedigree information and the cluster analysis. Tropical and subtropical inbreds possess a greater number of alleles and greater gene diversity than their temperate counterparts. The temperate Stiff Stalk lines are on average the most divergent from all other inbred groups. Comparison of diversity in equivalent samples of inbreds and open-pollinated landraces revealed that maize inbreds capture <80% of the alleles in the landraces, suggesting that landraces can provide additional genetic diversity for maize breeding. The contributions of four different segments of the landrace gene pool to each inbred group's gene pool were estimated using a novel likelihood-based model. The estimates are largely consistent with known histories of the inbreds and indicate that tropical highland germplasm is poorly represented in maize inbreds. Core sets of inbreds that capture maximal allelic richness were defined. These or similar core sets can be used for a variety of genetic applications in maize. PMID:14704191

  12. A Reassessment of the Impact of European Contact on the Structure of Native American Genetic Diversity.

    PubMed

    Hunley, Keith; Gwin, Kiela; Liberman, Brendan

    2016-01-01

    Our current understanding of pre-Columbian history in the Americas rests in part on several trends identified in recent genetic studies. The goal of this study is to reexamine these trends in light of the impact of post-Columbian admixture and the methods used to study admixture. The previously-published data consist of 645 autosomal microsatellite genotypes from 1046 individuals in 63 populations. We used STRUCTURE to estimate ancestry proportions and tested the sensitivity of these estimates to the choice of the number of clusters, K. We used partial correlation analyses to examine the relationship between gene diversity and geographic distance from Beringia, controlling for non-Native American ancestry (from Africa, Europe and East Asia), and taking into account alternative paths of migration. Principal component analysis and multidimensional scaling were used to investigate the relationships between Andean and non-Andean populations and to explore gene-language correspondence. We found that 1) European and East Asian ancestry estimates decline as K increases, especially in Native Canadian populations, 2) a north-south decline in gene diversity is driven by low diversity in Amazonian and Paraguayan populations, not serial founder effects from Beringia, 3) controlling for non-Native American ancestry, populations in the Andes and Mesoamerica have higher gene diversity than populations in other regions, and 4) patterns of genetic and linguistic diversity are poorly correlated. We conclude that patterns of diversity previously attributed to pre-Columbian processes may in part reflect post-Columbian admixture and the choice of K in STRUCTURE analyses. Accounting for admixture, the pattern of diversity is inconsistent with a north-south founder effect process, though the genetic similarities between Mesoamerican and Andean populations are consistent with rapid dispersal along the western coast of the Americas. Further, even setting aside the disruptive effects of

  13. EVOLUTION OF BRIGHTEST CLUSTER GALAXY STRUCTURAL PARAMETERS IN THE LAST {approx}6 Gyr: FEEDBACK PROCESSES VERSUS MERGER EVENTS

    SciTech Connect

    Ascaso, B.; Aguerri, J. A. L.; Varela, J.; Cava, A.; Moles, M.

    2011-01-10

    We present results on the evolution of the structural parameters of two samples of brightest cluster galaxies (BCGs) in the last 6 Gyr. The nearby sample of BCGs consists of 69 galaxies from the WINGS survey spanning a redshift range of 0.04 < z < 0.07. The intermediate-redshift (0.3 < z < 0.6) sample is formed by 20 BCGs extracted from the Hubble Space Telescope archive. Both samples have similar spatial resolution and their host clusters have similar X-ray luminosities. We report an increase in the size of the BCGs from intermediate to local redshift. However, we do not detect any variation in the Sersic shape parameter in both samples. These results prove to be robust since the observed tendencies are model independent. We also obtain significant correlations between some of the BCG parameters and the main properties of the host clusters. More luminous, larger, and centrally located BCGs are located in more massive and dominant galaxy clusters. These facts indicate that the host galaxy cluster has played an important role in the formation of their BCGs. We discuss the possible mechanisms that can explain the observed evolution of the structural parameters of the BCGs. We conclude that the main mechanisms that can explain the increase in size and the non-evolution in the Sersic shape parameter of the BCGs in the last 6 Gyr are feedback processes. This result disagrees with semi-analytical simulation results supporting the idea that merging processes are the main mechanism responsible for the evolution of the BCGs up until the present epoch.

  14. Measuring the Fraction of Bars and Offset Bars Using the Spitzer Survey of Stellar Structure in Galaxies

    NASA Astrophysics Data System (ADS)

    Ross, Alexa

    2012-01-01

    Using the Spitzer Survey of Stellar Structure in Galaxies at 3.6 and 4.5μm, I have measured a preliminary bar fraction and offset bar fraction in the local universe by visually identifying bar structure within a sample of 2,140 local galaxies. A sample this large has not been used since 1963, when Gerard de Vaucouleurs found the bar fraction to be roughly fbar ˜ 0.6 in the Third Reference Catalog of Bright Galaxies. Since then, there has been much debate over the true value of the bar fraction. The purpose of finding a bar fraction using S4G is to provide a final say in this debate. I have found that the bar fraction in the local universe is fbar = 0.69 when including both definite bars (SB) and candidate bars (SAB). I have also measured a preliminary value for the fraction of offset bars using the same sample. Offset bars are a very rare phenomenon. Of the sample used, 91 galaxies are found to be definite offset bars while an additional 39 are found to be candidate offset bars. When including both definite offset bars and candidate offset bars, the offset bar fraction in the local universe becomes fob = 0.12. I also measure the fraction of offset bars as a function of Hubble type and stellar mass. We find that 54% of offset bars are found in disks having a stellar mass of M ≤ 108 M⊙. Late-type disks possess significantly more offset bars than early-type with 60% of offset bars being found in disks having a Hubble type t ≥ 6.

  15. Genetic diversity and population structure of Arabidopsis thaliana along an altitudinal gradient

    PubMed Central

    Tyagi, Antariksh; Singh, Shivani; Mishra, Parneeta; Singh, Akanksha; Tripathi, Abhinandan Mani; Jena, Satya Narayan; Roy, Sribash

    2016-01-01

    The natural genetic variation within a plant species is primarily a consequence of its phylogeography and evolutionary history. This variation largely determines its present-day population structure. Arabidopsis thaliana, as a model plant, has been studied in great detail including its probable origin, local as well as global genetic diversity pattern, population structure, adaptation, etc. However, no such studies have so far been reported from the Indian Himalayan region. Here, we describe a comprehensive study on the genetic diversity and population structure of A. thaliana from an altitudinal range of 700–3400 m above mean sea level the highest altitudinal range reported so far. We also compare these populations with previously reported worldwide populations. A total of 48 accessions representing six populations were analysed using 19 microsatellites and 11 chloroplast markers. Genetic diversity analysis indicated populations to be highly diverse and comparable with worldwide populations. STRUCTURE, principal coordinate and isolation by distance (IBD) analyses showed that genetic variation in different populations is structured at geographical and altitudinal level. Further analyses indicate that these populations are genetically distinct from the rest of the world populations. Different parameters of the demographic expansion model support a rapid expansion. Based on mismatch distribution, the initial time of expansion of west Himalayan populations was found to be about 130 000 years. Bayesian analysis of divergence time indicated that these populations have a long evolutionary history in this region. Based on the results of genetic diversity parameters, demographic expansion and divergence time estimation, it appears that west Himalayan populations may be the source of the west–east expansion model. PMID:26672075

  16. Structural Properties and Evidence for Interactions in a Sample of Luminous Blue Compact Galaxies

    NASA Astrophysics Data System (ADS)

    Newton, Cassidy L.; Fanelli, M.; Marcum, P.

    2010-01-01

    Understanding the life cycles of galaxies over cosmic time is a primary effort in modern astrophysics. Here we explore the nature of luminous blue compact galaxies (LBCGs), a class of galaxy in the local (z < 0.05) universe exhibiting blue optical colors [(B-V) < 0.5], high luminosity (MB < -19), one or more high surface brightness regions, and moderate to high star formation rates [> 5 M(sun) per year]. LBCGs appear to be similar in their global properties to the early evolutionary phases of most galaxies, but are more amenable to detailed analysis due to their low redshifts. We describe an ultraviolet and optical investigation of a sample of 50 LBCGs using UBVR & Hα imagery obtained at McDonald Observatory, ultraviolet photometry from GALEX, and correlative data from IRAS, 2MASS, and SDSS. Using these data, we explore the evolutionary state of LBCGs. In particular, we determine the radial and azimuthal light distributions, explore the spatial extent of ionized gas (e.g., centrally- concentrated versus spatially diffuse), compare multiwavelength measures of the high-mass star formation rate, and quantify the interaction strength using a variety of merger diagnostics. Although selected independent of their environment, most systems display either a close companion or the signature of an interaction such as tails, bridges, and possible polar rings. Interpretation of the assembly history of LBCGs provides insight on massive galaxy evolution at earlier epochs.

  17. W.W. Morgan and the Discovery of the Spiral Arm Structure of our Galaxy

    NASA Astrophysics Data System (ADS)

    Sheehan, William

    2008-03-01

    William Wilson Morgan was one of the great astronomers of the twentieth century. He considered himself a morphologist, and was preoccupied throughout his career with matters of classification. Though, his early life was difficult, and his pursuit of astronomy as a career was opposed by his father, he took a position at Yerkes Observatory in 1926 and remained there for the rest of his working life. Thematically, his work was also a unified whole. Beginning with spectroscopic studies under Otto Struve at Yerkes Observatory, by the late 1930s he concentrated particularly on the young O and B stars. His work an stellar classification led to the Morgan-Keenan-Kellman [MKK] system of classification of stars, and later - as he grappled with the question of the intrinsic color and brightness of stars at great distances - to the Johnson-Morgan UBV system for measuring stellar colors. Eventually these concerns with classification and method led to his greatest single achievement - the recognition of the nearby spiral arms of our Galaxy by tracing the OB associations and HII regions that outline them. After years of intensive work on the problem of galactic structure, the discovery came in a blinding flash of Archimedean insight as he walked under the night sky between his office and his house in the autumn of 1951. His optical discovery of the spiral arms preceded the radio-mapping of the spiral arms by more than a year. Morgan suffered a nervous breakdown soon after he announced his discovery, however, and so was prevented from publishing a complete account of his work. As a result of that, and the announcement soon afterward of the first radio maps of the spiral arms, the uniqueness of his achievement was not fully appreciated at the time.

  18. Morphological diversity and evolution of egg and clutch structure in amphibians

    USGS Publications Warehouse

    Altig, R.; McDiarmid, R.W.

    2007-01-01

    The first part of this synthesis summarizes the morphology of the jelly layers surrounding an amphibian ovum. We propose a standard terminology and discuss the evolution of jelly layers. The second part reviews the morphological diversity and arrangement of deposited eggs?the ovipositional mode; we recognize 5 morphological classes including 14 modes. We discuss some of the oviductal, ovipositional, and postovipositional events that contribute to these morphologies. We have incorporated data from taxa from throughout the world but recognize that other types will be discovered that may modify understanding of these modes. Finally, we discuss the evolutionary context of the diversity of clutch structure and present a first estimate of its evolution.

