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Sample records for low-redshift 3cr radio

  1. The Extreme Ultraviolet Spectra of Low Redshift Radio Loud Quasars

    CERN Document Server

    Punsly, Brian; Marziani, Paola; O'Dea, Christopher P

    2016-01-01

    This paper reports on the extreme ultraviolet (EUV) spectrum of three low redshift ($z \\sim 0.6$) radio loud quasars, 3C 95, 3C 57 and PKS 0405-123. The spectra were obtained with the Cosmic Origins Spectrograph (COS) of the Hubble Space Telescope. The bolometric thermal emission, $L_{bol}$, associated with the accretion flow is a large fraction of the Eddington limit for all of these sources. We estimate the long term time averaged jet power, $\\overline{Q}$, for the three sources. $\\overline{Q}/L_{bol}$, is shown to lie along the correlation of $\\overline{Q}/L_{bol}$ and $\\alpha_{EUV}$ found in previous studies of the EUV continuum of intermediate and high redshift quasars, where the EUV continuum flux density between 1100 \\AA\\, and 700 \\AA\\, is defined by $F_{\

  2. Radio Properties of Low Redshift Broad Line Active Galactic Nuclei Including Multiple Component Radio Sources

    Science.gov (United States)

    Rafter, Stephen E.

    2010-01-01

    We present results on the radio properties of a low redshift (z FRIIs. From these data we find an FRI/FRII luminosity dividing line like that found by Fanaroff & Riley (1974), where we use our core-only sources as proxies for FRIs, and our multi-component sources for the FRIIs. We find a bimodal distribution for the radio loudness (R = L(radio)/L(opt)) where the lower radio luminosity core-only sources appear as a population separate from the multi-component extended sources, compared with no evidence for bimodality when just the core-only sources are used. We also find that a log(R) value of 1.75 is well suited to separate the FRIs from the FRIIs, and that the R bimodality seen here is really a manifestation of the FRI/FRII break originally found by Fanaroff & Riley (1974). We find modest trends in the radio loud fraction as a function of Eddington ratio and black hole mass, where the fraction of RL AGNs decreases with increasing Eddington ratio, and increases when the black hole mass is above 2 x 108 solar masses.

  3. LOFAR discovery of a 700-kpc remnant radio galaxy at low redshift

    NARCIS (Netherlands)

    Brienza, M.; Godfrey, L.; Morganti, R.; Vilchez, N.; Maddox, N.; Murgia, M.; Orru, E.; Shulevski, A.; Best, P. N.; Brüggen, M.; Harwood, J. J.; Jamrozy, M.; Jarvis, M. J.; Mahony, E. K.; McKean, J.; Röttgering, H. J. A.

    2016-01-01

    Context. Remnant radio galaxies represent the final dying phase of radio galaxy evolution in which the jets are no longer active. Remnants are rare in flux-limited samples, comprising at most a few percent. As a result of their rarity and because they are difficult to identify, this dying phase

  4. LOFAR discovery of a 700-kpc remnant radio galaxy at low redshift

    CERN Document Server

    Brienza, M; Morganti, R; Vilchez, N; Maddox, N; Murgia, M; Orru, E; Shulevski, A; Best, P N; Brüggen, M; Harwood, J J; Jamrozy, M; Jarvis, M J; Mahony, E K; McKean, J; Röttgering, H J A

    2015-01-01

    Remnant radio galaxies represent the final "dying" phase of radio galaxy evolution, in which the jets are no longer active. Due to their rarity in flux limited samples and the difficulty of identification, this "dying" phase remains poorly understood and the luminosity evolution largely unconstrained. Here we present the discovery, and detailed analysis of a large (700 kpc), low surface brightness remnant radio galaxy that has been identified in LOFAR images at 150 MHz. Combining LOFAR data with new follow-up Westerbork observations and archival data at higher frequencies we investigate the source morphology and spectral properties from 116 to 4850 MHz. By modelling the radio spectrum we probe characteristic timescales of the radio activity. The source has a relatively smooth, diffuse, amorphous appearance together with a very weak central compact core which is associated with the host galaxy located at z=0.051. From our ageing and morphological analysis it is clear that the nuclear engine is currently switch...

  5. VLBI observations of the CORALZ sample: young radio sources at low redshift

    CERN Document Server

    de Vries, N; Schilizzi, R T; Mack, K -H; Kaiser, C R

    2009-01-01

    Young radio-loud active galactic nuclei form an important tool to investigate the evolution of extragalactic radio sources. To study the early phases of expanding radio sources, we have constructed CORALZ, a sample of 25 compact ($\\theta<2"$) radio sources associated with nearby ($z<0.16$) galaxies. In this paper we determine the morphologies, linear sizes, and put first constraints on the lobe expansion speeds of the sources in the sample. We observed the radio sources from the CORALZ sample with MERLIN at 1.4 GHz or 1.6 GHz, the EVN at 1.6 GHz, and global VLBI at 1.6 GHz and/or 5.0 GHz. Radio maps, morphological classifications, and linear sizes are presented for all sources in the CORALZ sample. We have determined a first upper limit to the expansion velocity of one of the sources, which is remarkably low compared to the brighter GPS sources at higher redshifts, indicating a relation between radio luminosity and expansion speed, in agreement with analytical models. In addition we present further stro...

  6. LOFAR discovery of a 700-kpc remnant radio galaxy at low redshift

    Science.gov (United States)

    Brienza, M.; Godfrey, L.; Morganti, R.; Vilchez, N.; Maddox, N.; Murgia, M.; Orru, E.; Shulevski, A.; Best, P. N.; Brüggen, M.; Harwood, J. J.; Jamrozy, M.; Jarvis, M. J.; Mahony, E. K.; McKean, J.; Röttgering, H. J. A.

    2016-01-01

    Context. Remnant radio galaxies represent the final dying phase of radio galaxy evolution in which the jets are no longer active. Remnants are rare in flux-limited samples, comprising at most a few percent. As a result of their rarity and because they are difficult to identify, this dying phase remains poorly understood and the luminosity evolution is largely unconstrained. Aims: Here we present the discovery and detailed analysis of a large (700 kpc) remnant radio galaxy with a low surface brightness that has been identified in LOFAR images at 150 MHz. Methods: By combining LOFAR data with new follow-up Westerbork observations and archival data at higher frequencies, we investigated the source morphology and spectral properties from 116 to 4850 MHz. By modelling the radio spectrum, we probed characteristic timescales of the radio activity. Results: The source has a relatively smooth, diffuse, amorphous appearance together with a very weak central compact core that is associated with the host galaxy located at z = 0.051. From our ageing and morphological analysis it is clear that the nuclear engine is currently switched off or, at most, active at a very low power state. We find that the source has remained visible in the remnant phase for about 60 Myr, significantly longer than its active phase of 15 Myr, despite being located outside a cluster. The host galaxy is currently interacting with another galaxy located at a projected separation of 15 kpc and a radial velocity offset of ~ 300 km s-1. This interaction may have played a role in the triggering and/or shut-down of the radio jets. Conclusions: The spectral shape of this remnant radio galaxy differs from most of the previously identified remnant sources, which show steep or curved spectra at low to intermediate frequencies. Our results demonstrate that remnant radio galaxies can show a wide range of evolutionary paths and spectral properties. In light of this finding and in preparation for new-generation deep

  7. Star formation in 3CR radio galaxies and quasars at $z < 1$

    CERN Document Server

    Westhues, Christian; Barthel, Peter; Wilkes, Belinda J; Willner, S P; Kuraszkiewicz, Joanna; Podigachoski, Pece; Leipski, Christian; Meisenheimer, Klaus; Siebenmorgen, Ralf; Chini, Rolf

    2016-01-01

    Using the Herschel Space Observatory we have observed a representative sample of 87 powerful 3CR sources at redshift $z < 1$. The far-infrared (FIR, 70-500~$\\mu m$) photometry is combined with mid-infrared (MIR) photometry from the Wide-Field Infrared Survey Explorer (WISE) and catalogued data to analyse the complete spectral energy distributions (SEDs) of each object from optical to radio wavelength. To disentangle the contributions of different components, the SEDs are fitted with a set of templates to derive the luminosities of host galaxy starlight, dust torus emission powered by active galactic nuclei (AGN) and cool dust heated by stars. The level of emission from relativistic jets is also estimated, in order to isolate the thermal host galaxy contribution. The new data are in line with the orientation-based unification of high-excitation radio-loud AGN, in that the dust torus becomes optically thin longwards of $30~\\mu m$. The low excitation radio galaxies and the MIR weak sources represent MIR- and ...

  8. Dust in 3CR radio galaxies: On the FR 1 - FR 2 difference

    Science.gov (United States)

    Müller, S. A. H.; Haas, M.; Siebenmorgen, R.; Klaas, U.; Meisenheimer, K.; Chini, R.; Albrecht, M.

    2004-11-01

    We compare three 3CR samples of 11 FR 1 galaxies, 17 FR 2 galaxies and 18 lobe-dominated quasars contained in the ISO Data Archive. In contrast to the powerful FR 2 galaxies with edge-brightened lobes, the low radio power FR 1 galaxies in our sample do not exhibit any high MIR or FIR dust luminosity, which is typical for a buried, intrinsically more luminous AGN. This consolidates the fact already inferred from optical studies that their AGNs have only a relatively low luminosity. Also the FR 1 galaxies show a high FIR/MIR luminosity ratio, compared to quasars, suggesting that their FIR luminosity is substantially powered by the interstellar radiation field (ISRF) of the giant elliptical hosts. Finally, we discuss the FR 1 - FR 2 morphological dichotomy. FR 1 galaxies do not have more interstellar matter (ISM) than FR 2s as traced - on the large scale - by the cool FIR emitting dust and - in the nuclear region - by the warm MIR emitting dust. Due to the lack of central gas we suggest that the black holes of our FR 1 galaxies are fed at a lower accretion rate than those of the FR 2 galaxies. Based on observations with the Infrared Space Observatory ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the UK) and with the participation of ISAS and NASA.

  9. An optical spectroscopic survey of the 3CR sample of radio galaxies with z<0.3. II. Spectroscopic classes and accretion modes in radio-loud AGN

    CERN Document Server

    Buttiglione, Sara; Celotti, Annalisa; Axon, David J; Chiaberge, Marco; Macchetto, F Duccio; Sparks, William B

    2009-01-01

    We use the emission line measurements of 3CR radio sources with redshift 32.8. Conversely LEG cover the whole range of radio power encompassed by this 3CR subsample (30.7 < log L(178) < 35.4) and they are of both FRI and FRII type. The brightest LEG are all FRII. HEG and LEG obey to two (quasi) linear correlations between the optical line and extended radio luminosities, with HEG being brighter than LEG in the [OIII] line by a factor of ~10. HEG and LEG are offset also in a plane that compares the black hole mass and the ionizing nuclear luminosity. However, although HEG are associated with higher nuclear luminosities, we find LEG among the brightest radio sources of the sample and with a clear FRII morphology, indistinguishable from those seen in HEG. This suggests that LEG are not simply objects with a lower level of accretion. We speculate that the differences between LEG and HEG are related to a different mode of accretion: LEG a re powered by hot gas, while HEG require the presence of cold accreti...

  10. The Environment of z >1 3CR Radio Galaxies and QSOs: From Proto-Clusters to Clusters of Galaxies?

    CERN Document Server

    Kotyla, John Paul; Baum, Stefi A; Capetti, Alessandro; Hilbert, Bryan; Macchetto, F Duccio; Miley, George K; O'Dea, Christopher P; Perlman, Eric S; Sparks, William B; Tremblay, Grant R

    2016-01-01

    We study the cluster environment for a sample of 21 radio loud AGN from the 3CR catalog at z>1, 12 radio galaxies and 9 quasars with HST images in the optical and IR. We use two different approaches to determine cluster candidates. We identify the early type galaxies (ETGs) in every field by modeling each of the sources within a 40" radius of the targets with a Sersic profile. Using a simple passive evolution model, we derive the expected location of the ETGs on the red sequence (RS) in the color-magnitude diagram for each of the fields of our sources. For seven targets, the model coincides with the position of the ETGs. A second approach involves a search for over densities. We compare the object densities of the sample as a whole and individually against control fields taken from the GOODS-S region of 3D-HST survey. With this method we determine the fields of 10 targets to be cluster candidates. Four cluster candidates are found by both methods. The two methods disagree in some cases, depending on the speci...

  11. Modifying Gravity at Low Redshift

    CERN Document Server

    Brax, Philippe; Davis, Anne-Christine; Shaw, Douglas

    2010-01-01

    We consider the growth of cosmological perturbations in modified gravity models where a scalar field mediates a non-universal Yukawa force between different matter species. The growth of the density contrast is altered for scales below the Compton wave-length of the scalar field. As the universe expands, the Compton wave-length varies in time in such a way that scales which where outside the range of the scalar field force may feel it at a lower redshift. In this case, both the exponent $\\gamma$ measuring the growth of Cold Dark Matter perturbations and the shift function representing the ratio of the two Newtonian potentials $\\psi$ and $\\phi$ may differ from their values in General Relativity at low redshift.

  12. Lost Baryons at Low Redshift

    CERN Document Server

    Mathur, Smita; Williams, Rik J

    2007-01-01

    We review our attempts to discover lost baryons at low redshift with ``X-ray forest'' of absorption lines from the warm-hot intergalactic medium. We discuss the best evidence to date along the Mrk 421 sightline. We then discuss the missing baryons in the Local Group and the significance of the z=0 absorption systems in X-ray spectra. We argue that the debate over the Galactic vs. extragalactic origin of the z=0 systems is premature as these systems likely contain both components. Observations with next generation X-ray missions such as Constellation-X and XEUS will be crucial to map out the warm-hot intergalactic medium.

  13. An optical spectroscopic survey of the 3CR sample of radio galaxies with z < 0.3. V. Implications for the unified model for FR IIs

    Science.gov (United States)

    Baldi, Ranieri D.; Capetti, Alessandro; Buttiglione, Sara; Chiaberge, Marco; Celotti, Annalisa

    2013-12-01

    We explore the implications of our optical spectroscopic survey of 3CR radio sources with z edge-brightened" (FR II) radio morphology. The sample contains 33 high ionization galaxies (HIGs) and 18 broad line objects (BLOs). According to the UM, HIGs, the narrow line sources, are the nuclearly obscured counterparts of BLOs. The fraction of HIGs indicates a covering factor of the circumnuclear matter of 65% that corresponds, adopting a torus geometry, to an opening angle of 50° ± 5. No dependence on redshift and luminosity on the torus opening angle emerges. We also consider the implications for a "clumpy" torus. The distributions of total radio luminosity of HIGs and BLOs are not statistically distinguishable, as expected from the UM. Conversely, BLOs have a radio core dominance, R, more than ten times larger with respect to HIGs, as expected in case of Doppler boosting when the jets in BLOs are preferentially oriented closer to the line of sight than in HIGs. Modeling the R distributions leads to an estimate of the jet bulk Lorentz factor of Γ ~ 3-5. The test of the UM based on the radio source size is not conclusive due to the limited number of objects and because the size distribution is dominated by the intrinsic scatter rather than by projection effects. The [O II] line luminosities in HIGs and BLOs are similar but the [O III] and [O I] lines are higher in BLOs by a factor of ~2. We ascribe this effect to the presence of a line emitting region located within the walls of the obscuring torus, visible in BLOs but obscured in HIGs, with a density higher than the [O II] critical density. We find evidence that BLOs have broader [O I] and [O III] lines than HIGs of similar [O II] width, as expected in the presence of high density gas in the proximity of the central black hole. In conclusion, the radio and narrow line region (NLR) properties of HIGs and BLOs are consistent with the UM predictions when the partial obscuration of the NLR is taken into account. We

  14. Hubble Space Telescope Ultraviolet spectroscopy of 14 low-redshift quasars

    NARCIS (Netherlands)

    Ganguly, R.; Kaastra, J.S.

    2007-01-01

    We present low-resolution ultraviolet spectra of 14 low-redshift quasars observed with the Hubble Space Telescope STIS as part of a Snapshot project to understand the relationship between quasar outflows and luminosity. The quasar is radio-loud but has a steep spectral index and a lobe-dominated

  15. THE LOW-REDSHIFT CARNEGIE SUPERNOVA PROJECT

    Directory of Open Access Journals (Sweden)

    G. Folatelli

    2009-01-01

    Full Text Available We present the low-redshift Carnegie Supernova Project (CSP, an undergoing program to follow up about 250 nearby supernovae (SNe of all types. We brie y describe the observations which yield well-sampled, highly precise optical and near-infrared light curves in a well-understood photometric system, complemented with optical spectroscopy. As one of the main goals of the CSP, we preliminarily present the rst Hubble diagram using a sample of 30 Type-Ia SNe (SNe Ia.

  16. The Low-Redshift Intergalactic Medium

    CERN Document Server

    Shull, J M; Stocke, J T; Penton, Steven V.; Stocke, John T.

    1999-01-01

    The low-redshift Ly-alpha forest of absorption lines provides a probe of large-scale baryonic structures in the intergalactic medium, some of which may be remnants of physical conditions set up during the epoch of galaxy formation. We discuss our recent Hubble Space Telescope (HST) observations and interpretation of low-z Ly-alpha clouds toward nearby Seyferts and QSOs, including their frequency, space density, estimated mass, association with galaxies, and contribution to Omega-baryon. Our HST/GHRS detections of 70 Ly-alpha absorbers with N_HI > 10^12.6 cm-2 along 11 sightlines covering pathlength Delta(cz) = 114,000 km/s show f(>N_HI) ~ N_HI^{-0.63 +- 0.04} and a line frequency dN/dz = 200 +- 40 for N_HI > 10^12.6 cm-2 (one every 1500 km/s of redshift). A group of strong absorbers toward PKS 2155-304 may be associated with gas (400-800) h_75^-1 kpc from 4 large galaxies, with low metallicity (< 0.003 solar) and D/H < 2 x 10^-4. At low-z, we derive a metagalactic ionizing radiation field from AGN of J_...

  17. The environment of low redshift quasar pairs

    CERN Document Server

    Sandrinelli, Angela; Treves, Aldo; Farina, Emanuele Paolo; Uslenghi, Michela

    2014-01-01

    We investigate the properties of the galaxy environment of a sample of 14 low redshift (z $<$ 0.85) quasar physical pairs extracted from SDSS DR10 archives. The pairs have a systemic radial velocity difference $\\Delta V_\\parallel \\leqslant$ 600 $km \\ s^{-1}$ (based on [OIII]5007 \\AA \\ line) and projected distance $ R_\\bot \\leqslant$ 600 kpc. The physical association of the pairs is statistically confirmed at a level of $\\sim$ 90 %. For most of the images of these quasars we are able to resolve their host galaxies that turn out to be on average similar to those of quasars not in pairs. We also found that quasars in a pair are on average in region of modest galaxy overdensity extending up 0.5 Mpc from the QSO. This galaxy overdensity is indistinguishable from that of a homogeneous sample of isolated quasars at the same redshift and with similar host galaxy luminosity. These results, albeit derived from a small (but homogeneous) sample of objects, suggest that the rare activation of two quasars with small phy...

  18. Cosmological limits on neutrino unknowns versus low redshift priors

    CERN Document Server

    Di Valentino, Eleonora; Mena, Olga; Melchiorri, Alessandro; Silk, Joseph

    2015-01-01

    Recent Cosmic Microwave Background (CMB) temperature and polarization anisotropy measurements from the Planck mission have significantly improved previous constraints on the neutrino masses as well as the bounds on extended models with massless or massive sterile neutrino states. However, due to parameter degeneracies, additional low redshift priors are mandatory in order to sharpen the CMB neutrino bounds. We explore here the role of different priors on low redshift quantities, such as the Hubble constant, the cluster mass bias, and the reionization optical depth $\\tau$. Concerning current priors on the Hubble constant and the cluster mass bias, the bounds on the neutrino parameters may differ appreciably depending on the choices adopted in the analyses. With regard to future improvements in the priors on the reionization optical depth, a value of $\\tau=0.05\\pm 0.01$, motivated by astrophysical estimates of the reionization redshift, would lead to $\\sum m_\

  19. Low-redshift evolution of the Lyman $\\alpha$ Forest

    CERN Document Server

    Theuns, T; Efstathiou, G P

    1998-01-01

    The low-redshift evolution of the intergalactic medium is investigated using hydrodynamic cosmological simulations. The assumed cosmological model is a critical density cold dark matter universe. The imposed uniform background of ionizing radiation has the amplitude, shape and redshift evolution as computed from the observed quasar luminosity function by Haardt & Madau. We have analysed simulated Lyman-alpha spectra using Voigt-profile fitting, mimicking the procedure with which quasar spectra are analysed. Our simulations reproduce the observed evolution of the number of Lyman-alpha absorption lines over the whole observed interval of z=0.5 to z=4. In particular, our simulations show that the decrease in the rate of evolution of Lyman-alpha absorption lines at z< 2, as observed by Hubble Space Telescope, can be explained by the steep decline in the photo-ionizing background resulting from the rapid decline in quasar numbers at low redshift.

  20. The length of the low-redshift standard ruler

    Science.gov (United States)

    Verde, Licia; Bernal, José Luis; Heavens, Alan F.; Jimenez, Raul

    2017-01-01

    Assuming the existence of standard rulers, standard candles and standard clocks, requiring only the cosmological principle, a metric theory of gravity, a smooth expansion history, and using state-of-the-art observations, we determine the length of the "low-redshift standard ruler". The data we use are a compilation of recent baryon acoustic oscillation data (relying on the standard ruler), Type 1A supernovæ (as standard candles), ages of early type galaxies (as standard clocks) and local determinations of the Hubble constant (as a local anchor of the cosmic distance scale). In a standard Λ cold dark matter cosmology the "low-redshift standard ruler" coincides with the sound horizon at radiation drag, which can also be determined -in a model dependent way- from cosmic microwave background observations. However, in general, the two quantities need not coincide. We obtain constraints on the length of the low-redshift standard ruler: r{^h}_s = 101.0 {±} 2.3 h^{-1} Mpc, when using only Type 1A supernovæ and Baryon acoustic oscillations, and rs = 150.0 ± 4.7 Mpc when using clocks to set the Hubble normalisation, while rs = 141.0 ± 5.5 Mpc when using the local Hubble constant determination (using both yields rs = 143.9 ± 3.1 Mpc). The low-redshift determination of the standard ruler has an error which is competitive with the model-dependent determination from cosmic microwave background measurements made with the Planck satellite, which assumes it is the sound horizon at the end of baryon drag.

  1. The length of the low-redshift standard ruler

    Science.gov (United States)

    Verde, Licia; Bernal, José Luis; Heavens, Alan F.; Jimenez, Raul

    2017-05-01

    Assuming the existence of standard rulers, standard candles and standard clocks, requiring only the cosmological principle, a metric theory of gravity, a smooth expansion history and using state-of-the-art observations, we determine the length of the 'low-redshift standard ruler'. The data we use are a compilation of recent baryon acoustic oscillation data (relying on the standard ruler), Type Ia supernovae (as standard candles), ages of early-type galaxies (as standard clocks) and local determinations of the Hubble constant (as a local anchor of the cosmic distance scale). In a standard Λ cold dark matter cosmology, the 'low-redshift standard ruler' coincides with the sound horizon at radiation drag, which can also be determined - in a model dependent way - from cosmic microwave background observations. However, in general, the two quantities need not coincide. We obtain constraints on the length of the low-redshift standard ruler: r^h_s=101.0 ± 2.3 h^{-1} Mpc, when using only Type Ia supernovae and baryon acoustic oscillations, and rs = 150.0 ± 4.7 Mpc when using clocks to set the Hubble normalization, while rs = 141.0 ± 5.5 Mpc when using the local Hubble constant determination (using both yields rs = 143.9 ± 3.1 Mpc). The low-redshift determination of the standard ruler has an error, which is competitive with the model-dependent determination from cosmic microwave background measurements made with the Planck satellite, which assumes that it is the sound horizon at the end of baryon drag.

  2. The length of the low-redshift standard ruler

    CERN Document Server

    Verde, Licia; Heavens, Alan F; Jimenez, Raul

    2016-01-01

    Assuming the existence of standard rulers, standard candles and standard clocks, requiring only the cosmological principle, a metric theory of gravity, a smooth expansion history, and using state-of-the-art observations, we determine the length of the "low-redshift standard ruler". The data we use are a compilation of recent Baryon acoustic oscillation data (relying on the standard ruler), Type 1A supernov\\ae\\ (as standard candles), ages of early type galaxies (as standard clocks) and local determinations of the Hubble constant (as a local anchor of the cosmic distance scale). In a standard $\\Lambda$CDM cosmology the "low-redshift standard ruler" coincides with the sound horizon at radiation drag, which can also be determined --in a model dependent way-- from CMB observations. However, in general, the two quantities need not coincide. We obtain constraints on the length of the low-redshift standard ruler: $r^h_{\\rm s}=101.0 \\pm 2.3 h^{-1}$ Mpc, when using only Type 1A supernov\\ae\\ and Baryon acoustic oscillat...

  3. A Low-redshift Sample of E+A Galaxies

    Science.gov (United States)

    Walker, K. M.; Bergmann, M. P.; Turner, J.

    2004-12-01

    We present the results of a low-redshift survey for E+A galaxies. These galaxies are spectroscopically classified as having strong Balmer and metallic absorption with the absence of any emission. The absorption lines indicate an abundance of A-type stars as well as an old stellar population, while the absence of emission, especially {O ii}, denotes the lack of current star formation. Essential in determining the evolution of early-type galaxies, a low-redshift sample will allow easier morphology observations and further spectroscopic study. Fourteen low-redshift E+A galaxies were found using the Sloan Digital Sky Survey Data Release One following similar criteria as the H-delta strong survey of Goto (2003), except that only galaxies with a redshift lower than z=0.05 were selected. Two of these E+A galaxies were observed with the Cerro Tololo Inter-American Observatory 1.5-m telescope and confirmed to have no emission anywhere along the longslit, including outside the 3" region sampled by the SDSS fibers. This work was supported by the NSF through the CTIO REU program.

  4. Are GRBs the same at high and low redshift?

    CERN Document Server

    Littlejohns, O M; Willingale, R; O'Brien, P T; Evans, P A; Levan, A J

    2013-01-01

    Due to their highly luminous nature, gamma-ray bursts (GRBs) are useful tools in studying the early Universe (up to z = 10). We consider whether the available subset of Swift high redshift GRBs are unusual when compared to analogous simulations of a bright low redshift sample. By simulating data from the Burst Alert Telescope (BAT; Barthelmy et al. 2005) the light curves of these bright bursts are obtained over an extensive range of redshifts, revealing complicated evolution in properties of the prompt emission such as T90.

  5. Hubble Space Telescope Ultraviolet Spectroscopy of Fourteen Low-Redshift Quasars

    DEFF Research Database (Denmark)

    Ganguly, Rajib; Brotherton, Michael S.; Arav, Nahum

    2007-01-01

    We present low-resolution ultraviolet spectra of 14 low redshift (z zz 1.4 Large Bright Quasar samples. By design, our objects sample luminosities in between these two surveys, and our four absorbed objects are consistent with the v ~ L^0.62 relation derived by Laor & Brandt (2002). Another quasar......, HE0441-2826, contains extremely weak emission lines and our spectrum is consistent with a simple power-law continuum. The quasar is radio-loud, but has a steep spectral index and a lobe-dominated morphology, which argues against it being a blazar. The unusual spectrum of this quasar resembles...... the spectra of the quasars PG1407+265, SDSSJ1136+0242, and PKS1004+13 for which several possible explanations have been entertained....

  6. Hubble Space Telescope Ultraviolet Spectroscopy of Fourteen Low-Redshift Quasars

    CERN Document Server

    Ganguly, R; Arav, N; Heap, S R; Wisotzki, L; Aldcroft, T L; Alloin, D; Behar, E; Canalizo, G; Crenshaw, D M; De Kool, M; Chambers, K; Cecil, G; Chatzichristou, E T; Everett, J; Gabel, J; Gaskell, C M; Galliano, E; Green, R F; Hall, P B; Hines, D C; Junkkarinen, V T; Kaastra, J S; Kaiser, M E; Kazanas, D; Konigl, A; Korista, K T; Kriss, G A; Laor, A; Leighly, K M; Mathur, S; Ogle, P; Proga, D; Sabra, B; Sivron, R; Snedden, S A; Telfer, R; Vestergaard, M; Ganguly, Rajib; Brotherton, Michael S.; Arav, Nahum; Heap, Sara R.; Wisotzki, Lutz; Aldcroft, Thomas L.; Alloin, Danielle; Behar, Ehud; Canalizo, Gabriela; Kool, Martijn de; Chambers, Kenneth; Cecil, Gerald; Chatzichristou, Eleni; Everett, John; Gabel, Jack; Galliano, Emmanuel; Green, Richard F.; Hall, Patrick B.; Hines, Dean C.; Junkkarinen, Vesa T.; Kaastra, Jelle S.; Kaiser, Mary Elizabeth; Kazanas, Demosthenes; Konigl, Arieh; Korista, Kirk T.; Kriss, Gerard A.; Laor, Ari; Leighly, Karen M.; Mathur, Smita; Ogle, Patrick; Proga, Daniel; Sabra, Bassem; Sivron, Ran; Snedden, Stephanie; Telfer, Randal; Vestergaard, Marianne

    2006-01-01

    We present low-resolution ultraviolet spectra of 14 low redshift (z1.4 Large Bright Quasar samples. By design, our objects sample luminosities in between these two surveys, and our four absorbed objects are consistent with the v ~ L^0.62 relation derived by Laor & Brandt (2002). Another quasar, HE0441-2826, contains extremely weak emission lines and our spectrum is consistent with a simple power-law continuum. The quasar is radio-loud, but has a steep spectral index and a lobe-dominated morphology, which argues against it being a blazar. The unusual spectrum of this quasar resembles the spectra of the quasars PG1407+265, SDSSJ1136+0242, and PKS1004+13 for which several possible explanations have been entertained.

  7. Photometric Properties of Low-Redshift Galaxy Clusters (LOCOS)

    CERN Document Server

    López-Cruz, O

    2000-01-01

    A comprehensive multicolor survey was undertaken to investigate global optical properties of Abell clusters of galaxies. This survey was christened the "Low-Redshift Cluster Optical Survey" (LOCOS). LOCOS was devised to search for patterns of galaxy evolution induced by the environment. The generated data base contains accurate deep CCD photometric measurements (Kron-Cousins R,,B and I) for a sample of 46 low-redshift (0.04 <= z <= 0.18) Abell clusters. This is one of the few large surveys that included the contribution due to dwarf galaxies (about 5.5 mag deeper than the R characteristic magnitude (M*); Ho=50 km/s/Mpc, qo=0). Due to space restrictions only the main results concerning the variations at the bright-end of the luminosity function (LF) are presented here. Other results are presented elsewhere (Lopez-Cruz & Yee 2000a,b). We have detected clear variations at both the bright end and the faint end of the LF. The nature of the variations at the bright end revealed that poor cD clusters have ...

  8. Evidence for Matter Bounce Cosmology in Low Redshift Observations

    CERN Document Server

    Cai, Yi-Fu; Easson, Damien A; Wang, Dong-Gang

    2015-01-01

    The Matter Bounce scenario allows for a sizable parameter space where cosmological fluctuations originally exit the Hubble radius when the background energy density was small. In this scenario and its extended versions, the low energy degrees of freedom are likely responsible for the statistical properties of the cosmic microwave background (CMB) power spectrum at large length scales. An interesting consequence is that these modes might be observable only at relatively late times. Therefore low redshift observations could provide evidence for, or even falsify, various bouncing models. We provide an example where a recently hinted potential deviation from $\\Lambda$-Cold-Dark-Matter ($\\Lambda$CDM) cosmology results from a dark matter (DM) and dark energy (DE) interaction. The same interaction allows Matter Bounce models to generate a red tilt for the primordial curvature perturbations in corroboration with CMB experiments.

