24,350 research outputs found

    Outflows in Infrared-Luminous Starbursts at z < 0.5. II. Analysis and Discussion

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    We have performed an absorption-line survey of outflowing gas in 78 starburst-dominated, infrared-luminous galaxies. This is the largest study of superwinds at z < 3. Superwinds are found in almost all infrared-luminous galaxies, and changes in detection rate with SFR--winds are found twice as often in ultraluminous infrared galaxies (ULIRGs) as in less-luminous galaxies--reflect different wind geometries. The maximum velocities we measure are 600 km/s, though most of the outflowing gas has lower velocities (100-200 km/s). (One galaxy has velocities exceeding 1000 km/s.) Velocities in LINERs are higher than in HII galaxies, and outflowing ionized gas often has higher velocities than the neutral gas. Wind properties (velocity, mass, momentum, and energy) scale with galaxy properties (SFR, luminosity, and galaxy mass), consistent with ram-pressure driving of the wind. Wind properties increase strongly with increasing galactic mass, contrary to expectation. These correlations flatten at high SFR (> 10-100 M_sun/yr), luminosities, and masses. This saturation is due to a lack of gas remaining in the wind's path, a common neutral gas terminal velocity, and/or a decrease in the efficiency of thermalization of the supernovae energy. It means that mass entrainment efficiency, rather than remaining constant, declines in galaxies with SFR > 10 M_sun/yr and M_K < -24. Half of our sample consists of ULIRGs, which host as much as half of the star formation in the universe at z > 1. The powerful, ubiquitous winds we observe in these galaxies imply that superwinds in massive galaxies at redshifts above unity play an important role in the evolution of galaxies and the intergalactic medium.Comment: 68 pages, 20 figures in AASTeX preprint style; to appear in September issue of ApJS; Figure 17 replaced with correct versio

    New Results from a Near-Infrared Search for Hidden Broad-Line Regions in Ultraluminous Infrared Galaxies

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    This paper reports the latest results from a near-infrared search for hidden broad-line regions (BLRs: FWHM >~ 2,000 km/s) in ultraluminous infrared galaxies (ULIGs). The new sample contains thirty-nine ULIGs from the 1-Jy sample selected for their lack of BLRs at optical wavelengths. The results from this new study are combined with those from our previous optical and near-infrared surveys to derive the fraction of all ULIGs with optical or near-infrared signs of genuine AGN activity (either a BLR or [Si VI] emission). Comparisons of the dereddened emission-line luminosities of the optical or obscured BLRs detected in the ULIGs of the 1-Jy sample with those of optical quasars indicate that the obscured AGN/quasar in ULIGs is the main source of energy in at least 15 -- 25% of all ULIGs in the 1-Jy sample. This fraction is 30 -- 50% among ULIGs with L_ir > 10^{12.3} L_sun. These results are compatible with those from recent mid-infrared spectroscopic surveys carried out with ISO. (abridged)Comment: 40 pages including 10 figures and 3 tables (Table 3 should be printed in landscape mode

    Newtonian limit of String-Dilaton Gravity

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    We study the weak-field limit of string-dilaton gravity and derive corrections to the Newtonian potential which strength directly depends on the self interaction potential and the nonminimal coupling of the dilaton scalar field. We discuss also possible astrophysical applications of the results, in particular the flat rotation curves of spiral galaxies.Comment: 11 pages, LATEX file, to appear in IJMP

    Phylogenetic and functional analysis of the Cation Diffusion Facilitator (CDF) family: improved signature and prediction of substrate specificity

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    BACKGROUND The Cation Diffusion Facilitator (CDF) family is a ubiquitous family of heavy metal transporters. Much interest in this family has focused on implications for human health and bioremediation. In this work a broad phylogenetic study has been undertaken which, considered in the context of the functional characteristics of some fully characterised CDF transporters, has aimed at identifying molecular determinants of substrate selectivity and at suggesting metal specificity for newly identified CDF transporters. RESULTS Representative CDF members from all three kingdoms of life (Archaea, Eubacteria, Eukaryotes) were retrieved from genomic databases. Protein sequence alignment has allowed detection of a modified signature that can be used to identify new hypothetical CDF members. Phylogenetic reconstruction has classified the majority of CDF family members into three groups, each containing characterised members that share the same specificity towards the principally-transported metal, i.e. Zn, Fe/Zn or Mn. The metal selectivity of newly identified CDF transporters can be inferred by their position in one of these groups. The function of some conserved amino acids was assessed by site-directed mutagenesis in the poplar Zn2+ transporter PtdMTP1 and compared with similar experiments performed in prokaryotic members. An essential structural role can be assigned to a widely conserved glycine residue, while aspartate and histidine residues, highly conserved in putative transmembrane domains, might be involved in metal transport. The potential role of group-conserved amino acid residues in metal specificity is discussed. CONCLUSION In the present study phylogenetic and functional analyses have allowed the identification of three major substrate-specific CDF groups. The metal selectivity of newly identified CDF transporters can be inferred by their position in one of these groups. The modified signature sequence proposed in this work can be used to identify new hypothetical CDF members