  19. Microgastrinae (Hymenoptera: Braconidae) in the Forest State of Artikutza (Navarra: Spain): Diversity and Community Structure

    PubMed Central

    Pérez-Rodríguez, Jesica; Oltra-Moscardó, Teresa; Peris-Felipo, Francisco Javier; Jiménez-Peydró, Ricardo

    2013-01-01

    Microgastrinae is one of the largest subfamilies of the Braconidae with about 2,000 described species worldwide. These wasps are of enormous ecological interest due to their role in controlling the caterpillar populations. This study analyses diversity and community structure within the Microgastrinae in the Artikutza Forest, located in the Peñas de Aia Natural Park, western Pyrenees, Spain. The specimens were collected in two different habitats: mixed forest and beech forest. A total of 524 specimens, belonging to nine separate genera and 27 species were captured. Alpha, beta and gamma diversity were analyzed. Additionally, the relationship between Microgastrinae phenology and climatic conditions were studied. PMID:26462432

  20. Ontogenetic functional diversity: size structure of a keystone predator drives functioning of a complex ecosystem.

    PubMed

    Rudolf, Volker H W; Rasmussen, Nick L

    2013-05-01

    A central challenge in community ecology is to understand the connection between biodiversity and the functioning of ecosystems. While traditional approaches have largely focused on species-level diversity, increasing evidence indicates that there exists substantial ecological diversity among individuals within species. By far, the largest source of this intraspecific diversity stems from variation among individuals in ontogenetic stage and size. Although such ontogenetic shifts are ubiquitous in natural communities, whether and how they scale up to influence the structure and functioning of complex ecosystems is largely unknown. Here we take an experimental approach to examine the consequences of ontogenetic niche shifts for the structure of communities and ecosystem processes. In particular we experimentally manipulated the stage structure in a keystone predator, larvae of the dragonfly Anax junius, in complex experimental pond communities to test whether changes in the population stage or size structure of a keystone species scale up to alter community structure and ecosystem processes, and how functional differences scale with relative differences in size among stages. We found that the functional role of A. junius was stage-specific. Altering what stages were present in a pond led to concurrent changes in community structure, primary producer biomass (periphyton and phytoplankton), and ultimately altered ecosystem processes (respiration and net primary productivity), indicating a strong, but stage-specific, trophic cascade. Interestingly, the stage-specific effects did not simply scale with size or biomass of the predator, but instead indicated clear ontogenetic niche shifts in ecological interactions. Thus, functional differences among stages within a keystone species scaled up to alter the functioning of entire ecosystems. Therefore, our results indicate that the classical approach of assuming an average functional role of a species can be misleading because

  1. Metal-line absorption around z ≈ 2.4 star-forming galaxies in the Keck Baryonic Structure Survey

    NASA Astrophysics Data System (ADS)

    Turner, Monica L.; Schaye, Joop; Steidel, Charles C.; Rudie, Gwen C.; Strom, Allison L.

    2014-11-01

    We study metal absorption around 854 z ≈ 2.4 star-forming galaxies taken from the Keck Baryonic Structure Survey. The galaxies examined in this work lie in the fields of 15 hyperluminous background quasi-stellar objects, with galaxy impact parameters ranging from 35 proper kpc (pkpc) to 2 proper Mpc (pMpc). Using the pixel optical depth technique, we present the first galaxy-centred 2D maps of the median absorption by O VI, N V, C IV, C III, and Si IV, as well as updated results for H I. At small galactocentric radii we detect a strong enhancement of the absorption relative to randomly located regions that extend out to at least 180 pkpc in the transverse direction, and ±240 km s-1 along the line of sight (LOS, ˜1 pMpc in the case of pure Hubble flow) for all ions except N V. For C IV (and H I) we detect a significant enhancement of the absorption signal out to 2 pMpc in the transverse direction, corresponding to the maximum impact parameter in our sample. After normalizing the median absorption profiles to account for variations in line strengths and detection limits, in the transverse direction we find no evidence for a sharp drop-off in metals distinct from that of H I. We argue instead that non-detection of some metal-line species in the extended circumgalactic medium is consistent with differences in the detection sensitivity. Along the LOS, the normalized profiles reveal that the enhancement in the absorption is more extended for O VI, C IV, and Si IV than for H I. We also present measurements of the scatter in the pixel optical depths, covering fractions, and equivalent widths as a function of projected galaxy distance. Limiting the sample to the 340 galaxies with redshifts measured from nebular emission lines does not decrease the extent of the enhancement along the LOS compared to that in the transverse direction. This rules out redshift errors as the source of the observed redshift-space anisotropy and thus implies that we have detected the signature

  2. Genetic diversity, population structure and association analysis in cut chrysanthemum (Chrysanthemum morifolium Ramat.).

    PubMed

    Li, Pirui; Zhang, Fei; Chen, Sumei; Jiang, Jiafu; Wang, Haibin; Su, Jiangshuo; Fang, Weimin; Guan, Zhiyong; Chen, Fadi

    2016-06-01

    Characterizing the genetic diversity present in a working set of plant germplasm can contribute to its effective management and genetic improvement. The cut flower chrysanthemum (Chrysanthemum morifolium Ramat.) is an economically important ornamental species. With the repeated germplasm exchange and intensive breeding activities, it remains a major task in genetic research. The purpose of the present study was to characterize the genetic diversity and the population structure of a worldwide collection of 159 varieties, and to apply an association mapping approach to identify DNA-based markers linked to five plant architecture traits and six inflorescence traits. The genotyping demonstrated that there was no lack of genetic diversity in the collection and that pair-wise kinship values were relatively low. The clustering based on a Bayesian model of population structure did not reflect known variation in either provenance or inflorescence type. A principal coordinate analysis was, however, able to discriminate most of the varieties according to both of these criteria. About 1 in 100 marker pairs exhibited a degree of linkage disequilibrium. The association analysis identified a number of markers putatively linked to one or more of the traits. Some of these associations were robust over two seasons. The findings provide an in-depth understanding of genetic diversity and population structure present in cut flower chrysanthemum varieties, and an insight into the genetic control of plant architecture and inflorescence-related traits. PMID:26780102

  3. Effects of grazer presence on genetic structure of a phenotypically diverse diatom population.

    PubMed

    Sjöqvist, C; Kremp, A; Lindehoff, E; Båmstedt, U; Egardt, J; Gross, S; Jönsson, M; Larsson, H; Pohnert, G; Richter, H; Selander, E; Godhe, A

    2014-01-01

    Studies of predator-prey systems in both aquatic and terrestrial environments have shown that grazers structure the intraspecific diversity of prey species, given that the prey populations are phenotypically variable. Populations of phytoplankton have traditionally considered comprising only low intraspecific variation, hence selective grazing as a potentially structuring factor of both genetic and phenotypic diversity has not been comprehensively studied. In this study, we compared strain specific growth rates, production of polyunsaturated aldehydes, and chain length of the marine diatom Skeletonema marinoi in both grazer and non-grazer conditions by conducting monoclonal experiments. Additionally, a mesocosm experiment was performed with multiclonal experimental S. marinoi populations exposed to grazers at different levels of copepod concentration to test effects of grazer presence on diatom diversity in close to natural conditions. Our results show that distinct genotypes of a geographically restricted population exhibit variable phenotypic traits relevant to grazing interactions such as chain length and growth rates. Grazer presence affected clonal richness and evenness of multiclonal Skeletonema populations in the mesocosms, likely in conjunction with intrinsic interactions among the diatom strains. Only the production of polyunsaturated aldehydes was not affected by grazer presence. Our findings suggest that grazing can be an important factor structuring diatom population diversity in the sea and emphasize the importance of considering clonal differences when characterizing species and their role in nature. PMID:24272280

  4. Structure and genetic diversity of natural Brazilian pepper populations (Schinus terebinthifolius Raddi).

    PubMed

    Álvares-Carvalho, S V; Duarte, J F; Santos, T C; Santos, R M; Silva-Mann, R; Carvalho, D

    2016-01-01

    In the face of a possible loss of genetic diversity in plants due the environmental changes, actions to ensure the genetic variability are an urgent necessity. The extraction of Brazilian pepper fruits is a cause of concern because it results in the lack of seeds in soil, hindering its distribution in space and time. It is important to address this concern and explore the species, used by riparian communities and agro-factories without considering the need for keeping the seeds for natural seed banks and for species sustainability. The objective of this study was to evaluate the structure and the genetic diversity in natural Brazilian pepper populations (Schinus terebinthifolius Raddi). Twenty-two alleles in 223 individuals were identified from eight forest remnants located in the states of Minas Gerais, Espírito Santo, and Sergipe. All populations presented loci in Hardy-Weinberg equilibrium deviation. Four populations presented six combinations of loci in linkage disequilibrium. Six exclusive alleles were detected in four populations. Analysis of molecular variance showed the absence of diversity between regions and that between the populations (GST) was 41%. Genetic diversity was structured in seven clusters (ΔK7). Brazilian pepper populations were not structured in a pattern of isolation by distance and present genetic bottleneck. The populations São Mateus, Canastra, Barbacena, and Ilha das Flores were identified as management units and may support conservation projects, ecological restoration and in implementation of management plans for Brazilian pepper in the State of Sergipe. PMID:27323193

  5. Tidal Dwarf Galaxies In Gas-rich Interacting Galaxy Groups

    NASA Astrophysics Data System (ADS)

    Eigenthaler, Paul

    2014-01-01

    Galaxy-galaxy interactions in gas-rich galaxy groups or pairs can form tidal bridges and tails. These tidal arms can contain kinematically decoupled structures with active star formation in the same mass range as dwarf galaxies, so-called tidal dwarf galaxies (TDGs). They differ from ordinary dwarf galaxies by their lack of dark matter and higher metallicity content. Compact groups of galaxies are an ideal environment to study the origin and evolution of TDGs since the high spatial volume density of member galaxies allows for frequent and efficient interactions between galaxies forming tidal tails. Hunsberger et al. (1996) identified 47 TDG candidates in Hickson compact groups (HCGs) and estimated that more than 50% of all dwarf galaxies in compact groups are former TDGs. Statistical considerations based on observations of interacting galaxies illustrate that a significant fraction of today's dwarf galaxies could have had a tidal origin. In their early evolution, TDGs can easily be distinguished from classical dwarf galaxies as they are still embedded in large tidal structures and show ongoing star formation, identified via strong Hα emission in these aggregates. Simulations of interacting galaxies, and of TDGs in particular, have shown that TDGs can survive their first starburst event and turn into long-lived dwarf sized objects. Preliminary results from deep Hα imaging with the SOAR telescope to detect new TDGs in a sample of 10 Hickson compact groups will be presented.

  6. Dynamical evolution of topology of large-scale structure. [in distribution of galaxies

    NASA Technical Reports Server (NTRS)

    Park, Changbom; Gott, J. R., III

    1991-01-01

    The nonlinear effects of statistical biasing and gravitational evolution on the genus are studied. The biased galaxy subset is picked for the first time by actually identifying galaxy-sized peaks above a fixed threshold in the initial conditions, and their subsequent evolution is followed. It is found that in the standard cold dark matter (CDM) model the statistical biasing in the locations of galaxies produces asymmetry in the genus curve and coupling with gravitational evolution gives rise to a shift in the genus curve to the left in moderately nonlinear regimes. Gravitational evolution alone reduces the amplitude of the genus curve due to strong phase correlations in the density field and also produces asymmetry in the curve. Results on the genus of the mass density field for both CDM and hot dark matter models are consistent with previous work by Melott, Weinberg, and Gott (1987).