  9. The Carnegie Supernova Project: The Low-Redshift Survey

    CERN Document Server

    Hamuy, M; Morrell, N I; Phillips, M M; Suntzeff, N B; Persson, S E; Roth, M; González, S; Krzeminski, W; Contreras, C S; Freedman, W L; Murphy, D C; Madore, B F; Wyatt, P; Maza, J; Filippenko, A V; Li, W; Pinto, P A; Hamuy, Mario; Folatelli, Gast\\'on; Morrell, Nidia I.; Phillips, Mark M.; Suntzeff, Nicholas B.; Roth, Miguel; Gonzalez, Sergio; Krzeminski, Wojtek; Contreras, Carlos; Freedman, Wendy L.; Madore, Barry F.; Maza, Jos\\'{e}; Filippenko, Alexei V.; Li, Weidong

    2005-01-01

    Supernovae are essential to understanding the chemical evolution of the Universe. Type Ia supernovae also provide the most powerful observational tool currently available for studying the expansion history of the Universe and the nature of dark energy. Our basic knowledge of supernovae comes from the study of their photometric and spectroscopic properties. However, the presently available data sets of optical and near-infrared light curves of supernovae are rather small and/or heterogeneous, and employ photometric systems that are poorly characterized. Similarly, there are relatively few supernovae whose spectral evolution has been well sampled, both in wavelength and phase, with precise spectrophotometric observations. The low-redshift portion of the Carnegie Supernova Project (CSP) seeks to remedy this situation by providing photometry and spectrophotometry of a large sample of supernovae taken on telescope/filter/detector systems that are well understood and well characterized. During a five-year program w...

  10. Galaxy groups in the low-redshift Universe

    Science.gov (United States)

    Lim, S. H.; Mo, H. J.; Lu, Yi; Wang, Huiyuan; Yang, Xiaohu

    2017-09-01

    We apply a halo-based group finder to four large redshift surveys, the 2MRS (Two Micron All-Sky Redshift Survey), 6dFGS (Six-degree Field Galaxy Survey), SDSS (Sloan Digital Sky Survey) and 2dFGRS (Two-degree Field Galaxy Redshift Survey), to construct group catalogues in the low-redshift Universe. The group finder is based on that of Yang et al. but with an improved halo mass assignment so that it can be applied uniformly to various redshift surveys of galaxies. Halo masses are assigned to groups according to proxies based on the stellar mass/luminosity of member galaxies. The performances of the group finder in grouping galaxies according to common haloes and in halo mass assignments are tested using realistic mock samples constructed from hydrodynamical simulations and empirical models of galaxy occupation in dark matter haloes. Our group finder finds ∼94 per cent of the correct true member galaxies for 90-95 per cent of the groups in the mock samples; the halo masses assigned by the group finder are un-biased with respect to the true halo masses, and have a typical uncertainty of ∼0.2 dex. The properties of group catalogues constructed from the observational samples are described and compared with other similar catalogues in the literature.

  11. The Luminosity Function of Low-Redshift Abell Galaxy Clusters

    CERN Document Server

    Barkhouse, Wayne A; López-Cruz, Omar

    2007-01-01

    We present the results from a survey of 57 low-redshift Abell galaxy clusters to study the radial dependence of the luminosity function (LF). The dynamical radius of each cluster, r200, was estimated from the photometric measurement of cluster richness, Bgc. The shape of the LFs are found to correlate with radius such that the faint-end slope, alpha, is generally steeper on the cluster outskirts. The sum of two Schechter functions provides a more adequate fit to the composite LFs than a single Schechter function. LFs based on the selection of red and blue galaxies are bimodal in appearance. The red LFs are generally flat for -22 -18. The blue LFs contain a larger contribution from faint galaxies than the red LFs. The blue LFs have a rising faint-end component (alpha ~ -1.7) for M_Rc > -21, with a weaker dependence on radius than the red LFs. The dispersion of M* was determined to be 0.31 mag, which is comparable to the median measurement uncertainty of 0.38 mag. This suggests that the bright-end of the LF is...

  12. The Galaxy Population of Low-Redshift Abell Clusters

    CERN Document Server

    Barkhouse, Wayne A; Lopez-Cruz, Omar

    2009-01-01

    We present a study of the luminosity and color properties of galaxies selected from a sample of 57 low-redshift Abell clusters. We utilize the non-parametric dwarf-to-giant ratio (DGR) and the blue galaxy fraction (fb) to investigate the clustercentric radial-dependent changes in the cluster galaxy population. Composite cluster samples are combined by scaling the counting radius by r200 to minimize radius selection bias. The separation of galaxies into a red and blue population was achieved by selecting galaxies relative to the cluster color-magnitude relation. The DGR of the red and blue galaxies is found to be independent of cluster richness (Bgc), although the DGR is larger for the blue population at all measured radii. A decrease in the DGR for the red and red+blue galaxies is detected in the cluster core region, while the blue galaxy DGR is nearly independent of radius. The fb is found not to correlate with Bgc; however, a steady decline toward the inner-cluster region is observed for the giant galaxies....

  13. Low redshift quasars in the SDSS Stripe 82. The local environments

    CERN Document Server

    Karhunen, K; Falomo, R; Bettoni, D

    2014-01-01

    We study the environments of low redshift (z < 0.5) quasars based on a large and homogeneous dataset from the Stripe 82 region of the Sloan Digital Sky Survey (SDSS). We have compared the < 1 Mpc scale envi- ronments of 302 quasars that were resolved in our recent study to those of 288 inactive galaxies with closely matched redshifts. Crucially, the lu- minosities of the inactive galaxies and the quasar host galaxies are also closely matched, unlike in most previous studies. The environmental overdensities were studied by measuring the num- ber density of galaxies within a projected distance of 200 kpc to 1 Mpc. The galaxy number density of the quasar environments is comparable to that of the inactive galaxies with similar luminosities, both classes of ob- jects showing significant excess compared to the background galaxy density for distances < 400 kpc. There is no significant dependence of the galaxy number density on redshift, quasar or host galaxy luminosity, black hole mass or radio loudness. Th...

  14. Intervening O vi Quasar Absorption Systems at Low Redshift: A Significant Baryon Reservoir.

    Science.gov (United States)

    Tripp; Savage; Jenkins

    2000-05-01

    Far-UV echelle spectroscopy of the radio-quiet QSO H1821+643 (zem=0.297), obtained with the Space Telescope Imaging Spectrograph (STIS) at approximately 7 km s-1 resolution, reveals four definite O vi absorption-line systems and one probable O vi absorber at 0.15quasar in redshift; these are likely intervening systems unrelated to the background QSO. In the case of the strong O vi system at zabs=0.22497, multiple components are detected in Si iii and O vi as well as H i Lyman series lines, and the differing component velocity centroids and b-values firmly establish that this is a multiphase absorption system. A weak O vi absorber is detected at zabs=0.22637, i.e., offset by approximately 340 km s-1 from the zabs=0.22497 system. Lyalpha absorption is detected at zabs=0.22613, but no Lyalpha absorption is significantly detected at 0.22637. Other weak O vi absorbers at zabs=0.24531 and 0.26659 and the probable O vi system at 0.21326 have widely diverse O vi/H i column density ratios with N(O vi)/N(H i) ranging from low-redshift intergalactic medium. We conservatively estimate that the cosmological mass density of the O vi systems is Omegab(Ovi&parr0; greater, similar0.0008 h-175. With an assumed metallicity of 1/10 solar and a conservative assumption that the fraction of oxygen in the O vi ionization stage is 0.2, we obtain Omegab(Ovi&parr0; greater, similar0.004 h-175. This is comparable to the combined cosmological mass density of stars and cool gas in galaxies and X-ray-emitting gas in galaxy clusters at low redshift.

  15. Wide Field Multiband Imaging of Low Redshift Quasar Environments

    CERN Document Server

    Scott, Jennifer E; Bechtold, Jill; Ellingson, Erica; Thibodeau, Christopher; Richmond, Michael

    2015-01-01

    We present photometry of the large scale environments of a sample of twelve broad line AGN with $0.06 < z < 0.37$ from deep images in the SDSS $u$, $g$, $r$, and $i$ filters taken with the 90Prime prime focus camera on the Steward Observatory Bok Telescope. We measure galaxy clustering around these AGN using two standard techniques: correlation amplitude (B$_{gq}$) and the two point correlation function. We find average correlation amplitudes for the 10 radio quiet objects in the sample equal to (9$\\pm$18, 144$\\pm$114, -39$\\pm$56, 295$\\pm$260) Mpc$^{1.77}$ in ($u$, $g$, $r$, $i$), all consistent with the expectation from galaxy clustering. Using a ratio of the galaxy-quasar cross-correlation function to the galaxy autocorrelation function, we calculate the relative bias of galaxies and AGN, $b_{gq}$. The bias in the $u$ band, $b_{gq}=3.08\\pm0.51$ is larger compared to that calculated in the other bands, but it does not correlate with AGN luminosity, black hole mass, or AGN activity via the luminosity of...

  16. Outflow and metallicity in the broad-line region of low-redshift active galactic nuclei

    CERN Document Server

    Shin, Jaejin; Woo, Jong-Hak

    2016-01-01

    Outflows in active galactic nuclei (AGNs) are crucial to understand in investigating the co-evolution of supermassive black holes (SMBHs) and their host galaxies since outflows may play an important role as an AGN feedback mechanism. Based on the archival UV spectra obtained with HST and IUE, we investigate outflows in the broad-line region (BLR) in low-redshift AGNs (z < 0.4) through the detailed analysis of the velocity profile of the CIV emission line. We find a dependence of the outflow strength on the Eddington ratio and the BLR metallicity in our low-redshift AGN sample, which is consistent with the earlier results obtained for high-redshift quasars. These results suggest that the BLR outflows, gas accretion onto SMBH, and past star-formation activity in the host galaxies are physically related in low-redshift AGNs as in powerful high-redshift quasars.

  17. Exploring the spectral diversity of low-redshift Type Ia supernovae using the Palomar Transient Factory

    CERN Document Server

    Maguire, Kate; Pan, Yen-Chen; Gal-Yam, Avishay; Hook, Isobel M; Howell, D Andrew; Nugent, Peter E; Mazzali, Paolo; Chotard, Nicolas; Clubb, Kelsey I; Filippenko, Alexei V; Kasliwal, Mansi M; Kandrashoff, Michael T; Poznanski, Dovi; Saunders, Clare M; Silverman, Jeffrey M; Walker, Emma; Xu, Dong

    2014-01-01

    We present an investigation of the optical spectra of 264 low-redshift (z 40 per cent of SNe Ia observed at these phases show signs of unburnt material in their spectra, and that C II features are more likely to be found in SNe Ia having narrower light curves.

  18. Hubble Space Telescope Ultraviolet Spectroscopy of Fourteen Low-Redshift Quasars

    DEFF Research Database (Denmark)

    Ganguly, Rajib; Brotherton, Michael S.; Arav, Nahum;

    2007-01-01

    We present low-resolution ultraviolet spectra of 14 low redshift (z zz 1.4 Large Bright Quasar samples. By design, our objects sample luminosities in between these two surveys, and our four absorbed objects are consistent with the v ~ L^0.62 relation derived by Laor & Brandt (2002). Another quasar...

  19. Dark energy equation of state parameter and its variation at low redshifts

    CERN Document Server

    Tripathi, Ashutosh; Jassal, H K

    2016-01-01

    In this paper, we constrain dark energy models using a compendium of observations at low redshifts. We consider the dark energy as a barotropic fluid, with the equation of state a constant as well the case where dark energy equation of state is a function of time. The observations considered here are Supernova Type Ia data, Baryonic Acoustic Oscillation data and Hubble parameter measurements. We compare constraints obtained from these data and also do a combined analysis. The combined observational constraints put strong limits on variation of dark energy energy density with redshift. For varying dark energy models, the range of parameters preferred by the supernova type Ia data is in tension with the other low redshift distance measurements.

  20. Diagnosing galactic feedback with the line broadening in the low redshift Lyman-alpha forest

    CERN Document Server

    Viel, M; Bolton, J S; Kim, T -S; Puchwein, E; Nasir, F; Wakker, B P

    2016-01-01

    We compare the low redshift (z ~ 0.1) Lyman-alpha forest from hydrodynamical simulations with data from the Cosmic Origin Spectrograph (COS). We find tension between the observed number of lines with b-parameters in the range 25-45 km/s and the predictions from simulations that incorporate either vigorous feedback from active galactic nuclei or that exclude feedback altogether. The gas in these simulations is, respectively, either too hot to contribute to the Lyman-alpha absorption or too cold to produce the required line widths. Matching the observed b-parameter distribution therefore requires feedback processes that thermally or turbulently broaden the absorption features without collisionally (over-)ionising hydrogen. This suggests the Lyman-alpha forest b-parameter distribution is a valulable diagnostic of galactic feedback in the low redshift Universe. We furthermore confirm the low redshift Lyman-alpha forest column density distribution is better reproduced by an ultraviolet background with an HI photo-...

  1. Imaging of Three Possible Low Redshift Analogs to High Redshift Compact Red Galaxies

    CERN Document Server

    Shih, Hsin-Yi

    2011-01-01

    As part of a larger program to identify and characterize possible low-redshift analogs to massive compact red galaxies found at high redshift, we have examined the morphologies of three low-redshift compact galaxies drawn from the sample of Trujillo et al. (2009). Using deeper and higher resolution images, we have found faint and relatively extensive outer structures in addition to the compact cores identified in the earlier measurements. One object appears to have a small companion that may be involved in an ongoing minor merger of the sort that could be responsible for building up the outer parts of these galaxies. The ages of the dominant stellar populations in these objects are found to be around 2--4 Gyr, in good agreement with the previous estimates. The presence of diffuse outer structures in these galaxies indicates that truly compact and massive red galaxies are exceedingly rare at low redshift. The relatively young stellar populations suggest that the accretion of the extensive outer material must o...

  2. The HerMES sub-millimetre local and low-redshift luminosity functions

    CERN Document Server

    Marchetti, L; Franceschini, A; Arumugam, V; Aussel, H; Bethermin, M; Bock, J; Boselli, A; Buat, V; Burgarella, D; Clements, D L; Conley, A; Conversi, L; Cooray, A; Dowell, C D; Farrah, D; Feltre, A; Glenn, J; Griffin, M; Hatziminaoglou, E; Heinis, S; Ibar, E; Ivison, R J; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Page, M J; Papageorgiou, A; Pearson, C P; Perez-Fournon, I; Pohlen, M; Rigopoulou, D; Roseboom, I G; Rowan-Robinson, M; Schulz, B; Scott, Douglas; Seymour, N; Shupe, D L; Smith, A J; Symeonidis, M; Valtchanov, I; Viero, M; Wang, L; Wardlow, J; Xu, C K; Zemcov, M

    2015-01-01

    We used wide area surveys over 39 deg$^2$ by the HerMES collaboration, performed with the Herschel Observatory SPIRE multi-wavelength camera, to estimate the low-redshift, $0.02low redshifts, $0.02

  3. The Low Redshift Lyman $\\alpha$ Forest in Cold Dark Matter Cosmologies

    CERN Document Server

    Davé, R; Katz, N; Weinberg, D H; Davé, Romeel; Hernquist, Lars; Katz, Neal; Weinberg, David

    1999-01-01

    We study the physical origin of the low-redshift Lyman alpha forest in hydrodynamic simulations of four CDM cosmologies. Our main conclusions are insensitive to the cosmological model but depend on our assumption that the UV background declines at low redshift. We find that the expansion of the universe drives rapid evolution of dN/dz (the number of absorbers per unit z) at z > 1.7, but that at lower redshift the fading of the UV background counters the influence of expansion, leading to slow evolution. At every redshift, weaker lines come primarily from moderate fluctuations of the diffuse, unshocked IGM, and stronger lines originate in shocked or radiatively cooled gas of higher overdensity. However, the neutral hydrogen column density associated with structures of fixed overdensity drops as the universe expands, so an absorber at z = 0 is dynamically analogous to an absorber with neutral hydrogen column density 10 to 50 times higher at z = 2-3. We find no clear distinction between lines arising in "galaxy ...

  4. The Green Peas: Searching for LyC Emitters at Low Redshift

    Science.gov (United States)

    Jaskot, Anne; Oey, Sally

    The escape fraction of Lyman continuum (LyC) radiation from galaxies remains one of the primary uncertainties in studies of reionization. However, few LyC-emitting galaxies are known. The recently identified, low-redshift ``Green Pea'' (GP) galaxies exhibit a number of similarities with high-redshift galaxies, and their optical emission lines suggest they may be some of the elusive LyC emitters. Recent HST COS and ACS observations of four GPs suggest further evidence for LyC escape and give new insights into the origins of Lyα and low-ionization UV lines in high-redshift galaxies. The Lyα emission and low-ionization emission and absorption lines provide a coherent physical picture of the neutral gas distribution in the GPs and may identify LyC emitters at high redshift. The rare, low-redshift GPs hint at possible factors that may enable LyC and Lyα escape from high-redshift galaxies.

  5. Intermittent Self-Sustaining Star Formation in Low-Redshift Galaxies Exhibiting a Peak Metallicity Plateau

    CERN Document Server

    Harwit, Martin

    2015-01-01

    The decline of star formation in massive low-redshift galaxies, often referred to as quenching, has been attributed to a variety of factors. Some proposals suggest that erupting active galactic nuclei may strip galaxies of their interstellar medium, and thus the ability to form stars. Here, we note that, whereas star formation is universal in small, low-redshift galaxies, fractional duty cycles of star formation steadily decline in galaxies of increasing mass, although star formation may not cease entirely. We show that, when infall of gas from extragalactic space ceases, galaxies of high stellar mass appear to sustain star formation on gas liberated in mass loss from evolved low- and intermediate-mass stars admixed with occasional Type II supernova ejecta. This model quantitatively accounts for the universal limiting metallicity plateau at a ratio of oxygen to hydrogen atoms, Z(O) = n(O)/n(H) = 0.0013, characterizing high-mass intermittently star-forming galaxies. We show that, when fractional duty cycles ar...

  6. The Connections between QSO Absorption Systems and Galaxies: Low-Redshift Observations

    CERN Document Server

    Tripp, T M; Tripp, Todd M.; Bowen, David V.

    2005-01-01

    Quasar absorption lines have long been recognized to be a sensitive probe of the abundances, physical conditions, and kinematics of gas in a wide variety of environments including low-density intergalactic regions that probably cannot be studied by any other means. While some pre-Hubble Space Telescope (HST) observations indicated that Mg II absorption lines arise in gaseous galactic halos with a large covering factor, many early QSO absorber studies were hampered by a lack of information about the context of the absorbers and their connections with galaxies. By providing access to crucial ultraviolet resonance lines at low redshifts, deployment of HST and the Far Ultraviolet Spectroscopic Explorer enabled detailed studies of the relationships between QSO absorbers and galaxies. The advent of large surveys such as the Sloan Digital Sky Survey (SDSS) has also advanced the topic by greatly improving the size of absorber and galaxy samples. This paper briefly reviews some observational results on absorber-galaxy...

  7. Low-Redshift Lyman Limit Systems as Diagnostics of Cosmological Inflows and Outflows

    CERN Document Server

    Hafen, Z; Angles-Alcazar, D; Keres, D; Feldmann, R; Chan, T K; Quataert, E; Murray, N; Hopkins, P F

    2016-01-01

    We use cosmological hydrodynamic simulations with stellar feedback from the FIRE project to study the physical nature of Lyman limit systems (LLSs) at z~2) tend to have higher metallicities ([X/H] ~ -0.5) while very low metallicity ([X/H] < -2) LLSs are typically associated with gas infalling from the intergalactic medium. However, most LLSs occupy an intermediate region in metallicity-radial velocity space, for which there is no clear trend between metallicity and radial kinematics. Metal-enriched inflows arise in the FIRE simulations as a result of galactic winds that fall back onto galaxies at low redshift. The overall simulated LLS metallicity distribution has a mean (standard deviation) [X/H] = -0.9 (0.4) and does not show significant evidence for bimodality, in contrast to recent observational studies but consistent with LLSs arising from halos with a broad range of masses and metallicities.

  8. Revealing the nature of star forming blue early-type galaxies at low redshift

    CERN Document Server

    George, Koshy

    2015-01-01

    Context: Star forming early-type galaxies with blue optical colours at low redshift can be used to test our current understanding of galaxy formation and evolution. Aims: We want to reveal the fuel and triggering mechanism for star formation in these otherwise passively evolving red and dead stellar systems. Methods: We undertook an optical and ultraviolet study of 55 star forming blue early-type galaxies, searching for signatures of recent interactions that could be driving the molecular gas into the galaxy and potentially triggering the star formation. Results: We report here our results on star forming blue early-type galaxies with tidal trails and in close proximity to neighbouring galaxies that are evidence of ongoing or recent interactions between galaxies. There are 12 galaxies with close companions with similar redshifts, among which two galaxies are having ongoing interactions that potentially trigger the star formation. Two galaxies show a jet feature that could be due to the complete tidal disrupti...

  9. The Highest Redshift Radio Galaxies

    CERN Document Server

    Van Breugel, W

    2000-01-01

    At low redshifts powerful radio sources are uniquely associated with massive galaxies, and are thought to be powered by supermassive black holes. Modern 8m -- 10m telescopes may be used used to find their likely progenitors at very high redshifts to study their formation and evolution.

  10. HUBBLE SPACE TELESCOPE Snapshot Survey of 3CR Quasars: The Data

    Science.gov (United States)

    Lehnert, Matthew D.; Miley, George K.; Sparks, William B.; Baum, Stefi A.; Biretta, John; Golombek, Daniel; de Koff, Sigrid; Macchetto, Ferdinando D.; McCarthy, Patrick J.

    1999-08-01

    We present images taken with the Wide Field Planetary Camera (WFPC-2) on the Hubble Space Telescope (HST) of 43 quasars selected from the 3CR radio catalog. The redshift range of the targets is large--0.3Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  11. Using Line Profiles to Test the Fraternity of Type Ia Supernovae at High and Low Redshifts

    Science.gov (United States)

    Blondin, Stéphane; Dessart, Luc; Leibundgut, Bruno; Branch, David; Höflich, Peter; Tonry, John L.; Matheson, Thomas; Foley, Ryan J.; Chornock, Ryan; Filippenko, Alexei V.; Sollerman, Jesper; Spyromilio, Jason; Kirshner, Robert P.; Wood-Vasey, W. Michael; Clocchiatti, Alejandro; Aguilera, Claudio; Barris, Brian; Becker, Andrew C.; Challis, Peter; Covarrubias, Ricardo; Davis, Tamara M.; Garnavich, Peter; Hicken, Malcolm; Jha, Saurabh; Krisciunas, Kevin; Li, Weidong; Miceli, Anthony; Miknaitis, Gajus; Pignata, Giuliano; Prieto, Jose Luis; Rest, Armin; Riess, Adam G.; Salvo, Maria Elena; Schmidt, Brian P.; Smith, R. Chris; Stubbs, Christopher W.; Suntzeff, Nicholas B.

    2006-03-01

    Using archival data of low-redshift (zdatabases) Type Ia supernovae (SNe Ia) and recent observations of high-redshift (0.161.7] SNe Ia, which are also subluminous. In addition, we give the first direct evidence in two high-z SN Ia spectra of a double-absorption feature in Ca II λ3945, an event also observed, although infrequently, in low-redshift SN Ia spectra (6 out of 22 SNe Ia in our local sample). Moreover, echoing the recent studies of Dessart & Hillier in the context of Type II supernovae (SNe II), we see similar P Cygni line profiles in our large sample of SN Ia spectra. First, the magnitude of the velocity location at maximum profile absorption may underestimate that at the continuum photosphere, as observed, for example, in the optically thinner line S II λ5640. Second, we report for the first time the unambiguous and systematic intrinsic blueshift of peak emission of optical P Cygni line profiles in SN Ia spectra, by as much as 8000 km s-1. All the high-z SNe Ia analyzed in this paper were discovered and followed up by the ESSENCE collaboration and are now publicly available. Based in part on observations obtained at the Cerro Tololo Inter-American Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under cooperative agreement with the National Science Foundation (NSF); the European Southern Observatory, Chile (ESO program 170.A-0519) the Gemini Observatory, which is operated by AURA under a cooperative agreement with the NSF on behalf of the Gemini partnership (the NSF [United States], the Particle Physics and Astronomy Research Council [United Kingdom], the National Research Council [Canada], CONICYT [Chile], the Australian Research Council [Australia], CNPq [Brazil], and CONICET [Argentina]) (programs GN-2002B-Q-14, GN-2003B-Q-11, and GS-2003B-Q-11) the Magellan Telescopes at Las Campanas Observatory; the MMT Observatory, a joint facility of the Smithsonian Institution and the University of

  12. The Effect of AGN Heating on the Low-redshift Lyα Forest

    Science.gov (United States)

    Gurvich, Alex; Burkhart, Blakesley; Bird, Simeon

    2017-02-01

    We investigate the effects of AGN heating and the ultraviolet background on the low-redshift Lyα forest column density distribution (CDD) using the Illustris simulation. We show that Illustris reproduces observations at z = 0.1 in the column density range {10}12.5{--}{10}13.5 cm‑2, relevant for the “photon underproduction crisis.” We attribute this to the inclusion of AGN feedback, which changes the gas distribution so as to mimic the effect of extra photons, as well as the use of the Faucher-Giguère ultraviolet background, which is more ionizing at z = 0.1 than the Haardt & Madau background previously considered. We show that the difference between simulations run with smoothed particle hydrodynamics and simulations using a moving mesh is small in this column density range but can be more significant at larger column densities. We further consider the effect of supernova feedback, Voigt profile fitting, and finite resolution, all of which we show to have little influence on the CDD. Finally, we identify a discrepancy between our simulations and observations at column densities {10}14{--}{10}16 cm‑2, where Illustris produces too few absorbers, which suggests the AGN feedback model should be further refined. Since the “photon underproduction crisis” primarily affects lower column density systems, we conclude that AGN feedback and standard ionizing background models can resolve the crisis.

  13. Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies

    CERN Document Server

    Izotov, Y I; Thuan, T X; Worseck, G; Orlitova, I; Verhamme, A

    2016-01-01

    Following our first detection reported in Izotov et al. (2016), we present the detection of Lyman continuum (LyC) radiation of four other compact star-forming galaxies observed with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST). These galaxies, at redshifts of z~0.3, are characterized by high emission-line flux ratios [OIII]5007/[OII]3727 > 5. The escape fractions of the LyC radiation fesc(LyC) in these galaxies are in the range of ~6%-13%, the highest values found so far in low-redshift star-forming galaxies. Narrow double-peaked Lyalpha emission lines are detected in the spectra of all four galaxies, compatible with predictions for Lyman continuum leakers. We find escape fractions of Lyalpha, fesc(Lyalpha) ~60%-90%, among the highest known for Lyalpha emitters (LAEs). Surface brightness profiles produced from the COS acquisition images reveal bright star-forming regions in the center and exponential discs in the outskirts with disc scale lengths alpha in the range ~0.6-1.4 k...

  14. Molecular gas properties of UV-luminous star-forming galaxies at low redshift

    CERN Document Server

    Gonçalves, T S; Overzier, R A; Pérez, L; Martin, D C

    2014-01-01

    Lyman break analogues (LBAs) are a population of star-forming galaxies at low redshift (z ~ 0.2) selected in the ultraviolet (UV). These objects present higher star formation rates and lower dust extinction than other galaxies with similar masses and luminosities in the local universe. In this work we present results from a survey with the Combined Array for Research in Millimetre-wave Astronomy (CARMA) to detect CO(1-0) emission in LBAs, in order to analyse the properties of the molecular gas in these galaxies. Our results show that LBAs follow the same Schmidt-Kennicutt law as local galaxies. On the other hand, they have higher gas fractions (up to 66%) and faster gas depletion time-scales (below 1 Gyr). These characteristics render these objects more akin to high-redshift star-forming galaxies. We conclude that LBAs are a great nearby laboratory for studying the cold interstellar medium in low-metallicity, UV-luminous compact star-forming galaxies.

  15. Herschel-ATLAS: The Angular Correlation Function of Submillimetre Galaxies at High and Low Redshift

    Science.gov (United States)

    Maddox, S. J.; Dunne, L.; Rigby, E.; Eales, S.; Cooray, A.; Scott, D.; Peacock, J. A.; Negrello, M.; Smith, D. J. B.; Benford, D.; Amblard, A.; Auld, R.; Baes, M.; Bonfield, D.; Burgarella, D.; Buttiglione, S.; Cava, A.; Clements, D.; Dariush, A.; deZotti, G.; Dye, S.; Frayer, D.; Fritz, J.; Gonzalez-Nuevo, J.; Herranz, D.

    2010-01-01

    We present measurements of the angular correlation function of galaxies selected from the first field of the H-ATLAS survey. Careful removal of the background from galactic cirrus is essential, and currently dominates the uncertainty in our measurements. For our 250 micrometer-selected sample we detect no significant clustering, consistent with the expectation that the 250 pm-selected sources are mostly normal galaxies at z < or equal to 1. For our 350 micrometer and 500 micrometer-selected samples we detect relatively strong clustering with correlation amplitudes A of 0.2 and 1.2 at 1', but with relatively large uncertainties. For samples which preferentially select high redshift galaxies at z approx. 2-3 we detect significant strong clustering, leading to an estimate of r(0) approx. 7-11/h Mpc. The slope of our clustering measurements is very steep. delta approx. 2. The measurements are consistent with the idea that sub-mm sources consist of a low redshift population of normal galaxies and a high redshift population of highly clustered star-bursting galaxies.

  16. UV Absorption Line Ratios in Circumgalactic Medium at Low Redshift in Realistic Cosmological Hydrodynamic Simulations

    CERN Document Server

    Cen, Renyue

    2016-01-01

    Utilizing high-resolution cosmological hydrodynamic simulations we investigate various ultra-violet absorption lines in the circumgalactic medium of star forming galaxies at low redshift, in hopes of checking and alleviating the claimed observational conundrum of the ratio of NV to OVI absorbers, among others. We find a satisfactory agreement between simulations and extant observational data with respect to the ratios of the following four line pairs examined, NV/OVI, SiIV/OVI, NIII/OVI and NII/OVI. For the pairs involving nitrogen lines, we examine two cases of nitrogen abundance, one with constant N/O ratio and the other with varying N/O ratio, with the latter motivated by theoretical considerations of two different synthetic sources of nitrogen that is empirically verified independently. Along a separate vector, for all line pairs, we examine two cases of radiation field, one with the Haardt-Madau background radiation field and the other with an additional local radiation field sourced by hot gas in the ho...

  17. Absorption signatures of warm-hot gas at low redshift: Broad Lyman-Alpha Absorbers

    CERN Document Server

    Tepper-García, Thorsten; Schaye, Joop; Booth, Craig M; Vecchia, Claudio Dalla; Theuns, Tom

    2012-01-01

    We investigate the physical state of HI absorbing gas at low redshift (z=0.25) using a subset of cosmological, hydrodynamic simulations from the OWLS project, focusing in particular on broad (b_HI > 40 km/s) Lyman-Alpha absorbers (BLAs), which are believed to originate in shock-heated gas in the Warm-Hot Intergalactic Medium (WHIM). Our fiducial model, which includes radiative cooling by heavy elements and feedback by supernovae and active galactic nuclei, predicts that by z=0.25 nearly 60 per cent of the gas mass ends up at densities and temperatures characteristic of the WHIM and we find that half of this fraction is due to outflows. The standard HI observables (distribution of HI column densities N_HI, distribution of Doppler parameters b_HI, b_HI - N_HI correlation) and the BLA line number density predicted by our simulations are in remarkably good agreement with observations. BLAs arise in gas that is hotter, more highly ionised and more enriched than the gas giving rise to typical Lyman-Alpha forest abs...

  18. Star-forming galaxies in low-redshift clusters: Data and integrated galaxy properties

    CERN Document Server

    Thomas, C F; James, P A; Bennett, S M; Aragón-Salamanca, A; Whittle, M

    2008-01-01

    This paper is a continuation of an ongoing study of the evolutionary processes affecting cluster galaxies. Both CCD R band and H alpha narrow-band imaging was used to determine photometric parameters (m_(r), r_(24), H alpha flux and equivalent width) and derive star formation rates for 227 CGCG galaxies in 8 low-redshift clusters. The galaxy sample is a subset of CGCG galaxies in an objective prism survey of cluster galaxies for H alpha emission. It is found that detection of emission-line galaxies in the OPS is 85%, 70%, and 50% complete at the mean surface brightness values of 1.25 x 10^(-19), 5.19 x 10^(-20), and 1.76 x 10^(-20) W m^(-2) arcsec^(-2), respectively, measured within the R band isophote of 24 mag arcsec^(-2) for the galaxy. The CCD data, together with matched data from a recent H alpha galaxy survey of UGC galaxies within 3000 km s^(-1), will be used for a comparative study of R band and H alpha surface photometry between cluster and field spirals.