    Robust strategies for lossy quantum interferometry

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    We give a simple multiround strategy that permits to beat the shot noise limit when performing interferometric measurements even in the presence of loss. In terms of the average photon number employed, our procedure can achieve twice the sensitivity of conventional interferometric ones in the noiseless case. In addition, it is more precise than the (recently proposed) optimal two-mode strategy even in the presence of loss.Comment: 4 pages, 3 figure

    Optimal states and almost optimal adaptive measurements for quantum interferometry

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    We derive the optimal N-photon two-mode input state for obtaining an estimate \phi of the phase difference between two arms of an interferometer. For an optimal measurement [B. C. Sanders and G. J. Milburn, Phys. Rev. Lett. 75, 2944 (1995)], it yields a variance (\Delta \phi)^2 \simeq \pi^2/N^2, compared to O(N^{-1}) or O(N^{-1/2}) for states considered by previous authors. Such a measurement cannot be realized by counting photons in the interferometer outputs. However, we introduce an adaptive measurement scheme that can be thus realized, and show that it yields a variance in \phi very close to that from an optimal measurement.Comment: 4 pages, 4 figures, journal versio

    Review of Recent Searches for Rare and Forbidden Dilepton Decays of Charmed Mesons

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    I briefly review the results of recent searches for flavor-changing neutral current and lepton-flavor and lepton-number violating decays of D+, Ds, and D0 mesons (and their antiparticles) into modes containing muons and electrons. The primary focus is the results from Fermilab charm hadroproduction experiment E791. E791 examined 24 pi,l,l and K,l,l decay modes of D+ and Ds and l+l- decay modes of D0. Limits presented by E791 for 22 rare and forbidden dilepton decays of D mesons were more stringent than those obtained from previous searches, or else were the first reported.Comment: 8 pages, 1 figure, uses psfig.sty and RevTeX, submitted to Modern Physics Letters A, based on a Fermilab "Joint Theoretical and Experimental" tal

    It’s gender Jim, but not as we know it 
 A critical review of constructions of gendered knowledge of the global south

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    This article explores how research helps construct a certain type of ‘gender’ knowledge that arises from, informs and reinforces ‘instrumentalist’ gendered policy perspectives on development of the Global South. It uses a case study of research funded under the ESRC-DFID Joint Fund for Poverty Alleviation which awarded 122 grants amounting to £66.2 million (around US$88 million) between 2005 and 2015. From a systematic review of the awards a typology of gender inclusion and exclusion was constructed that found 60% of all awards mentioned gender or included some level of gender analysis. The subsequent synthesis of the evidence suggested that in only 30% of all awards was the gendered knowledge produced central to the study and/or focused on better understanding gender roles, relations and identities. Applying a Feminist Institutionalist lens, the study highlights how institutional ideas around gender are reflected in the funding call specifications, and in turn influence how researchers ‘engendered’ their research, and the type of gendered knowledge produced. It finds much of the new gendered knowledge produced out of the Joint Fund emerged from non-gender focused research often produced by non-gendered researchers. It suggests that as gender becomes mainstreamed into research, and as more researchers ‘do gender’, so research becomes, conversely, less ‘gendered’. The ‘new’ gender knowledge produced may then merely evidence existing institutional policy positions rather than advance the policy agenda

    The development of structural adhesives systems suitable for use with liquid oxygen Annual summary report, 1 Jul. 1963 - 30 Jun. 1964

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    Fluorinated, chlorinated, and halogenated polymer adhesives prepared and tested for compatibility with liquid oxyge
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