  7. The rest-frame ultraviolet structure of 0.5 < z < 1.5 galaxies

    SciTech Connect

    Bond, Nicholas A.; Gardner, Jonathan P.; De Mello, Duilia F.; Teplitz, Harry I.; Rafelski, Marc; Koekemoer, Anton M.; Coe, Dan; Grogin, Norman; Gawiser, Eric; Ravindranath, Swara; Scarlata, Claudia

    2014-08-10

    We present the rest-frame UV wavelength dependence of the Petrosian-like half-light radius (r{sub 50}), and the concentration parameter for a sample of 198 star-forming galaxies at 0.5 < z < 1.5. We find a ∼5% decrease in r{sub 50} from 1500 Å to 3000 Å, with half-light radii at 3000 Å ranging from 0.6 kpc to 6 kpc. We also find a decrease in concentration of ∼0.07 (1.9 < C{sub 3000} < 3.9). The lack of a strong relationship between r{sub 50} and wavelength is consistent with a model in which clumpy star formation is distributed over length scales comparable to the galaxy's rest-frame optical light. While the wavelength dependence of r{sub 50} is independent of size at all redshifts, concentration decreases more sharply in the far-UV (∼1500 Å) for large galaxies at z ∼ 1. This decrease in concentration is caused by a flattening of the inner ∼20% of the light profile in disk-like galaxies, indicating that the central regions have different UV colors than the rest of the galaxy. We interpret this as a bulge component with older stellar populations and/or more dust. The size-dependent decrease in concentration is less dramatic at z ∼ 2, suggesting that bulges are less dusty, younger, and/or less massive than the rest of the galaxy at higher redshifts.

  8. H I Structure and Kinematics in the LITTLE THINGS Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Pokhrel, Nau Raj; Simpson, Caroline E.; LITTLE THINGS Team

    2016-01-01

    We present a catalog and analysis of the properties of neutral hydrogen gas (H I) holes/shells in the LITTLE THINGS (Local Irregulars That Trace Luminosity Extremes, The H I Nearby Galaxy Survey) galaxies. LITTLE THINGS uses high angular resolution (~6''), high spectral resolution (≤ 2.6 km s-1), and high sensitivity (≤ 1.1 mJy beam-1 channel-1) H I observations of 41 nearby (≤ 10.3 Mpc) gas-rich dwarf galaxies. We are interested in dwarf galaxies because they are the most common types of galaxies in the local universe and they are believed to be the first galaxies to form in the universe. Here we study the interaction between star formation evolution and the interstellar medium from which stars form. In the sample, we detected 306 holes with sizes ranging from about 38 pc to 2.3 kpc, the expansion rates varying from 5 to 30 km s-1, and the estimated kinetic age varying from 1 Myr to 127 Myr. The distribution of the holes per unit area is found nearly constant both inside (51%) and outside (49%) of the V-band break radius, where the radial luminosity function changes slope. We derived surface and volume porosity and found that porosity doesn't correlate with star formation rate (SFR) for the LITTLE THINGS sample. Assuming that the holes are formed from the stellar feedback, we calculated the supernova rate (SNR) and the SFR. We did find a correlation between the SFR calculated from Hα (a star formation tracer) and the SFR estimated from the SNR, consistent with hole formation from stellar feedback. The relation between the estimated kinetic ages of the holes with the SNR gives the indication of the star formation history.

  9. Population structure and genetic diversity of black redhorse (Moxostoma duquesnei) in a highly fragmented watershed

    USGS Publications Warehouse

    Reid, S.M.; Wilson, C.C.; Mandrak, N.E.; Carl, L.M.

    2008-01-01

    Dams have the potential to affect population size and connectivity, reduce genetic diversity, and increase genetic differences among isolated riverine fish populations. Previous research has reported adverse effects on the distribution and demographics of black redhorse (Moxostoma duquesnei), a threatened fish species in Canada. However, effects on genetic diversity and population structure are unknown. We used microsatellite DNA markers to assess the number of genetic populations in the Grand River (Ontario) and to test whether dams have resulted in a loss of genetic diversity and increased genetic differentiation among populations. Three hundred and seventy-seven individuals from eight Grand River sites were genotyped at eight microsatellite loci. Measures of genetic diversity were moderately high and not significantly different among populations; strong evidence of recent population bottlenecks was not detected. Pairwise FST and exact tests identified weak (global FST = 0.011) but statistically significant population structure, although little population structuring was detected using either genetic distances or an individual-based clustering method. Neither geographic distance nor the number of intervening dams were correlated with pairwise differences among populations. Tests for regional equilibrium indicate that Grand River populations were either in equilibrium between gene flow and genetic drift or that gene flow is more influential than drift. While studies on other species have identified strong dam-related effects on genetic diversity and population structure, this study suggests that barrier permeability, river fragment length and the ecological characteristics of affected species can counterbalance dam-related effects. ?? 2007 Springer Science+Business Media B.V.

  10. Overstory structure and soil nutrients effect on plant diversity in unmanaged moist tropical forest

    NASA Astrophysics Data System (ADS)

    Gautam, Mukesh Kumar; Manhas, Rajesh Kumar; Tripathi, Ashutosh Kumar

    2016-08-01

    Forests with intensive management past are kept unmanaged to restore diversity and ecosystem functioning. Before perpetuating abandonment after protracted restitution, understanding its effect on forest vegetation is desirable. We studied plant diversity and its relation with environmental variables and stand structure in northern Indian unmanaged tropical moist deciduous forest. We hypothesized that post-abandonment species richness would have increased, and the structure of contemporary forest would be heterogeneous. Vegetation structure, composition, and diversity were recorded, in forty 0.1 ha plots selected randomly in four forest ranges. Three soil samples per 0.1 ha were assessed for physicochemistry, fine sand, and clay mineralogy. Contemporary forest had less species richness than pre-abandonment reference period. Fourteen species were recorded as either seedling or sapling, suggesting reappearance or immigration. For most species, regeneration was either absent or impaired. Ordination and multiple regression results showed that exchangeable base cations and phosphorous affected maximum tree diversity and structure variables. Significant correlations between soil moisture and temperature, and shrub layer was observed, besides tree layer correspondence with shrub richness, suggesting that dense overstory resulting from abandonment through its effect on soil conditions, is responsible for dense shrub layer. Herb layer diversity was negatively associated with tree layer and shrub overgrowth (i.e. Mallotus spp.). Protracted abandonment may not reinforce species richness and heterogeneity; perhaps result in high tree and shrub density in moist deciduous forests, which can impede immigrating or reappearing plant species establishment. This can be overcome by density/basal area reduction strategies, albeit for both tree and shrub layer.

  11. THE STELLAR MASS STRUCTURE OF MASSIVE GALAXIES FROM z = 0 TO z = 2.5: SURFACE DENSITY PROFILES AND HALF-MASS RADII

    SciTech Connect

    Szomoru, Daniel; Franx, Marijn; Labbe, Ivo; Van Dokkum, Pieter G.; Trenti, Michele; Illingworth, Garth D.; Oesch, Pascal

    2013-02-15

    We present stellar mass surface density profiles of a mass-selected sample of 177 galaxies at 0.5 < z < 2.5, obtained using very deep Hubble Space Telescope optical and near-infrared data over the GOODS-South field, including recent CANDELS data. Accurate stellar mass surface density profiles have been measured for the first time for a complete sample of high-redshift galaxies more massive than 10{sup 10.7} M {sub Sun }. The key advantage of this study compared to previous work is that the surface brightness profiles are deconvolved for point-spread function smoothing, allowing accurate measurements of the structure of the galaxies. The surface brightness profiles account for contributions from complex galaxy structures such as rings and faint outer disks. Mass profiles are derived using radial rest-frame ug color profiles and a well-established empirical relation between these colors and the stellar mass-to-light ratio. We derive stellar half-mass radii from the mass profiles, and find that these are on average {approx}25% smaller than rest-frame g-band half-light radii. This average size difference of 25% is the same at all redshifts, and does not correlate with stellar mass, specific star formation rate, effective surface density, Sersic index, or galaxy size. Although on average the difference between half-mass size and half-light size is modest, for approximately 10% of massive galaxies this difference is more than a factor of two. These extreme galaxies are mostly extended, disk-like systems with large central bulges. These results are robust, but could be impacted if the central dust extinction becomes high. ALMA observations can be used to explore this possibility. These results provide added support for galaxy growth scenarios wherein massive galaxies at these epochs grow by accretion onto their outer regions.

  12. Identify the diversity of mesoscopic structures in networks: A mixed random walk approach

    NASA Astrophysics Data System (ADS)

    Ma, Yifang; Jiang, Xin; Li, Meng; Shen, Xin; Guo, Quantong; Lei, Yanjun; Zheng, Zhiming

    2013-10-01

    Community or cluster structure, which can provide insight into the natural partitions and inner connections of a network, is a key feature in studying the mesoscopic structure of complex systems. Although numerous methods for community detection have been proposed ever since, there is still a lack of understanding on how to quantify the diversity of pre-divided community structures, or rank the roles of communities in participating in specific dynamic processes. Inspired by the Law of Mass Action in chemical kinetics, we introduce here the community random walk energy (CRWE), which reflects a potential based on the diffusion phase of a mixed random walk process taking place on the network, to identify the configuration of community structures. The difference of CRWE allows us to distinguish the intrinsic topological diversity between individual communities, on condition that all the communities are pre-arranged in the network. We illustrate our method by performing numerical simulations on constructive community networks and a real social network with distinct community structures. As an application, we apply our method to characterize the diversity of human genome communities, which provides a possible use of our method in inferring the genetic similarity between human populations.

  13. The spiral structure of the Galaxy revealed by CS sources and evidence for the 4:1 resonance

    NASA Astrophysics Data System (ADS)

    Lépine, J. R. D.; Roman-Lopes, A.; Abraham, Zulema; Junqueira, T. C.; Mishurov, Yu. N.

    2011-06-01

    We present a map of the spiral structure of the Galaxy, as traced by molecular carbon monosulphide (CS) emission associated with IRAS sources which are believed to be compact H II regions. The CS line velocities are used to determine the kinematic distances of the sources in order to investigate their distribution in the galactic plane. This allows us to use 870 objects to trace the arms, a number larger than that of previous studies based on classical H II regions. The distance ambiguity of the kinematic distances, when it exists, is solved by different procedures, including the latitude distribution and an analysis of the longitude-velocity diagram. The study of the spiral structure is complemented with other tracers: open clusters, Cepheids, methanol masers and H II regions. The well-defined spiral arms are seen to be confined inside the corotation radius, as is often the case in spiral galaxies. We identify a square-shaped sub-structure in the CS map with that predicted by stellar orbits at the 4:1 resonance (four epicycle oscillations in one turn around the galactic centre). The sub-structure is found at the expected radius, based on the known pattern rotation speed and epicycle frequency curve. An inner arm presents an end with strong inwards curvature and intense star formation that we tentatively associate with the region where this arm surrounds the extremity of the bar, as seen in many barred galaxies. Finally, a new arm with concave curvature is found in the Sagitta to Cepheus region of the sky. The observed arms are interpreted in terms of perturbations similar to grooves in the gravitational potential of the disc, produced by crowding of stellar orbits.