  19. The Column Density Distribution of the Low-Redshift Lyman-Alpha Forest in Illustris

    CERN Document Server

    Gurvich, Alex; Bird, Simeon

    2016-01-01

    We investigate the low-redshift Lyman-alpha forest column density distribution in the Illustris simulation. We show that Illustris reproduces observations extremely well in the column density range 10^12.5-10^14.5 cm^-2, relevant for the "photon underproduction crisis." We attribute this to the inclusion of AGN feedback, which changes the gas distribution so as to mimic the effect of extra photons, as well as the use of the Faucher-Giguere (2009) ultra-violet background, which is more ionizing at z=0.1 than the Haardt & Madau (2012) background previously considered. We show that the difference between simulations run with smoothed particle hydrodynamics and simulations using a moving mesh is small in this column density range. We further consider the effect of supernova feedback, Voigt profile fitting and finite resolution, all of which we show to be small. Finally, we identify a discrepancy between our simulations and observations at column densities 10^14-10^16 cm^-2, where Illustris produces too few ab...

  20. Absorption signatures of warm-hot gas at low redshift: OVI

    CERN Document Server

    Tepper-Garcia, Thorsten; Schaye, Joop; Booth, C M; Vecchia, Claudio Dalla; Theuns, Tom; Wiersma, Robert P C

    2010-01-01

    [abridged] We investigate the origin and physical properties of OVI absorbers at low redshift (z = 0.25) using a subset of cosmological, hydrodynamical simulations from the OverWhelmingly Large Simulations (OWLS) project. Intervening OVI absorbers are believed to trace shock-heated gas in the Warm-Hot Intergalactic Medium (WHIM) and may thus play a key role in the search for the missing baryons in the present-day Universe. When compared to observations, the predicted distributions of the different OVI line parameters (column density, Doppler parameter, rest equivalent width) from our simulations exhibit a lack of strong OVI absorbers, a discrepancy that has also been found by Oppenheimer & Dave (2009b). This suggests that physical processes on sub-grid scales (e.g. turbulence) may strongly influence the observed properties of OVI systems. We find that the intervening OVI absorption arises in highly metal-enriched (10^{-1} < 10^2 and temperatures T =10^{5.3\\pm0.5} K. While the OVI resides in a similar ...

  1. Resolved gas kinematics in a sample of low-redshift high star-formation rate galaxie

    CERN Document Server

    Varidel, Matthew; Croom, Scott; Owers, Matt; Sadler, Elaine

    2016-01-01

    We have used integral field spectroscopy of a sample of six nearby (z~0.01-0.04) high star-formation rate (SFR~10-40 solar masses per year) galaxies to investigate the relationship between local velocity dispersion and star formation rate on sub-galactic scales. The low redshift mitigates, to some extent, the effect of beam smearing which artificially inflates the measured dispersion as it combines regions with different line-of-sight velocities into a single spatial pixel. We compare the parametric maps of the velocity dispersion with the Halpha flux (a proxy for local star-formation rate), and the velocity gradient (a proxy for the local effect of beam smearing). We find, even for these very nearby galaxies, the Halpha velocity dispersion correlates more strongly with velocity gradient than with Halpha flux - implying that beam smearing is still having a significant effect on the velocity dispersion measurements. We obtain a first-order non parametric correction for the unweighted and flux weighted mean vel...

  2. The High-Ion Content and Kinematics of Low-Redshift Lyman Limit Systems

    CERN Document Server

    Fox, Andrew J; Tumlinson, Jason; Howk, J Christopher; Tripp, Todd M; Prochaska, J Xavier; O'Meara, John M; Werk, Jessica K; Bordoloi, Rongmon; Katz, Neal; Oppenheimer, Benjamin D; Dave, Romeel

    2013-01-01

    We study the high-ionization phase and kinematics of the circumgalactic medium around low-redshift galaxies using a sample of 23 Lyman Limit Systems (LLSs) at 0.08

  3. Current Dark Matter Annihilation Constraints from CMB and Low-Redshift Data

    CERN Document Server

    Madhavacheril, Mathew S; Slatyer, Tracy R

    2013-01-01

    Updated constraints on dark matter cross section and mass are presented combining CMB power spectrum measurements from Planck, WMAP9, ACT, and SPT as well as several low-redshift datasets (BAO, HST, supernovae). For the CMB datasets, we combine WMAP9 temperature and polarization data for l 2500, and Planck CMB four-point lensing measurements. We allow for redshift-dependent energy deposition from dark matter annihilation by using a `universal' energy absorption curve. We also include an updated treatment of the excitation, heating, and ionization energy fractions, and provide updated deposition efficiency factors (f_eff) for 41 different dark matter models. Assuming perfect energy deposition (f_eff = 1) and a thermal cross section, dark matter masses below 26 GeV are excluded at the 2-sigma level. Assuming a more generic efficiency of f_eff = 0.2, thermal dark matter masses below 5 GeV are disfavored at the 2-sigma level. These limits are a factor of ~2 improvement over those from WMAP9 data alone. These cur...

  4. Low redshift quasars in the SDSS Stripe 82. Host galaxy colors and close environment

    CERN Document Server

    Bettoni, D; Kotilainen, J K; Karhunen, K; Uslenghi, M

    2015-01-01

    We present a photometrical and morphological multicolor study of the properties of low redshift (z<0.3) quasar hosts based on a large and homogeneous dataset of quasars derived from the Sloan Digital Sky Survey (DR7). We used quasars that were imaged in the SDSS Stripe82 that is up to 2 mag deeper than standard Sloan images. This sample is part of a larger dataset of ~400 quasars at z<0.5 for which both the host galaxies and their galaxy environments were studied (Falomo et al. 2014,Karhunen et al. 2014). For 52 quasars we undertake a study of the color of the host galaxies and of their close environments in u,g,r,i and z bands. We are able to resolve almost all the quasars in the sample in the filters g,r,i and z and also in $u$ for about 50% of the targets. We found that the mean colors of the QSO host galaxy (g-i=0.82+-0.26; r-i=0.26+-0.16 and u-g=1.32+-0.25) are very similar to the values of a sample of inactive galaxies matched in terms of redshift and galaxy luminosity with the quasar sample. Ther...

  5. The First Observations of Low Redshift Damped Lyman-alpha Systems with the Cosmic Origins Spectrograph

    CERN Document Server

    Meiring, Joseph D; Prochaska, Jason X; Tumlinson, Jason; Werk, Jessica; Jenkins, Edward B; Thom, Chris; O'Meara, John M; Sembach, Kenneth R

    2011-01-01

    We report on the first Cosmic Origins Spectrograph (COS) observations of damped and sub-damped Lyman-alpha (DLA) systems discovered in a new survey of the gaseous halos of low-redshift galaxies. From observations of 37 sightlines, we have discovered three DLAs and four sub-DLAs. We measure the neutral gas density Omega(HI), and redshift density dN/dz, of DLA and sub-DLA systems at z<0.35. We find dN/dz=0.25 and Omega(HI)=1.4x10^-3 for DLAs, and dN/dz=0.08 with Omega(HI)=4.2x10^-5 for sub-DLAs over a redshift path delta z=11.9. To demonstrate the scientific potential of such systems, we present a detailed analysis of the DLA at z=0.1140 in the spectrum of SDSS J1009+0713. Profile fits to the absorption lines determine log N(H I)=20.68pm0.10 with a metallicity determined from the undepleted element Sulfur of [S/H]=-0.62pm0.18. The abundance pattern of this DLA is similar to that of higher z DLAs, showing mild depletion of the refractory elements Fe and Ti with [S/Fe]=+0.24pm0.22 and [S/Ti]=+0.28pm0.15. Nitro...

  6. Actively Star Forming Elliptical Galaxies at Low Redshifts in the Sloan Digital Sky Survey

    CERN Document Server

    Fukugita, M; Turner, E L; Helmboldt, J; Nichol, R C; Fukugita, Masataka; Nakamura, Osamu; Turner, Edwin L.; Helmboldt, Joe

    2004-01-01

    We report discovery of actively star forming elliptical galaxies in a morphologically classified sample of bright galaxies at a low redshift obtained from the Sloan Digital Sky Survey. The emission lines of these galaxies do not show the characteristics of active galactic nuclei, and thus their strong H$\\alpha$ emission is ascribed to star formation with a rate nearly as high as that is seen in typical late spiral galaxies. This is taken as evidence against the traditional view that all elliptical galaxies formed early and now evolve only passively. The frequency of such star forming elliptical galaxies is a few tenths of a percent in the sample, but increases to 3% if we include active S0 galaxies. We may identify these galaxies as probable progenitors of so-called E+A galaxies that show the strong Balmer absorption feature of A stars superimposed on an old star population. The approximate match of the abundance of active elliptical plus S0 galaxies with that of E+A galaxies indicates that the duration of su...

  7. Hubble and FUSE studies of Ly-alpha absorbers at low redshift

    CERN Document Server

    Shull, J M

    2001-01-01

    Ultraviolet spectrographs aboard the Hubble Space Telescope (HST) and the Far Ultraviolet Spectroscopic Explorer (FUSE) have proved their value as sensitive probes of the low-density intergalactic medium (IGM) at low redshifts (z < 0.1). Recent observations in Ly-alpha, Ly-beta, and occasional higher Lyman lines show that warm photoionized gas in the low-z IGM may contain 20-25% of the baryons, with a N(HI)^-1.8 distribution in column density. Measurements of resonance lines of Si III, C III, C IV, and O VI suggest that the metallicity of these absorbers ranges from 1-10% of solar abundance down to values below 0.003 Z(solar). A comparison of Ly-beta/Ly-alpha ratios (FUSE and HST) yields a distribution of Doppler parameters with mean b = 31.4 +/- 7.4 km/s and median 28 km/s, comparable to values at z = 2-3. The curve-of-growth (CoG) b-values are considerably less than widths derived from Ly-alpha profile fitting, with mean b(CoG)/b(width) = 0.52, which suggests that low-z absorbers contain sizable non-ther...

  8. The Carnegie Supernova Project: Second Photometry Data Release of Low-Redshift Type Ia Supernovae

    CERN Document Server

    Stritzinger, Maximilian; S., Luis Boldt; Burns, Chris; Campillay, Abdo; Contreras, Carlos; Gonzalez, Sergio; Folatelli, Gaston; Morrell, Nidia; Krzeminski, Wojtek; Roth, Miguel; Salgado, Francisco; Depoy, Darren L; Hamuy, Mario; Freedman, Wendy L; Madore, Barry; Marshall, Jennifer L; Persson, Sven E; Rheault, Jean-Philippe; Suntzeff, Nicholas; Villanueva, Steven; Li, Weidong; Filippenko, Alexei V

    2011-01-01

    The Carnegie Supernova Project (CSP) was a five-year observational survey conducted at Las Campanas Observatory that obtained, among other things, high-quality light curves of ~100 low-redshift Type Ia supernovae (SNe Ia). Presented here is the second data release of nearby SN Ia photometry consisting of 50 objects, with a subset of 45 having near-infrared follow-up observations. Thirty-three objects have optical pre-maximum coverage with a subset of 15 beginning at least 5 days before maximum light. In the near-infrared, 27 objects have coverage beginning before the epoch of B-band maximum, with a subset of 13 beginning at least 5 days before maximum. In addition, we present results of a photometric calibration program to measure the CSP optical (uBgVri)bandpasses with an accuracy of ~1%. Finally, we report the discovery of a second SN Ia, SN 2006ot, similar in its characteristics to the peculiar SN 2006bt.

  9. Color Magnitude Relation and Morphology of Low-Redshift ULIRGs in SDSS

    CERN Document Server

    Chen, Yuxi; Yun, Min S

    2010-01-01

    We present color-magnitude and morphological analysis of 54 low-redshift ULIRGs, a subset of the IRAS 1Jy sample (Kim & Sanders, 1998), in the SDSS. The ULIRGs are on average 1 magnitude brighter in M0.1r than the SDSS galaxies within the same redshift range. The majority of the ULIRGs (~87%) have the colors typical of the blue cloud, and only 4 sources (~7%) are located in the red sequence. While ULIRGs are popularly thought to be precursors to a QSO phase, we find few (~6%) in the "green valley" where the majority of the X-ray and IR selected AGNs are found, and none of which harbors an AGN. For the 14 previously spectroscopic identified AGNs (~28%), we perform PSF subtractions and find that on average the central point sources contribute less than one third to the total luminosity, and that their high optical luminosities and overall blue colors are apparently the result of star formation activity of the host galaxies. Visual inspection of the SDSS images reveals a wide range of disturbed morphologies....

  10. Spectroscopic Determination of the Low Redshift Type Ia Supernova Rate from the Sloan Digital Sky Survey

    Energy Technology Data Exchange (ETDEWEB)

    Krughoff, K.Simon; Connolly, Andrew J.; Frieman, Joshua; SubbaRao, Mark; Kilper, Gary; Schneider, Donald P.

    2011-04-10

    Supernova rates are directly coupled to high mass stellar birth and evolution. As such, they are one of the few direct measures of the history of cosmic stellar evolution. In this paper we describe an probabilistic technique for identifying supernovae within spectroscopic samples of galaxies. We present a study of 52 type Ia supernovae ranging in age from -14 days to +40 days extracted from a parent sample of \\simeq 50,000 spectra from the SDSS DR5. We find a Supernova Rate (SNR) of 0.472^{+0.048}_{-0.039}(Systematic)^{+0.081}_{-0.071}(Statistical)SNu at a redshift of = 0.1. This value is higher than other values at low redshift at the 1{\\sigma}, but is consistent at the 3{\\sigma} level. The 52 supernova candidates used in this study comprise the third largest sample of supernovae used in a type Ia rate determination to date. In this paper we demonstrate the potential for the described approach for detecting supernovae in future spectroscopic surveys.

  11. Tracing the cosmic metal evolution in the low-redshift intergalactic medium

    Energy Technology Data Exchange (ETDEWEB)

    Michael Shull, J. [Also at Institute of Astronomy, University of Cambridge, Cambridge CB3 OHA, UK. (United Kingdom); Danforth, Charles W.; Tilton, Evan M., E-mail: michael.shull@colorado.edu, E-mail: danforth@colorado.edu, E-mail: evan.tilton@colorado.edu [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States)

    2014-11-20

    Using the Cosmic Origins Spectrograph aboard the Hubble Space Telescope, we measured the abundances of six ions (C III, C IV, Si III, Si IV, N V, and O VI) in the low-redshift (z ≤ 0.4) intergalactic medium (IGM). Both C IV and Si IV have increased in abundance by a factor of ∼10 from z ≈ 5.5 to the present. We derive ion mass densities, ρ{sub ion} ≡ Ω{sub ion}ρ{sub cr}, with Ω{sub ion} expressed relative to the closure density. Our models of mass-abundance ratios, (Si III/Si IV) =0.67{sub −0.19}{sup +0.35}, (C III/C IV) =0.70{sub −0.20}{sup +0.43}, and (Ω{sub C} {sub III}+Ω{sub C} {sub IV})/(Ω{sub Si} {sub III}+Ω{sub Si} {sub IV})=4.9{sub −1.1}{sup +2.2}, are consistent with the photoionization parameter log U = –1.5 ± 0.4, hydrogen photoionization rate Γ{sub H} = (8 ± 2) × 10{sup –14} s{sup –1} at z < 0.4, and specific intensity I {sub 0} = (3 ± 1) × 10{sup –23} erg cm{sup –2} s{sup –1} Hz{sup –1} sr{sup –1} at the Lyman limit. Consistent ionization corrections for C and Si are scaled to an ionizing photon flux Φ{sub 0} = 10{sup 4} cm{sup –2} s{sup –1}, baryon overdensity Δ {sub b} ≈ 200 ± 50, and ''alpha-enhancement'' (Si/C enhanced to three times its solar ratio). We compare these metal abundances to the expected IGM enrichment and abundances in higher photoionized states of carbon (C V) and silicon (Si V, Si VI, and Si VII). Our ionization modeling infers IGM metal densities of (5.4 ± 0.5) × 10{sup 5} M {sub ☉} Mpc{sup –3} in the photoionized Lyα forest traced by the C and Si ions and (9.1 ± 0.6) × 10{sup 5} M {sub ☉} Mpc{sup –3} in hotter gas traced by O VI. Combining both phases, the heavy elements in the IGM have mass density ρ {sub Z} = (1.5 ± 0.8) × 10{sup 6} M {sub ☉} Mpc{sup –3} or Ω {sub Z} ≈ 10{sup –5}. This represents 10% ± 5% of the metals produced by (6 ± 2) × 10{sup 8} M {sub ☉} Mpc{sup –3} of integrated star formation with yield y{sub m} = 0

  12. Standard rulers, candles, and clocks from the low-redshift universe.

    Science.gov (United States)

    Heavens, Alan; Jimenez, Raul; Verde, Licia

    2014-12-12

    We measure the length of the baryon acoustic oscillation (BAO) feature, and the expansion rate of the recent Universe, from low-redshift data only, almost model independently. We make only the following minimal assumptions: homogeneity and isotropy, a metric theory of gravity, a smooth expansion history, and the existence of standard candles (supernovæ) and a standard BAO ruler. The rest is determined by the data, which are compilations of recent BAO and type IA supernova results. Making only these assumptions, we find for the first time that the standard ruler has a length of 103.9±2.3h⁻¹ Mpc. The value is a measurement, in contrast to the model-dependent theoretical prediction determined with model parameters set by Planck data (99.3±2.1h⁻¹ Mpc). The latter assumes the cold dark matter model with a cosmological constant, and that the ruler is the sound horizon at radiation drag. Adding passive galaxies as standard clocks or a local Hubble constant measurement allows the absolute BAO scale to be determined (142.8±3.7 Mpc), and in the former case the additional information makes the BAO length determination more precise (101.9±1.9h⁻¹ Mpc). The inverse curvature radius of the Universe is weakly constrained and consistent with zero, independently of the gravity model, provided it is metric. We find the effective number of relativistic species to be N(eff)=3.53±0.32, independent of late-time dark energy or gravity physics.

  13. Low-redshift Lyman limit systems as diagnostics of cosmological inflows and outflows

    Science.gov (United States)

    Hafen, Zachary; Faucher-Giguère, Claude-André; Anglés-Alcázar, Daniel; Kereš, Dušan; Feldmann, Robert; Chan, T. K.; Quataert, Eliot; Murray, Norman; Hopkins, Philip F.

    2017-08-01

    We use cosmological hydrodynamic simulations with stellar feedback from the FIRE (Feedback In Realistic Environments) project to study the physical nature of Lyman limit systems (LLSs) at z ≤ 1. At these low redshifts, LLSs are closely associated with dense gas structures surrounding galaxies, such as galactic winds, dwarf satellites and cool inflows from the intergalactic medium. Our analysis is based on 14 zoom-in simulations covering the halo mass range Mh ≈ 109-1013 M⊙ at z = 0, which we convolve with the dark matter halo mass function to produce cosmological statistics. We find that the majority of cosmologically selected LLSs are associated with haloes in the mass range 1010 ≲ Mh ≲ 1012 M⊙. The incidence and H I column density distribution of simulated absorbers with columns in the range 10^{16.2} ≤ N_{H I} ≤ 2× 10^{20} cm-2 are consistent with observations. High-velocity outflows (with radial velocity exceeding the halo circular velocity by a factor of ≳ 2) tend to have higher metallicities ([X/H] ∼ -0.5) while very low metallicity ([X/H] < -2) LLSs are typically associated with gas infalling from the intergalactic medium. However, most LLSs occupy an intermediate region in metallicity-radial velocity space, for which there is no clear trend between metallicity and radial kinematics. The overall simulated LLS metallicity distribution has a mean (standard deviation) [X/H] = -0.9 (0.4) and does not show significant evidence for bimodality, in contrast to recent observational studies, but consistent with LLSs arising from haloes with a broad range of masses and metallicities.

  14. Resolved Gas Kinematics in a Sample of Low-Redshift High Star-Formation Rate Galaxies

    Science.gov (United States)

    Varidel, Mathew; Pracy, Michael; Croom, Scott; Owers, Matt S.; Sadler, Elaine

    2016-03-01

    We have used integral field spectroscopy of a sample of six nearby (z 0.01-0.04) high star-formation rate (SFR ˜ 10-40 M_⊙ yr^{-1}) galaxies to investigate the relationship between local velocity dispersion and star-formation rate on sub-galactic scales. The low-redshift mitigates, to some extent, the effect of beam smearing which artificially inflates the measured dispersion as it combines regions with different line-of-sight velocities into a single spatial pixel. We compare the parametric maps of the velocity dispersion with the Hα flux (a proxy for local star-formation rate), and the velocity gradient (a proxy for the local effect of beam smearing). We find, even for these very nearby galaxies, the Hα velocity dispersion correlates more strongly with velocity gradient than with Hα flux-implying that beam smearing is still having a significant effect on the velocity dispersion measurements. We obtain a first-order non parametric correction for the unweighted and flux weighted mean velocity dispersion by fitting a 2D linear regression model to the spaxel-by-spaxel data where the velocity gradient and the Hα flux are the independent variables and the velocity dispersion is the dependent variable; and then extrapolating to zero velocity gradient. The corrected velocity dispersions are a factor of 1.3-4.5 and 1.3-2.7 lower than the uncorrected flux-weighted and unweighted mean line-of-sight velocity dispersion values, respectively. These corrections are larger than has been previously cited using disc models of the velocity and velocity dispersion field to correct for beam smearing. The corrected flux-weighted velocity dispersion values are σ m 20-50 km s-1.

  15. The high-ion content and kinematics of low-redshift Lyman limit systems

    Energy Technology Data Exchange (ETDEWEB)

    Fox, Andrew J.; Tumlinson, Jason; Bordoloi, Rongmon [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Lehner, Nicolas; Howk, J. Christopher [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Tripp, Todd M.; Katz, Neal [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Prochaska, J. Xavier; Werk, Jessica K. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); O' Meara, John M. [Department of Physics, Saint Michael' s College, One Winooski Park, Colchester, VT 05439 (United States); Oppenheimer, Benjamin D. [Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands); Davé, Romeel, E-mail: afox@stsci.edu [University of the Western Cape, Robert Sobukwe Road, Bellville 7535 (South Africa)

    2013-12-01

    We study the high-ion content and kinematics of the circumgalactic medium around low-redshift galaxies using a sample of 23 Lyman limit systems (LLSs) at 0.08 < z < 0.93 observed with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. In Lehner et al., we recently showed that low-z LLSs have a bimodal metallicity distribution. Here we extend that analysis to search for differences between the high-ion and kinematic properties of the metal-poor and metal-rich branches. We find that metal-rich LLSs tend to show higher O VI columns and broader O VI profiles than metal-poor LLSs. The total H I line width (Δv {sub 90} statistic) in LLSs is not correlated with metallicity, indicating that the H I kinematics alone cannot be used to distinguish inflow from outflow and gas recycling. Among the 17 LLSs with O VI detections, all but two show evidence of kinematic sub-structure, in the form of O VI-H I centroid offsets, multiple components, or both. Using various scenarios for how the metallicities in the high-ion and low-ion phases of each LLS compare, we constrain the ionized hydrogen column in the O VI phase to lie in the range log N(H II) ∼ 17.6-20. The O VI phase of LLSs is a substantial baryon reservoir, with M(high-ion) ∼ 10{sup 8.5-10.9} (r/150 kpc){sup 2} M {sub ☉}, similar to the mass in the low-ion phase. Accounting for the O VI phase approximately doubles the contribution of low-z LLSs to the cosmic baryon budget.

  16. Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies

    Science.gov (United States)

    Izotov, Y. I.; Schaerer, D.; Thuan, T. X.; Worseck, G.; Guseva, N. G.; Orlitová, I.; Verhamme, A.

    2016-10-01

    Following our first detection reported in Izotov et al., we present the detection of Lyman continuum (LyC) radiation of four other compact star-forming galaxies observed with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope. These galaxies, at redshifts of z ˜ 0.3, are characterized by high emission-line flux ratios [O III] λ5007/[O II] λ3727 ≳ 5. The escape fractions of the LyC radiation fesc(LyC) in these galaxies are in the range of ˜6-13 per cent, the highest values found so far in low-redshift star-forming galaxies. Narrow double-peaked Ly α emission lines are detected in the spectra of all four galaxies, compatible with predictions for LyC leakers. We find escape fractions of Ly α, fesc(Ly α) ˜ 20-40 per cent, among the highest known for Ly α emitting galaxies. Surface brightness profiles produced from the COS acquisition images reveal bright star-forming regions in the centre and exponential discs in the outskirts with disc scalelengths α in the range ˜0.6-1.4 kpc. Our galaxies are characterized by low metallicity, ˜1/8-1/5 solar, low stellar mass ˜(0.2-4) × 109 M⊙, high star formation rates, SFR ˜ 14-36 M⊙ yr-1, and high SFR densities, Σ ˜ 2-35 M⊙ yr-1 kpc-2. These properties are comparable to those of high-redshift star-forming galaxies. Finally, our observations, combined with our first detection reported in Izotov et al., reveal that a selection for compact star-forming galaxies showing high [O III] λ5007/[O II] λ3727 ratios appears to pick up very efficiently sources with escaping LyC radiation: all five of our selected galaxies are LyC leakers.

  17. Low-redshift effects of local structure on the Hubble parameter in presence of a cosmological constant

    Energy Technology Data Exchange (ETDEWEB)

    Romano, Antonio Enea [University of Crete, Department of Physics and CCTP, Heraklion (Greece); Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan); Universidad de Antioquia, Instituto de Fisica, Medellin (Colombia); Vallejo, Sergio Andres [Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan); Universidad de Antioquia, Instituto de Fisica, Medellin (Colombia)

    2016-04-15

    In order to estimate the effects of a local structure on the Hubble parameter we calculate the low-redshift expansion for H(z) and (δH)/(H) for an observer at the center of a spherically symmetric matter distribution in the presence of a cosmological constant. We then test the accuracy of the formulas comparing them with fully relativistic non-perturbative numerical calculations for different cases for the density profile. The low-redshift expansion we obtain gives results more precise than perturbation theory since it is based on the use of an exact solution of Einstein's field equations. For larger density contrasts the low-redshift formulas accuracy improves respect to the perturbation theory accuracy because the latter is based on the assumption of a small density contrast, while the former does not rely on such an assumption. The formulas can be used to take into account the effects on the Hubble expansion parameter due to the monopole component of the local structure. If the H(z) observations will show deviations from the ΛCDM prediction compatible with the formulas we have derived, this could be considered an independent evidence of the existence of a local inhomogeneity, and the formulas could be used to determine the characteristics of this local structure. (orig.)

  18. The properties of the extended warm ionised gas around low-redshift QSOs and the lack of extended high-velocity outflows

    CERN Document Server

    Husemann, B; Sánchez, S F; Jahnke, K

    2012-01-01

    (Abridged) We present a detailed analysis of a large sample of 31 low-redshift, mostly radio-quiet type 1 QSOs observed with integral field spectroscopy to study their extended emission-line regions (EELRs). We focus on the ionisation state of the gas, size and luminosity of extended narrow line regions (ENLRs), which corresponds to those parts of the EELR dominated by ionisation from the QSO, as well as the kinematics of the ionised gas. We detect EELRs around 19 of our 31 QSOs (61%) after deblending the unresolved QSO emission and the extended host galaxy light in the integral field data. We identify 13 EELRs to be entirely ionised by the QSO radiation, 3 EELRs are composed of HII regions and 3 EELRs display signatures of both ionisation mechanisms at different locations. The typical size of the ENLR is 10kpc at a median nuclear [OIII] luminosity of log(L([OIII])/[erg/s])=42.7+-0.15. We show that the ENLR sizes are least a factor of 2 larger than determined with HST, but are consistent with those of recentl...

  19. Magnetic fields in star-forming galaxies at high and low redshift

    CERN Document Server

    Garn, T; Alexander, P; Green, D A; Riley, J M

    2007-01-01

    As part of an ongoing series of deep GMRT surveys, we have observed the Spitzer extragalactic First Look Survey field at 610 MHz, producing the deepest wide-field 610 MHz survey published to date. We reach an rms noise of 30 microJy before primary beam correction, with a resolution of ~6 arcsec over an area of ~4 square degrees. By combining these observations with the existing 1.4 GHz VLA survey produced by Condon et al. (2003), along with infrared data in up to seven wavebands from the Spitzer Space Telescope, optical photometry from SDSS and a range of spectroscopic redshift surveys, we are able to study the relationship between radio luminosity and star formation rate in star-forming galaxies up to z ~ 1. The large amount of multi-wavelength data available allows accurate k-corrections to be performed in the radio, and in the infrared through the use of a semi-empirical radiative transfer model. We find a tight correlation between infrared-derived star formation rates and radio luminosities, but contrary ...

  20. Structure formation simulations with momentum exchange: alleviating tensions between high-redshift and low-redshift cosmological probes

    Science.gov (United States)

    Baldi, Marco; Simpson, Fergus

    2017-02-01

    Persisting tensions between the cosmological constraints derived from low-redshift probes and the ones obtained from temperature and polarization anisotropies of the cosmic microwave background (CMB) - although not yet providing compelling evidence against the Λcold dark matter model - seem to consistently indicate a slower growth of density perturbations as compared to the predictions of the standard cosmological scenario. Such behaviour is not easily accommodated by the simplest extensions of General Relativity, such as f(R) models, which generically predict an enhanced growth rate. In this work, we present the outcomes of a suite of large N-body simulations carried out in the context of a cosmological model featuring a non-vanishing scattering cross-section between the dark matter and the dark energy fields, for two different parametrizations of the dark energy equation of state. Our results indicate that these dark scattering models have very mild effects on many observables related to large-scale structures formation and evolution, while providing a significant suppression of the amplitude of linear density perturbations and the abundance of massive clusters. Our simulations therefore confirm that these models offer a promising route to alleviate existing tensions between low-redshift measurements and those of the CMB.

  1. Oxidation Behaviour of Sputtered Ni-3Cr-20Al Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The oxidation behavior of sputtered Ni-3Cr-20Al coating at 900°C in air was investigated. A dense Al2O3 layer was formed on the sputtered Ni-3Cr-20Al coating after 200 h oxidation.However, owing to the segregation of Ni3Al during oxidation Focess at high temperature, the spinel NiAl2O4 was also formed in the Al2O3 layer. It was found that the formation of NiAl2O4had no detrimental effect on the oxidation resistance of the sputtered Ni-3Cr-20Al coating due to the excellent adhesion shown by the Al2O3 and NiAl2O4 complex oxide scale.

  2. The Carnegie Supernova Project: Analysis of the First Sample of Low-Redshift Type-Ia Supernovae

    Science.gov (United States)

    Folatelli, Gaston; Phillips, M. M.; Burns, C. R.; Contreras, C.; Hamuy, M.; Freedman, W. L.; Persson, S. E.; Stritzinger, M.; Suntzeff, N. B.; Krisciunas, K.; Boldt, L.; Gonzalez, S.; Krzeminski, W.; Morrell, N.; Roth, M.; Salgado, F.; Madore, B. F.; Murphy, D.; Wyatt, P.; Li, W.; Filippenko, A. V.

    2009-05-01

    We present the analysis of the first set of 35 low-redshift (zcolors at maximum light. This is used to derive color excesses and thus study the properties of the reddening law in the host galaxies, with the advantage of combining optical and NIR bands. We study the calibration of absolute peak magnitudes in all bands using a two-parameter bilinear fit to decline rates and colors or, alternatively, color excesses. We obtain dispersions of 0.1_ 0.2 mag, depending on the filter--color combinations, and low values of the reddening-law parameter RV 1_ 2. We further investigate the validity of Type-Ia supernovae as true standard candles in the NIR, requiring no correction for decline rate.

  3. Structure formation simulations with momentum exchange: alleviating tensions between high-redshift and low-redshift cosmological probes

    CERN Document Server

    Baldi, Marco

    2016-01-01

    Persisting tensions between the cosmological constraints derived from low-redshift probes and the ones obtained from temperature and polarisation anisotropies of the Cosmic Microwave Background -- although not yet providing compelling evidence against the $\\Lambda $CDM model -- seem to consistently indicate a slower growth of density perturbations as compared to the predictions of the standard cosmological scenario. Such behavior is not easily accommodated by the simplest extensions of General Relativity, such as f(R) models, which generically predict an enhanced growth rate. In the present work we present the outcomes of a suite of large N-body simulations carried out in the context of a cosmological model featuring a non-vanishing scattering cross section between the dark matter and the dark energy fields, for two different parameterisations of the dark energy equation of state. Our results indicate that these Dark Scattering models have very mild effects on many observables related to large-scale structure...

  4. An Efficient Passerini Tetrazole Reaction (PT-3CR)

    NARCIS (Netherlands)

    Chandgude, Ajay L; Dömling, Alexander

    2016-01-01

    A sonication accelerated, catalyst free, simple, high yielding and efficient method for the Passerini-type three component reaction (PT-3CR) has been developed. It comprises reaction of an aldehyde/ketone, a isocyanide and a TMS-azide in methanol:water (1:1) as the solvent system. Use of sonication

  5. The Chandra Survey of Extragalactic Sources in the 3CR Catalog: X-ray Emission from Nuclei, Jets, and Hotspots in the Chandra Archival Observations

    CERN Document Server

    Massaro, F; Liuzzo, E; Orienti, M; Paladino, R; Paggi, A; Tremblay, G R; Wilkes, B J; Kuraszkiewicz, J; Baum, S A; O'Dea, C P

    2016-01-01

    As part of our program to build a complete radio and X-ray database of all the 3CR extragalactic radio sources, we present an analysis of 93 sources for which Chandra archival data are available. Most of these sources have been already published. Here we provide a uniform re-analysis and present nuclear X-ray fluxes and X-ray emission associated with radio jet knots and hotspots using both publicly available radio images and new radio images that have been constructed from data available in the VLA archive. For about 1/3 of the sources in the selected sample a comparison between the Chandra and the radio observations was not reported in the literature: we find X-ray detections of 2 new radio jet knots and 17 hotspots. We also report the X-ray detection of extended emission from the intergalactic medium of 15 galaxy clusters, two of which were most likely unknown previously.

  6. Star formation in z>1 3CR host galaxies as seen by Herschel

    CERN Document Server

    Podigachoski, P; Haas, M; Leipski, C; Wilkes, B; Kuraszkiewicz, J; Westhues, C; Willner, S P; Ashby, M L N; Chini, R; Clements, D L; Fazio, G G; Labiano, A; Lawrence, C; Meisenheimer, K; Peletier, R F; Siebenmorgen, R; Kleijn, G Verdoes

    2015-01-01

    We present Herschel (PACS and SPIRE) far-infrared (FIR) photometry of a complete sample of z>1 3CR sources, from the Herschel GT project The Herschel Legacy of distant radio-loud AGN (PI: Barthel). Combining these with existing Spitzer photometric data, we perform an infrared (IR) spectral energy distribution (SED) analysis of these landmark objects in extragalactic research to study the star formation in the hosts of some of the brightest active galactic nuclei (AGN) known at any epoch. Accounting for the contribution from an AGN-powered warm dust component to the IR SED, about 40% of our objects undergo episodes of prodigious, ULIRG-strength star formation, with rates of hundreds of solar masses per year, coeval with the growth of the central supermassive black hole. Median SEDs imply that the quasar and radio galaxy hosts have similar FIR properties, in agreement with the orientation-based unification for radio-loud AGN. The star-forming properties of the AGN hosts are similar to those of the general popul...

  7. The Ultraviolet Emission Properties of Five Low-Redshift Active Galactic Nuclei at High Signal to Noise and Spectral Resolution

    CERN Document Server

    Laor, A; Jannuzi, B T; Schneider, D P; Green, R F; Hartig, G F; Laor, Ari; Bahcall, John N.; Jannuzi, Buell T.; Schneider, Donald P.; Green, IAS; Richard F.; Hartig, NOAO; George F.; ScI, ST

    1994-01-01

    We analyze the ultraviolet (UV) emission line and continuum properties of five low-redshift active galactic nuclei (four luminous quasars: PKS~0405$-$123, H1821+643, PG~0953+414, and 3C273, and one bright Seyfert 1 galaxy: Mrk~205). The HST spectra have higher signal-to-noise ratios (typically $\\sim 60$ per resolution element) and spectral resolution ($R = 1300$) than all previously- published UV spectra used to study the emission characteristics of active galactic nuclei. We include in the analysis ground-based optical spectra covering \\hb\\ and the narrow [O~III]~$\\lambda\\lambda$4959,5007 doublet. The following new results are obtained: \\lyb/\\lya=0.03$-$0.12 for the four quasars, which is the first accurate measurement of the long-predicted \\lyb\\ intensity in QSOs. The cores of \\lya\\ and C~IV are symmetric to an accuracy of better than 2.5\\% within about 2000~km~s$^{-1}$ of the line peak. This high degree of symmetry of \\lya\\ argues against models in which the broad line cloud velocity field has a significan...

  8. Berkeley Supernova Ia Program I: Observations, Data Reduction, and Spectroscopic Sample of 582 Low-Redshift Type Ia Supernovae

    CERN Document Server

    Silverman, Jeffrey M; Filippenko, Alexei V; Ganeshalingam, Mohan; Barth, Aaron J; Chornock, Ryan; Griffith, Christopher V; Kong, Jason J; Lee, Nicholas; Leonard, Douglas C; Matheson, Thomas; Miller, Emily G; Steele, Thea N; Barris, Brian J; Bloom, Joshua S; Cobb, Bethany E; Coil, Alison L; Desroches, Louis-Benoit; Gates, Elinor L; Ho, Luis C; Jha, Saurabh W; Kandrashoff, Michael T; Li, Weidong; Mandel, Kaisey S; Modjaz, Maryam; Moore, Matthew R; Mostardi, Robin E; Papenkova, Marina S; Park, Sung; Perley, Daniel A; Poznanski, Dovi; Reuter, Cassie A; Scala, James; Serduke, Franklin J D; Shields, Joseph C; Swift, Brandon J; Tonry, John L; Van Dyk, Schuyler D; Wang, Xiaofeng; Wong, Diane S

    2012-01-01

    In this first paper in a series we present 1298 low-redshift (z < 0.2) optical spectra of 582 Type Ia supernovae (SNe Ia) observed from 1989 through 2008 as part of the Berkeley SN Ia Program (BSNIP). 584 spectra of 199 SNe Ia have well-calibrated light curves with measured distance moduli, and many of the spectra have been corrected for host-galaxy contamination. Most of the data were obtained using the Kast double spectrograph mounted on the Shane 3 m telescope at Lick Observatory and have a typical wavelength range of 3300-10,400 Ang., roughly twice as wide as spectra from most previously published datasets. We present our observing and reduction procedures, and we describe the resulting SN Database (SNDB), which will be an online, public, searchable database containing all of our fully reduced spectra and companion photometry. In addition, we discuss our spectral classification scheme (using the SuperNova IDentification code, SNID; Blondin & Tonry 2007), utilizing our newly constructed set of SNID ...

  9. Baryon Cycling in the Low-Redshift Circumgalactic Medium: A Comparison of Simulations to the COS-Halos Survey

    CERN Document Server

    Ford, Amanda Brady; Dave, Romeel; Tumlinson, Jason; Bordoloi, Rongmon; Katz, Neal; Kollmeier, Juna A; Oppenheimer, Benjamin D; Peeples, Molly S; Prochaska, Jason X; Weinberg, David H

    2015-01-01

    We analyze the low-redshift (z~0.2) circumgalactic medium by comparing absorption-line data from the COS-Halos Survey to absorption around a matched galaxy sample from two cosmological hydrodynamic simulations. The models include different prescriptions for galactic outflows, namely hybrid energy/momentum driven wind (ezw), and constant winds (cw). We extract for comparison direct observables including equivalent widths, covering factors, ion ratios, and kinematics. Both wind models are generally in good agreement with these observations for HI and certain low ionization metal lines, but show poorer agreement with higher ionization metal lines including SiIII and OVI that are well-observed by COS-Halos. These discrepancies suggest that both wind models predict too much cool, metal-enriched gas and not enough hot gas, and/or that the metals are not sufficiently well-mixed. This may reflect our model assumption of ejecting outflows as cool and unmixing gas. Our ezw simulation includes a heuristic prescription t...

  10. A Multi-Wavelength Study of Low Redshift Cluster of Galaxies II. Environmental Impact on Galaxy Growth

    CERN Document Server

    Atlee, David W

    2012-01-01

    Galaxy clusters provide powerful laboratories for the study of galaxy evolution, particularly the origin of correlations of morphology and star formation rate (SFR) with density. We construct visible to MIR spectral energy distributions (SEDs) of cluster galaxies and use them to measure stellar masses and SFRs in eight low redshift clusters, which we examine as a function of environment. A partial correlation analysis indicates that SFR depends strongly on R/R200 (>99.9% confidence) and is independent of projected local density at fixed radius. SFR also shows no residual dependence on stellar mass. We therefore conclude that interactions with the intra-cluster medium drive the evolution of SFRs in cluster galaxies. A merged sample of galaxies from the five most complete clusters shows \\propto(R/R200)^(1.3+/-0.7) for galaxies with R/R200<0.4. A decline in the fraction of SFGs toward the cluster center contributes most of this effect, but it is accompanied by a reduction in SFRs among star-forming galaxies (...

  11. The effect of stellar and AGN feedback on the low-redshift Lyman α forest in the Sherwood simulation suite

    Science.gov (United States)

    Nasir, Fahad; Bolton, James S.; Viel, Matteo; Kim, Tae-Sun; Haehnelt, Martin G.; Puchwein, Ewald; Sijacki, Debora

    2017-10-01

    We study the effect of different feedback prescriptions on the properties of the low-redshift (z ≤ 1.6) Lyα forest using a selection of hydrodynamical simulations drawn from the Sherwood simulation suite. The simulations incorporate stellar feedback, active galactic nuclei (AGN) feedback and a simplified scheme for efficiently modelling the low column density Lyα forest. We confirm a discrepancy remains between Cosmic Origins Spectrograph (COS) observations of the Lyα forest column density distribution function (CDDF) at z ≃ 0.1 for high column density systems (N_{H I}>10^{14} cm^{-2}), as well as Lyα velocity widths that are too narrow compared to the COS data. Stellar or AGN feedback - as currently implemented in our simulations - has only a small effect on the CDDF and velocity width distribution. We conclude that resolving the discrepancy between the COS data and simulations requires an increase in the temperature of overdense gas with Δ = 4-40, either through additional He II photoheating at z > 2 or fine-tuned feedback that ejects overdense gas into the intergalactic medium at just the right temperature for it to still contribute significantly to the Lyα forest. Alternatively a larger, currently unresolved turbulent component to the line width could resolve the discrepancy.

  12. Downregulation of CX3CR1 ameliorates experimental colitis: evidence for CX3CL1-CX3CR1-mediated immune cell recruitment.

    Science.gov (United States)

    Becker, Felix; Holthoff, Christina; Anthoni, Christoph; Rijcken, Emile; Alexander, J Steven; Gavins, Felicity N E; Spiegel, H U; Senninger, Norbert; Vowinkel, Thorsten

    2017-03-01

    Inflammatory conditions like inflammatory bowel diseases (IBD) are characterized by increased immune cell infiltration. The chemokine ligand CX3CL1 and its receptor CX3CR1 have been shown to be involved in leukocyte adhesion, transendothelial recruitment, and chemotaxis. Therefore, the objective of this study was to describe CX3CL1-CX3CR1-mediated signaling in the induction of immune cell recruitment during experimental murine colitis. Acute colitis was induced by dextran sodium sulfate (DSS), and sepsis was induced by injection of lipopolysaccharide (LPS). Serum concentrations of CX3CR1 and CX3CL1 were measured by ELISA. Wild-type and CX3CR1(-/-) mice were challenged with DSS, and on day 6, intravital microscopy was performed to monitor colonic leukocyte and platelet recruitment. Intestinal inflammation was assessed by disease activity, histopathology, and neutrophil infiltration. CX3CR1 was upregulated in DSS colitis and LPS-induced sepsis. CX3CR1(-/-) mice were protected from disease severity and intestinal injury in DSS colitis, and CX3CR1 deficiency resulted in reduced rolling of leukocytes and platelets. In the present study, we provide evidence for a crucial role of CX3CL1-CX3CR1 in experimental colitis, in particular for intestinal leukocyte recruitment during murine colitis. Our findings suggest that CX3CR1 blockade represents a potential therapeutic strategy for treatment of IBD.

  13. Dust heating in the cores of 3CRR radio galaxies

    CERN Document Server

    Birkinshaw, M; Bliss, A

    2015-01-01

    We have undertaken a Spitzer campaign to measure the IR structures and spectra of low-redshift 3CRR radio galaxies. The results show that the 3.6 - 160 micron infrared properties vary systematically with integrated source power, and so demonstrate that contemporary core activity is characteristic of the behaviour of sources over their lifetimes. IR synchrotron emission is seen from jets and hotspots in some cases. Thermal emission is found from a jet/gas interaction in NGC 7385. Most of the near-IR integrated colours of the low-redshift 3CRR radio galaxies are similar to those of passive galaxies, so that IR colours are poor indicators of radio activity.

  14. A blinded determination of H0 from low-redshift Type Ia supernovae, calibrated by Cepheid variables

    Science.gov (United States)

    Zhang, Bonnie R.; Childress, Michael J.; Davis, Tamara M.; Karpenka, Natallia V.; Lidman, Chris; Schmidt, Brian P.; Smith, Mathew

    2017-10-01

    Presently, a >3σ tension exists between values of the Hubble constant H0 derived from analysis of fluctuations in the cosmic microwave background by Planck, and local measurements of the expansion using calibrators of Type Ia supernovae (SNe Ia). We perform a blinded re-analysis of Riess et al. (2011) to measure H0 from low-redshift SNe Ia, calibrated by Cepheid variables and geometric distances including to NGC 4258. This paper is a demonstration of techniques to be applied to the Riess et al. (2016) data. Our end-to-end analysis starts from available Harvard -Smithsonian Center for Astrophysics (CfA3) and Lick Observatory Supernova Search (LOSS) photometries, providing an independent validation of Riess et al. (2011). We obscure the value of H0 throughout our analysis and the first stage of the referee process, because calibration of SNe Ia requires a series of often subtle choices, and the potential for results to be affected by human bias is significant. Our analysis departs from that of Riess et al. (2011) by incorporating the covariance matrix method adopted in Supernova Legacy Survey and Joint Lightcurve Analysis to quantify SN Ia systematics, and by including a simultaneous fit of all SN Ia and Cepheid data. We find H_0 = 72.5 ± 3.1 ({stat}) ± 0.77 ({sys}) km s-1 Mpc-1with a three-galaxy (NGC 4258+LMC+MW) anchor. The relative uncertainties are 4.3 per cent statistical, 1.1 per cent systematic, and 4.4 per cent total, larger than in Riess et al. (2011) (3.3 per cent total) and the Efstathiou (2014) re-analysis (3.4 per cent total). Our error budget for H0 is dominated by statistical errors due to the small size of the SN sample, whilst the systematic contribution is dominated by variation in the Cepheid fits, and for the SNe Ia, uncertainties in the host galaxy mass dependence and Malmquist bias.

  15. Cesium chromium halides Cs{sub 3}CrCl{sub 6}, Cs{sub 3}Cr{sub 2}Cl{sub 9}, and Cs{sub 3}CrBr{sub 6} - preparation, properties, crystal structure; Caesiumchromhalogenide Cs{sub 3}CrCl{sub 6}, Cs{sub 3}Cr{sub 2}Cl{sub 9} und Cs{sub 3}CrBr{sub 6} - Darstellung, Eigenschaften, Kristallstruktur

    Energy Technology Data Exchange (ETDEWEB)

    Sassmannshausen, M.; Lutz, H.D. [Siegen Univ. (Gesamthochschule) (Germany). Anorganische Chemie

    2001-05-01

    The crystal structures of Cs{sub 3}CrCl{sub 6} and Cs{sub 3}Cr{sub 2}Cl{sub 9} were determined and redetermined by X-ray single-crystal studies space group Pnnm, Z = 6, a = 1115.6(2) pm, b = 2291.3(5) pm, c = 743.8(1) pm, R{sub f} = 7.73%, 1025 unique reflections with I > 2{sigma}(I) (Cs{sub 3}CrCl{sub 6}); P6{sub 3}/mmc, Z = 2, a = 721.7(2) pm und c = 1791.0(1) pm; R{sub f} = 2.06%, 395 unique reflections with I > 2.5{sigma}(I) (Cs{sub 3}Cr{sub 2}Cl{sub 9}). The structure of Cs{sub 3}CrCl{sub 6} consists of two different isolated CrCl{sub 6} octahedra and five crystallographic different Cs{sup +} ions. The CrCl{sub 6} octahedra form ropes in the direction [001]. Because of orientational disordering of the Cr(1)Cl{sub 6} octahedra and the an only half-occupation of some cesium and chlorine sites Cs{sub 3}CrCl{sub 6} is strongly disordered in direction of the (020) plane. The ionic conductivity of Cs{sub 3}CrCl{sub 6}, which was expected owing to the great disorder, however, is with 7.3 x 10{sup -5} {omega}{sup -1} cm{sup -1} at 740 K relatively small. The compound Cs{sub 3}CrBr{sub 6}, which was firstly prepared by quenching stoichiometric amounts of CsBr and CrBr{sub 3} from 833 K, is metastable at ambient temperature. It is probably isostructural to Cs{sub 3}CrCl{sub 6} as shown by X-ray powder photographs. (orig.)

  16. Parsec-scale H I absorption structure in a low-redshift galaxy seen against a compact symmetric object

    Science.gov (United States)

    Biggs, A. D.; Zwaan, M. A.; Hatziminaoglou, E.; Péroux, C.; Liske, J.

    2016-11-01

    We present global VLBI observations of the 21-cm transition of atomic hydrogen seen in absorption against the radio source J0855+5751. The foreground absorber (SDSS J085519.05+575140.7) is a dwarf galaxy at z = 0.026. As the background source is heavily resolved by VLBI, the data allow us to map the properties of the foreground H I gas with a spatial resolution of 2 pc. The absorbing gas corresponds to a single coherent structure with an extent >35 pc, but we also detect significant and coherent variations, including a change in the H I optical depth by a factor of 5 across a distance of ≲ 6 pc. The large size of the structure provides support for the Heiles & Troland model of the interstellar medium, as well as its applicability to external galaxies. The large variations in H I optical depth also suggest that caution should be applied when interpreting TS measurements from radio-detected DLAs. In addition, the distorted appearance of the background radio source is indicative of a strong jet-cloud interaction in its host galaxy. We have measured its redshift (z = 0.541 86) using optical spectroscopy on the William Herschel Telescope and this confirms that J0855+5751 is an FR II radio source with a physical extent of compact symmetric object. These sources often show absorption associated with the host galaxy and we suggest that both H I and OH should be searched for in J0855+5751.

  17. Aleaciones cuasicristalinas Al93Fe3Cr2Ti2

    Directory of Open Access Journals (Sweden)

    García-Escorial, Asunción

    2015-12-01

    Full Text Available Aluminium alloy powder having a nominal composition of Al93Fe3Cr2Ti2 (at% has been prepared using gas atomisation. The atomised powder present a microstructure of an aluminium matrix reinforced with a spherical quasicrystalline icosahedral phase, in the range of nanometre in size. The powder was consolidated into bars using warm extrusion. The microstructure of the extruded bars retains the quasicrystalline microstructure and the bars present outstanding mechanical properties, i.e. proof stress of 280 MPa at 300 °C. Upon heating the microstructure evolves towards the equilibrium. The thermal evolution was investigated by means of x-ray diffraction, differential scanning calorimeter, scanning electron microscopy and transmission electron microscopy. According to these observations a transformation in two steps is proposed. A first step consists in the decomposition of the supersaturated solid solution of the matrix and the quasicrystals, and a second step in the transformation of the quasicrystals into the equilibrium phases.Se ha obtenido por atomización por gas polvo de la aleación Al93Fe3Cr2Ti2 (at%. Este polvo presenta una microestructura de una matriz de aluminio reforzada por precipitados icosaédricos de tamaño nanométrico. El polvo fue consolidado por extrusión en forma de barras cilíndricas. La microestructura de las barras retiene la microestructura cuasicristalina de las partículas de polvo. El material consolidado presenta propiedades mecánicas prometedoras, como un límite elástico de 280 MPA a 300 °C. Con los tratamientos térmicos, la microestructura evoluciona hacia el equilibrio. Esta evolución se estudia por difracción de rayos x, calorimetría diferencial de barrido, microscopías electrónicas de barrido y de transmisión. A la luz de los resultados obtenidos se propone que la transformación de las fases con el tiempo de tratamiento térmico ocurre en dos pasos. Primeramente, tiene lugar la descomposición de la

  18. Pancreatic stellate cells and CX3CR1: occurrence in normal pancreas, acute and chronic pancreatitis and effect of their activation by a CX3CR1 agonist

    Science.gov (United States)

    Uchida, Masahiko; Ito, Tetsuhide; Nakamura, Taichi; Hijioka, Masayuki; Igarashi, Hisato; Oono, Takamasa; Kato, Masaki; Nakamura, Kazuhiko; Suzuki, Koichi; Takayanagi, Ryoichi; Jensen, Robert T.

    2014-01-01

    Objectives Numerous studies suggest important roles of the chemokine, fractalkine (CX3CL1) in acute/chronic pancreatitis, however the possible mechanisms of the effects are unclear. Pancreatic stellate cells (PSCs) can play important roles in pancreatitis, secreting inflammatory cytokines/chemokines, as well as proliferation. Therefore, we investigated CX3CL1 receptor (CX3CR1) occurrence in normal pancreas and pancreatitis (acute/chronic) tissues, and the effects of CX3CL1 on activated-PSCs. Methods CX3CR1 expression/localization in normal pancreas and pancreatitis (acute/chronic) tissues were evaluated with immunohistochemical analysis. CX3CR1 expression and effects of CX3CL1 on activated-PSCs were examined with realtime-PCR, BrdU assays and Western Blotting. Results In normal pancreas, acinar cells expressed CX3CR1 within granule-like-formations in the cytoplasm, whereas in acute/chronic pancreatitis, acinar, ductal and activated-PSCs expressed CX3CR1 on cell membranes. With activation of normal PSCs, CX3CR1 is increased. CX3CL1 activated multiple signaling cascades in PSCs. CX3CL1, did not induce inflammatory-genes expression in activated-PSCs, but induced proliferation. Conclusions CX3CR1s are expressed in normal pancreas. Expression is increased in acute/chronic pancreatitis and the CX3CR1s are activated. CX3CL1 induces proliferation of activated-PSCs without increasing release of inflammatory-mediators. These results suggest that CX3CR1 activation of PSCs could be important in their effects in pancreatitis, especially to PSCs proliferation in pancreatitis where CX3CL1 levels are elevated. PMID:24681877

  19. Parsec-scale HI absorption structure in a low-redshift galaxy seen against a Compact Symmetric Object

    CERN Document Server

    Biggs, A D; Hatziminaoglou, E; Péroux, C; Liske, J

    2016-01-01

    We present global VLBI observations of the 21-cm transition of atomic hydrogen seen in absorption against the radio source J0855+5751. The foreground absorber (SDSS~J085519.05+575140.7) is a dwarf galaxy at $z$ = 0.026. As the background source is heavily resolved by VLBI, the data allow us to map the properties of the foreground HI gas with a spatial resolution of 2pc. The absorbing gas corresponds to a single coherent structure with an extent $>$35pc, but we also detect significant and coherent variations, including a change in the HI optical depth by a factor of five across a distance of $\\leq$6pc. The large size of the structure provides support for the Heiles & Troland model of the ISM, as well as its applicability to external galaxies. The large variations in HI optical depth also suggest that caution should be applied when interpreting $T_S$ measurements from radio-detected DLAs. In addition, the distorted appearance of the background radio source is indicative of a strong jet-cloud interaction in ...

  20. THE FIRST OBSERVATIONS OF LOW-REDSHIFT DAMPED Ly{alpha} SYSTEMS WITH THE COSMIC ORIGINS SPECTROGRAPH: CHEMICAL ABUNDANCES AND AFFILIATED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Battisti, A. J.; Meiring, J. D.; Tripp, T. M. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Prochaska, J. X.; Werk, J. K. [Department of Astronomy and Astrophysics, University of California Observatories-Lick Observatory, UC Santa Cruz, CA 95064 (United States); Jenkins, E. B. [Department of Astrophysical Sciences, Princeton University Observatory, Princeton, NJ 08544 (United States); Lehner, N. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Tumlinson, J.; Thom, C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2012-01-10

    We present Cosmic Origins Spectrograph (COS) measurements of metal abundances in eight 0.083 < z{sub abs} < 0.321 damped Ly{alpha} (DLA) and sub-DLA absorption systems serendipitously discovered in the COS-Halos survey. We find that these systems show a large range in metallicities, with -1.10 < [Z/H] < 0.31, similar to the spread found at higher redshifts. These low-redshift systems on average have subsolar metallicities, but do show a rise in metallicity over cosmic time when compared to higher-redshift systems. We find that the average sub-DLA metallicity is higher than the average DLA metallicity at all redshifts. Nitrogen is underabundant with respect to {alpha}-group elements in all but perhaps one of the absorbers. In some cases, [N/{alpha}] is significantly below the lowest nitrogen measurements in nearby galaxies. Systems for which depletion patterns can be studied show little, if any, depletion, which is characteristic of Milky Way halo-type gas. We also identify affiliated galaxies for three of the sub-DLAs using spectra obtained from a Keck/Low Resolution Imaging Spectrometer (LRIS). None of these sub-DLAs arise in the stellar disks of luminous galaxies; instead, these absorbers may exist in galaxy halos at impact parameters ranging from 38 to 92 kpc. Multiple galaxies are present near two of the sub-DLAs, and galaxy interactions may play a role in the dispersal of the gas. Many of these low-redshift absorbers exhibit simple kinematics, but one sub-DLA has a complicated mix of at least 13 components spread over 150 km s{sup -1}. We find three galaxies near this sub-DLA, which also suggests that galaxy interactions roil the gas. This study reinforces the view that DLAs have a variety of origins, and low-redshift studies are crucial for understanding absorber-galaxy connections.

  1. The ultraviolet emission properties of five low-redshift active galactic nuclei at high signal-to-noise ratio and spectral resolution

    Science.gov (United States)

    Laor, Ari; Bahcall, John N.; Jannuzi, Buell T.; Schneider, Donald P.; Green, Richard F.; Hartig, George F.

    1994-01-01

    We analyze the ultraviolet (UV) emission line and continuum properties of five low-redshift active galactic nuclei (four luminous quasars: PKS 0405-123, H1821 + 643, PG 0953 + 414, and 3C 273, and one bright Seyfert 1 galaxy: Mrk 205). The HST spectra have higher signal-to-noise ratios (typically approximately 60 per resolution element) and spectral resolution (R = 1300) than all previously published UV spectra used to study the emission characteristics of active galactic nuclei. We include in the analysis ground-based optical spectra covering H beta and the narrow (O III) lambda lambda 4959, 5007 doublet. New results are obtained and presented.

  2. Metabolic Effects of CX3CR1 Deficiency in Diet-Induced Obese Mice.

    Directory of Open Access Journals (Sweden)

    Rachana Shah

    Full Text Available The fractalkine (CX3CL1-CX3CR1 chemokine system is associated with obesity-related inflammation and type 2 diabetes, but data on effects of Cx3cr1 deficiency on metabolic pathways is contradictory. We examined male C57BL/6 Cx3cr1-/- mice on chow and high-fat diet to determine the metabolic effects of Cx3cr1 deficiency. We found no difference in body weight and fat content or feeding and energy expenditure between Cx3cr1-/- and WT mice. Cx3cr1-/- mice had reduced glucose intolerance assessed by intraperitoneal glucose tolerance tests at chow and high-fat fed states, though there was no difference in glucose-stimulated insulin values. Cx3cr1-/- mice also had improved insulin sensitivity at hyperinsulinemic-euglycemic clamp, with higher glucose infusion rate, rate of disposal, and hepatic glucose production suppression compared to WT mice. Enhanced insulin signaling in response to acute intravenous insulin injection was demonstrated in Cx3cr1-/- by increased liver protein levels of phosphorylated AKT and GSK3β proteins. There were no differences in adipose tissue macrophage populations, circulating inflammatory monocytes, adipokines, lipids, or inflammatory markers. In conclusion, we demonstrate a moderate and reproducible protective effect of Cx3cr1 deficiency on glucose intolerance and insulin resistance.

  3. Neuronal Cx3cr1 Deficiency Protects against Amyloid β-Induced Neurotoxicity.

    Directory of Open Access Journals (Sweden)

    Jenny Dworzak

    Full Text Available Cx3cr1, the receptor for the chemokine Cx3cl1 (fractalkine, has been implicated in the progression and severity of Alzheimer's disease-like pathology in mice, but the underlying mechanisms remain unclear. A complicating factor is that Cx3cr1 has been demonstrated in both neurons and microglia. Here, we have dissected the differences between neuronal and microglial Cx3cr1, specifically by comparing direct amyloid-β-induced toxicity in cultured, mature, microglia-depleted hippocampal neurons from wild-type and Cx3cr1-/- mice. Wild-type neurons expressed both Cx3cl1 and Cx3cr1 and released Cx3cl1 in response to amyloid-β. Knockout of neuronal Cx3cr1 abated amyloid-β-induced lactate dehydrogenase release. Furthermore, amyloid-β differentially induced depression of pre- and postsynaptic components of miniature excitatory postsynaptic currents, in a peptide conformation-dependent manner. Knockout of neuronal Cx3cr1 abated effects of both amyloid-β conformational states, which were differentiable by aggregation kinetics and peptide morphology. We obtained similar results after both acute and chronic treatment of cultured neurons with the Cx3cr1 antagonist F1. Thus, neuronal Cx3cr1 may impact Alzheimer's disease-like pathology by modulating conformational state-dependent amyloid-β-induced synaptotoxicity.

  4. Low-Redshift Damped Lyman Alpha Galaxies Towards the Quasars B2 0827+243, PKS 0952+179, PKS 1127-145, and PKS 1629+120

    CERN Document Server

    Rao, S M; Turnshek, D A; Lane, W M; Monier, E M; Bergeron, J; Rao, Sandhya M.; Nestor, Daniel B.; Turnshek, David A.; Lane, Wendy M.; Monier, Eric M.; Bergeron, Jacqueline

    2003-01-01

    We present optical and near-infrared ground-based imaging results on four low-redshift damped Lyman alpha (DLA) galaxies. The corresponding DLA systems were discovered in our Hubble Space Telescope spectroscopic surveys for DLAs in known strong MgII absorption-line systems towards the quasars B2 0827+243 (z{DLA}=0.525), PKS 0952+179 (z{DLA}=0.239), PKS 1127-145 (z_{DLA}=0.313), and PKS 1629+120 (z{DLA}=0.532). The DLA galaxies span a mixture of morphological types from patchy, irregular, and low-surface-brightness to spiral galaxies. The luminosities range from 0.02L_K^* to 1.2L_K^*. We also discovered several extremely red objects (EROs) in two of these fields and discuss the possibility that they are associated with the DLA galaxies. These observations add to the small but growing list of DLA galaxies at low redshift. At the present time, 14 DLA galaxies in the redshift range $0.05 \\lesssim z \\lesssim 1$ have been studied. The distributions of DLA galaxy properties for these 14 cases are discussed and some ...

  5. Immunohistochemical detection of CCR2 and CX3CR1 in sepsis-induced lung injury.

    Science.gov (United States)

    An, Jun-Ling; Ishida, Yuko; Kimura, Akihiko; Tsokos, Michael; Kondo, Toshikazu

    2009-11-20

    Sepsis is a systemic inflammatory disease with high mortality. In the present study, we immunohistochemically examined CCR2 and CX3CR1 expression in sepsis-induced lung injury, and discussed its availability for the postmortem diagnosis of sepsis. Lung samples were obtained from different lung lobes of nine sepsis and eight control cases with postmortem intervals between 12 and 48h. Immunohistochemically, mononuclear cells recruited into the lungs expressed CCR2 and CX3CR1 in both sepsis and non-septic groups. In double-color immunofluorescence analysis, CCR2- or CX3CR1-positive cells could be identified as CD68-positive macrophages. Moreover, most of CD68-positive macrophages expressed both CCR2 and CX3CR1. Morphometrically, the average of CCR2- and CX3CR1-positive macrophages was significantly increased in sepsis group, compared with control group (sepsis vs. control: 41.6+/-1.3% vs. 8.0+/-0.4% in CCR2; 36.2+/-1.3% vs. 9.2+/-0.4% in CX3CR1). These observations implied that CCR2- or CX3CR1-positive macrophages were recruited into the lungs under several pathological conditions. In particular, their recruitment might be more evident in sepsis. Moreover, from the forensic aspects, immunohistochemical detection of CCR2 and CX3CR1 expression in the lungs can be considered as valuable diagnostic tools for the postmortem diagnosis of sepsis.