  14. Chemical diversity among populations of Mikania micrantha: geographic mosaic structure and herbivory.

    PubMed

    Bravo-Monzón, Angel Eliezer; Ríos-Vásquez, Eunice; Delgado-Lamas, Guillermo; Espinosa-García, Francisco J

    2014-01-01

    Populations of the same species vary in their secondary metabolite content. This variation has been attributed to biotic and abiotic environmental conditions as well as to historical factors. Some studies have focused on the geographic variation of chemical diversity in plant populations, but whether this structure conforms to a central-marginal model or a mosaic pattern remains unclear. Furthermore, assessing the chemical diversity of invasive plants in their native distribution facilitates the understanding of their relationships with natural enemies. We examined the geographic variation of chemical diversity in Mexican populations of the bittervine weed Mikania micrantha and its relationship to herbivore damage. The foliar volatile terpenoid blend was analyzed in 165 individuals of 14 populations in the Pacific and Gulf of Mexico tropical watersheds. A cluster analysis grouped individuals with similar terpenoid blends into 56 compositional types. Chemical diversity was measured using the number of compounds and their concentration within the blends for individuals, and the number and frequency of compositional types for populations. A stepwise multiple regression analysis performed with geographic, climatic, and chemical diversity variables explained herbivore damage. However, population-level chemical diversity was the only variable found to be significant (β = -0.79, P = 0.042) in the model (R(2) = 0.89). A Mantel test using Euclidean distances did not indicate any separation by geographic origin; however, four barriers were identified using Monmonier's algorithm. We conclude that variation in population-level chemical diversity follows a mosaic pattern in which geographic factors (i.e., natural barriers) have some effect and that variation is also associated with the local intensity of herbivore attack. PMID:23942983

  15. Architectural design influences the diversity and structure of the built environment microbiome

    PubMed Central

    Kembel, Steven W; Jones, Evan; Kline, Jeff; Northcutt, Dale; Stenson, Jason; Womack, Ann M; Bohannan, Brendan JM; Brown, G Z; Green, Jessica L

    2012-01-01

    Buildings are complex ecosystems that house trillions of microorganisms interacting with each other, with humans and with their environment. Understanding the ecological and evolutionary processes that determine the diversity and composition of the built environment microbiome—the community of microorganisms that live indoors—is important for understanding the relationship between building design, biodiversity and human health. In this study, we used high-throughput sequencing of the bacterial 16S rRNA gene to quantify relationships between building attributes and airborne bacterial communities at a health-care facility. We quantified airborne bacterial community structure and environmental conditions in patient rooms exposed to mechanical or window ventilation and in outdoor air. The phylogenetic diversity of airborne bacterial communities was lower indoors than outdoors, and mechanically ventilated rooms contained less diverse microbial communities than did window-ventilated rooms. Bacterial communities in indoor environments contained many taxa that are absent or rare outdoors, including taxa closely related to potential human pathogens. Building attributes, specifically the source of ventilation air, airflow rates, relative humidity and temperature, were correlated with the diversity and composition of indoor bacterial communities. The relative abundance of bacteria closely related to human pathogens was higher indoors than outdoors, and higher in rooms with lower airflow rates and lower relative humidity. The observed relationship between building design and airborne bacterial diversity suggests that we can manage indoor environments, altering through building design and operation the community of microbial species that potentially colonize the human microbiome during our time indoors. PMID:22278670

  16. Genetic diversity and population structure of leafy kale and Brassica rupestris Raf. in south Italy.

    PubMed

    Maggioni, Lorenzo; von Bothmer, Roland; Poulsen, Gert; Branca, Ferdinando; Bagger Jørgensen, Rikke

    2014-12-01

    Local varieties of leafy kales (Brassica oleracea L.) are grown in home gardens in Calabria and Sicily for self-consumption, in the same area where the wild relative Brassica rupestris Raf. also grows. With the use of AFLP markers, comparisons were made of the genetic diversity and population structure of ten wild and 22 cultivated populations, as well as of a hybrid population and of four commercial cultivars of different B. oleracea crops. The level of genetic diversity was higher in leafy kales than in wild populations and this diversity was mainly distributed within populations. Wild populations remained distinct from cultivated material. Additionally, most wild populations were distinctively isolated from each other. On the other hand, it was not possible to molecularly distinguish even geographically distant leafy kale populations from each other or from different B. oleracea crops. It was possible to detect inter-crossing between leafy kales and B. rupestris. Findings from this study illustrate the existing level of genetic diversity in the B. oleracea gene pool. Individual populations (either wild or leafy kales) with higher levels of genetic diversity have been identified and suggestions are given for an informed conservation strategy. Domestication hypotheses are also discussed. PMID:25588302

  17. Microbial diversity in arctic freshwaters is structured by inoculation of microbes from soils

    PubMed Central

    Crump, Byron C; Amaral-Zettler, Linda A; Kling, George W

    2012-01-01

    Microbes are transported in hydrological networks through many environments, but the nature and dynamics of underlying microbial metacommunities and the impact of downslope inoculation on patterns of microbial diversity across landscapes are unknown. Pyrosequencing of small subunit ribosomal RNA gene hypervariable regions to characterize microbial communities along a hydrological continuum in arctic tundra showed a pattern of decreasing diversity downslope, with highest species richness in soil waters and headwater streams, and lowest richness in lake water. In a downstream lake, 58% and 43% of the bacterial and archaeal taxa, respectively, were also detected in diverse upslope communities, including most of the numerically dominant lake taxa. In contrast, only 18% of microbial eukaryotic taxa in the lake were detected upslope. We suggest that patterns of diversity in surface waters are structured by initial inoculation from microbial reservoirs in soils followed by a species-sorting process during downslope dispersal of both common and rare microbial taxa. Our results suggest that, unlike for metazoans, a substantial portion of bacterial and archaeal diversity in surface freshwaters may originate in complex soil environments. PMID:22378536

  18. Stellar Kinematics and Structural Properties of Virgo Cluster Dwarf Early-Type Galaxies from the SMAKCED Project

    NASA Astrophysics Data System (ADS)

    Toloba, Elisa; Guhathakurta, Puragra; Peletier, Reynier; Boselli, Alessandro; Lisker, Thorsten; Emsellem, Eric; Simon, Joshua D.; van de Ven, Glenn; Smakced Collaboration

    2015-01-01

    We analyze the stellar kinematics of 39 dwarf early-type galaxies (dEs) in the Virgo cluster. This is the largest survey conducted so far on spatially resolved kinematics of dEs. This sample is representative of the early-type population in the absolute magnitude range -19.0 < M_r < -16.0. For each dE, we measure the rotation curve and velocity dispersion profile and fit an analytic function to the rotation curve. We study the significance of the departure of the rotation curve from the best fit analytic function (poorly fit) and of the difference between the approaching and receding sides of the rotation curve (asymmetry). We find that 62+/-8% (23 out of the 39) of the dEs have a significant anomaly in their rotation curve. Analysis of the images reveals photometric anomalies for most galaxies. However, there is no clear correlation between the significance of the photometric and kinematic anomalies. Based on the specific stellar angular momentum and the ellipticity, we find 11 slow rotators and 28 fast rotators. The fast rotators in the outer parts of the Virgo cluster rotate significantly faster than fast rotators in the inner parts of the cluster. Moreover, 10 out of the 11 slow rotators are located in the inner Mpc of the cluster. The fast rotators contain subtle disky structures that are visible in high-pass filtered optical images, while the slow rotators do not exhibit these structures. In addition, two of the dEs have kinematically decoupled cores and four more have emission partially filling in the Balmer absorption lines. These properties suggest that Virgo cluster dEs may have originated from late-type star-forming galaxies that were transformed by the environment after their infall into the cluster. The correlation between the specific angular momentum and the clustercentric distance can be explained by a scenario where low luminosity star-forming galaxies fall into the cluster, their gas is rapidly removed by ram pressure stripping, although some of

  19. Population structure and genetic diversity of the perennial medicinal shrub Plumbago

    PubMed Central

    Panda, Sayantan; Naik, Dhiraj; Kamble, Avinash

    2015-01-01

    Knowledge of the natural genetic variation and structure in a species is important for developing appropriate conservation strategies. As genetic diversity analysis among and within populations of Plumbago zeylanica remains unknown, we aimed (i) to examine the patterns and levels of morphological and genetic variability within/among populations and ascertain whether these variations are dependent on geographical conditions; and (ii) to evaluate genetic differentiation and population structure within the species. A total of 130 individuals from 13 populations of P. zeylanica were collected, covering the entire distribution area of species across India. The genetic structure and variation within and among populations were evaluated using inter-simple sequence repeat (ISSR) and randomly amplified DNA polymorphism (RAPD) markers. High levels of genetic diversity and significantly high genetic differentiation were revealed by both the markers among all studied populations. High values of among-population genetic diversity were found, which accounted for 60 % of the total genetic variance. The estimators of genetic diversity were higher in northern and eastern populations than in southern and western populations indicating the possible loss of genetic diversity during the spread of this species to Southern India. Bayesian analysis, unweighted pair group method with arithmetic average cluster analysis and principal coordinates analysis all showed similar results. A significant isolation-by-distance pattern was revealed in P. zeylanica by ISSR (r = 0.413, P = 0.05) and RAPD (r = 0.279, P = 0.05) analysis. The results obtained suggest an urgent need for conservation of existing natural populations along with extensive domestication of this species for commercial purpose. PMID:25957315

  20. Spatiotemporal diversity, structure and trophic guilds of insect assemblages in a semi-arid Sabkha ecosystem.

    PubMed

    Chenchouni, Haroun; Menasria, Taha; Neffar, Souad; Chafaa, Smail; Bradai, Lyès; Chaibi, Rachid; Mekahlia, Mohamed Nacer; Bendjoudi, Djamel; Si Bachir, Abdelkrim

    2015-01-01

    The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria). The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness) were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA) was applied to determine how vegetation parameters (species richness and cover) influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, of which Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%), saprophages (26.7%), phytophages (20.5%), polyphages (10.8%), coprophages (4.6%); whereas in terms of numbers of species, they can be classified as phytophages (40%), predators (25.3%), polyphages (13.3%), saprophages (12%), coprophages (9.3%). The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different stations of the wetland and seasons. PMID:25825682

  1. Spatiotemporal diversity, structure and trophic guilds of insect assemblages in a semi-arid Sabkha ecosystem

    PubMed Central

    Menasria, Taha; Neffar, Souad; Chafaa, Smail; Bradai, Lyès; Chaibi, Rachid; Mekahlia, Mohamed Nacer; Bendjoudi, Djamel; Si Bachir, Abdelkrim

    2015-01-01

    The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria). The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness) were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA) was applied to determine how vegetation parameters (species richness and cover) influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, of which Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%), saprophages (26.7%), phytophages (20.5%), polyphages (10.8%), coprophages (4.6%); whereas in terms of numbers of species, they can be classified as phytophages (40%), predators (25.3%), polyphages (13.3%), saprophages (12%), coprophages (9.3%). The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different stations of the wetland and seasons. PMID:25825682

  2. Correlation analysis of genetic diversity and population structure of Houttuynia cordata Thunb with regard to environment.