  6. Ccl2, Cx3cr1 and Ccl2/Cx3cr1 chemokine deficiencies are not sufficient to cause age-related retinal degeneration.

    Science.gov (United States)

    Luhmann, Ulrich F O; Carvalho, Livia S; Robbie, Scott J; Cowing, Jill A; Duran, Yanai; Munro, Peter M G; Bainbridge, James W B; Ali, Robin R

    2013-02-01

    Monocytes, macrophages, dendritic cells and microglia play critical roles in the local immune response to acute and chronic tissue injury and have been implicated in the pathogenesis of age-related macular degeneration. Defects in Ccl2-Ccr2 and Cx3cl1-Cx3cr1 chemokine signalling cause enhanced accumulation of bloated subretinal microglia/macrophages in senescent mice and this phenomenon is reported to result in the acceleration of age-related retinal degeneration. The purpose of this study was to determine whether defects in CCL2-CCR2 and CX3CL1-CX3CR1 signalling pathways, alone or in combination, cause age-dependent retinal degeneration. We tested whether three chemokine knockout mouse lines, Ccl2(-/-), Cx3cr1(-/-) and Ccl2(-/-)/Cx3cr1(-/-), in comparison to age-matched C57Bl/6 control mice show differences in subretinal macrophage accumulation and loss of adjacent photoreceptor cells at 12-14 months of age. All mouse lines are derived from common parental strains and do not carry the homozygous rd8 mutation in the Crb1 gene that has been a major confounding factor in previous reports. We quantified subretinal macrophages by counting autofluorescent lesions in fundus images obtained by scanning laser ophthalmoscopy (AF-SLO) and by immunohistochemistry for Iba1 positive cells. The accumulation of subretinal macrophages was enhanced in Ccl2(-/-), but not in Cx3cr1(-/-) or Ccl2(-/-)/Cx3cr1(-/-) mice. We identified no evidence of retinal degeneration in any of these mouse lines by TUNEL staining or semithin histology. In conclusion, CCL2-CCR2 and/or CX3CL1-CX3CR1 signalling defects may differentially affect the trafficking of microglia and macrophages in the retina during ageing, but do not appear to cause age-related retinal degeneration in mice.

  7. Fractalkine receptor (CX3CR1 deficiency sensitizes mice to the behavioral changes induced by lipopolysaccharide

    Directory of Open Access Journals (Sweden)

    Kelley Keith W

    2010-12-01

    Full Text Available Abstract Background Interactions between fractalkine (CX3CL1 and fractalkine receptor (CX3CR1 regulate microglial activation in the CNS. Recent findings indicate that age-associated impairments in CX3CL1 and CX3CR1 are directly associated with exaggerated microglial activation and an impaired recovery from sickness behavior after peripheral injection of lipopolysaccharide (LPS. Therefore, the purpose of this study was to determine the extent to which an acute LPS injection causes amplified and prolonged microglial activation and behavioral deficits in CX3CR1-deficient mice (CX3CR1-/-. Methods CX3CR1-/- mice or control heterozygote mice (CX3CR1+/- were injected with LPS (0.5 mg/kg i.p. or saline and behavior (i.e., sickness and depression-like behavior, microglial activation, and markers of tryptophan metabolism were determined. All data were analyzed using Statistical Analysis Systems General Linear Model procedures and were subjected to one-, two-, or three-way ANOVA to determine significant main effects and interactions. Results LPS injection caused a prolonged duration of social withdrawal in CX3CR1-/- mice compared to control mice. This extended social withdrawal was associated with enhanced mRNA expression of IL-1β, indolamine 2,3-dioxygenase (IDO and kynurenine monooxygenase (KMO in microglia 4 h after LPS. Moreover, elevated expression of IL-1β and CD14 was still detected in microglia of CX3CR1-/- mice 24 h after LPS. There was also increased turnover of tryptophan, serotonin, and dopamine in the brain 24 h after LPS, but these increases were independent of CX3CR1 expression. When submitted to the tail suspension test 48 and 72 h after LPS, an increased duration of immobility was evident only in CX3CR1-/- mice. This depression-like behavior in CX3CR1-/- mice was associated with a persistent activated microglial phenotype in the hippocampus and prefrontal cortex. Conclusions Taken together, these data indicate that a deficiency of CX3CR1

  8. Precision casting of Ti-15V-3Cr-3AI-3Sn alloy setting

    Institute of Scientific and Technical Information of China (English)

    Nan Hai; Liu Changkui; Huang Dong; Zhao Jiaqi; Zhao Hongxia

    2008-01-01

    In this research, Ti-15V-3Cr-3Al-3Sn alloy ingots were prepared using ceramic mold and centrifugal casting. The Ti-15V-3Cr-3Al-3Sn setting casting, for aeronautic engine, with 1.5 mm in thickness was manufactured.The alloy melting process, precision casting process, and problems in casting application were discussed. Effects of Hot Isostatic Pressing and heat treatment on the mechanical properties and microstructure of the Ti-15V-3Cr-3Al-3Sn alloy were studied.

  9. Precision casting of Ti-15V-3Cr-3Al-3Sn alloy setting

    Directory of Open Access Journals (Sweden)

    Nan Hai

    2008-02-01

    Full Text Available In this research, Ti-15V-3Cr-3Al-3Sn alloy ingots were prepared using ceramic mold and centrifugal casting. The Ti-15V-3Cr-3Al-3Sn setting casting, for aeronautic engine, with 1.5 mm in thickness was manufactured. The alloy melting process, precision casting process, and problems in casting application were discussed. Effects of Hot Isostatic Pressing and heat treatment on the mechanical properties and microstructure of the Ti-15V-3Cr-3Al-3Sn alloy were studied.

  10. CX3CL1 (fractalkine and CX3CR1 expression in myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis: kinetics and cellular origin

    Directory of Open Access Journals (Sweden)

    Olsson Tomas

    2005-07-01

    Full Text Available Abstract Background Multiple sclerosis (MS is a chronic inflammatory disease of the central nervous system (CNS. It is associated with local activation of microglia and astroglia, infiltration of activated macrophages and T cells, active degradation of myelin and damage to axons and neurons. The proposed role for CX3CL1 (fractalkine in the control of microglia activation and leukocyte infiltration places this chemokine and its receptor CX3CR1 in a potentially strategic position to control key aspects in the pathological events that are associated with development of brain lesions in MS. In this study, we examine this hypothesis by analyzing the distribution, kinetics, regulation and cellular origin of CX3CL1 and CX3CR1 mRNA expression in the CNS of rats with an experimentally induced MS-like disease, myelin oligodendrocyte glycoprotein (MOG-induced autoimmune encephalomyelitis (EAE. Methods The expression of CX3CL1 and its receptor CX3CR1 was studied with in situ hybridization histochemical detection of their mRNA with radio labeled cRNA probes in combination with immunohistochemical staining of phenotypic cell markers. Both healthy rat brains and brains from rats with MOG EAE were analyzed. In defined lesional stages of MOG EAE, the number of CX3CR1 mRNA-expressing cells and the intensity of the in situ hybridization signal were determined by image analysis. Data were statistically evaluated by ANOVA, followed by Tukeyprimes multiple comparison test. Results Expression of CX3CL1 mRNA was present within neuronal-like cells located throughout the neuraxis of the healthy rat. Expression of CX3CL1 remained unaltered in the CNS of rats with MOG-induced EAE, with the exception of an induced expression in astrocytes within inflammatory lesions. Notably, the brain vasculature of healthy and encephalitic animals did not exhibit signs of CX3CL1 mRNA expression. The receptor, CX3CR1, was expressed by microglial cells in all regions of the healthy brain

  11. TLR4-dependent internalization of CX3CR1 aggravates sepsis-induced immunoparalysis.

    Science.gov (United States)

    Ge, Xin-Yu; Fang, Shang-Ping; Zhou, Miao; Luo, Jing; Wei, Juan; Wen, Xue-Ping; Yan, Xiao-Di; Zou, Zui

    2016-01-01

    Sepsis, the most severe manifestation of infection, poses a major challenge to health-care systems around the world. Limited ability to clean and remove the pathogen renders difficulty in septic patients to recover from the phase of immunoparalysis. The present study found the vital role of CX3CR1 internalization on sepsis-induced immunoparalysis. A mouse model with cecal ligation and puncture (CLP) and cell model with lipopolysaccharides (LPS) were employed to explore the relationship between CX3CR1 internalization and septic immunoparalysis. Immunoparalysis model in mice was established 4 days after CLP with significantly decreased proinflammatory cytokines. Flow cytometry analysis found a decreased surface expression of CX3CR1 during immunoparalysis, which was associated with reduced mRNA level and increased internalization of CX3CR1. G-protein coupled receptor kinase 2 (GRK2) and β-arrestin2 were significantly increased during septic immunoparalysis and involved in the internalization of CX3CR1. TLR4(-/-) or TLR4 inhibitor-treated macrophages exhibited an inhibited expression of GRK2 and β-arrestin2, along with reduced internalization of CX3CR1. Moreover, the knockdown of GRK2 and β-arrestin2 inhibited the internalization of CX3CR1 and led to a higher response on the second hit, which was associated with an increased activation of NF-κB. The critical association between internalization of CX3CR1 and immunosuppression in sepsis may provide a novel reference for clinical therapeutics.

  12. CX3CR1 is a modifying gene of survival and progression in amyotrophic lateral sclerosis.

    Directory of Open Access Journals (Sweden)

    Alan Lopez-Lopez

    Full Text Available The objective of this study was to investigate the association of functional variants of the human CX3CR1 gene (Fractalkine receptor with the risk of Amyotrophic Lateral Sclerosis (ALS, the survival and the progression rate of the disease symptoms in a Spanish ALS cohort. 187 ALS patients (142 sporadic [sALS] and 45 familial and 378 controls were recruited. We investigated CX3CR1 V249I (rs3732379 and T280M (rs3732378 genotypes and their haplotypes as predictors of survival, the progression rate of the symptoms (as measured by ALSFRS-R and FVC decline and the risk of suffering ALS disease. The results indicated that sALS patients with CX3CR1 249I/I or 249V/I genotypes presented a shorter survival time (42.27 ± 4.90 than patients with 249V/V genotype (67.65 ± 7.42; diff -25.49 months 95%CI [-42.79,-8.18]; p = 0.004; adj-p = 0.018. The survival time was shorter in sALS patients with spinal topography and CX3CR1 249I alleles (diff =  -29.78 months; 95%CI [-49.42,-10.14]; p = 0.003. The same effects were also observed in the spinal sALS patients with 249I-280M haplotype (diff =  -27.02 months; 95%CI [-49.57, -4.48]; p = 0.019. In the sALS group, the CX3CR1 249I variant was associated with a faster progression of the disease symptoms (OR = 2.58; 95IC% [1.32, 5.07]; p = 0.006; adj-p = 0.027. There was no evidence for association of these two CX3CR1 variants with ALS disease risk. The association evidenced herein is clinically relevant and indicates that CX3CR1 could be a disease-modifying gene in sALS. The progression rate of the disease's symptoms and the survival time is affected in patients with one or two copies of the CX3CR1 249I allele. The CX3CR1 is the most potent ALS survival genetic factor reported to date. These results reinforce the role of the immune system in ALS pathogenesis.

  13. Differential modulation of retinal degeneration by Ccl2 and Cx3cr1 chemokine signalling.

    Science.gov (United States)

    Luhmann, Ulrich F O; Lange, Clemens A; Robbie, Scott; Munro, Peter M G; Cowing, Jill A; Armer, Hannah E J; Luong, Vy; Carvalho, Livia S; MacLaren, Robert E; Fitzke, Frederick W; Bainbridge, James W B; Ali, Robin R

    2012-01-01

    Microglia and macrophages are recruited to sites of retinal degeneration where local cytokines and chemokines determine protective or neurotoxic microglia responses. Defining the role of Ccl2-Ccr2 and Cx3cl1-Cx3cr1 signalling for retinal pathology is of particular interest because of its potential role in age-related macular degeneration (AMD). Ccl2, Ccr2, and Cx3cr1 signalling defects impair macrophage trafficking, but have, in several conflicting studies, been reported to show different degrees of age-related retinal degeneration. Ccl2/Cx3cr1 double knockout (CCDKO) mice show an early onset retinal degeneration and have been suggested as a model for AMD. In order to understand phenotypic discrepancies in different chemokine knockout lines and to study how defects in Ccl2 and/or Cx3cr1 signalling contribute to the described early onset retinal degeneration, we defined primary and secondary pathological events in CCDKO mice. To control for genetic background variability, we compared the original phenotype with that of single Ccl2, Cx3cr1 and Ccl2/Cx3cr1 double knockout mice obtained from backcrosses of CCDKO with C57Bl/6 mice. We found that the primary pathological event in CCDKO mice develops in the inferior outer nuclear layer independently of light around postnatal day P14. RPE and vascular lesions develop secondarily with increasing penetrance with age and are clinically similar to retinal telangiectasia not to choroidal neovascularisation. Furthermore, we provide evidence that a third autosomal recessive gene causes the degeneration in CCDKO mice and in all affected re-derived lines and subsequently demonstrated co-segregation of the naturally occurring RD8 mutation in the Crb1 gene. By comparing CCDKO mice with re-derived CCl2(-/-)/Crb1(Rd8/RD8), Cx3cr1(-/-)/Crb1(Rd8/RD8) and CCl2(-/-)/Cx3cr1(-/-)/Crb1(Rd8/RD8) mice, we observed a differential modulation of the retinal phenotype by genetic background and both chemokine signalling pathways. These findings

  14. Creep-rupture behavior of 3Cr-3W-V bainitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L. [Oak Ridge National Laboratory, TN 37831-6138 (United States)]. E-mail: kluehrl@ornl.gov; Evans, N.D. [Oak Ridge National Laboratory, TN 37831-6138 (United States); Maziasz, P.J. [Oak Ridge National Laboratory, TN 37831-6138 (United States); Sikka, V.K. [Oak Ridge National Laboratory, TN 37831-6138 (United States)

    2007-01-15

    A nominally Fe-3.0Cr-3.0W-0.25 V (3Cr-3WV) steel and this composition with 0.07% Ta (3Cr-3WVTa) were developed for elevated-temperature service in the power-generation and petrochemical industries. Creep-rupture strengths of the new steels to 600 deg. C exceeded those of the two advanced commercial 2.25Cr steels T23 (Fe-2.25Cr-1.6W-0.25V-0.05Nb-0.07C) and T24 (Fe-2.25Cr-1.0Mo-0.25V-0.07Ti-0.005B-0.07C). Moreover, the strength of 3Cr-3WVTa approached that of modified 9Cr-1Mo (T91) at 650 deg. C. Elevated-temperature strength in the new steels is obtained from a bainitic microstructure with a high number density of fine needle-like MX precipitates in the matrix. The presence of tantalum promotes a finer MX precipitate in the 3Cr-3WVTa than in the 3Cr-3WV, and it suppresses the coarsening of these fine precipitates during creep.

  15. Fractalkine and CX3CR1 regulate hippocampal neurogenesis in adult and aged rats

    Science.gov (United States)

    Bachstetter, Adam D.; Morganti, Josh M.; Jernberg, Jennifer; Schlunk, Andrea; Mitchell, Staten H.; Brewster, Kaelin W.; Hudson, Charles E.; Cole, Michael J; Harrison, Jeffrey K.; Bickford, Paula C.; Gemma, Carmelina

    2010-01-01

    Microglia have neuroprotective capacities, yet chronic activation can promote neurotoxic inflammation. Neuronal fractalkine (FKN), acting on CX3CR1, has been shown to suppress excessive microglia activation. We found that disruption in FKN/ CX3CR1 signaling in young adult rodents decreased survival and proliferation of neural progenitor cells through IL-1β. Aged rats were found to have decreased levels of hippocampal FKN protein; moreover, interruption of CX3CR1 function in these animals did not affect neurogenesis. The age-related loss of FKN could be restored by exogenous FKN reversing the age-related decrease in hippocampal neurogenesis. There were no measureable changes in young animals by the addition of exogenous FKN. The results suggest that FKN/ CX3CR1 signaling has a regulatory role in modulating hippocampal neurogenesis via mechanisms that involve indirect modification of the niche environment. As elevated neuroinflammation is associated with many age-related neurodegenerative diseases, enhancing FKN/ CX3CR1 interactions could provide an alternative therapeutic approach to slow age-related neurodegeneration. PMID:20018408

  16. Functional classification of memory CD8+ T cells by CX3CR1 expression

    Science.gov (United States)

    Böttcher, Jan P.; Beyer, Marc; Meissner, Felix; Abdullah, Zeinab; Sander, Jil; Höchst, Bastian; Eickhoff, Sarah; Rieckmann, Jan C.; Russo, Caroline; Bauer, Tanja; Flecken, Tobias; Giesen, Dominik; Engel, Daniel; Jung, Steffen; Busch, Dirk H.; Protzer, Ulrike; Thimme, Robert; Mann, Matthias; Kurts, Christian; Schultze, Joachim L.; Kastenmüller, Wolfgang; Knolle, Percy A.

    2015-01-01

    Localization of memory CD8+ T cells to lymphoid or peripheral tissues is believed to correlate with proliferative capacity or effector function. Here we demonstrate that the fractalkine-receptor/CX3CR1 distinguishes memory CD8+ T cells with cytotoxic effector function from those with proliferative capacity, independent of tissue-homing properties. CX3CR1-based transcriptome and proteome-profiling defines a core signature of memory CD8+ T cells with effector function. We find CD62LhiCX3CR1+ memory T cells that reside within lymph nodes. This population shows distinct migration patterns and positioning in proximity to pathogen entry sites. Virus-specific CX3CR1+ memory CD8+ T cells are scarce during chronic infection in humans and mice but increase when infection is controlled spontaneously or by therapeutic intervention. This CX3CR1-based functional classification will help to resolve the principles of protective CD8+ T-cell memory. PMID:26404698

  17. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: galaxy clustering measurements in the low redshift sample of Data Release 11

    CERN Document Server

    Tojeiro, Rita; Burden, Angela; Samushia, Lado; Manera, Marc; Percival, Will J; Beutler, Florian; Cuesta, Antonio J; Dawson, Kyle; Eisenstein, Daniel J; Ho, Shirley; Howett, Cullan; McBride, Cameron K; Montesano, Francisco; Parejko, John K; Reid, Beth; Sánchez, Ariel G; Schlegel, David J; Schneider, Donald P; Tinker, Jeremy L; Magaña, Mariana Vargas; White, Martin

    2014-01-01

    We present the distance measurement to z = 0.32 using the 11th data release of the Sloan Digital Sky Survey-III Baryon Acoustic Oscillation Survey (BOSS). We use 313,780 galaxies of the low-redshift (LOWZ) sample over 7,341 square-degrees to compute $D_V = (1264 \\pm 25)(r_d/r_{d,fid})$ - a sub 2% measurement - using the baryon acoustic feature measured in the galaxy two-point correlation function and power-spectrum. We compare our results to those obtained in DR10. We study observational systematics in the LOWZ sample and quantify potential effects due to photometric offsets between the northern and southern Galactic caps. We find the sample to be robust to all systematic effects found to impact on the targeting of higher-redshift BOSS galaxies, and that the observed north-south tensions can be explained by either limitations in photometric calibration or by sample variance, and have no impact on our final result. Our measurement, combined with the baryonic acoustic scale at z = 0.57, is used in Anderson et a...

  18. An HST/COS legacy survey of intervening SiIII absorption in the extended gaseous halos of low-redshift galaxies

    CERN Document Server

    Richter, P; Fechner, C; Herenz, P; Tepper-Garcia, T; Fox, A J

    2015-01-01

    Doubly ionized silicon (SiIII) is a powerful tracer of diffuse ionized gas inside and outside of galaxies. It can be observed in the local Universe in ultraviolet (UV) absorption against bright extragalactic background sources. We here present an extensive study of intervening SiIII- selected absorbers and their relation to the circumgalactic medium (CGM) of galaxies at low redshift (z12.2. We develop a geometrical model for the absorption-cross section of the CGM around the local galaxy population and find excellent agreement between the model predictions and the observations. We further compare redshifts and positions of the absorbers with that of ~64,000 galaxies using archival galaxy-survey data. For the majority of the absorbers we identify possible L>0.5L* host galaxies within 300 km/s of the absorbers and derive impact parameters rho<200 kpc, demonstrating that the spatial distributions of SiIII absorbers and galaxies are highly correlated. Our study indicates that the majority of SiIII-selected abs...

  19. A Cluster of Low-Redshift Lyman-$\\alpha$ Clouds toward PKS 2155-304; 1, Limits on Metals and D/H

    CERN Document Server

    Shull, J M; Stocke, J T; Giroux, M L; Van Gorkom, J H; Lee, Y H; Carilli, C L; Penton, Steven V.; Stocke, John T.; Giroux, Mark L.; Lee, Yong-Han; Carilli, Chris

    1998-01-01

    We report observations from the Hubble Space Telescope (HST) and the VLA on the galactic environment, metallicity, and D/H in strong low-redshift Lya absorption systems toward the bright BL Lac object PKS 2155-304. GHRS/G160M spectra at 20 km/s resolution show 14 Lya absorbers, 6 clustered at cz = 16,100-18,500 km/s. ORFEUS claimed LyC absorption at z = 0.056 with N(HI) = (2-5)x10^16 cm^-2, while our Lya data suggest N(HI) = (3-10)x10^14 cm^-2. Higher columns are possible if the Lya line core at 17,000 +/- 50 km/s contains narrow HI components. We identify the Lya cluster with a group of five HI galaxies offset by 400-800 kpc from the sightline. The two strongest absorption features cover the same velocity range as the HI emission in the two galaxies closest to the line of sight. If the Lya is associated with these galaxies, they must have huge halos of highly turbulent, mostly ionized gas. The Lya absorption could also arise from an extended sheet of intragroup gas, or from smaller primordial clouds and halo...

  20. The First Observations of Low-Redshift Damped Lyman-{\\alpha} Systems with the Cosmic Origins Spectrograph: Chemical Abundances and Affiliated Galaxies

    CERN Document Server

    Battisti, A J; Tripp, T M; Prochaska, J X; Werk, J K; Jenkins, E B; Lehner, N; Tumlinson, J; Thom, C

    2011-01-01

    We present Cosmic Origins Spectrograph (COS) measurements of metal abundances in eight 0.083 < zabs < 0.321 damped Lyman-{\\alpha} (DLA) and sub-damped Ly{\\alpha} absorption systems serendipitously discovered in the COS-Halos survey. We find that these systems show a large range in metallicities, with -1.10 < [Z/H] < 0.31, similar to the spread found at higher redshifts. These low-redshift systems on average have subsolar metallicities, but do show a rise in metallicity over cosmic time when compared to higher-redshift systems. Utilizing our sources and those in the literature, we find the average sub-DLA metallicity is higher than the average DLA metallicity at all redshifts. Nitrogen is underabundant with respect to {\\alpha}-group elements in all but perhaps one of the absorbers. In some cases, [N/{\\alpha}] is significantly below the lowest nitrogen measurements in nearby galaxies; the nitrogen abundances are more similar to those observed in high-redshift DLAs. Systems for which depletion patter...

  1. Jellyfish galaxies at low redshift

    CERN Document Server

    Poggianti, B M; Omizzolo, A; Gullieuszik, M; Bettoni, D; Moretti, A; Paccagnella, A; Jaffe', Y L; Vulcani, B; Fritz, J; Couch, W; D'Onofrio, M

    2015-01-01

    Jellyfish galaxies are galaxies that exhibit tentacles of debris material suggestive of gas stripping. We have conducted the first systematic search for jellyfish galaxies at low-z (z=0.04-0.07) in different environments. We have visually inspected B and V-band images and identified 241+153 candidates in 41+31 galaxy clusters of the OMEGAWINGS+WINGS sample and 99 candidates in groups and lower mass structures in the PM2GC sample. This large sample is well suited for follow-up studies of the gas and for a detailed analysis of the environments where such episodes of gas stripping occur. We present here the atlas of jellyfish candidates, a first analysis of their environment and their basic properties, such as morphologies, star formation rates and galaxy stellar masses. Jellyfish candidates are found in all clusters and at all clustercentric radii, and their number does not correlate with the cluster velocity dispersion or X-ray luminosity. Interestingly, convincing cases of jellyfish candidates are also found ...

  2. Radio Loud AGNs are Mergers

    CERN Document Server

    Chiaberge, Marco; Lotz, Jennifer; Norman, Colin

    2015-01-01

    We measure the merger fraction of Type 2 radio-loud and radio-quiet active galactic nuclei at z>1 using new samples. The objects have HST images taken with WFC3 in the IR channel. These samples are compared to the 3CR sample of radio galaxies at z>1 and to a sample of non-active galaxies. We also consider lower redshift radio galaxies with HST observations and previous generation instruments (NICMOS and WFPC2). The full sample spans an unprecedented range in both redshift and AGN luminosity. We perform statistical tests to determine whether the different samples are differently associated with mergers. We find that all (92%) radio-loud galaxies at z>1 are associated with recent or ongoing merger events. Among the radio-loud population there is no evidence for any dependence of the merger fraction on either redshift or AGN power. For the matched radio-quiet samples, only 38% are merging systems. The merger fraction for the sample of non-active galaxies at z>1 is indistinguishable from radio-quiet objects. This...

  3. CX3CR1-expressing inflammatory dendritic cells contribute to the progression of steatohepatitis.

    Science.gov (United States)

    Sutti, Salvatore; Locatelli, Irene; Bruzzì, Stefania; Jindal, Aastha; Vacchiano, Marco; Bozzola, Cristina; Albano, Emanuele

    2015-11-01

    Liver monocytes play a major role in the development of NASH (non-alcoholic steatohepatitis). In inflamed tissues, monocytes can differentiate in both macrophages and dendritic cells. In the present study, we investigated the role of moDCs (monocyte-derived inflammatory dendritic cells) in experimental steatohepatitis induced in C57BL/6 mice by feeding on a MCD (methionine/choline-deficient) diet. The evolution of steatohepatitis was characterized by an increase in hepatic CD45+ / CD11b+ myeloid cells displaying the monocyte/macrophage marker F4-80(+). In the early phases (4 weeks of treatment), Ly6C(high)/CD11b(+)/F4-80(+) inflammatory macrophages predominated. However, their frequency did not grow further with the disease progression (8 weeks of treatment), when a 4-fold expansion of CD11b(+)/F4-80(+) cells featuring the fractalkine receptor (CX3CR1) was evident. These CX3CR1+ cells were also characterized by the combined expression of inflammatory monocyte (Ly6C, CD11b) and dendritic cell (CD11c, MHCII) markers as well as by a sustained TNFα (tumour necrosis factor α) production, suggesting monocyte differentiation into inflammatory moDCs. The expansion of TNFα-producing CX3CR1+ moDCs was associated with an elevation in hepatic and circulating TNFα level and with the worsening of parenchymal injury. Hydrogen sulfide (H2S) has been shown to interfere with CX3CR1 up-regulation in monocyte-derived cells exposed to pro-inflammatory stimuli. Treating 4-week-MCD-fed mice with the H2S donor NaHS while continuing on the same diet prevented the accumulation of TNFα-producing CX3CR1+ moDCs without interfering with hepatic macrophage functions. Furthermore, NaHS reduced hepatic and circulating TNFα levels and ameliorated transaminase release and parenchymal injury. Altogether, these results show that inflammatory CX3CR1+ moDCs contributed in sustaining inflammation and liver injury during steatohepatitis progression.

  4. An HST/COS legacy survey of intervening Si III absorption in the extended gaseous halos of low-redshift galaxies

    Science.gov (United States)

    Richter, P.; Wakker, B. P.; Fechner, C.; Herenz, P.; Tepper-García, T.; Fox, A. J.

    2016-05-01

    Aims: Doubly ionized silicon (Si iii) is a powerful tracer of diffuse ionized gas inside and outside of galaxies. It can be observed in the local Universe in ultraviolet (UV) absorption against bright extragalactic background sources. We here present an extensive study of intervening Si iii-selected absorbers and study the properties of the warm circumgalactic medium (CGM) around low-redshift (z ≤ 0.1) galaxies. Methods: We analyzed the UV absorption spectra of 303 extragalactic background sources, as obtained with the Cosmic Origins Spectrograph (COS) on-board the Hubble Space Telescope (HST). We developed a geometrical model for the absorption-cross section of the CGM around the local galaxy population and compared the observed Si iii absorption statistics with predictions provided by the model. We also compared redshifts and positions of the absorbers with those of ~64 000 galaxies using archival galaxy-survey data to investigate the relation between intervening Si iii absorbers and the CGM. Results: Along a total redshift path of Δz ≈ 24, we identify 69 intervening Si iii systems that all show associated absorption from other low and high ions (e.g., H i, Si ii, Si iv, C ii, C iv). We derive a bias-corrected number density of dN/dz(Si iii)= 2.5 ± 0.4 for absorbers with column densities log N(Si iii) > 12.2, which is ~3 times the number density of strong Mg ii systems at z = 0. This number density matches the expected cross section of a Si iii absorbing CGM around the local galaxy population with a mean covering fraction of ⟨ fc ⟩ = 0.69. For the majority (~60 percent) of the absorbers, we identify possible host galaxies within 300 km s-1 of the absorbers and derive impact parameters ρ files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/590/A68

  5. Infrared imaging of WENSS radio sources

    CERN Document Server

    Villani, D

    1999-01-01

    We have performed deep imaging in the IR J- and K-bands for three sub-samples of radio sources extracted from the Westerbork Northern Sky Survey, a large low-frequency radio survey containing Ultra Steep Spectrum (USS), Gigahertz Peaked Spectrum (GPS) and Flat Spectrum (FS) sources. We present the results of these IR observations, carried out with the ARcetri Near Infrared CAmera (ARNICA) at the Nordic Optical Telescope (NOT), providing photometric and morphologic information on high redshift radio galaxies and quasars. We find that the radio galaxies contained in our sample do not show the pronounced radio/IR alignment claimed for 3CR sources. IR photometric measurements of the gravitational lens system 1600+434 are also presented.

  6. Magnetic Dimer Excitations in Cs3Cr2CI9 Studied by Neutron Scattering

    DEFF Research Database (Denmark)

    Leuenberger, Bruno; Güdel, Hans U.; Kjems, Jørgen

    1985-01-01

    nearest-neighbor interactions need to be considered. From the excellent fit, three exchange parameters were obtained: J = -1.75 meV (intradimer), J = -0.032 meV (interdimer, intrasublattice) and J, = -0.031 meV (interdimer,i ntersublattice). These values indicate that Cs3Cr26I9is far from ordering......The energy dispersion of the singlet-triplet dimer excitation in Cs3Cr2CI9h as been studied by inelastic neutron scattering (INS) at temperatures down to 1.3 K. The results can be accounted for by using a completely isotropic Heisenberg Hamiltonian in the random phase approximation (RPA). Only...

  7. Fatigue properties of 48MnV steel with twin arc spraying 3Cr13 coatings

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-qing; SU Bing; PU Geng-qiang; WANG Cheng-tao

    2005-01-01

    The fatigue behaviors of 48MnV steel, both uncoated and coated with different thicknesses of 3Cr13 deposits using twin arc spraying, were investigated. The fatigue properties of the 48MnV steel, determined under axial loading conditions, can be substantially decreased by coating 3Cr13 films, deposited by twin arc spraying. And the fatigue behavior of the thinner coatings is better than that of the thicker ones, of which the fatigue limits decrease by 9%- 14%. The decrease in fatigue life attributes to the less mechanical properties of the coatings in comparison with those of the substrate, their relative bad bonding strength and trapped oxide or Al2O3 particles retain in the matrix after blasting responsible for the initiation of fatigue cracks.

  8. A comprehensive radio view of the extremely bright gamma-ray burst 130427A

    OpenAIRE

    van der Horst, A. J.; Paragi, Z.; De Bruyn, A. G.; Granot, J.; Kouveliotou, C; Wiersema, K.; Starling, R. L. C.; Curran, P. A.; Wijers, R. A. M. J.; Rowlinson, A.; Anderson, G. A.; Fender, R. P.; Yang, J.; Strom, R. G.