    PubMed

    Zhong, J; Wu, F-C; Qiu, P; Dai, L-J

    2016-01-01

    To study the levels of genetic diversity, and population structure, of Houttuynia cordata Thunb, the genetic background and relationships of populations were analyzed in terms of environmental factors. The genetic diversity and population structure of H. cordata were investigated using sequence-related amplified polymorphisms and correlation with environmental factors was analyzed using the SPSS software. Two thousand one hundred sixty-three sites were amplified from 41 pairs of primers, 1825 of which were polymorphic, and the percentage of polymorphic loci was 84.37%; the percentage of polymorphic sites was 72.14 and 67.77% at the species and population level, respectively. The observed number of alleles was 1.52 and 1.30 at species and population level, respectively. The effective number of alleles was 1.38 and 1.24 at species and population level, respectively. The Nei's diversity was 0.26 and 0.15 at species and population level, respectively. The Shannon's information index was 0.87 and 0.63 at species and population level, respectively. The genetic differentiation coefficient of populations was 0.51, and 12 populations were divided into three classes based on D = 0.20; the genetic diversities of different populations are correlated at different significance levels (P < 0.05) with environmental factors. Genetic differentiation existed among populations and the populations exhibited heteroplasmy. PMID:27525953

  3. [Diversity and community structure of endophytic fungi from Taxus chinensis var. mairei].

    PubMed

    2014-07-01

    A total of 628 endophytic fungi were isolated from 480 tissue segments of needles and branches of Taxus chinensis var. mairei. According to morphological characteristics and ITS sequences, they represented 43 taxa in 28 genera, of which 10 Hyphomycetes, 20 Coelomycetes, 12 Ascomycetes and 1 unknown fungus. Phomopsis mali was confirmed as the dominant species. In accordance with relative frequency, Alternaria alternata, Aureobasidium pullulans, Colletotrichum boninense, C. gloeosporioides, Epicoccum nigrum , Fungal sp., Fusarium lateritium, Glomerella cingulata, Magnaporthales sp. , Nigrospora oryzae, Pestalotiopsis maculiformans, P. microspora, Peyronellaea glomerata and Xylaria sp. 1 were more common in T. chinensis var. mairei. T. chinensis var. mairei were severely infected by endophytic fungi. Endophytic fungi were found in 81 percent of plant tissues with a high diversity. Distribution ranges of endophytic fungi were influenced by tissue properties. The colonization rate, richness, diversity of endophytic fungi in needles were obviously lower than in branches, and kinds of endophytic fungi between branches were more similar than those in needles, thus endophytic fungi had tissue preference. In addition, tissue age influenced the community structure of endophytic fungi. The elder branch tissues were, the higher colonization rate, richness, diversity of endophytic fungi were. Systematic studying the diversity and community structure of endophytic fungi in T. chinensis var. mairei and clarifying their distribution regularity in plant tissues would offer basic data and scientific basis for their development and utilization. Discussing the presence of fungal pathogens in healthy plant tissues would be of positive significance for source protection of T. chinensis var. mairei. PMID:25345060

  4. Effects of understory structure on the abundance, richness and diversity of Collembola (Arthropoda) in southern Brazil.

    PubMed

    Ribeiro-Troian, Vera R; Baldissera, Ronei; Hartz, Sandra M

    2009-01-01

    The purpose of this study was to investigate the effects of different landscape structures on the understory Collembola community. Four different forest physiognomies were compared: Pinus spp. plantation, Eucalyptus spp. plantation, Araucaria angustifolia plantation, and a remaining native Araucaria forest. Three areas containing two sampling units (25 mx2 m each) were selected in each forest physiognomy. Understory Collembola collection was done with a 1x1 m canvas sheet held horizontally below the vegetation, which was beaten with a 1 m long stick, seasonally from September 2003 to August 2004. We evaluated the influence of forest physiognomies on the abundance, richness and diversity of Collembola communities. It was also verified if the habitat structure of each physiognomy was associated with the composition of the Collembola community. A total number of 4,111 individuals were collected belonging to the families Entomobrydae and Tomocerida (Entomobryomorpha), and Sminthuridae (Symphypleona), and divided in 12 morphospecies. Pinus plantation presented the highest richness, abundance and diversity of Collembola and it was associated to diverse understory vegetation. The abundance of Entomobrydae and Sminthuridae was associated to the presence of bushes, while Tomoceridae abundance was associated to the presence of trees. The habitat structure, measured through understory vegetation density and composition, plays an important role on the determination of the structure and composition of the Collembola community. PMID:19618049

  5. Superluminous Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Ogle, Patrick M.; Lanz, Lauranne; Nader, Cyril; Helou, George

    2016-02-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity Lr = 8-14L* (4.3-7.5 × 1044 erg s-1). These super spiral galaxies are also giant and massive, with diameter D = 57-134 kpc and stellar mass Mstars = 0.3-3.4 × 1011M⊙. We find 53 super spirals out of a complete sample of 1616 SDSS galaxies with redshift z < 0.3 and Lr > 8L*. The closest example is found at z = 0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and Wide-field Infrared Survey Explorer colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5-65 M⊙ yr-1 place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers—a possible clue to their formation. We suggest that super spirals are a remnant population of unquenched, massive disk galaxies. They may eventually become massive lenticular galaxies after they are cut off from their gas supply and their disks fade.

  6. High Redshift Simulations Using the GALEX Ultraviolet Images of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Yeom, Bum-Suk; Kim, Young Kwang; Rey, Soo-Chang; Joe, Young Hoon; Gil de Paz, Armando

    2009-03-01

    We present simulated optical images of galaxies at high redshift using diverse and high-quality ultraviolet (UV) images of nearby galaxies obtained through the GALEX (Galaxy Evolution Explorer). Galaxy morphology plays an important role in the study of the evolution of galaxies. In this respect, the appearance of galaxies at high redshift requires images of nearby galaxies with various morphologies in the UV bandpass. Our simulation will be important in providing the basic information needed to study the evolution of galaxies.

  7. Large-scale structure and galaxy motions in the Leo/Cancer constellations

    NASA Astrophysics Data System (ADS)

    Karachentsev, I. D.; Nasonova, O. G.; Karachentseva, V. E.

    2015-01-01

    In the region of the sky limited by the coordinates RA = 7ḥ0-12ḥ0, Dec = 0°...+20° and extending from the Virgo Cluster to the South Pole of the Local Supercluster, we consider the data on the galaxies with radial velocities V LG ≲ 2000 km/s. For 290 among them, we determine individual distances and peculiar velocities. In this region, known as the local velocity anomaly zone, there are 23 groups and 20 pairs of galaxies for which the estimates of virial/orbital masses are obtained. A nearby group around NGC3379 = Leo I and NGC3627 as well as the Local Group show the motion from the Local Void in the direction of Leo cloud with a characteristic velocity of about 400 km/s. Another rich group of galaxies around NGC3607 reveals peculiar velocity of about -420 km/s in the frame of reference related with the cosmic background radiation. A peculiar scattered association of dwarf galaxies Gemini Flock at a distance of 8 Mpc has the radial velocity dispersion of only 20 km/s and the size of approximately 0.7 Mpc. The virial mass estimate for it is 300 times greater than the total stellar mass. The ratio of the sum of virial masses of groups and pairs in the Leo/Can region to the sum of stellar masses of the galaxies contained in them equals 26, which is equivalent to the local average density Ω m (local) = 0.074, which is 3-4 times smaller than the global average density of matter.

  8. FAR-INFRARED FINE-STRUCTURE LINE DIAGNOSTICS OF ULTRALUMINOUS INFRARED GALAXIES

    SciTech Connect

    Farrah, D.; Petty, S. M.; Harris, K.; Lebouteiller, V.; Spoon, H. W. W.; Bernard-Salas, J.; Pearson, C.; Rigopoulou, D.; Smith, H. A.; González-Alfonso, E.; Clements, D. L.; Efstathiou, A.; Cormier, D.; Afonso, J.; Hurley, P.; Borys, C.; Verma, A.; Cooray, A.; Salvatelli, V.

    2013-10-10

    We present Herschel observations of 6 fine-structure lines in 25 ultraluminous infrared galaxies at z < 0.27. The lines, [O III]52 μm, [N III]57 μm, [O I]63 μm, [N II]122 μm, [O I]145 μm, and [C II]158 μm, are mostly single Gaussians with widths <600 km s{sup –1} and luminosities of 10{sup 7}-10{sup 9} L{sub ☉}. There are deficits in the [O I]63/L{sub IR}, [N II]/L{sub IR}, [O I]145/L{sub IR}, and [C II]/L{sub IR} ratios compared to lower luminosity systems. The majority of the line deficits are consistent with dustier H II regions, but part of the [C II] deficit may arise from an additional mechanism, plausibly charged dust grains. This is consistent with some of the [C II] originating from photodissociation regions or the interstellar medium (ISM). We derive relations between far-IR line luminosities and both the IR luminosity and star formation rate. We find that [N II] and both [O I] lines are good tracers of the IR luminosity and star formation rate. In contrast, [C II] is a poor tracer of the IR luminosity and star formation rate, and does not improve as a tracer of either quantity if the [C II] deficit is accounted for. The continuum luminosity densities also correlate with the IR luminosity and star formation rate. We derive ranges for the gas density and ultraviolet radiation intensity of 10{sup 1} < n < 10{sup 2.5} and 10{sup 2.2} < G{sub 0} < 10{sup 3.6}, respectively. These ranges depend on optical type, the importance of star formation, and merger stage. We do not find relationships between far-IR line properties and several other parameters: active galactic nucleus (AGN) activity, merger stage, mid-IR excitation, and SMBH mass. We conclude that these far-IR lines arise from gas heated by starlight, and that they are not strongly influenced by AGN activity.

  9. Community diversity, structure and carbon footprint of nematode food web following reforestation on degraded Karst soil

    PubMed Central

    Hu, Ning; Li, Hui; Tang, Zheng; Li, Zhongfang; Tian, Jing; Lou, Yilai; Li, Jianwei; Li, Guichun; Hu, Xiaomin

    2016-01-01

    We examined community diversity, structure and carbon footprint of nematode food web along a chronosequence of T. Sinensis reforestation on degraded Karst. In general, after the reforestation: a serious of diversity parameters and community indices (Shannon-Weinier index (H′), structure index (SI), etc.) were elevated; biomass ratio of fungivores to bacterivores (FFC/BFC), and fungi to bacteria (F/B) were increased, and nematode channel ratio (NCR) were decreased; carbon footprints of all nematode trophic groups, and biomass of bacteria and fungi were increased. Our results indicate that the Karst aboveground vegetation restoration was accompanied with belowground nematode food web development: increasing community complexity, function and fungal dominance in decomposition pathway, and the driving forces included the bottom-up effect (resource control), connectedness of functional groups, as well as soil environments. PMID:27311984

  10. Characterizing diverse orthologues of the cystic fibrosis transmembrane conductance regulator protein for structural studies.

    PubMed

    Pollock, Naomi L; Rimington, Tracy L; Ford, Robert C

    2015-10-01

    As an ion channel, the cystic fibrosis transmembrane conductance regulator (CFTR) protein occupies a unique niche within the ABC family. Orthologues of CFTR are extant throughout the animal kingdom from sharks to platypods to sheep, where the osmoregulatory function of the protein has been applied to differing lifestyles and diverse organ systems. In humans, loss-of-function mutations to CFTR cause the disease cystic fibrosis, which is a significant health burden in populations of white European descent. Orthologue screening has proved fruitful in the pursuit of high-resolution structural data for several membrane proteins, and we have applied some of the princples developed in previous studies to the expression and purification of CFTR. We have overexpressed this protein, along with evolutionarily diverse orthologues, in Saccharomyces cerevisiae and developed a purification to isolate it in quantities sufficient for structural and functional studies. PMID:26517900

  11. Community diversity, structure and carbon footprint of nematode food web following reforestation on degraded Karst soil.

    PubMed

    Hu, Ning; Li, Hui; Tang, Zheng; Li, Zhongfang; Tian, Jing; Lou, Yilai; Li, Jianwei; Li, Guichun; Hu, Xiaomin

    2016-01-01

    We examined community diversity, structure and carbon footprint of nematode food web along a chronosequence of T. Sinensis reforestation on degraded Karst. In general, after the reforestation: a serious of diversity parameters and community indices (Shannon-Weinier index (H'), structure index (SI), etc.) were elevated; biomass ratio of fungivores to bacterivores (FFC/BFC), and fungi to bacteria (F/B) were increased, and nematode channel ratio (NCR) were decreased; carbon footprints of all nematode trophic groups, and biomass of bacteria and fungi were increased. Our results indicate that the Karst aboveground vegetation restoration was accompanied with belowground nematode food web development: increasing community complexity, function and fungal dominance in decomposition pathway, and the driving forces included the bottom-up effect (resource control), connectedness of functional groups, as well as soil environments. PMID:27311984

  12. Community diversity, structure and carbon footprint of nematode food web following reforestation on degraded Karst soil

    NASA Astrophysics Data System (ADS)

    Hu, Ning; Li, Hui; Tang, Zheng; Li, Zhongfang; Tian, Jing; Lou, Yilai; Li, Jianwei; Li, Guichun; Hu, Xiaomin

    2016-06-01

    We examined community diversity, structure and carbon footprint of nematode food web along a chronosequence of T. Sinensis reforestation on degraded Karst. In general, after the reforestation: a serious of diversity parameters and community indices (Shannon-Weinier index (H‧), structure index (SI), etc.) were elevated; biomass ratio of fungivores to bacterivores (FFC/BFC), and fungi to bacteria (F/B) were increased, and nematode channel ratio (NCR) were decreased; carbon footprints of all nematode trophic groups, and biomass of bacteria and fungi were increased. Our results indicate that the Karst aboveground vegetation restoration was accompanied with belowground nematode food web development: increasing community complexity, function and fungal dominance in decomposition pathway, and the driving forces included the bottom-up effect (resource control), connectedness of functional groups, as well as soil environments.

  13. Environmental and Climatic Determinants of Molecular Diversity and Genetic Population Structure in a Coenagrionid Damselfly

    PubMed Central

    Wellenreuther, Maren; Sánchez-Guillén, Rosa A.; Cordero-Rivera, Adolfo; Svensson, Erik I.; Hansson, Bengt

    2011-01-01

    Identifying environmental factors that structure intraspecific genetic diversity is of interest for both habitat preservation and biodiversity conservation. Recent advances in statistical and geographical genetics make it possible to investigate how environmental factors affect geographic organisation and population structure of molecular genetic diversity within species. Here we present a study on a common and wide ranging insect, the blue tailed damselfly Ischnuraelegans, which has been the target of many ecological and evolutionary studies. We addressed the following questions: (i) Is the population structure affected by longitudinal or latitudinal gradients?; (ii) Do geographic boundaries limit gene flow?; (iii) Does geographic distance affect connectivity and is there a signature of past bottlenecks?; (iv) Is there evidence of a recent range expansion and (vi) what is the effect of geography and climatic factors on population structure? We found low to moderate genetic sub-structuring between populations (mean FST = 0.06, Dest = 0.12), and an effect of longitude, but not latitude, on genetic diversity. No significant effects of geographic boundaries (e.g. water bodies) were found. FST-and Dest-values increased with geographic distance; however, there was no evidence for recent bottlenecks. Finally, we did not detect any molecular signatures of range expansions or an effect of geographic suitability, although local precipitation had a strong effect on genetic differentiation. The population structure of this small insect has probably been shaped by ecological factors that are correlated with longitudinal gradients, geographic distances, and local precipitation. The relatively weak global population structure and high degree of genetic variation within populations suggest that I. elegans has high dispersal ability, which is consistent with this species being an effective and early coloniser of new habitats. PMID:21655216

  14. Allozyme diversity and genetic structure of the leafy cactus (Pereskia guamacho [Cactaceae]).

    PubMed

    Nassar, J M; Hamrick, J L; Fleming, T H

    2002-01-01

    We examined levels of genetic variation and genetic structure in the leafy cactus (Pereskia guamacho) in arid and semiarid zones in Venezuela. We surveyed genetic diversity within 17 populations using 19 allozyme loci. Genetic diversity was relatively high at both the species (P(s) = 89%, A(s) = 3.26, AP(s) = 3.53, H(es) = 0.24) and population (P(p) = 63%, A(p) = 1.90, AP(p) = 2.42, H(ep) = 0.20) levels. A significant deficit of heterozygote individuals was detected within populations in the Paraguana Peninsula region (F(IS) = 0.301). Relatively low levels of population differentiation were detected at macrogeographic (G(ST) = 0.112) and regional levels (G(ST) = 0.044 for peninsula region and G(ST) = 0.074 for mainland region), suggesting substantial genetic exchange among populations; however, gene flow in this species seems to be regulated by the distance among populations. Overall, estimates of genetic diversity found in P. guamacho are concordant with the pattern observed for other cacti surveyed, namely high levels of polymorphism and genetic diversity with one common allele and several rare alleles per locus. Differences in gene dispersal systems between this species and other cacti studied were not reflected in the patterns of genetic diversity observed. The concentration of the highest estimates of genetic variation in northwestern Venezuela suggests a potential reservoir of plant genetic diversity within xerophilous ecosystems in northern South America. PMID:12195035

  15. Synergy of VSWIR and LiDAR for Ecosystem Structure, Biomass, and Canopy Diversity

    NASA Technical Reports Server (NTRS)

    Cook, Bruce D.; Asner, Gregory P.

    2010-01-01

    This slide presentation reviews the use of Visible ShortWave InfraRed (VSWIR) Imaging Spectrometer and LiDAR to study ecosystem structure, biomass and canopy diversity. It is shown that the biophysical data from LiDAR and biochemical information from hyperspectral remote sensing provides complementary data for: (1) describing spatial patterns of vegetation and biodiversity, (2) characterizing relationships between ecosystem form and function, and (3) detecting natural and human induced change that affects the biogeochemical cycles.

  16. Science Highlights from the Spitzer Survey of Stellar Structure in Galaxies (S4G) & Public Release of S4G Data

    NASA Astrophysics Data System (ADS)

    Sheth, Kartik

    2013-01-01

    The Spitzer Survey of Stellar Structure in Galaxies (S4G) is the largest and the most homogenous survey of the distribution of mass and stellar structure in over 2,300 nearby galaxies. With an integration time of four minutes per pixel at 3.6 and 4.5 microns, the S4G maps are extremely deep, tracing the stellar surface densities of < 1 solar mass per square parsec! S4G is the ultimate survey of the endoskeleton of nearby galaxies from dwarfs to ellipticals and affords an incredible treasury of data which we can address a host of outstanding questions in galaxy evolution. At this special session we will present details on the public release of this survey which will include science ready images, masks for the foreground and background stars, globally integrated properties and radial profiles of all galaxies. In addition we will release the results from a GALFIT decomposition of 200 galaxies which will be supplemented with the remainder of the survey within six months. The data are being released through the NASA/IPAC Infrared Science Archive (IRSA). I will present an overview of the survey, the data we are releasing, introduce the speakers and present science highlights from the team.

  17. Morphology of High Redshifted Galaxies using GALEX Ultraviolet Observations of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Yeom, Bum-Suk; Kim, Y.; Rey, S.; Kim, S.; Joe, Y.; Gil de Paz, A.

    2009-01-01

    Galaxy morphology provides clues about the processes in the understanding of the formation and evolution of galaxies. In this respect, the prediction of optical-band morphologies at high redshifts requires ultraviolet (UV) images of local galaxies with various morphologies. We simulated optical images at high redshifts using more diverse and high-quality nearby galaxies obtained through the Galaxy Evolution Explorer (GALEX) UV observations. We present a quantitative analysis of the morphology of galaxies at near-ultraviolet (NUV) and simulated optical images. We also present a correlation between the isophotal-shape parameter and UV colors for nearby early-type galaxies.

  18. First regional evaluation of nuclear genetic diversity and population structure in northeastern coyotes ( Canis latrans).

    PubMed

    Monzón, Javier

    2014-01-01

    Previous genetic studies of eastern coyotes ( Canis latrans) are based on one of two strategies: sampling many individuals using one or very few molecular markers, or sampling very few individuals using many genomic markers. Thus, a regional analysis of genetic diversity and population structure in eastern coyotes using many samples and several molecular markers is lacking. I evaluated genetic diversity and population structure in 385 northeastern coyotes using 16 common single nucleotide polymorphisms (SNPs). A region-wide analysis of population structure revealed three primary genetic populations, but these do not correspond to the same three subdivisions inferred in a previous analysis of mitochondrial DNA sequences. More focused geographic analyses of population structure indicated that ample genetic structure occurs in coyotes from an intermediate contact zone where two range expansion fronts meet. These results demonstrate that genotyping several highly heterozygous SNPs in a large, geographically dense sample is an effective way to detect cryptic population genetic structure. The importance of SNPs in studies of population and wildlife genomics is rapidly increasing; this study adds to the growing body of recent literature that demonstrates the utility of SNPs ascertained from a model organism for evolutionary inference in closely related species. PMID:25075291

  19. First regional evaluation of nuclear genetic diversity and population structure in northeastern coyotes ( Canis latrans)

    PubMed Central

    Monzón, Javier

    2014-01-01

    Previous genetic studies of eastern coyotes ( Canis latrans) are based on one of two strategies: sampling many individuals using one or very few molecular markers, or sampling very few individuals using many genomic markers. Thus, a regional analysis of genetic diversity and population structure in eastern coyotes using many samples and several molecular markers is lacking. I evaluated genetic diversity and population structure in 385 northeastern coyotes using 16 common single nucleotide polymorphisms (SNPs). A region-wide analysis of population structure revealed three primary genetic populations, but these do not correspond to the same three subdivisions inferred in a previous analysis of mitochondrial DNA sequences. More focused geographic analyses of population structure indicated that ample genetic structure occurs in coyotes from an intermediate contact zone where two range expansion fronts meet. These results demonstrate that genotyping several highly heterozygous SNPs in a large, geographically dense sample is an effective way to detect cryptic population genetic structure. The importance of SNPs in studies of population and wildlife genomics is rapidly increasing; this study adds to the growing body of recent literature that demonstrates the utility of SNPs ascertained from a model organism for evolutionary inference in closely related species. PMID:25075291

  20. Population structure and diversity of an invasive pine needle pathogen reflects anthropogenic activity.

    PubMed

    Barnes, Irene; Wingfield, Michael J; Carbone, Ignazio; Kirisits, Thomas; Wingfield, Brenda D