    2014-01-01

    GRB130427A was extremely bright as a result of occurring at low redshift whilst the energetics were more typical of high-redshift gamma-ray bursts (GRBs). We collected well-sampled light curves at 1.4 and 4.8 GHz of GRB 130427A with the Westerbork Synthesis Radio Telescope (WSRT); and we obtained its most accurate position with the European Very Long Baseline Interferometry Network (EVN). Our flux density measurements are combined with all the data available at radio, optical and X-ray freque...

  9. CX3CR1 is dysregulated in blood and brain from schizophrenia patients.

    Science.gov (United States)

    Bergon, Aurélie; Belzeaux, Raoul; Comte, Magali; Pelletier, Florence; Hervé, Mylène; Gardiner, Erin J; Beveridge, Natalie J; Liu, Bing; Carr, Vaughan; Scott, Rodney J; Kelly, Brian; Cairns, Murray J; Kumarasinghe, Nishantha; Schall, Ulrich; Blin, Olivier; Boucraut, José; Tooney, Paul A; Fakra, Eric; Ibrahim, El Chérif

    2015-10-01

    The molecular mechanisms underlying schizophrenia remain largely unknown. Although schizophrenia is a mental disorder, there is increasing evidence to indicate that inflammatory processes driven by diverse environmental factors play a significant role in its development. With gene expression studies having been conducted across a variety of sample types, e.g., blood and postmortem brain, it is possible to investigate convergent signatures that may reveal interactions between the immune and nervous systems in schizophrenia pathophysiology. We conducted two meta-analyses of schizophrenia microarray gene expression data (N=474) and non-psychiatric control (N=485) data from postmortem brain and blood. Then, we assessed whether significantly dysregulated genes in schizophrenia could be shared between blood and brain. To validate our findings, we selected a top gene candidate and analyzed its expression by RT-qPCR in a cohort of schizophrenia subjects stabilized by atypical antipsychotic monotherapy (N=29) and matched controls (N=31). Meta-analyses highlighted inflammation as the major biological process associated with schizophrenia and that the chemokine receptor CX3CR1 was significantly down-regulated in schizophrenia. This differential expression was also confirmed in our validation cohort. Given both the recent data demonstrating selective CX3CR1 expression in subsets of neuroimmune cells, as well as behavioral and neuropathological observations of CX3CR1 deficiency in mouse models, our results of reduced CX3CR1 expression adds further support for a role played by monocyte/microglia in the neurodevelopment of schizophrenia. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. B cell lymphomas express CX3CR1 a non-B cell lineage adhesion molecule

    DEFF Research Database (Denmark)

    Andreasson, U.; Ek, S.; Merz, H.

    2008-01-01

    To study the differential expression of cell membrane-bound receptors and their potential role in growth and/or survival of the tumor cells, highly purified follicular lymphoma cells were analyzed, using gene expression analysis, and compared to non-malignant B cell populations. Filtering...... the genome for overexpressed genes coding for cell membrane-bound proteins/receptors resulted in a hit list of 27 identified genes. Among these, we have focused on the aberrant over expression of CX3CR1, in different types of B cell lymphoma, as compared to non-malignant B cells. We show that CX3CR1, which...... normally is not expressed on B cells, is expressed both at the mRNA and protein level in several subtypes of lymphoma. CX3CR1 has also shown to be involved in the homing to specific tissues that express the ligand, CX3CL1, in breast and prostate cancer and may thus be involved in dissemination of lymphoma...

  11. Pancreatic stellate cells and CX3CR1: occurrence in normal pancreas and acute and chronic pancreatitis and effect of their activation by a CX3CR1 agonist.

    Science.gov (United States)

    Uchida, Masahiko; Ito, Tetsuhide; Nakamura, Taichi; Hijioka, Masayuki; Igarashi, Hisato; Oono, Takamasa; Kato, Masaki; Nakamura, Kazuhiko; Suzuki, Koichi; Takayanagi, Ryoichi; Jensen, Robert T

    2014-07-01

    Numerous studies suggest important roles of the chemokine, fractalkine (CX3CL1), in acute/chronic pancreatitis; however, the possible mechanisms of the effects are unclear. Pancreatic stellate cells (PSCs) can play important roles in pancreatitis, secreting inflammatory cytokines/chemokines, as well as proliferation. Therefore, we investigated CX3CL1 receptor (CX3CR1) occurrence in normal pancreas and pancreatitis (acute/chronic) tissues and the effects of CX3CL1 on activated PSCs. CX3CR1 expression/localization in normal pancreas and pancreatitis (acute/chronic) tissues was evaluated with immunohistochemical analysis. CX3CR1 expression and effects of CX3CL1 on activated PSCs were examined with real-time polymerase chain reaction, BrdU (5-bromo-2-deoxyuridine) assays, and Western blotting. In normal pancreas, acinar cells expressed CX3CR1 within granule-like formations in the cytoplasm, whereas in acute/chronic pancreatitis, acinar, ductal, and activated PSCs expressed CX3CR1 on cell membranes. With activation of normal PSCs, CX3CR1 is increased. CX3CL1 activated multiple signaling cascades in PSCs. CX3CL1 did not induce inflammatory genes expression in activated PSCs, but induced proliferation. CX3CR1s are expressed in normal pancreas. Expression is increased in acute/chronic pancreatitis, and the CX3CR1s are activated. CX3CL1 induces proliferation of activated PSCs without increasing release of inflammatory mediators. These results suggest that CX3CR1 activation of PSCs could be important in their effects in pancreatitis, especially to PSC proliferation in pancreatitis where CX3CL1 levels are elevated.

  12. Radio Journalism.

    Science.gov (United States)

    Bittner, John R.; Bittner, Denise A.

    This book, a how-to-do-it guide for the novice and the professional alike, deals with several aspects of radio journalism: producing documentaries, preparing and announcing radio news, ethics and responsibility, regulation of radio journalism, and careers. It traces the history and growth of radio news, shows its impact on the public, and…

  13. Monocyte subsets differentially employ CCR2, CCR5, and CX3CR1 to accumulate within atherosclerotic plaques

    OpenAIRE

    2007-01-01

    Monocytes participate critically in atherosclerosis. There are 2 major subsets expressing different chemokine receptor patterns: CCR2+CX3CR1+Ly-6Chi and CCR2–CX3CR1++Ly-6Clo monocytes. Both C-C motif chemokine receptor 2 (CCR2) and C-X3-C motif chemokine receptor 1 (CX3CR1) are linked to progression of atherosclerotic plaques. Here, we analyzed mouse monocyte subsets in apoE-deficient mice and traced their differentiation and chemokine receptor usage as they accumulated within atherosclerotic...

  14. Analysis of High Temperature Deformed Structure and Dynamic Precipitation in W9Mo3Cr4V Steel

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With TEM、SEM, various high-temperature deformed structures inW9Mo3Cr4V steel were investigated. The sub-structures,recrystallized nuclei, as well as the dynamic precipitation were also studied and analyzed. The relationship between recrystallized structures and dynamic precipitation was discussed. The results showed that the deformed structures in W9Mo3Cr4V steel are more complicated than those in low alloy steels. Because W9Mo3Cr4V steel is a high-speed steel, there are a large number of residual carbides on the matrix. Also, much dynamic precipitating carbides will precipitate during deformation at high temperature.

  15. Ti3CrCu4: A possible 2-D ferromagnetic spin fluctuating system

    Directory of Open Access Journals (Sweden)

    S. K. Dhar

    2016-05-01

    Full Text Available Ti3CrCu4 is a new ternary compound which crystallizes in the tetragonal Ti3Pd5 structure type. The Cr atoms form square nets in the a-b plane (a = 3.124 Å which are separated by an unusually large distance c = 11.228 Å along the tetragonal axis, thus forming a -2-D Cr-sublattice. The paramagnetic susceptibility is characterized by a low effective moment, μeff = 1.1 μB, a low paramagnetic Curie temperature θP (below 7 K and a temperature independent χ0 = 6.7 x 10−4 emu/mol. The magnetization at 1.8 K increases rapidly with field nearly saturating to 0.2 μB/f.u. The zero field heat capacity C/T shows an upturn below 7 K (∼190 mJ/mol K2 at ∼0.1K which is suppressed in applied magnetic fields and interpreted as suggesting the presence of spin fluctuations. The resistivity at low temperatures shows non-Fermi liquid behavior. Overall, the experimental data thus reveal an unusual magnetic state in Ti3CrCu4, which likely has its origin in the layered nature of the Cr sub-lattice and ferromagnetic spin fluctuations. Density functional theoretical calculations reveal a sharp Cr density of states peak just above the Fermi level, indicating the propensity of Ti3CrCu4 to become magnetic.

  16. The research of axial corrosion fatigue on 10Ni3CrMoV steel

    Science.gov (United States)

    Xie, Xing; Yi, Hong; Xu, Jian; Xie, Kun

    2017-09-01

    Fatigue life had been studied with 10CrNi3MoV steel at different load ratios and in different environmental medias. The microstructure and micro-topography had been observed and analyzed by means of SEM, EDS and TEM. Our findings indicated that, the fatigue life of 10Ni3CrMoV steel in seawater was shorter than in air, the difference in longevity was larger with the decreasing of axis stress. Corrosion pits had a great influence on corrosion fatigue life.

  17. 3C 57 as an atypical radio-loud quasar: implications for the radio-loud/radio-quiet dichotomy

    Science.gov (United States)

    Sulentic, J. W.; Martínez-Carballo, M. A.; Marziani, P.; del Olmo, A.; Stirpe, G. M.; Zamfir, S.; Plauchu-Frayn, I.

    2015-06-01

    Lobe-dominated radio-loud (LD RL) quasars occupy a restricted domain in the 4D Eigenvector 1 (4DE1) parameter space which implies restricted geometry/physics/kinematics for this subclass compared to the radio-quiet (RQ) majority of quasars. We discuss how this restricted domain for the LD RL parent population supports the notion for a RQ-RL dichotomy among type 1 sources. 3C 57 is an atypical RL quasar that shows both uncertain radio morphology and falls in a region of 4DE1 space where RL quasars are rare. We present new radio flux and optical spectroscopic measures designed to verify its atypical optical/UV spectroscopic behaviour and clarify its radio structure. The former data confirms that 3C 57 falls off the 4DE1 quasar `main sequence' with both extreme optical Fe II emission (R_{Fe II} ˜ 1) and a large C IV λ1549 profile blueshift (˜-1500 km s-1). These parameter values are typical of extreme Population A sources which are almost always RQ. New radio measures show no evidence for flux change over a 50+ year time-scale consistent with compact steep-spectrum (or young LD) over core-dominated morphology. In the 4DE1 context where LD RL are usually low L/LEdd quasars, we suggest that 3C 57 is an evolved RL quasar (i.e. large blackhole mass) undergoing a major accretion event leading to a rejuvenation reflected by strong Fe II emission, perhaps indicating significant heavy metal enrichment, high bolometric luminosity for a low-redshift source and resultant unusually high Eddington ratio giving rise to the atypical C IV λ1549.

  18. CX3CR1 deficiency alters hippocampal-dependent plasticity phenomena blunting the effects of enriched environment

    Directory of Open Access Journals (Sweden)

    Laura eMaggi

    2011-10-01

    Full Text Available In recent years several evidence demonstrated that some features of hippocampal biology, like neurogenesis, synaptic transmission, learning and memory performances are deeply modulated by social, motor and sensorial experiences. Fractalkine/CX3CL1 is a transmembrane chemokine abundantly expressed in the brain by neurons, where it modulates glutamatergic transmission and long-term plasticity processes regulating the intercellular communication between glia and neurons, being its specific receptor CX3CR1 expressed by microglia. In this paper we investigated the role of CX3CL1/CX3CR1 signaling on experience-dependent hippocampal plasticity processes. At this aim wt and CX3CR1GFP/GFP mice were exposed to long-lasting-enriched environment (EE and the effects on hippocampal functions were studied by electrophysiological recordings of long-term potentiation (LTP of synaptic activity, behavioral tests of learning and memory in the Morris water maze paradigm and analysis of neurogenesis in the subgranular zone of the dentate gyrus (DG.We found that CX3CR1 deficiency increases hippocampal plasticity and spatial memory blunting the potentiating effects of EE. In contrast, exposure to EE increased the number and migration of neural progenitors in the DG of both wt and CX3CR1GFP/GFP mice. These data indicate that CX3CL1/CX3CR1-mediated signaling is crucial for a normal experience-dependent modulation of hippocampal functions.

  19. A Revised Host Galaxy Association for GRB 020819B: A High-Redshift Dusty Starburst, Not a Low-Redshift Gas-Poor Spiral

    CERN Document Server

    Perley, Daniel A; Schady, Patricia; Michałowski, Michał J; Thöne, Christina C; Petry, Dirk; Graham, John F; Greiner, Jochen; Schulze, Steve; Kim, Sam

    2016-01-01

    The purported spiral host galaxy of GRB 020819B at z=0.41 has been seminal in establishing our view of the diversity of long-duration gamma-ray burst environments: optical spectroscopy of this host provided evidence that GRBs can form even at high metallicities, while millimetric observations suggested that GRBs may preferentially form in regions with minimal molecular gas. We report new observations from VLT (MUSE and X-shooter) which demonstrate that the purported host is an unrelated foreground galaxy. The probable radio afterglow is coincident with a compact, highly star-forming, dusty galaxy at z=1.9621. The revised redshift naturally explains the apparent nondetection of CO(3-2) line emission at the afterglow site from ALMA. There is no evidence that molecular gas properties in GRB host galaxies are unusual, and limited evidence that GRBs can form readily at super-Solar metallicity.

  20. CX3CR1在炎症性肠病(IBD)中的表达及意义

    Institute of Scientific and Technical Information of China (English)

    陆海炳; 屠惠明; 胡小丹

    2013-01-01

    目的探讨趋化因子受体CX3CR1在炎症性肠病患者肠组织中的表达以及与疾病活动的相关性。方法收集45例确诊的IBD患者及30例正常人的肠组织标本。用免疫组化技术检测CX3CR1蛋白的表达,并进一步分析其与IBD的关系。结果 CX3CR1在正常中表达阳性率为13.3%(4/30),明显低于IBD组77.8%(35/45)、IBD活动期组87.5%(28/32)及IBD缓解期组53.8%(7/13);其中后二者又在统计学上有显著差异性,同时活动期组淋巴细胞CX3CR1较其他组明显高表达。结论 CX3CR1在IBD中显著高表达,且CX3CR1蛋白与IBD的严重程度相关。提示CX3CR1可能在IBD的发生发展中发挥重要作用。

  1. Sintering AL2O3-CR composites made from micro-and Nan powders

    Directory of Open Access Journals (Sweden)

    Pietrzak K.

    2004-01-01

    Full Text Available This paper presents the results of studies on sintering Al2O3-Cr composites of different chemical compositions (from 25 to 75 vol.% of each component. The factor analyzed was the influence of time (from 15 to 60 min temperature (from 1200-1600°C, pressure (0.5 and 30 MPa and powder graining (for Al2O3 powders-80nm or 1μm on the density of sinters obtained. It was found that Nan powder composites are characterized by a higher density (by about 1-2% than the micro powder composite, the remaining conditions of the process intact. Using the pressure of 30MPa allows obtaining of a definite sintering degree at a temperature of about 200°C lower than at a pressure of 0.5 MPa.

  2. Modulating neurotoxicity through CX3CL1/CX3CR1 signaling

    Directory of Open Access Journals (Sweden)

    Cristina eLimatola

    2014-08-01

    Full Text Available Since the initial cloning of fractalkine/CX3CL1, it was proposed that the only known member of the CX3C or delta subfamily of chemotactic cytokines could play some significant role in the nervous system, due to its high expression on neurons. The pivotal description of the localization of the unique CX3CL1 receptor, CX3CR1, on microglial cells, firmed up by the generation of cx3cr1GFP/GFP mice, opened the road to the hypothesis of some specific key interactions between microglia and neurons mediated by this pair. This expectation has been indeed supported by recent exciting evidence indicating that CX3CL1-mediated microglia-neuron interaction modulates basic physiological activities during development, adulthood and aging, including: synaptic pruning; promoting survival of neurons and neural precursors; modulating synaptic transmission and plasticity; enhancing synapse and network maturation; and facilitating the establishment of neuropathic pain circuits. Beyond playing such fascinating roles in physiological conditions, CX3CL1 signaling has been implicated in different neuropathologies. Early papers demonstrated that the levels of CX3CL1 may be modulated by various toxic stimuli in vitro and that CX3CL1 signaling is positively or negatively regulated in EAE and MS, in HIV infection and LPS challenge, in epilepsy, in brain tumors, and in other neuropathologies. In this review we focus on the experimental evidence of CX3CL1 involvement in neuroprotection and survey the common molecular and cellular mechanisms described in different brain diseases.

  3. Hydrogen sulfide inhibits the development of atherosclerosis with suppressing CX3CR1 and CX3CL1 expression.

    Directory of Open Access Journals (Sweden)

    Huili Zhang

    Full Text Available Hydrogen sulfide, as a novel gaseous mediator, has been suggested to play a key role in atherogenesis. However, the precise mechanisms by which H(2S affects atherosclerosis remain unclear. Therefore, the present study aimed to investigate the potential role of H(2S in atherosclerosis and the underlying mechanism with respect to chemokines (CCL2, CCL5 and CX3CL1 and chemokine receptors (CCR2, CCR5, and CX3CR1 in macrophages. Mouse macrophage cell line RAW 264.7 or mouse peritoneal macrophages were pre-incubated with saline or NaHS (50 µM, 100 µM, 200 µM, an H(2S donor, and then stimulated with interferon-γ (IFN-γ or lipopolysaccharide (LPS. It was found that NaHS dose-dependently inhibited IFN-γ or LPS-induced CX3CR1 and CX3CL1 expression, as well as CX3CR1-mediated chemotaxis in macrophages. Overexpression of cystathionine γ-lyase (CSE, an enzyme that catalyzes H(2S biosynthesis resulted in a significant reduction in CX3CR1 and CX3CL1 expression as well as CX3CR1-mediated chemotaxis in stimulated macrophages. The inhibitory effect of H(2S on CX3CR1 and CX3CL1 expression was mediated by modulation of proliferators-activated receptor-γ (PPAR-γ and NF-κB pathway. Furthermore, male apoE(-/- mice were fed a high-fat diet and then randomly given NaHS (1 mg/kg, i.p., daily or DL-propargylglycine (PAG, 10 mg/kg, i.p., daily. NaHS significantly inhibited aortic CX3CR1 and CX3CL1 expression and impeded aortic plaque development. NaHS had a better anti-atherogenic benefit when it was applied at the early stage of atherosclerosis. However, inhibition of H(2S formation by PAG increased aortic CX3CR1 and CX3CL1 expression and exacerbated the extent of atherosclerosis. In addition, H(2S had minimal effect on the expression of CCL2, CCL5, CCR2 and CCR5 in vitro and in vivo. In conclusion, these data indicate that H(2S hampers the progression of atherosclerosis in fat-fed apoE(-/- mice and downregulates CX3CR1 and CX3CL1 expression on macrophages and

  4. EFFECT OF LONGEVITY OF 3Cr2W8V HOT-FORGE-DIE BY STRENGTHENING AND TOUGHENING%强韧化处理对3Cr2W8V热锻模寿命的影响

    Institute of Scientific and Technical Information of China (English)

    胡斌梁; 彭妙才

    1999-01-01

    通过对3Cr2W8V热锻模失效组织的电镜观测和对断裂韧性KIC值的测定,认为KIC值偏低是3Cr2W8V热锻模早期开裂和热疲劳的主要原因.实践证明,采用1 200 ℃高温淬火和680 ℃高温回火(即高淬高回)的新工艺,能大幅度提高材料的KIC值,延长该类模具寿命4倍左右.因而KIC值是3Cr2W8V热锻模的主要韧性指标,而冲击韧性αK值仅能作为参考.图2,表1,参6.

  5. Preliminary study correlating CX3CL1/CX3CR1 expression with gastric carcinoma and gastric carcinoma perineural invasion.

    Science.gov (United States)

    Lv, Cheng-Yu; Zhou, Tao; Chen, Wei; Yin, Xin-Dao; Yao, Jian-Hong; Zhang, Yi-Fan

    2014-04-21

    To study the relationship between the CX3CL1 chemokine, its receptor CX3CR1, and gastric carcinoma/gastric carcinoma perineural invasion (PNI). Thirty cases of gastric carcinoma were surgically resected (radical resection or palliative resection) between February 2012 and July 2012. Tumour and tumour-adjacent tissues were evaluated for the presence of CX3CL1 (ELISA) and CX3CR1 (immunohistochemistry and Western blotting) in an effort to analyse the relationship between CX3CL1/CX3CR1 and gastric carcinoma/gastric carcinoma PNI. Of these 30 cases, 14 were PNI-positive (46.7%). No significant differences in CX3CL and CX3CR1 expression in tumour-adjacent tissues were found between the PNI positive and negative groups. Expression levels of CX3CL and CX3CR1 in tumour tissues were significantly higher than those in adjacent tissues (P gastric carcinoma as well as gastric carcinoma PNI.

  6. A revised host galaxy association for GRB 020819B: a high-redshift dusty starburst, not a low-redshift gas-poor spiral

    Science.gov (United States)

    Perley, Daniel A.; Krühler, Thomas; Schady, Patricia; Michałowski, Michał J.; Thöne, Christina C.; Petry, Dirk; Graham, John F.; Greiner, Jochen; Klose, Sylvio; Schulze, Steve; Kim, Sam

    2017-02-01

    The purported spiral host galaxy of GRB 020819B at z = 0.41 has been seminal in establishing our view of the diversity of long-duration gamma-ray burst environments: Optical spectroscopy of this host provided evidence that gamma-ray bursts (GRBs) can form even at high metallicities, whereas millimetric observations suggested that GRBs may preferentially form in regions with minimal molecular gas. We report new observations from the Very Large Telescope (Multi Unit Spectroscopic Explorer and X-shooter), which demonstrate that the purported host is an unrelated foreground galaxy. The probable radio afterglow is coincident with a compact, highly star forming, dusty galaxy at z = 1.9621. The revised redshift naturally explains the apparent non-detection of CO(3-2) line emission at the afterglow site from the Atacama Large Millimetre Observatory. There is no evidence that molecular gas properties in GRB host galaxies are unusual, and limited evidence that GRBs can form readily at a super-Solar metallicity.

  7. Effect of silty sand with different sizes on corrosion behavior of 3Cr steel in CO2 aqueous environment

    Science.gov (United States)

    Liu, Wei; Lu, Songle; Zhang, Peng; Dou, Juanjuan; Zhao, Qinghe

    2016-08-01

    Corrosion behavior of 3Cr steel in CO2 aqueous environment containing silty sand was investigated by immersion test. The results show that CO2 corrosion rate and morphology of 3Cr steel were obviously affected by the size of silty sand. 5000 mesh silty sand mixed with corrosion products, forming compact Cr-rich corrosion scale and resulting in low corrosion rate and uniform corrosion. 1000 mesh silty sand mixed with corrosion products, forming porous corrosion scale without Cr enrichment and resulting in high corrosion rate and pitting corrosion. 5000 mesh silty sand enhanced Cr enrichment in corrosion scale, leading to low anodic current. However, 1000 mesh silty sand deteriorated Cr enrichment in corrosion scale, leading to high anodic current. Cathodic current was reduced by silty sand, but was not affected by two sizes of silty sand. Cr enrichment in corrosion scale of 3Cr steel was obviously affected by separation effect of silty sand.

  8. Properties of sintered Al2O3-Cr composites depending on the method of preparation of the powder mixture

    Directory of Open Access Journals (Sweden)

    Chmielewski M.

    2006-01-01

    Full Text Available Continuous progress in modern science and industry depends on the availability of new effective devices and materials. New generation materials should be characterized by a specified combination of properties which sometimes exclude one another. Al2O3-Cr composites belong to this group of materials. This study is concerned with the effect of the method of preparation of the starting powders upon the properties of sintered Al2O3-Cr composites. The composites were produced using powder mixtures with various volumetric shares of the starting powders (from 25 to 75vol.%. The mixtures were prepared by conventional mechanical mixing in a ball-mill or by mechanical alloying in a high-energy mill of the attritor type. It has been found that with mechanically alloyed powders the Al2O3-Cr composites have better bending strength, hardness and frictional wear resistance.

  9. Constraining the Redshift Evolution of FIRST Radio Sources in RCS1 Galaxy Clusters

    CERN Document Server

    Gralla, Megan B; Yee, H K C; Barrientos, L Felipe

    2010-01-01

    We conduct a statistical analysis of the radio source population in galaxy clusters as a function of redshift by matching radio sources from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) catalog with 618 optically-selected galaxy clusters from the first Red-Sequence Cluster Survey (RCS1). The number of excess radio sources (above the background level) per cluster is 0.14 +/- 0.02 for clusters with 0.35 1.5 sigma) in the number of radio sources per unit of cluster mass for the galaxy clusters with 0.35 4.1 X 10^(24) W/Hz) radio sources per unit (10^14 solar masses) mass, which we measure to be 0.031 +/- 0.004. We further characterize the population of galaxy cluster-related radio sources through visual inspection of the RCS1 images, finding that although the radio activity of brightest cluster galaxies (BCGs) also does not strongly evolve between our high and low redshift samples, the lower-redshift, richest clusters are more likely to host radio-loud BCGs than the higher-redshift, rich est...

  10. Accretion/Jet Activity and Narrow [O III] Kinematics in Young Radio Galaxies

    CERN Document Server

    Wu, Qingwen; Humphrey, Andrew

    2009-01-01

    We estimate black hole masses and Eddington ratios for a sample of 81 young radio galaxies (42 CSS +39 GPS). We find that the average black hole (BH) mass of these young radio galaxies is ~8.3, which is less than that of radio loud QSOs and low redshift radio galaxies. The CSS/GPS sources have relatively high Eddington ratios, with an average value of =-0.75, which are similar to those of narrow line Seyfert 1 galaxies (NLS1s). This suggests that young radio galaxies may not only be in the early stages of their radio activity, but also in the early stage of their accretion activity. We find that the young radio galaxies as a class deviate systematically from M_bh-\\sigma relation defined by nearby inactive galaxies, when using [O III] as a surrogate for stellar velocity dispersion, \\sigma_* . We also find that the deviation of the [O III] line width is correlated with the Eddington ratio and sources with Lbol/LEdd~1 have the largest deviations, which are similar to those of radio quiet QSOs/NLS1s (radio jets i...

  11. Constraining neutrino mass and extra relativistic degrees of freedom in dynamical dark energy models using Planck 2015 data in combination with low-redshift cosmological probes: basic extensions to $\\Lambda$CDM cosmology

    CERN Document Server

    Zhao, Ming-Ming; Zhang, Xin

    2016-01-01

    We investigate how the properties of dark energy affect the cosmological measurements of neutrino mass and extra relativistic degrees of freedom. We limit ourselves to the most basic extensions of $\\Lambda$CDM model, i.e., the $w$CDM model with one additional parameter $w$, and the $w_{0}w_{a}$CDM model with two additional parameters, $w_{0}$ and $w_{a}$. In the cosmological fits, we employ the 2015 CMB temperature and polarization data from the Planck mission, in combination with low-redshift measurements such as the baryon acoustic oscillations (BAO), type Ia supernovae (SN) and the Hubble constant ($H_{0}$). Given effects of massive neutrinos on large-scale structure, we further include weak lensing (WL), redshift space distortion (RSD), Sunyaev-Zeldovich cluster counts (SZ), and Planck lensing data. We find that $w$ is anti-correlated with $\\sum m_{\

  12. Radio archive

    OpenAIRE

    Street, Sean

    2008-01-01

    The Centre for Broadcasting History Research, in association with the\\ud British Universities Film and Video Council, is developing an online\\ud audio archive of UK commercial radio, from 1973 to 1992. Work produced\\ud before the Broadcasting Act 1990 represents a different ethos to the role\\ud commercial radio played, and subsequently,continues to play, in the UK.\\ud The change in commercial radio since this period is extraordinary. It is\\ud impossible for the young student of radio, born si...

  13. Galaxy Clusters Around z 1-2 Low Luminosity Radio Galaxies

    Science.gov (United States)

    Castignani, Gianluca

    2017-07-01

    At variance with powerful radio galaxies Low Luminosity Radio Galaxies (LLRGs) are almost invariably found in clusters and often associated with the brightest cluster galaxies, at least at low-redshifts. In order to prove that this holds also at high-z we exploit a sample of 32 LLRGs at z 1-2 drawn from the COSMOS survey and search for Mpc-scale overdensities using photometric redshifts and our recently developed Poisson Probability Method. We find that 70% of the LLRGs reside in rich groups or (proto-)clusters. This fraction is higher than that found for powerful radio galaxies at similar redshifts and is in excellent agreement with results obtained at low redshifts. Independent confirmation of some of our cluster candidates is found in catalogs of clusters selected in X-rays or spectroscopically. Our strategy is unbiased with respect to colors and star formation history of cluster galaxies and represents a valuable alternative to conventional methods that search for clusters. We observed with the 30 m IRAM telescope two of our z = 1 LLRGs in clusters to search for molecular gas and set CO upper limits. Our clusters are optimal targets for mm observations with NOEMA and ALMA.

  14. Microglial CX3CR1 promotes adult neurogenesis by inhibiting Sirt 1/p65 signaling independent of CX3CL1.

    Science.gov (United States)

    Sellner, Sabine; Paricio-Montesinos, Ricardo; Spieß, Alena; Masuch, Annette; Erny, Daniel; Harsan, Laura A; Elverfeldt, Dominik V; Schwabenland, Marius; Biber, Knut; Staszewski, Ori; Lira, Sergio; Jung, Steffen; Prinz, Marco; Blank, Thomas

    2016-09-17

    Homo and heterozygote cx3cr1 mutant mice, which harbor a green fluorescent protein (EGFP) in their cx3cr1 loci, represent a widely used animal model to study microglia and peripheral myeloid cells. Here we report that microglia in the dentate gyrus (DG) of cx3cr1 (-/-) mice displayed elevated microglial sirtuin 1 (SIRT1) expression levels and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) p65 activation, despite unaltered morphology when compared to cx3cr1 (+/-) or cx3cr1 (+/+) controls. This phenotype was restricted to the DG and accompanied by reduced adult neurogenesis in cx3cr1 (-/-) mice. Remarkably, adult neurogenesis was not affected by the lack of the CX3CR1-ligand, fractalkine (CX3CL1). Mechanistically, pharmacological activation of SIRT1 improved adult neurogenesis in the DG together with an enhanced performance of cx3cr1 (-/-) mice in a hippocampus-dependent learning and memory task. The reverse condition was induced when SIRT1 was inhibited in cx3cr1 (-/-) mice, causing reduced adult neurogenesis and lowered hippocampal cognitive abilities. In conclusion, our data indicate that deletion of CX3CR1 from microglia under resting conditions modifies brain areas with elevated cellular turnover independent of CX3CL1.

  15. Effect of microstructure on slag resistance of Al2 O3-Cr2 O3 bricks%Al2O3-Cr2O3砖显微结构对抗渣性能的影响

    Institute of Scientific and Technical Information of China (English)

    孙红刚; 李鹏涛; 付建莹; 闫双志; 王刚; 耿可明

    2014-01-01

    The slag resistance of two Al2 O3-Cr2 O3 bricks (with 10 mass%Cr2 O3 )A and B were researched using static crucible method and rotary slag method,respectively.The results show that,two Al2 O3-Cr2 O3 bricks have similar properties such as apparent porosity,bulk density,thermal shock resistance,and chem-ical compositions.Brick B has higher strength than brick A.Compared with brick B:brick A has smaller in-ner pores,because the white corundum aggregates in brick A are smoother and denser with continuous particle size distribution;Al2 O3-Cr2 O3 solid solution in brick A is smaller,crossing and forming net structure with small gaps,which reduces the penetration and wear of slag to refractories,meaning that brick A has better slag resistance than brick B.It’s obvious that optimizing microstructure is an effective way to im-prove the slag resistance of Al2 O3-Cr2 O3 materials.%分别采用静态坩埚抗渣法和回转抗渣法,对w(Cr2 O3)=10%的A和B两种Al2 O3-Cr2 O3砖进行了抗渣性能对比。结果发现:两种砖的化学组成、显气孔率、体积密度和抗热震性相近,B砖强度优于A砖的。但由于与B砖相比,A砖内部气孔尺寸更小,所用电熔白刚玉骨料形貌平滑,较为致密,粒度呈连续式分布,且A砖中Al2 O3-Cr2 O3固溶体发育较小,相互交错,形成了孔隙较小的空间网状结构,这种显微结构显著降低了熔渣对耐火材料的渗透和破坏,使A砖的抗渣性优于B砖的。因此,制备微气孔化结构的制品是提高Al2 O3-Cr2 O3材料抗渣性能的有效途径。

  16. Wear Resistance of 3Cr2W8V Rough Surfaces

    Institute of Scientific and Technical Information of China (English)

    Zhou Hong; Wang Wei; Ren Lu-quan; Li Yue; Li Chen

    2005-01-01

    Three types of rough surface were processed by laser irradiation on the 3Cr2W8V material hot-work die steel surface.The wear experiments with smooth surface and rough surface samples were repeated on the pin-tray wear machine. According to the wear results, we studied the regularity of wear resistance of different rough surface samples. The results indicated that bionic rough surface can improve the wear resistance of the material and the wear resistance can be increased 1 -2times, compared with the smooth surface. Also, the wear resistance of the rough surface was affected by laser current and duration of impulse. The bigger the laser current or the impulse duration, the better is the wear resistance. When the distance between the same kind of units which are distributed on the surfaces is changed, the wear resistance changes. The wear resistance of a bionic rough surface on which the grid units were distributed at spacing of 1 mm was the best. And we designed the wear models.

  17. Magnetic Properties of Epitaxial Cr/Cr2O3/ Cr Multilayers

    Science.gov (United States)

    Mukherjee, Tathagata; Sahoo, Sarbeswar; Binek, Christian

    2007-03-01

    We study Cr/Cr2O3/Cr trilayer structures grown by Molecular Beam Epitaxy on (111) oriented Al2O3 substrates. X-ray diffraction reveals perfect single crystalline (110) Cr and stoichiometric single crystalline Cr2O3 (111) films. Both, Cr and Cr2O3 order antiferromagnetically with bulk N'eel temperatures of 311 and 307K, respectively. Cr is an itinerant antiferromagnet where the antiferromagnetic (AF) order establishes as an incommensurate spin density wave. Cr2O3 in contrast is an AF insulator with localized magnetic moments where magnetoelectric and piezomagnetic effects are both symmetry allowed. Its insulating, magnetoelectric and piezoelectric properties make Cr2O3 an interesting material for extrinsically controlled tunnel barriers in TMR type structures. The lattice mismatch of ˜1.2% at the Cr -- Cr2O3 interface creates a strong stress induced piezomagnetic moment revealed by SQUID measurements. The interaction between the piezomoment and the spin distribution at the Cr- interface gives rise to a rich scenario of magnetic proximity effects which we study by SQUID magnetometry, magneto-optical Kerr effect and electrical transport measurements.

  18. Effect of calcium ions on CO2 corrosion of 3Cr low-alloy steel

    Institute of Scientific and Technical Information of China (English)

    Zhijun JIA; Cuiwei DU; Zhiyong LIU; Jin GAO; Xiaogang LI

    2011-01-01

    The effect of calcium ions on the corrosion behavior of 3Cr low-alloy steel in CO2containing sodium chloride solution was investigated by immersion test and electrochemical measurements.It is found that with the addition of Ca2+ to CO2-containing solution,the crazing level of the corrosion scale on the specimen is much slighter than that of the specimen immersed in solution without Ca2+.The pitting on the surface of the specimens immersed in the solution with Ca2+ is relatively small and distributes uniformly all over the surface.The significant change in the anodic polarization curve is attributed to the deposition of the CaCO3.CaCO3 deposits on the specimen surface and gives a protection to the metal substrate.And with the anodic proceeding,the concentration of H+ in the solution increases.The CaCO3 deposition dissolves in the low pH solution and the protection effect disappears.

  19. Garnet-type Mn3Cr2(GeO43

    Directory of Open Access Journals (Sweden)

    Christian Lipp

    2012-05-01

    Full Text Available Single crystals of garnet-type trimanganese(II dichromium(III tris[orthogermanate(IV], MnII3CrIII2(GeO43, were obtained by utilizing a chemical transport reaction. Corresponding to the mineral garnet with the general formula AII3BIII2(SiO43, each of the four elements occupies only one crystallographically distinct position. Mn2+ occupies the respective A position (Wyckoff site 24c, site symmetry 2.22, being surrounded by eight O atoms that form a distorted cube [d(Mn—O = 2.291 (2 and 2.422 (2 Å, 4× each], while Cr3+ on the B position (Wyckoff site 16a, site symmetry .-3. is situated in a slightly distorted octahedron of six O2− anions [d(Cr—O = 1.972 (2 Å, 6×]. In addition, the O atoms on general site 96h form isolated [GeO4]4− tetrahedra with Ge4+ on site 24d [site symmetry -4..; d(Ge—O = 1.744 (2 Å, 4×].

  20. Extragalactic Jets as Probes of Distant Clusters of Galaxies and the Clusters Occupied by Bent Radio AGN (COBRA) Survey

    CERN Document Server

    Blanton, Elizabeth L; Wing, Joshua D; Ashby, M L N; Golden-Marx, Emmet; Brodwin, Mark; Douglass, E M; Randall, Scott W; Clarke, T E

    2014-01-01

    We are conducting a large survey of distant clusters of galaxies using radio sources with bent jets and lobes as tracers. These radio sources are driven by AGN and achieve their bent morphologies through interaction with the surrounding gas found in clusters of galaxies. Based on low-redshift studies, these types of sources can be used to identify clusters very efficiently. We present initial results from our survey of 653 bent-double radio sources with optical hosts too faint to appear in the SDSS. The sample was observed in the infrared with Spitzer, and it has revealed $\\sim$200 distant clusters or proto-clusters in the redshift range $z\\sim0.7 - 3.0$. The sample of bent-doubles contains both quasars and radio galaxies enabling us to study both radiative and kinetic mode feedback in cluster and group environments at a wide range of redshifts.

  1. Polymorphism of the Fractalkine Receptor CX3CR1 and Systemic Sclerosis-associated Pulmonary Arterial Hypertension

    Directory of Open Access Journals (Sweden)

    Bianca Marasini

    2005-01-01

    Full Text Available Fractalkine (FKN and its receptor CX3CR1 are critical mediators in the vascular and tissue damage of several chronic diseases, including systemic sclerosis (SSc and pulmonary arterial hypertension (PAH. Interestingly, the V249I and T280M genetic polymorphisms influence CX3CR1 expression and function. We investigated whether these polymorphisms are associated with PAH secondary to SSc. CX3CR1 genotypes were analyzed by PCR and sequencing in 76 patients with limited SSc and 204 healthy controls. PAH was defined by colorDoppler echocardiography. Homozygosity for 249II as well as the combined presence of 249II and 280MM were significantly more frequent in patients with SSc compared to controls (17 vs 6%, p = 0.0034 and 5 vs 1%, p = 0.0027, respectively. The 249I and 280M alleles were associated with PAH (odd ratio [OR] 2.2, 95% confidence interval [CI] 1.01-4.75, p = 0.028 and OR 7.37, 95%CI: 2.45-24.60, p = 0.0001, respectively. In conclusion, the increased frequencies of 249I and 280M CX3CR1 alleles in a subgroup of patients with SSc-associated PAH suggest a role for the fractalkine system in the pathogenesis of this condition. Further, the 249I allele might be associated with susceptibility to SSc.

  2. Two polymorphisms in the Fractalkine receptor CX3CR1 gene influence the development of atherosclerosis: a meta-analysis.

    Science.gov (United States)

    Wu, Jian; Yin, Rui-Xing; Lin, Quan-Zhen; Guo, Tao; Shi, Guang-Yuan; Sun, Jia-Qi; Shen, Shao-Wen; Li, Qing

    2014-01-01

    The associations between the Fractalkine receptor (CX3CR1) gene T280M (rs3732378) and V249I (rs3732379) polymorphisms and atherosclerosis (AS) risk are conflicting. The aim of this meta-analysis was undertaken to assess their associations. PubMed, Embase, Web of Science, Medline, Cochrane database, and CNKI were searched to get the genetic association studies. All statistical analyses were done with Stata 11.0. Twenty-five articles involving 49 studies were included in the final meta-analysis. The analysis showed that the 280M allele carriers of the CX3CR1 T280M polymorphism decreased the risk of AS and coronary artery disease (CAD) in the heterozygous state but increased the risk of ischemic cerebrovascular disease (ICVD) in the homozygote state. The 249I allele carriers of the CX3CR1 V249I polymorphism decreased the risk of AS and CAD in the heterozygous state. The V249I-T280M combined genotype VITM and IITM also decreased the risk of AS. The present meta-analysis suggests that the CX3CR1 T280M and V249I polymorphisms are associated with the susceptibility to AS. However, the results should be interpreted with caution because of the high heterogeneity in the meta-analysis.

  3. Two Polymorphisms in the Fractalkine Receptor CX3CR1 Gene Influence the Development of Atherosclerosis: A Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Jian Wu

    2014-01-01

    Full Text Available Background. The associations between the Fractalkine receptor (CX3CR1 gene T280M (rs3732378 and V249I (rs3732379 polymorphisms and atherosclerosis (AS risk are conflicting. The aim of this meta-analysis was undertaken to assess their associations. Methods. PubMed, Embase, Web of Science, Medline, Cochrane database, and CNKI were searched to get the genetic association studies. All statistical analyses were done with Stata 11.0. Results. Twenty-five articles involving 49 studies were included in the final meta-analysis. The analysis showed that the 280M allele carriers of the CX3CR1 T280M polymorphism decreased the risk of AS and coronary artery disease (CAD in the heterozygous state but increased the risk of ischemic cerebrovascular disease (ICVD in the homozygote state. The 249I allele carriers of the CX3CR1 V249I polymorphism decreased the risk of AS and CAD in the heterozygous state. The V249I-T280M combined genotype VITM and IITM also decreased the risk of AS. Conclusions. The present meta-analysis suggests that the CX3CR1 T280M and V249I polymorphisms are associated with the susceptibility to AS. However, the results should be interpreted with caution because of the high heterogeneity in the meta-analysis.

  4. Radio Eska Lodz, Commercial Radio As a Local Radio

    OpenAIRE

    Szews, Przemysław

    2015-01-01

    The article discusses aspects of network-based local radio using the example of Radio Eska Lodz. The author responds to questions about whether a commercial network radio station can fulfill the functions of local radio and on what this locality is actually based. In this respect, Radio Eska Lodz is characterized as part of the most popular commercial radio network in Poland. The introduction focuses on the process of transformation that local radio stations are undergoing, along with its gen...

  5. Solar Radio

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Scientists monitor the structure of the solar corona, the outer most regions of the Sun's atmosphere, using radio waves (100?s of MHz to 10?s of GHz). Variations in...

  6. Microglia and their CX3CR1 signaling are involved in hippocampal- but not olfactory bulb-related memory and neurogenesis.

    Science.gov (United States)

    Reshef, Ronen; Kreisel, Tirzah; Beroukhim Kay, Dorsa; Yirmiya, Raz

    2014-10-01

    Recent studies demonstrate that microglia play an important role in cognitive and neuroplasticity processes, at least partly via microglial CX3C receptor 1 (CX3CR1) signaling. Furthermore, microglia are responsive to environmental enrichment (EE), which modulates learning, memory and neurogenesis. In the present study we examined the role of microglial CX3CR1 signaling in hippocampal- and olfactory-bulb (OB)-related memory and neurogenesis in homozygous mice with microglia-specific transgenic expression of GFP under the CX3CR1 promoter (CX3CR1(-/-) mice), in which the CX3CR1 gene is functionally deleted, as well as heterozygous CX3CR1(+/-) and WT controls. We report that the CX3CR1-deficient mice displayed better hippocampal-dependent memory functioning and olfactory recognition, along with increased number and soma size of hippocampal microglia, suggestive of mild activation status, but no changes in OB microglia. A similar increase in hippocampal-dependent memory functioning and microglia number was also induced by pharmacological inhibition of CX3CR1 signaling, using chronic (2weeks) i.c.v. administration of CX3CR1 blocking antibody. In control mice, EE improved hippocampal-dependent memory and neurogenesis, and increased hippocampal microglia number and soma size, whereas odor enrichment (OE) improved olfactory recognition and OB neurogenesis without changing OB microglia status. In CX3CR1-deficient mice, EE and OE did not produce any further improvement in memory functioning or neurogenesis and had no effect on microglial status. These results support the notion that in the hippocampus microglia and their interactions with neurons via the CX3CR1 play an important role in memory functioning and neurogenesis, whereas in the OB microglia do not seem to be involved in these processes.

  7. W9Mo3Cr4V钢软氮化及组织性能%Microstructure and Properties of W9Mo3Cr4V Steel After Nitrocarburizing

    Institute of Scientific and Technical Information of China (English)

    邓莉萍; 罗军明

    2013-01-01

    对W9Mo3Cr4V钢进行气体软氮化处理,研究氮化处理对钢组织及性能的影响.结果表明:采用甲酰胺为渗剂进行气体软氮化可得到约50μm的致密渗层,可有效提高W9Mo3Cr4V钢的硬度和耐磨性.经软氮化后,钢的表面硬度达到1150 HV0.1,而磨损速率约为3.9 mg/h,为未经软氮化的1/5.

  8. 3Cr-1Mo-1/4V钢制加氢反应器的设计%Dising of 3Cr-1Mo-1/4V Steel Hydrogenated Reactor

    Institute of Scientific and Technical Information of China (English)

    栾海林; 崔云海

    2002-01-01

    抚顺石化分公司1200kt/a催化柴油中压加氢精制(改质)装置中的两台高温高压加氢反应器,由于采用了抗氢性能好、应力强度高的3Cr-1Mo-1/4V新材料,同时采用了有限元分析设计法,因此不仅降低了反应器壳体的厚度,更重要的是提高了反应器的综合技术性能.另外,对3Cr-1Mo-1/4V新型抗氢钢的推广应用起到了积极的促进作用.

  9. Determinations of Key Physical Parameters Related to Classical Double Radio Sources

    CERN Document Server

    Wan, L; Guerra, E J; Wan, Lin; Daly, Ruth A.

    2000-01-01

    Multi-frequency radio observations of the radio bridge of a powerful classical double radio source can be used to determine: the beam power of the jets emanating from the AGN; the total time the source will actively produce jets that power large-scale radio emission; the thermal pressure of the medium in the vicinity of the radio source; and the total mass, including dark matter, of the galaxy or cluster of galaxies traced by the ambient gas that surrounds the radio source. Empirical determinations of each of these quantities are obtained and analyzed for 22 radio sources. Typical beam powers are about $10^{45} {erg s}^{-1}$. The characteristic or total time the AGN will actively produce a collimated outflow is estimated. Typical total lifetimes are $\\sim (10^7$ to $10^8$) years. Total masses, and mass-density profiles, similar to those of low-redshift clusters of galaxies are obtained. Thus, some clusters of galaxies, or cores of clusters, exist at redshifts of one to two. A new method of estimating the ther...

  10. The link between accretion mode and environment in radio-loud active galaxies

    CERN Document Server

    Ineson, Judith; Hardcastle, Martin J; Kraft, Ralph P; Evans, Daniel A; Jarvis, Matt J

    2015-01-01

    The interactions between radio-loud AGN and their environments play an important r\\^{o}le in galaxy and cluster evolution. Recent work has demonstrated fundamental differences between High and Low Excitation Radio Galaxies (HERGs and LERGs), and shown that they may have different relationships with their environments. In the Chandra Large Project ERA (Environments of Radio-loud AGN), we made the first systematic X-ray environmental study of the cluster environments of radio galaxies at a single epoch (z~0.5), and found tentative evidence for a correlation between radio luminosity and cluster X-ray luminosity. We also found that this relationship appeared to be driven by the LERG sub-population (Ineson et al. 2013). We have now repeated the analysis with a low redshift sample (z~0.1), and found strong correlations between radio luminosity and environment richness and between radio luminosity and central density for the LERGs but not for the HERGs. These results are consistent with models in which the HERGs are...

  11. $\\textit{Herschel}$-ATLAS:The connection between star formation and AGN activity in radio-loud and radio-quiet active galaxies

    CERN Document Server

    Gurkan, G; Jarvis, M J; Smith, D J B; Bourne, N; Dunne, L; Maddox, S; Ivison, R J; Fritz, J

    2015-01-01

    We examine the relationship between star formation and AGN activity by constructing matched samples of local ($0radio-loud and radio-quiet AGN in the $\\textit{Herschel}$-ATLAS fields. Radio-loud AGN are classified as high-excitation and low-excitation radio galaxies (HERGs, LERGs) using their emission lines and $\\textit{WISE}$ 22-$\\mu$m luminosity. AGN accretion and jet powers in these active galaxies are traced by [OIII] emission-line and radio luminosity, respectively. Star formation rates (SFRs) and specific star formation rates (SSFRs) were derived using $\\textit{Herschel}$ 250-$\\mu$m luminosity and stellar mass measurements from the SDSS$-$MPA-JHU catalogue. In the past, star formation studies of AGN have mostly focused on high-redshift sources to observe the thermal dust emission that peaks in the far-infrared, which limited the samples to powerful objects. However, with $\\textit{Herschel}$ we can expand this to low redshifts. Our stacking analyses show that SFRs and SSFRs of both radio-l...

  12. Síntese do pigmento cerâmico verde vitória (Ca3Cr2Si3O12 a partir de CaCO3, Cr2O3 e SiO2 Synthesis of the Ceramic Pigment Victoria Green (Ca3Cr2Si3O12 from CaCO3, Cr2O3 and SiO2

    Directory of Open Access Journals (Sweden)

    Viviana Possamai Della

    2008-01-01

    Full Text Available The synthesis of the ceramic pigment Victoria Green (Ca3Cr2Si3O12 is described. As raw materials CaCO3, Cr2O3, and SiO2 obtained from rice husk were used. Borax was used as mineralizer. Raw materials were formulated stoichiometrically and calcined from 1000 to 1200 ºC for 180 min. The main phase detected was uvarovite with particle size below 45 mm. The pigments were applied on ceramic tiles and sintered at 1150 ºC for 40 min. The synthesis process showed to be adequate to produce the green pigment, whose characteristics resemble those of a commercial pigment.

  13. Chandra ACIS-S Observations of Three Quasars with Low-Redshift Damped Ly-alpha Absorption Constraints on the Cosmic Neutral-Gas-Phase Metallicity at Redshift z \\approx 0.4

    CERN Document Server

    Turnshek, D A; Ptak, A F; Griffiths, R E; Monier, E M; Turnshek, David A.; Rao, Sandhya M.; Ptak, Andrew F.; Griffiths, Richard E.; Monier, Eric M.

    2003-01-01

    Chandra X-Ray Observatory (CXO) ACIS-S spectra of three quasars which lie behind three foreground damped Lyman alpha (DLA) absorbers are analyzed in order to attempt to determine the amount of photoelectric absorption due to metals present in their x-ray spectra. These absorbers are the three largest neutral hydrogen column density absorption-line systems known at low redshift (0.313 \\le z_abs \\le 0.524). They have HI column densities which lie between 3E21 and 5E21 atoms/cm^2. At these redshifts the amount of photoelectric absorption at x-ray energies is primarily an indicator of the oxygen abundance. Since the column densities of these systems are so high, one would expect accurate metallicity measurements of them to yield a robust estimate of the column-density-weighted cosmic neutral-gas-phase metallicity at z \\approx 0.4. We consider cases where the DLA gas has solar element abundance ratios and ones with the alpha-group element abundance ratios enhanced. For the adopted assumptions, the column-density-w...

  14. The SINFONI Nearby Elliptical Lens Locator Survey: Discovery of two new low-redshift strong lenses and implications for the initial mass function in giant early-type galaxies

    CERN Document Server

    Smith, Russell J; Conroy, Charlie

    2015-01-01

    We present results from a blind survey to identify strong gravitational lenses among the population of low-redshift early-type galaxies. The SINFONI Nearby Elliptical Lens Locator Survey (SNELLS) uses integral-field infrared spectroscopy to search for lensed emission line sources behind massive lens candidates at $z$300 km/s) and \\alpha-element abundances ([Mg/Fe]>0.3). From the lensing configurations we derive total J-band mass-to-light ratios of 1.8$\\pm$0.1, 2.1$\\pm$0.1 and 1.9$\\pm$0.2 within the $\\sim$2 kpc Einstein radius. Correcting for estimated dark-matter contributions, and comparing to stellar population models with a Milky Way (Kroupa) initial mass function (IMF), we determine the "mass excess factor", \\alpha. Assuming the lens galaxies have "old" stellar populations (10$\\pm$1 Gyr), the average IMF mass factor is $\\langle\\alpha\\rangle$=1.10$\\pm$0.08$\\pm$0.10, where the first error is random and the second is systematic. If we instead fit the stellar populations from 6dF optical survey spectra, all t...

  15. A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: III. A Galaxy Sample Complete to 0.01 L* and Evidence for Environmental Effects

    CERN Document Server

    Burchett, Joseph N; Bordoloi, Rongmon; Werk, Jessica K; Prochaska, J Xavier; Tumlinson, Jason; Willmer, C N A; O'Meara, John; Katz, Neal

    2015-01-01

    We employ a blindly selected sample of low-redshift C IV absorption systems identified in spectra from the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS), combined with galaxy data from the Sloan Digital Sky Survey (SDSS), to study the metal-enriched circumgalactic medium (CGM) with ~100% completeness for galaxy luminosities L > 0.01 L* at z ~0.1 L* galaxies (7/8) than for less luminous galaxies (1/10). We also find that the occurrence of C IV absorbers depends strongly on the broader environment: 67% (8/12) of galaxies with rho < 150 kpc in regions of low galaxy density (regions with fewer than ten 0.1 L* galaxies within 1 Mpc) have affiliated C IV absorption while none (0/9) of the galaxies in denser regions show C IV within rho < 150 kpc. The reduced detection rate of C IV in denser environments persists for massive group dark matter halos. In contrast, H I is pervasive in the CGM without regard to mass or environment, although some of these Ly-alpha absorbers could arise in unrelated...

  16. Self-Mode-Locking in a Diode-Pumped Self-Q-Switched Nd3+,Cr4+:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    杨林; 冯宝华; 张治国; Volker Gaebler; 刘百宁; Hans J. Eichler; 张世文

    2002-01-01

    We report for the first time on the observation of self-mode-locking in a diode pumped self-Q-switched (SQS)Nd3+,Cr4+ : YA G laser. This phenomenon results from significant excited state absorption of the Cr4+ ions in theco-doped host during the SQS laser pulses. The self-mode-locking occurs already slightly above the SQS laserthreshold. Experiments using relatively low saturable intensity achieved a modulation depth of more than 40%.

  17. The Evaluation of Varying Ductile Fracture Criteria for 3Cr20Ni10W2 Austenitic Heat-Resistant Alloy

    OpenAIRE

    Yu-Feng Xia; Gui-Chang Luo; Dong-Sen Wu; Guo-Zheng Quan; Jie Zhou

    2013-01-01

    Most bulk metal forming processes may be limited by ductile fracture, such as an internal or surface fracture developing in the workpiece. Finding a way to evaluate the ductile fracture criteria (DFC) and identify the relationships between damage evolution and strain-softening behavior of 3Cr20Ni10W2 heat-resistant alloy is very important, which, however, is a nontrivial issue that still needs to be addressed in greater depth. Based on cumulative damage theory, an innovative approach involvin...

  18. Surface Nanocrystallization of 3Cr13 Stainless Steel Induced by High-Current Pulsed Electron Beam Irradiation

    OpenAIRE

    2013-01-01

    The nanocrystalline surface was produced on 3Cr13 martensite stainless steel surface using high-current pulsed electron beam (HCPEB) technique. The structures of the nanocrystallized surface were characterized by X-ray diffraction and electron microscopy. Two nanostructures consisting of fine austenite grains (50–150 nm) and very fine carbides precipitates are formed in melted surface layer after multiple bombardments via dissolution of carbides and crater eruption. It is demonstrated that th...

  19. Magnons in the quantum dimer antiferromagnet Sr{sub 3}Cr{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Quintero-Castro, Diana Lucia; Lake, Bella [Helmholtz Zentrum Berlin, Berlin 14109 (Germany); Institut fuer Festkoerperphysik, Technische Universitaet Berlin, D-10623 Berlin (Germany); Wheeler, Elisa Maria; Islam, Nazmul [Helmholtz Zentrum Berlin, Berlin 14109 (Germany)

    2011-07-01

    Sr{sub 3}Cr{sub 2}O{sub 8} consists of a three-dimensional frustrated arrangement of antiferromagnetically coupled pairs of Cr ions or dimers. The Cr ions are in the unusual 5+ valence state resulting in one electron in the 3d shell and a spin value of 1/2 while a tetrahedral crystal field ensures that this electron occupies the doubly degenerate eg orbitals. Below room temperature Sr{sub 3}Cr{sub 2}O{sub 8} undergoes a cooperative Jahn Teller distortion that lifts the orbital degeneracy so that only the 3z{sup 2}-r{sup 2} orbital is occupied. The low temperature structure is characterized by monoclinic crystal symmetry and antiferro-orbital ordering. The transition also gives rise to spatially anisotropic exchange paths and results in three crystal twins. We have grown single crystals of Sr{sub 3}Cr{sub 2}O{sub 8} and have performed DC susceptibility measurements, high field magnetisation and powder and single crystal inelastic neutron scattering experiments. The data reveals a singlet ground state and gapped triplet excitations consisting of three modes, coming from the three crystal twins. Using a random phase approximation, we have extracted the magnetic exchange interactions within the dimer and between dimers. Sr{sub 3}Cr{sub 2}O{sub 8} is a candidate for the study of the critical properties in the quantum phase transition as the magnetic field can drive a Bose Einstein condensation of magnons.

  20. Fractalkine upregulates inflammation through CX3CR1 and the Jak-Stat pathway in severe acute pancreatitis rat model.

    Science.gov (United States)

    Huang, Li-ya; Chen, Ping; Xu, Ling-xiao; Zhou, Yu-fen; Zhang, Yong-ping; Yuan, Yao-zong

    2012-06-01

    Based on the function of chemokine fractalkine (FKN), acting as both adhesion and chemoattractant, FKN plays a role in acute inflammatory response. In this study, we investigated the mechanism of FKN mediated upregulation inflammation in severe acute pancreatitis (SAP) rat models. Western blot, reverse transcriptase-polymerase chain reaction, and immunofluorescence demonstrated that FKN and its receptor CX3CR1 were overexpressed in cerulein-stimulated AR42J cells. AG490 and FKN-siRNA inhibited activation of Janus kinase/signal transducers and activators of transcription (Jak/Stat) in cerulein-stimulated AR42J cells. Following exposure AG490 and FKN-siRNA inhibited tumor necrosis factor-alpha expression by enzyme-linked immunosorbent assay and immunohistochemistry in vivo the SAP rat models. These results showed FKN and CX3CR1 were involved inflammatory response in cerulein-stimulated AR42J cells. FKN upregulates inflammation through CX3CR1 and the Jak/Stat pathway in SAP rat models.

  1. Fractalkine-CX3CR1 signaling is critical for progesterone-mediated neuroprotection in the retina

    Science.gov (United States)

    Roche, Sarah L.; Wyse-Jackson, Alice C.; Ruiz-Lopez, Ana M.; Byrne, Ashleigh M.; Cotter, Thomas G.

    2017-01-01

    Retinitis pigmentosa (RP) encompasses a group of retinal diseases resulting in photoreceptor loss and blindness. We have previously shown in the rd10 mouse model of RP, that rd10 microglia drive degeneration of viable neurons. Norgestrel, a progesterone analogue, primes viable neurons against potential microglial damage. In the current study we wished to investigate this neuroprotective effect further. We were particularly interested in the role of fractalkine-CX3CR1 signaling, previously shown to mediate photoreceptor-microglia crosstalk and promote survival in the rd10 retina. Norgestrel upregulates fractalkine-CX3CR1 signaling in the rd10 retina, coinciding with photoreceptor survival. We show that Norgestrel-treated photoreceptor-like cells, 661Ws, and C57 explants modulate rd10 microglial activity in co-culture, resulting in increased photoreceptor survival. Assessment of Norgestrel’s neuroprotective effects when fractalkine was knocked-down in 661 W cells and release of fractalkine was reduced in rd10 explants confirms a crucial role for fractalkine-CX3CR1 signaling in Norgestrel-mediated neuroprotection. To further understand the role of fractalkine in neuroprotection, we assessed the release of 40 cytokines in fractalkine-treated rd10 microglia and explants. In both cases, treatment with fractalkine reduced a variety of pro-inflammatory cytokines. These findings further our understanding of Norgestrel’s neuroprotective properties, capable of modulating harmful microglial activity indirectly through photoreceptors, leading to increased neuroprotection. PMID:28216676

  2. The Environment of Galaxies at Low Redshift

    CERN Document Server

    Ivezic, Nicolas B Cowan Zeljko

    2008-01-01

    We compare environmental effects in two analogous samples of galaxies, one from the Sloan Digital Sky Survey (SDSS) and the other from a semi-analytic model (SAM) based on the Millennium Simulation (MS), to test to what extent current SAMs of galaxy formation are reproducing environmental effects. We estimate the large-scale environment of each galaxy using a Bayesian density estimator based on distances to all ten nearest neighbors and compare broad-band photometric properties of the two samples as a function of environment. The feedbacks implemented in the semi-analytic model produce a qualitatively correct galaxy population with similar environmental dependence as that seen in SDSS galaxies. In detail, however, the colors of MS galaxies exhibit an exaggerated dependence on environment: the field contains too many blue galaxies while clusters contain too many red galaxies, compared to the SDSS sample. We also find that the MS contains a population of highly clustered, relatively faint red galaxies with velo...

  3. Jellyfish Galaxy Candidates at Low Redshift

    Science.gov (United States)

    Poggianti, B. M.; Fasano, G.; Omizzolo, A.; Gullieuszik, M.; Bettoni, D.; Moretti, A.; Paccagnella, A.; Jaffé, Y. L.; Vulcani, B.; Fritz, J.; Couch, W.; D'Onofrio, M.

    2016-03-01

    Galaxies that are being stripped of their gas can sometimes be recognized from their optical appearance. Extreme examples of stripped galaxies are the so-called “jellyfish galaxies” that exhibit tentacles of debris material with a characteristic jellyfish morphology. We have conducted the first systematic search for galaxies that are being stripped of their gas at low-z (z = 0.04-0.07) in different environments, selecting galaxies with varying degrees of morphological evidence for stripping. We have visually inspected B- and V-band images and identified 344 candidates in 71 galaxy clusters of the OMEGAWINGS+WINGS sample and 75 candidates in groups and lower mass structures in the PM2GC sample. We present the atlas of stripping candidates and a first analysis of their environment and their basic properties, such as morphologies, star formation rates and galaxy stellar masses. Candidates are found in all clusters and at all clustercentric radii, and their number does not correlate with the cluster velocity dispersion σ or X-ray luminosity LX. Interestingly, convincing cases of candidates are also found in groups and lower mass halos (1011-1014M⊙), although the physical mechanism at work needs to be securely identified. All the candidates are disky, have stellar masses ranging from log M/M⊙ 11.5 and the majority of them form stars at a rate that is on average a factor of 2 higher (2.5σ) compared to non-stripped galaxies of similar mass. The few post-starburst and passive candidates have weak stripping evidence. We conclude that disturbed morphologies suggestive of stripping phenomena are ubiquitous in clusters and could be present even in groups and low mass halos. Further studies will reveal the physics of the gas stripping and clarify the mechanisms at work.

  4. COMPOSITION OF LOW-REDSHIFT HALO GAS

    Energy Technology Data Exchange (ETDEWEB)

    Cen Renyue, E-mail: cen@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Peyton Hall, Ivy Lane, Princeton, NJ 08544 (United States)

    2013-06-20

    Halo gas in low-z (z < 0.5) {>=}0.1 L{sub *} galaxies in high-resolution, large-scale cosmological hydrodynamic simulations is examined with respect to three components: cold, warm, and hot with temperatures of <10{sup 5}, 10{sup 5-6}, and >10{sup 6} K, respectively. Utilizing O VI {lambda}{lambda}1032, 1038 absorption lines, the warm component is compared to observations, and agreement is found with respect to the galaxy-O VI line correlation, the ratio of the O VI line incidence rate in blue to red galaxies, and the amount of O VI mass in star-forming galaxies. A detailed account of the sources of warm halo gas (stellar feedback heating, gravitational shock heating, and accretion from the intergalactic medium), inflowing and outflowing warm halo gas metallicity disparities, and their dependencies on galaxy types and environment is also presented. With the warm component securely anchored, our simulations make the following additional predictions. First, cold gas is the primary component in inner regions with its mass comprising 50% of all gas within galactocentric radius r = (30, 150) kpc in (red, blue) galaxies. Second, at r > (30, 200) kpc in (red, blue) galaxies the hot component becomes the majority. Third, the warm component is a perpetual minority, with its contribution peaking at {approx}30% at r = 100-300 kpc in blue galaxies and never exceeding 5% in red galaxies. The significant amount of cold gas in low-z early-type galaxies, which was found in simulations and in agreement with recent observations (Thom et al.), is intriguing, as is the dominance of hot gas at large radii in blue galaxies.