    2014-09-01

    Dothistroma septosporum is a haploid fungal pathogen that causes a serious needle blight disease of pines, particularly as an invasive alien species on Pinus radiata in the Southern Hemisphere. During the course of the last two decades, the pathogen has also incited unexpected epidemics on native and non-native pine hosts in the Northern Hemisphere. Although the biology and ecology of the pathogen has been well documented, there is a distinct lack of knowledge regarding its movement or genetic diversity in many of the countries where it is found. In this study we determined the global population diversity and structure of 458 isolates of D. septosporum from 14 countries on six continents using microsatellite markers. Populations of the pathogen in the Northern Hemisphere, where pines are native, displayed high genetic diversities and included both mating types. Most of the populations from Europe showed evidence for random mating, little population differentiation and gene flow between countries. Populations in North America (USA) and Asia (Bhutan) were genetically distinct but migration between these continents and Europe was evident. In the Southern Hemisphere, the population structure and diversity of D. septosporum reflected the anthropogenic history of the introduction and establishment of plantation forestry, particularly with Pinus radiata. Three introductory lineages in the Southern Hemisphere were observed. Countries in Africa, that have had the longest history of pine introductions, displayed the greatest diversity in the pathogen population, indicating multiple introductions. More recent introductions have occurred separately in South America and Australasia where the pathogen population is currently reproducing clonally due to the presence of only one mating type. PMID:25478155

  1. Characterization of the genetic diversity, structure and admixture of British chicken breeds.

    PubMed

    Wilkinson, S; Wiener, P; Teverson, D; Haley, C S; Hocking, P M

    2012-10-01

    The characterization of livestock genetic diversity can inform breed conservation initiatives. The genetic diversity and genetic structure were assessed in 685 individual genotypes sampled from 24 British chicken breeds. A total of 239 alleles were found across 30 microsatellite loci with a mean number of 7.97 alleles per locus. The breeds were highly differentiated, with an average F(ST) of 0.25, similar to that of European chicken breeds. The genetic diversity in British chicken breeds was comparable to that found in European chicken breeds, with an average number of alleles per locus of 3.59, ranging from 2.00 in Spanish to 4.40 in Maran, and an average expected heterozygosity of 0.49, ranging from 0.20 in Spanish to 0.62 in Araucana. However, the majority of breeds were not in Hardy-Weinberg Equilibrium, as indicated by heterozygote deficiency in the majority of breeds (average F(IS) of 0.20), with an average observed heterozygote frequency of 0.39, ranging from 0.15 in Spanish to 0.49 in Cochin. Individual-based clustering analyses revealed that most individuals clustered to breed origin. However, genetic subdivisions occurred in several breeds, and this was predominantly associated with flock supplier and occasionally by morphological type. The deficit of heterozygotes was likely owing to a Wahlund effect caused by sampling from different flocks, implying structure within breeds. It is proposed that gene flow amongst flocks within breeds should be enhanced to maintain the current levels of genetic diversity. Additionally, certain breeds had low levels of both genetic diversity and uniqueness. Consideration is required for the conservation and preservation of these potentially vulnerable breeds. PMID:22497565

  2. Diversity and population structure of a dominant deciduous tree based on morphological and genetic data.

    PubMed

    Zhang, Qin-di; Jia, Rui-Zhi; Meng, Chao; Ti, Chao-Wen; Wang, Yi-Ling

    2015-01-01

    Knowledge of the genetic diversity and structure of tree species across their geographic ranges is essential for sustainable use and management of forest ecosystems. Acer grosseri Pax., an economically and ecologically important maple species, is mainly distributed in North China. In this study, the genetic diversity and population differentiation of 24 natural populations of this species were evaluated using sequence-related amplified polymorphism markers and morphological characters. The results show that highly significant differences occurred in 32 morphological traits. The coefficient of variation of 34 characters was 18.19 %. Principal component analysis indicated that 18 of 34 traits explained 60.20 % of the total variance. The phenotypic differentiation coefficient (VST) was 36.06 % for all morphological traits. The Shannon-Wiener index of 34 morphological characters was 6.09, while at the population level, it was 1.77. The percentage of polymorphic bands of all studied A. grosseri populations was 82.14 %. Nei's gene diversity (He) and Shannon's information index (I) were 0.35 and 0.50, respectively. Less genetic differentiation was detected among the natural populations (GST = 0.20, ΦST = 0.10). Twenty-four populations of A. grosseri formed two main clusters, which is consistent with morphological cluster analysis. Principal coordinates analysis and STRUCTURE analysis supported the UPGMA-cluster dendrogram. There was no significant correlation between genetic and geographical distances among populations. Both molecular and morphological data suggested that A. grosseri is rich in genetic diversity. The high level of genetic variation within populations could be affected by the biological characters, mating system and lifespan of A. grosseri, whereas the lower genetic diversity among populations could be caused by effective gene exchange, selective pressure from environmental heterogeneity and the species' geographical range. PMID:26311734

  3. Diversity and population structure of a dominant deciduous tree based on morphological and genetic data

    PubMed Central

    Zhang, Qin-di; Jia, Rui-Zhi; Meng, Chao; Ti, Chao-Wen; Wang, Yi-Ling

    2015-01-01

    Knowledge of the genetic diversity and structure of tree species across their geographic ranges is essential for sustainable use and management of forest ecosystems. Acer grosseri Pax., an economically and ecologically important maple species, is mainly distributed in North China. In this study, the genetic diversity and population differentiation of 24 natural populations of this species were evaluated using sequence-related amplified polymorphism markers and morphological characters. The results show that highly significant differences occurred in 32 morphological traits. The coefficient of variation of 34 characters was 18.19 %. Principal component analysis indicated that 18 of 34 traits explained 60.20 % of the total variance. The phenotypic differentiation coefficient (VST) was 36.06 % for all morphological traits. The Shannon–Wiener index of 34 morphological characters was 6.09, while at the population level, it was 1.77. The percentage of polymorphic bands of all studied A. grosseri populations was 82.14 %. Nei's gene diversity (He) and Shannon's information index (I) were 0.35 and 0.50, respectively. Less genetic differentiation was detected among the natural populations (GST = 0.20, ΦST = 0.10). Twenty-four populations of A. grosseri formed two main clusters, which is consistent with morphological cluster analysis. Principal coordinates analysis and STRUCTURE analysis supported the UPGMA-cluster dendrogram. There was no significant correlation between genetic and geographical distances among populations. Both molecular and morphological data suggested that A. grosseri is rich in genetic diversity. The high level of genetic variation within populations could be affected by the biological characters, mating system and lifespan of A. grosseri, whereas the lower genetic diversity among populations could be caused by effective gene exchange, selective pressure from environmental heterogeneity and the species' geographical range. PMID:26311734

  4. Population structure and diversity of an invasive pine needle pathogen reflects anthropogenic activity

    PubMed Central

    Barnes, Irene; Wingfield, Michael J; Carbone, Ignazio; Kirisits, Thomas; Wingfield, Brenda D

    2014-01-01

    Dothistroma septosporum is a haploid fungal pathogen that causes a serious needle blight disease of pines, particularly as an invasive alien species on Pinus radiata in the Southern Hemisphere. During the course of the last two decades, the pathogen has also incited unexpected epidemics on native and non-native pine hosts in the Northern Hemisphere. Although the biology and ecology of the pathogen has been well documented, there is a distinct lack of knowledge regarding its movement or genetic diversity in many of the countries where it is found. In this study we determined the global population diversity and structure of 458 isolates of D. septosporum from 14 countries on six continents using microsatellite markers. Populations of the pathogen in the Northern Hemisphere, where pines are native, displayed high genetic diversities and included both mating types. Most of the populations from Europe showed evidence for random mating, little population differentiation and gene flow between countries. Populations in North America (USA) and Asia (Bhutan) were genetically distinct but migration between these continents and Europe was evident. In the Southern Hemisphere, the population structure and diversity of D. septosporum reflected the anthropogenic history of the introduction and establishment of plantation forestry, particularly with Pinus radiata. Three introductory lineages in the Southern Hemisphere were observed. Countries in Africa, that have had the longest history of pine introductions, displayed the greatest diversity in the pathogen population, indicating multiple introductions. More recent introductions have occurred separately in South America and Australasia where the pathogen population is currently reproducing clonally due to the presence of only one mating type. PMID:25478155

  5. Genetic diversity and population structure of an extremely endangered species: the world's largest Rhododendron

    PubMed Central

    Wu, Fu Qin; Shen, Shi Kang; Zhang, Xin Jun; Wang, Yue Hua; Sun, Wei Bang

    2015-01-01

    Comprehensive studies on the genetic diversity and structure of endangered species are urgently needed to promote effective conservation and management activities. The big tree rhododendron, Rhododendron protistum var. giganteum, is a highly endangered species with only two known endemic populations in a small area in the southern part of Yunnan Province in China. Unfortunately, limited information is available regarding the population genetics of this species. Therefore, we conducted amplified fragment length polymorphism (AFLP) analysis to characterize the genetic diversity and variation of this species within and between remaining populations. Twelve primer combinations of AFLP produced 447 unambiguous and repetitious bands. Among these bands, 298 (66.67 %) were polymorphic. We found high genetic diversity at the species level (percentage of polymorphic loci = 66.67 %, h = 0.240, I = 0.358) and low genetic differentiation (Gst = 0.110) between the two populations. Gene flow between populations (Nm) was relatively high at 4.065. Analysis of molecular variance results revealed that 22 % of the genetic variation was partitioned between populations and 78 % of the genetic variation was within populations. The presence of moderate to high genetic diversity and low genetic differentiation in the two populations can be explained by life history traits, pollen dispersal and high gene flow (Nm = 4.065). Bayesian structure and principal coordinate analysis revealed that 56 sampled trees were clustered into two groups. Our results suggest that some rare and endangered species are able to maintain high levels of genetic diversity even at small population sizes. These results will assist with the design of conservation and management programmes, such as in situ and ex situ conservation, seed collection for germplasm conservation and reintroduction. PMID:25477251

  6. Diversity and genetic structure analysis of three Amazonian Amerindian populations of Colombia.

    PubMed Central

    Braga, Yamid; Arias B, Leonardo

    2012-01-01

    Introduction: In the departments of the Vaupés and Guaviare, in southeastern Colombia, in a transitional area between Amazonia and the eastern plains, inhabit indigenous groups belonging to the Tukanoan (East) and Guahiban linguistic families. Although some studies have dealt with the culture and the cosmology description of these groups, little research has been done on the biological diversity and genetic relationships of such groups. Objective: To estimate the diversity, the structure, and the genetic relationships of one Guahiban and two Tukanoan groups of the Colombian Amazonian region. Methods: Samples were collected (n = 106) from unrelated individuals belonging to the Vaupés native indigenous communities. The DNA was extracted and nine autosomal microsatellites were typed. Several measures of diversity, FST, pairwise FST, and population differentiation between groups were calculated. Finally, it was estimated the genetic distances of the groups studied in relation with other Amazonian, Andean and Central American indigenous people. Results: 1. The genetic diversity found stands within the range of other Amazonian populations, whereas compared to the mestizo and afro-descendant Colombian populations, such diversity showed to be lower. 2. The structure and population differentiation tests showed two clusters; one consisting of the Vaupés Tukanoan and Guaviare Tukanoan groups, and a second one formed by the Guayabero. 3. Tukanoan groups are found to be closer related to the Brazilian Amazonian populations than to the Guayabero. Conclusion: The results of this study suggest that the Guayabero group from Guaviare, are genetically differentiated from those Tukanoan groups of the Vaupés and Guaviare. PMID:24893054

  7. Genetic Diversity and Structure of Sinopodophyllum hexandrum (Royle) Ying in the Qinling Mountains, China

    PubMed Central

    Liu, Wei; Yin, Dongxue; Liu, Jianjun; Li, Na

    2014-01-01

    Sinopodophyllum hexandrum is an important medicinal plant whose genetic diversity must be conserved because it is endangered. The Qinling Mts. are a S. hexandrum distribution area that has unique environmental features that highly affect the evolution of the species. To provide the reference data for evolutionary and conservation studies, the genetic diversity and population structure of S. hexandrum in its overall natural distribution areas in the Qinling Mts. were investigated through inter-simple sequence repeats analysis of 32 natural populations. The 11 selected primers generated a total of 135 polymorphic bands. S. hexandrum genetic diversity was low within populations (average He = 0.0621), but higher at the species level (He = 0.1434). Clear structure and high genetic differentiation among populations were detected by using the unweighted pair group method for arithmetic averages, principle coordinate analysis and Bayesian clustering. The clustering approaches supported a division of the 32 populations into three major groups, for which analysis of molecular variance confirmed significant variation (63.27%) among populations. The genetic differentiation may have been attributed to the limited gene flow (Nm = 0.3587) in the species. Isolation by distance among populations was determined by comparing genetic distance versus geographic distance by using the Mantel test. Result was insignificant (r = 0.212, P = 0.287) at 0.05, showing that their spatial pattern and geographic locations are not correlated. Given the low within-population genetic diversity, high differentiation among populations and the increasing anthropogenic pressure on the species, in situ conservation measures were recommended to preserve S. hexandrum in Qinling Mts., and other populations must be sampled to retain as much genetic diversity of the species to achieve ex situ preservation as a supplement to in situ conservation. PMID:25333788

  8. Diversity, Antimicrobial Action and Structure-Activity Relationship of Buffalo Cathelicidins.

    PubMed

    Brahma, Biswajit; Patra, Mahesh Chandra; Karri, Satyanagalakshmi; Chopra, Meenu; Mishra, Purusottam; De, Bidhan Chandra; Kumar, Sushil; Mahanty, Sourav; Thakur, Kiran; Poluri, Krishna Mohan; Datta, Tirtha Kumar; De, Sachinandan

    2015-01-01

    Cathelicidins are an ancient class of antimicrobial peptides (AMPs) with broad spectrum bactericidal activities. In this study, we investigated the diversity and biological activity of cathelicidins of buffalo, a species known for its disease resistance. A series of new homologs of cathelicidin4 (CATHL4), which were structurally diverse in their antimicrobial domain, was identified in buffalo. AMPs of newly identified buffalo CATHL4s (buCATHL4s) displayed potent antimicrobial activity against selected Gram positive (G+) and Gram negative (G-) bacteria. These peptides were prompt to disrupt the membrane integrity of bacteria and induced specific changes such as blebing, budding, and pore like structure formation on bacterial membrane. The peptides assumed different secondary structure conformations in aqueous and membrane-mimicking environments. Simulation studies suggested that the amphipathic design of buCATHL4 was crucial for water permeation following membrane disruption. A great diversity, broad-spectrum antimicrobial action, and ability to induce an inflammatory response indicated the pleiotropic role of cathelicidins in innate immunity of buffalo. This study suggests short buffalo cathelicidin peptides with potent bactericidal properties and low cytotoxicity have potential translational applications for the development of novel antibiotics and antimicrobial peptidomimetics. PMID:26675301

  9. Diversity, Antimicrobial Action and Structure-Activity Relationship of Buffalo Cathelicidins

    PubMed Central

    Brahma, Biswajit; Patra, Mahesh Chandra; Karri, Satyanagalakshmi; Chopra, Meenu; Mishra, Purusottam; De, Bidhan Chandra; Kumar, Sushil; Mahanty, Sourav; Thakur, Kiran; Poluri, Krishna Mohan; Datta, Tirtha Kumar; De, Sachinandan

    2015-01-01

    Cathelicidins are an ancient class of antimicrobial peptides (AMPs) with broad spectrum bactericidal activities. In this study, we investigated the diversity and biological activity of cathelicidins of buffalo, a species known for its disease resistance. A series of new homologs of cathelicidin4 (CATHL4), which were structurally diverse in their antimicrobial domain, was identified in buffalo. AMPs of newly identified buffalo CATHL4s (buCATHL4s) displayed potent antimicrobial activity against selected Gram positive (G+) and Gram negative (G-) bacteria. These peptides were prompt to disrupt the membrane integrity of bacteria and induced specific changes such as blebing, budding, and pore like structure formation on bacterial membrane. The peptides assumed different secondary structure conformations in aqueous and membrane-mimicking environments. Simulation studies suggested that the amphipathic design of buCATHL4 was crucial for water permeation following membrane disruption. A great diversity, broad-spectrum antimicrobial action, and ability to induce an inflammatory response indicated the pleiotropic role of cathelicidins in innate immunity of buffalo. This study suggests short buffalo cathelicidin peptides with potent bactericidal properties and low cytotoxicity have potential translational applications for the development of novel antibiotics and antimicrobial peptidomimetics. PMID:26675301

  10. Genetic Diversity and Population Structure of Cowpea (Vigna unguiculata L. Walp)

    PubMed Central

    Xiong, Haizheng; Shi, Ainong; Mou, Beiquan; Qin, Jun; Motes, Dennis; Lu, Weiguo; Ma, Jianbing; Weng, Yuejin; Yang, Wei; Wu, Dianxing

    2016-01-01

    The genetic diversity of cowpea was analyzed, and the population structure was estimated in a diverse set of 768 cultivated cowpea genotypes from the USDA GRIN cowpea collection, originally collected from 56 countries. Genotyping by sequencing was used to discover single nucleotide polymorphism (SNP) in cowpea and the identified SNP alleles were used to estimate the level of genetic diversity, population structure, and phylogenetic relationships. The aim of this study was to detect the gene pool structure of cowpea and to determine its relationship between different regions and countries. Based on the model-based ancestry analysis, the phylogenetic tree, and the principal component analysis, three well-differentiated genetic populations were postulated from 768 worldwide cowpea genotypes. According to the phylogenetic analyses between each individual, region, and country, we may trace the accession from off-original, back to the two candidate original areas (West and East of Africa) to predict the migration and domestication history during the cowpea dispersal and development. To our knowledge, this is the first report of the analysis of the genetic variation and relationship between globally cultivated cowpea genotypes. The results will help curators, researchers, and breeders to understand, utilize, conserve, and manage the collection for more efficient contribution to international cowpea research. PMID:27509049

  11. Genetic Diversity and Population Structure of Cowpea (Vigna unguiculata L. Walp).

    PubMed

    Xiong, Haizheng; Shi, Ainong; Mou, Beiquan; Qin, Jun; Motes, Dennis; Lu, Weiguo; Ma, Jianbing; Weng, Yuejin; Yang, Wei; Wu, Dianxing

    2016-01-01

    The genetic diversity of cowpea was analyzed, and the population structure was estimated in a diverse set of 768 cultivated cowpea genotypes from the USDA GRIN cowpea collection, originally collected from 56 countries. Genotyping by sequencing was used to discover single nucleotide polymorphism (SNP) in cowpea and the identified SNP alleles were used to estimate the level of genetic diversity, population structure, and phylogenetic relationships. The aim of this study was to detect the gene pool structure of cowpea and to determine its relationship between different regions and countries. Based on the model-based ancestry analysis, the phylogenetic tree, and the principal component analysis, three well-differentiated genetic populations were postulated from 768 worldwide cowpea genotypes. According to the phylogenetic analyses between each individual, region, and country, we may trace the accession from off-original, back to the two candidate original areas (West and East of Africa) to predict the migration and domestication history during the cowpea dispersal and development. To our knowledge, this is the first report of the analysis of the genetic variation and relationship between globally cultivated cowpea genotypes. The results will help curators, researchers, and breeders to understand, utilize, conserve, and manage the collection for more efficient contribution to international cowpea research. PMID:27509049

  12. Population genetic structure of Plasmodium falciparum across a region of diverse endemicity in West Africa

    PubMed Central

    2012-01-01

    Background Malaria parasite population genetic structure varies among areas of differing endemicity, but this has not been systematically studied across Plasmodium falciparum populations in Africa where most infections occur. Methods Ten polymorphic P. falciparum microsatellite loci were genotyped in 268 infections from eight locations in four West African countries (Republic of Guinea, Guinea Bissau, The Gambia and Senegal), spanning a highly endemic forested region in the south to a low endemic Sahelian region in the north. Analysis was performed on proportions of mixed genotype infections, genotypic diversity among isolates, multilocus standardized index of association, and inter-population differentiation. Results Each location had similar levels of pairwise genotypic diversity among isolates, although there were many more mixed parasite genotype infections in the south. Apart from a few isolates that were virtually identical, the multilocus index of association was not significant in any population. Genetic differentiation between populations was low (most pairwise FST values < 0.03), and an overall test for isolation by distance was not significant. Conclusions Although proportions of mixed genotype infections varied with endemicity as expected, population genetic structure was similar across the diverse sites. Very substantial reduction in transmission would be needed to cause fragmented or epidemic sub-structure in this region. PMID:22759447

  13. Genetic Diversity and Population Structure Analysis of European Hexaploid Bread Wheat (Triticum aestivum L.) Varieties

    PubMed Central

    Nielsen, Nanna Hellum; Backes, Gunter; Stougaard, Jens; Andersen, Stig Uggerhøj; Jahoor, Ahmed

    2014-01-01

    Progress in plant breeding is facilitated by accurate information about genetic structure and diversity. Here, Diversity Array Technology (DArT) was used to characterize a population of 94 bread wheat (Triticum aestivum L.) varieties of mainly European origin. In total, 1,849 of 7,000 tested markers were polymorphic and could be used for population structure analysis. Two major subgroups of wheat varieties, GrI and GrII, were identified using the program STRUCTURE, and confirmed by principal component analysis (PCA). These subgroups were largely separated according to origin; GrI comprised varieties from Southern and Eastern Europe, whereas GrII contained mostly modern varieties from Western and Northern Europe. A large proportion of the markers contributing most to the genetic separation of the subgroups were located on chromosome 2D near the Reduced height 8 (Rht8) locus, and PCR-based genotyping suggested that breeding for the Rht8 allele had a major impact on subgroup separation. Consistently, analysis of linkage disequilibrium (LD) suggested that different selective pressures had acted on chromosome 2D in the two subgroups. Our data provides an overview of the allele composition of bread wheat varieties anchored to DArT markers, which will facilitate targeted combination of alleles following DArT-based QTL studies. In addition, the genetic diversity and distance data combined with specific Rht8 genotypes can now be used by breeders to guide selection of crossing parents. PMID:24718292

  14. Effects of Predation by Protists on Prokaryotic Community Function, Structure, and Diversity in Anaerobic Granular Sludge

    PubMed Central

    Hirakata, Yuga; Oshiki, Mamoru; Kuroda, Kyohei; Hatamoto, Masashi; Kubota, Kengo; Yamaguchi, Takashi; Harada, Hideki; Araki, Nobuo

    2016-01-01

    Predation by protists is top-down pressure that regulates prokaryotic abundance, community function, structure, and diversity in natural and artificial ecosystems. Although the effects of predation by protists have been studied in aerobic ecosystems, they are poorly understood in anoxic environments. We herein studied the influence of predation by Metopus and Caenomorpha ciliates—ciliates frequently found in anoxic ecosystems—on prokaryotic community function, structure, and diversity. Meto