  5. Composition of Low Redshift Halo Gas

    CERN Document Server

    Cen, Renyue

    2013-01-01

    Halo gas in low-z (z0.1L* galaxies in high-resolution, large-scale cosmological hydrodynamic simulations is examined with respect to three components: (cold, warm, hot) with temperatures equal to (10^6)K, respectively. The warm component is compared, utilizing O VI \\lambda\\lambda 1032, 1038 absorption lines, to observations and agreement is found with respect to the galaxy-O VI line correlation, the ratio of O VI line incidence rate in blue to red galaxies and the amount of O VI mass in star-forming galaxies. A detailed account of the sources of warm halo gas (stellar feedback heating, gravitational shock heating and accretion from the intergalactic medium), inflowing and outflowing warm halo gas metallicity disparities and their dependencies on galaxy types and environment is also presented. Having the warm component securely anchored, our simulations make the following additional predictions. First, cold gas is the primary component in inner regions, with its mass comprising 50% of all gas within galacto-ce...

  6. Composition of Low-redshift Halo Gas

    Science.gov (United States)

    Cen, Renyue

    2013-06-01

    Halo gas in low-z (z =0.1 L * galaxies in high-resolution, large-scale cosmological hydrodynamic simulations is examined with respect to three components: cold, warm, and hot with temperatures of 106 K, respectively. Utilizing O VI λλ1032, 1038 absorption lines, the warm component is compared to observations, and agreement is found with respect to the galaxy-O VI line correlation, the ratio of the O VI line incidence rate in blue to red galaxies, and the amount of O VI mass in star-forming galaxies. A detailed account of the sources of warm halo gas (stellar feedback heating, gravitational shock heating, and accretion from the intergalactic medium), inflowing and outflowing warm halo gas metallicity disparities, and their dependencies on galaxy types and environment is also presented. With the warm component securely anchored, our simulations make the following additional predictions. First, cold gas is the primary component in inner regions with its mass comprising 50% of all gas within galactocentric radius r = (30, 150) kpc in (red, blue) galaxies. Second, at r > (30, 200) kpc in (red, blue) galaxies the hot component becomes the majority. Third, the warm component is a perpetual minority, with its contribution peaking at ~30% at r = 100-300 kpc in blue galaxies and never exceeding 5% in red galaxies. The significant amount of cold gas in low-z early-type galaxies, which was found in simulations and in agreement with recent observations (Thom et al.), is intriguing, as is the dominance of hot gas at large radii in blue galaxies.

  7. JELLYFISH GALAXY CANDIDATES AT LOW REDSHIFT

    Energy Technology Data Exchange (ETDEWEB)

    Poggianti, B. M.; Fasano, G.; Omizzolo, A.; Gullieuszik, M.; Bettoni, D.; Paccagnella, A. [INAF-Astronomical Observatory of Padova (Italy); Moretti, A.; D’Onofrio, M. [Physics and Astronomy Department, University of Padova (Italy); Jaffé, Y. L. [Department of Astronomy, Universidad de Concepción, Concepción (Chile); Vulcani, B. [Kavli Institute for the Physics and Mathematics of the universe (WPI), The University of Tokyo Institutes for Advanced Study (UTIAS), the University of Tokyo, Kashiwa, 277-8582 (Japan); Fritz, J. [Centro de Radioastronomía y Astrofísica, CRyA, UNAM, Michoacán (Mexico); Couch, W. [Australian Astronomical Observatory, North Ryde, NSW 1670 (Australia)

    2016-03-15

    Galaxies that are being stripped of their gas can sometimes be recognized from their optical appearance. Extreme examples of stripped galaxies are the so-called “jellyfish galaxies” that exhibit tentacles of debris material with a characteristic jellyfish morphology. We have conducted the first systematic search for galaxies that are being stripped of their gas at low-z (z = 0.04−0.07) in different environments, selecting galaxies with varying degrees of morphological evidence for stripping. We have visually inspected B- and V-band images and identified 344 candidates in 71 galaxy clusters of the OMEGAWINGS+WINGS sample and 75 candidates in groups and lower mass structures in the PM2GC sample. We present the atlas of stripping candidates and a first analysis of their environment and their basic properties, such as morphologies, star formation rates and galaxy stellar masses. Candidates are found in all clusters and at all clustercentric radii, and their number does not correlate with the cluster velocity dispersion σ or X-ray luminosity L{sub X}. Interestingly, convincing cases of candidates are also found in groups and lower mass halos (10{sup 11}−10{sup 14}M{sub ⊙}), although the physical mechanism at work needs to be securely identified. All the candidates are disky, have stellar masses ranging from log M/M{sub ⊙} < 9 to > 11.5 and the majority of them form stars at a rate that is on average a factor of 2 higher (2.5σ) compared to non-stripped galaxies of similar mass. The few post-starburst and passive candidates have weak stripping evidence. We conclude that disturbed morphologies suggestive of stripping phenomena are ubiquitous in clusters and could be present even in groups and low mass halos. Further studies will reveal the physics of the gas stripping and clarify the mechanisms at work.

  8. Radio astronomy

    CERN Document Server

    Alder, Berni

    1975-01-01

    Methods in Computational Physics, Volume 14: Radio Astronomy is devoted to the role of the digital computer both as a control device and as a calculator in addressing problems related to galactic radio noise. This volume contains four chapters and begins with a technical description of the hardware and the special data-handling problems of using radioheliography, with an emphasis on a selection of observational results obtained with the Culgoora radioheliograph and their significance to solar physics and to astrophysics in general. The subsequent chapter examines interstellar dispersion, i

  9. Association of chemokine receptor CX3CR1 V249I and T280M polymorphisms with chronic kidney disease

    Directory of Open Access Journals (Sweden)

    A K Yadav

    2016-01-01

    Full Text Available The chemokine fractalkine (CX3CL1 and its receptor CX3CR1 are involved in the activation of leukocytes. Two common single-nucleotide polymorphisms of the CX3CR1 gene, V249I and T280M, have been associated with reduced fractalkine signaling, leading to decreased adhesive function and leukocyte chemotaxis. We hypothesized that variation in the CX3CR1 gene could be associated with chronic kidney disease (CKD, a disease of inflammatory activation. We studied the association between CX3CR1 V249I and T280M polymorphisms, and fractalkine and highly sensitive C-reactive protein (hs-CRP levels in 123 patients with CKD and 100 healthy controls (HCs. Genotype analysis was done by polymerase chain reaction-restriction fragment length polymorphism, and fractalkine and hs-CRP levels were analyzed by enzyme-linked immunosorbent assay. MM genotype of T280M was absent in CKD patients, while in controls it was seen in 1% of the individuals. The allele frequencies in both the groups were similar (P = 0.059. Compared to HC, M280M + T280M genotype was more frequent in CKD (P = 0.041. The frequency of II genotype of V249I was 0.8% in CKD, whereas in HC, it was 2%. I249I + V249I genotype was more frequent in CKD as compared to HC (P = 0.034. No difference in allelic frequency of V249I was noted between the two groups (P = 0.061, odds ratios = 1.74, 95% confidence intervals = 0.96–3.12. Plasma fractalkine and serum hs-CRP levels were higher in CKD subjects (P = 0.004 and P 's 0.0001. No association of either genotype was found with fractalkine and hs-CRP levels. Polymorphisms at I249 and M280 genotype in CX3CR1 gene are associated with CKD; however, there was no association of fractalkine or inflammatory marker with these genotypes.

  10. Accretion/jet activity and narrow [O III] kinematics in young radio galaxies

    Institute of Scientific and Technical Information of China (English)

    Andrew; HUMPHREY

    2010-01-01

    We estimate black hole masses and Edenton ratios for a sample of 81 young radio galaxies,which includes 42 compact steep-spectrum(CSS) and 39 gigahertz-peaked spectrum(GPS) sources.We find that the average black hole(BH) mass of these young radio galaxies is〈log Mbh〉-8.3,which is less than that of radio loud QSOs and low redshift radio galaxies(〈 log Mbh〉-9.0).The CSS/GPS sources have relatively high Eddington ratios,with an average value of〈log Lbol/LEdd〉=-0.75,which are similar to those of narrow line Seyfert 1 galaxies(NLS1s).This suggests that young radio galaxies may not only be in the early stages of their radio activity,but also in the early stage of their accretion activity.We find that the young radio galaxies,as a class,systematically deviate from the Mbh-σ relation defined by nearby inactive galaxies,when using σ[O III] as a surrogate for stellar velocity dispersion σ.We also find that the deviation of the [O III] line width,Δσ =σ[O III]-σ[pred],is correlated with the Eddington ratio;sources with Lbol/LEdd-1 have the largest deviations,which are similar to those of radio quiet QSOs/NLS1s(i.e.,sources in which the radio jets are absent or weak),and where σ[pred] is calculated from the Tremaine et al.relation using our estimated BH masses.A similar result has been obtained for 9 linear radio Seyfert galaxies.On the basis of these results,we suggest that,in addition to the possible jet-gas interactions,accretion activities may also play an important role in shaping the kinematics of the narrow [O III] line in young radio galaxies.

  11. Digitale radio

    NARCIS (Netherlands)

    Schiphorst, Roel; Zondervan, L.

    2007-01-01

    Als eerste in Europa heeft Nederland begin december 2006 de omschakeling van analoge naar digitale ethertelevisie gemaakt. Voor de analoge FM-radio is er ook een digitale variant, T-DAB. T-DAB staat voor 'Terrestrial Digital Audio Broadcasting'. Dit artikel gaat verder in op deze techniek en de veld

  12. The Energetics and Lifetimes of Local Radio Active Galactic Nuclei

    CERN Document Server

    Turner, Ross J

    2015-01-01

    We present a model describing the evolution of Fanaroff-Riley type I and II radio AGN, and the transition between these classes. We quantify galaxy environments using a semi-analytic galaxy formation model, and apply our model to a volume-limited low redshift ($0.03 \\leqslant z \\leqslant 0.1$) sample of observed AGN to determine the distribution of jet powers and active lifetimes at the present epoch. Radio sources in massive galaxies are found to remain active for longer, spend less time in the quiescent phase, and inject more energy into their hosts than their less massive counterparts. The jet power is independent of the host stellar mass within uncertainties, consistent with maintenance-mode AGN feedback paradigm. The environments of these AGN are in or close to long-term heating-cooling balance. We also examine the properties of high- and low-excitation radio galaxy sub-populations. The HERGs are younger than LERGs by an order of magnitude, whilst their jet powers are greater by a factor of four. The Edd...

  13. AGN and Starburst Radio Emission from Optically Selected QSOs

    CERN Document Server

    Condon, J J; Kimball, Amy E; Ivezic, Zeljko; Perley, R A

    2013-01-01

    We used the 1.4 GHz NVSS to study radio sources in two color-selected QSO samples: a volume-limited sample of 1313 QSOs defined by M_i < -23 in the redshift range 0.2 < z < 0.45 and a magnitude-limited sample of 2471 QSOs with m_r < 18.5 and 1.8 < z < 2.5. About 10% were detected above the 2.4 mJy NVSS catalog limit and are powered primarily by AGNs. The space density of the low-redshift QSOs evolves as rho proportional to (1+z)^6. In both redshift ranges the flux-density distributions and luminosity functions of QSOs stronger than 2.4 mJy are power laws, with no features to suggest more than one kind of radio source. Extrapolating the power laws to lower luminosities predicts the remaining QSOs should be extremely radio quiet, but they are not. Most were detected statistically on the NVSS images with median peak flux densities S_p(mJy/beam) ~ 0.3 and 0.05 in the low- and high-redshift samples, corresponding to 1.4 GHz spectral luminosities log[L(W/Hz)] ~ 22.7$ and 24.1, respectively. We sug...

  14. Arteriolar and venular remodeling are differentially regulated by bone marrow-derived cell-specific CX3CR1 and CCR2 expression.

    Directory of Open Access Journals (Sweden)

    Joshua K Meisner

    Full Text Available The chemokine receptors CCR2 and CX3CR1 are critical for the recruitment of "inflammatory" and "resident" monocytes, respectively, subpopulations that differentially affect vascular remodeling in atherosclerosis. Here, we tested the hypothesis that bone marrow-derived cell (BMC-specific CCR2 and CX3CR1 differentially control venular and arteriolar remodeling. Venular and arteriolar lumenal remodeling were observed by intravital microscopy in mice with either CCR2 or CX3CR1 deficient BMCs after implantation of a dorsal skinfold window chamber, a model in which arterioles and venules lumenally enlarge in wild-type (WT mice. Arteriolar remodeling was abolished in mice with either CCR2 or CX3CR1-deficient BMCs. In contrast, the loss of CX3CR1 from BMCs, but not CCR2, significantly reduced small venule remodeling compared to WT controls. We conclude that microvascular remodeling is differentially regulated by BMC-expressed chemokine receptors. Both CCR2 and CX3CR1 regulate arteriole growth; however, only BMC-expressed CX3CR1 impacts small venule growth. These findings may provide a basis for additional investigations aimed at determining how patterns of monocyte subpopulation recruitment spatially influence microvascular remodeling.

  15. The Far-Infrared-Radio Correlation in MS0451-03

    CERN Document Server

    Randriamampandry, S M; Cress, C M; Hess, K M; Vaccari, M; Wilcots, E M; Bershady, M A; Wirth, G D

    2014-01-01

    We present a multi-wavelength analysis of star-forming galaxies in the massive cluster MS0451.6-0305 at z $\\sim$ 0.54 to shed new light on the evolution of the far-infrared-radio relationship in distant rich clusters. We have derived total infrared luminosities for a spectroscopically confirmed sample of cluster and field galaxies through an empirical relation based on $Spitzer$ MIPS 24 $\\mu$m photometry. The radio flux densities were measured from deep Very Large Array 1.4 GHz radio continuum observations. We find the ratio of far-infrared to radio luminosity for galaxies in an intermediate redshift cluster to be $q_{\\rm FIR}$ = 1.80$\\pm$0.15 with a dispersion of 0.53. Due to the large intrinsic dispersion, we do not find any observable change in this value with either redshift or environment. However, a higher percentage of galaxies in this cluster show an excess in their radio fluxes when compared to low redshift clusters ($27^{+23}_{-13}\\%$ to $11\\%$), suggestive of a cluster enhancement of radio-excess s...

  16. Deletion of the Fractalkine Receptor, CX3CR1, Improves Endogenous Repair, Axon Sprouting, and Synaptogenesis after Spinal Cord Injury in Mice.

    Science.gov (United States)

    Freria, Camila M; Hall, Jodie C E; Wei, Ping; Guan, Zhen; McTigue, Dana M; Popovich, Phillip G

    2017-03-29

    Impaired signaling via CX3CR1, the fractalkine receptor, promotes recovery after traumatic spinal contusion injury in mice, a benefit achieved in part by reducing macrophage-mediated injury at the lesion epicenter. Here, we tested the hypothesis that CX3CR1-dependent changes in microglia and macrophage functions also will enhance neuroplasticity, at and several segments below the injury epicenter. New data show that in the presence of inflammatory stimuli, CX3CR1-deficient (CX3CR1(-/-)) microglia and macrophages adopt a reparative phenotype and increase expression of genes that encode neurotrophic and gliogenic proteins. At the lesion epicenter (mid-thoracic spinal cord), the microenvironment created by CX3CR1(-/-) microglia/macrophages enhances NG2 cell responses, axon sparing, and sprouting of serotonergic axons. In lumbar spinal cord, inflammatory signaling is reduced in CX3CR1(-/-) microglia. This is associated with reduced dendritic pathology and improved axonal and synaptic plasticity on ventral horn motor neurons. Together, these data indicate that CX3CR1, a microglia-specific chemokine receptor, is a novel therapeutic target for enhancing neuroplasticity and recovery after SCI. Interventions that specifically target CX3CR1 could reduce the adverse effects of inflammation and augment activity-dependent plasticity and restoration of function. Indeed, limiting CX3CR1-dependent signaling could improve rehabilitation and spinal learning.SIGNIFICANCE STATEMENT Published data show that genetic deletion of CX3CR1, a microglia-specific chemokine receptor, promotes recovery after traumatic spinal cord injury in mice, a benefit achieved in part by reducing macrophage-mediated injury at the lesion epicenter. Data in the current manuscript indicate that CX3CR1 deletion changes microglia and macrophage function, creating a tissue microenvironment that enhances endogenous repair and indices of neuroplasticity, at and several segments below the injury epicenter

  17. Diode-Pumped Self Q-Switched and Mode-Locking Nd3+,Cr4+:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    LI Chun-Yong; LI Ping-Xue; LI De-Hua; FENG Bao-Hua; FU Pan-Ming; ZHANG Zhi-Guo; ZHANG Shi-Wen

    2004-01-01

    @@ Using Nd3+,Cr4+ : YAG as a laser crystal and saturable absorber simultaneously, we obtain a self-Q-switched and mode-locking laser at 1.06 μm with straight cavity structure. Self mode-locking phenomenon was observed at an intracavity intensity of only about 2000 W/cm2. More than 90% modulation depth is achieved at an intracavity intensity of less than 3.0 × 104 W/cm2 for the first time. The Q-switched pulse width and repetition rate are found to be connected with the cavity length and the output power.

  18. Studies on the properties of Al2O3:Cr2O3 (50:50) thin film

    Science.gov (United States)

    Ponmudi, S.; Sivakumar, R.; Sanjeeviraja, C.

    2016-05-01

    Aluminium oxide (Al2O3) and chromium oxide (Cr2O3) thin films have received great attention of researchers because of their unique properties of corrosion/oxidation resistance and high dielectric constant. In addition, chromium aluminium oxide has been considered as a best candidate for deep-ultraviolet optical masks. In the present work, thin films of Al2O3:Cr2O3 (50:50) were deposited on pre-cleaned microscopic glass substrate by RF magnetron sputtering technique. The substrate temperature and RF power induced changes in structural, surface morphological, compositional and optical properties of the films have been studied.

  19. The Radio JOVE Project - Shoestring Radio Astronomy

    Science.gov (United States)

    Thieman, J.; Flagg, R.; Greenman, W.; Higgins, C.; Reyes, F.; Sky, J.

    2010-01-01

    Radio JOVE is an education and outreach project intended to give students and other interested individuals hands-on experience in learning radio astronomy. They can do this through building a radio telescope from a relatively inexpensive kit that includes the parts for a receiver and an antenna as well as software for a computer chart recorder emulator (Radio Skypipe) and other reference materials

  20. The Radio JOVE Project - Shoestring Radio Astronomy

    Science.gov (United States)

    Thieman, J.; Flagg, R.; Greenman, W.; Higgins, C.; Reyes, F.; Sky, J.

    2010-01-01

    Radio JOVE is an education and outreach project intended to give students and other interested individuals hands-on experience in learning radio astronomy. They can do this through building a radio telescope from a relatively inexpensive kit that includes the parts for a receiver and an antenna as well as software for a computer chart recorder emulator (Radio Skypipe) and other reference materials

  1. Space Telecommunications Radio System STRS Cognitive Radio

    Science.gov (United States)

    Briones, Janette C.; Handler, Louis M.

    2013-01-01

    Radios today are evolving from awareness toward cognition. A software defined radio (SDR) provides the most capability for integrating autonomic decision making ability and allows the incremental evolution toward a cognitive radio. This cognitive radio technology will impact NASA space communications in areas such as spectrum utilization, interoperability, network operations, and radio resource management over a wide range of operating conditions. NASAs cognitive radio will build upon the infrastructure being developed by Space Telecommunication Radio System (STRS) SDR technology. This paper explores the feasibility of inserting cognitive capabilities in the NASA STRS architecture and the interfaces between the cognitive engine and the STRS radio. The STRS architecture defines methods that can inform the cognitive engine about the radio environment so that the cognitive engine can learn autonomously from experience, and take appropriate actions to adapt the radio operating characteristics and optimize performance.

  2. Field-induced Bose-Einstein condensation of triplons up to 8 K in Sr3Cr2O8.

    Science.gov (United States)

    Aczel, A A; Kohama, Y; Marcenat, C; Weickert, F; Jaime, M; Ayala-Valenzuela, O E; McDonald, R D; Selesnic, S D; Dabkowska, H A; Luke, G M

    2009-11-13

    Single crystals of the spin dimer system Sr(3)Cr(2)O(8) have been grown for the first time. Magnetization, heat capacity, and magnetocaloric effect data up to 65 T reveal magnetic order between applied fields of H(c1) approximately 30.4 T and H(c2) approximately 62 T. This field-induced order persists up to T(c)(max) approximately 8 K at H approximately 44 T, the highest observed in any quantum magnet where H(c2) is experimentally accessible. We fit the temperature-field phase diagram boundary close to H(c1) using the expression T(c) = A(H-H(c1))(nu). The exponent nu = 0.65(2), obtained at temperatures much smaller than T(c)(max), is that of the 3D Bose-Einstein condensate (BEC) universality class. This finding strongly suggests that Sr(3)Cr(2)O(8) is a new realization of a triplon BEC where the universal regimes corresponding to both H(c1) and H(c2) are accessible at (4)He temperatures.

  3. The Evaluation of Varying Ductile Fracture Criteria for 3Cr20Ni10W2 Austenitic Heat-Resistant Alloy

    Directory of Open Access Journals (Sweden)

    Yu-Feng Xia

    2013-01-01

    Full Text Available Most bulk metal forming processes may be limited by ductile fracture, such as an internal or surface fracture developing in the workpiece. Finding a way to evaluate the ductile fracture criteria (DFC and identify the relationships between damage evolution and strain-softening behavior of 3Cr20Ni10W2 heat-resistant alloy is very important, which, however, is a nontrivial issue that still needs to be addressed in greater depth. Based on cumulative damage theory, an innovative approach involving heat physical compression experiments, numerical simulations, and mathematical computations provides mutual support to evaluate ductile damage cumulating process and DFC diagram along with deformation conditions. It is concluded that, as for strain-softening material, ductile damage starts at work hardening phase, and the damage cumulation is more sensitive in work hardening phase than in work softening phase. In addition, DFC of 3Cr20Ni10W2 heat-resistant alloy in a wide temperature range of 1203∼1403 K and the strain rate of 0.01∼10 s−1 are not constant but change in a range of 0.099∼0.197; thus they have been defined as varying ductile fracture criteria (VDFC and characterized by a function of strain rate and temperature. According to VDFC diagram, the exact fracture moment and position during various forming processes will be predicted conveniently.

  4. Delayed triggering of radio Active Galactic Nuclei in gas-rich minor mergers in the local Universe

    Science.gov (United States)

    Shabala, S. S.; Deller, A.; Kaviraj, S.; Middelberg, E.; Turner, R. J.; Ting, Y. S.; Allison, J. R.; Davis, T. A.

    2016-10-01

    We examine the processes triggering star formation and Active Galactic Nucleus (AGN) activity in a sample of 25 low redshift (z 107 K) brightness temperature required for an mJIVE-20 detection allows us to unambiguously identify the radio AGN in our sample. We find three such objects. Our VLBI AGN identifications are classified as Seyferts or LINERs in narrow line optical diagnostic plots; mid-infrared colours of our targets and the comparison of Hα star formation rates with integrated radio luminosity are also consistent with the VLBI identifications. We reconstruct star formation histories in our galaxies using optical and UV photometry, and find that these radio AGN are not triggered promptly in the merger process, consistent with previous findings for non-VLBI samples of radio AGN. This delay can significantly limit the efficiency of feedback by radio AGN triggered in galaxy mergers. We find that radio AGN hosts have lower star formation rates than non-AGN radio-selected galaxies at the same starburst age. Conventional and VLBI radio imaging shows these AGN to be compact on arcsecond scales. Our modeling suggests that the actual sizes of AGN-inflated radio lobes may be much larger than this, but these are too faint to be detected in existing observations. Deep radio imaging is required to map out the true extent of the AGN, and to determine whether the low star formation rates in radio AGN hosts are a result of the special conditions required for radio jet triggering, or the effect of AGN feedback.

  5. Delayed triggering of radio active galactic nuclei in gas-rich minor mergers in the local Universe

    Science.gov (United States)

    Shabala, S. S.; Deller, A.; Kaviraj, S.; Middelberg, E.; Turner, R. J.; Ting, Y. S.; Allison, J. R.; Davis, T. A.

    2017-02-01

    We examine the processes triggering star formation and active galactic nucleus (AGN) activity in a sample of 25 low-redshift (z 107 K) brightness temperature required for an mJIVE-20 detection allows us to unambiguously identify the radio AGN in our sample. We find three such objects. Our VLBI AGN identifications are classified as Seyferts or low-ionization nuclear emission-line regions (LINERs) in narrow line optical diagnostic plots; mid-infrared colours of our targets and the comparison of Hα star formation rates with integrated radio luminosity are also consistent with the VLBI identifications. We reconstruct star formation histories in our galaxies using optical and UV photometry, and find that these radio AGN are not triggered promptly in the merger process, consistent with previous findings for non-VLBI samples of radio AGN. This delay can significantly limit the efficiency of feedback by radio AGN triggered in galaxy mergers. We find that radio AGN hosts have lower star formation rates than non-AGN radio-selected galaxies at the same starburst age. Conventional and VLBI radio imaging shows these AGN to be compact on arcsecond scales. Our modelling suggests that the actual sizes of AGN-inflated radio lobes may be much larger than this, but these are too faint to be detected in existing observations. Deep radio imaging is required to map out the true extent of the AGN, and to determine whether the low star formation rates in radio AGN hosts are a result of the special conditions required for radio jet triggering, or the effect of AGN feedback.

  6. Delayed triggering of radio Active Galactic Nuclei in gas-rich minor mergers in the local Universe

    CERN Document Server

    Shabala, Stanislav; Kaviraj, Sugata; Middelberg, Enno; Turner, Ross; Ting, Yuan-Sen; Allison, James; Davis, Tim

    2016-01-01

    We examine the processes triggering star formation and Active Galactic Nucleus (AGN) activity in a sample of 25 low redshift ($z10^7$ K) brightness temperature required for an mJIVE-20 detection allows us to unambiguously identify the radio AGN in our sample. We find three such objects. Our VLBI AGN identifications are classified as Seyferts or LINERs in narrow line optical diagnostic plots; mid-infrared colours of our targets and the comparison of H$\\alpha$ star formation rates with integrated radio luminosity are also consistent with the VLBI identifications. We reconstruct star formation histories in our galaxies using optical and UV photometry, and find that these radio AGN are not triggered promptly in the merger process, consistent with previous findings for non-VLBI samples of radio AGN. This delay can significantly limit the efficiency of feedback by radio AGN triggered in galaxy mergers. We find that radio AGN hosts have lower star formation rates than non-AGN radio-selected galaxies at the same star...

  7. 3Cr2W8V铝合金热挤压模具气体氮碳共渗处理%Nitrocarburizing of 3Cr2W8V Aluminum Alloy Hot Extrusion Die

    Institute of Scientific and Technical Information of China (English)

    杨凯军

    2005-01-01

    采用两段气体氮碳共渗工艺对3Cr2W8V铝合金热挤压模具进行热处理,解决了因磨损和开裂所造成的模具早期失效问题.与常规热处理相比,使用寿命提高1~2倍.其原因在于此工艺强化了过渡层对表面化合物层的支撑能力,同时心部获得良好的强韧性配合.

  8. Radio galaxies in ZFOURGE/NMBS: no difference in the properties of massive galaxies with and without radio-AGN out to z = 2.25

    CERN Document Server

    Rees, G A; Norris, R P; Cowley, M J; Papovich, C; Glazebrook, K; Quadri, R F; Straatman, C M S; Allen, R; Kacprzak, G G; Labbe, I; Nanayakkara, T; Tomczak, A R; Tran, K -V

    2015-01-01

    In order to reproduce the high-mass end of the galaxy mass-distribution, some process must be responsible for the suppression of star-formation in the most massive of galaxies. Commonly Active Galactic Nuclei (AGN) are invoked to fulfil this role, but the exact means by which they do so is still the topic of much debate, with studies finding evidence for both the suppression and enhancement of star-formation in AGN hosts. Using the ZFOURGE and NMBS galaxy surveys, we investigate the host galaxy properties of a mass-limited (M$_{\\odot}$ $\\ge$ 10$^{10.5}$ M$_{\\odot}$), high-luminosity (L$_{1.4}$ $>$ 10$^{24}$ W Hz$^{-1}$) sample of radio-loud Active Galactic Nuclei to a redshift of z = 2.25. In contrast to low redshift studies, which associate radio-AGN activity with quiescent hosts, we find that the majority of z $>$ 1.5 radio-AGN are hosted by star-forming galaxies. Indeed, the stellar populations of radio-AGN are found to evolve with redshift in a manner that is consistent with the non-AGN mass-similar galax...

  9. Surface Nanocrystallization of 3Cr13 Stainless Steel Induced by High-Current Pulsed Electron Beam Irradiation

    Directory of Open Access Journals (Sweden)

    Zhiyong Han

    2013-01-01

    Full Text Available The nanocrystalline surface was produced on 3Cr13 martensite stainless steel surface using high-current pulsed electron beam (HCPEB technique. The structures of the nanocrystallized surface were characterized by X-ray diffraction and electron microscopy. Two nanostructures consisting of fine austenite grains (50–150 nm and very fine carbides precipitates are formed in melted surface layer after multiple bombardments via dissolution of carbides and crater eruption. It is demonstrated that the dissolution of the carbides and the formation of the supersaturated Fe (C solid solution play a determining role on the microstructure evolution. Additionally, the formation of fine austenite structure is closely related to the thermal stresses induced by the HCPEB irradiation. The effects of both high carbon content and high value of stresses increase the stability of the austenite, which leads to the complete suppression of martensitic transformation.

  10. Surface Hardening of Ti-15V-3Al-3Cr-3Sn Alloy after Cyclic Hydrogenation and Subsequent Solution Treatment

    Directory of Open Access Journals (Sweden)

    Chia-Po Hung

    2014-01-01

    Full Text Available The as-received and preheated (1000°C-30 min. and 500°C-30 min. sheets of Ti-15V-3Al-3Cr-3Sn alloy (Ti-153 were treated according to the predetermined process including a cyclic electrolytic hydrogenation (at 50 mA/cm2 for 1 hr and at 5 mA/cm2 for 10 hrs combining a subsequent solution treatment to see the effects of various operating parameters on the evolution of microstructure and the variations of hardness. The hardening effect deriving from solid-solution strengthening of hydrogen eventually overrode that from precipitation hardening. The maximum hardness elevation was from 236.9 to 491.1 VHN.

  11. Theoretical study of magnetism and electronic structure of Fe{sub 3}/Cr{sub n}(1 1 0) superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Hu Haiquan [College of Physics Science and Information Engineering, Liaocheng University, Liaocheng 252059 (China)], E-mail: huhq@lcu.edu.cn; Li Hengshuai [College of Physics Science and Information Engineering, Liaocheng University, Liaocheng 252059 (China)], E-mail: hengshuaili@sina.com; Wang Yuanxu [College of Physics and Electron, Henan University, Kaifeng 475001 (China); Ren Zhongming [College of Car and Traffic Engineering, Liaocheng University, Liaocheng 252059 (China)

    2008-03-01

    The electronic structure and magnetism of Fe{sub 3}/Cr{sub n}(1 1 0) (n=1, 3, 5) superlattices (SL) with varying layer thickness have been studied using the full-potential linearized augmented plane-wave (FLAPW) method within the first-principle formalism. The results show that the ferromagnetic state is the preferable phase in the ground state. The magnetic moments of the Fe layers are slightly modified by the presence of the Cr layers. The Cr magnetic moments alternate direction from layer to layer, and an antiferromagnetic coupling between Fe and Cr at the interfacial layer is seen. The magnetic moments of the Cr layers are suppressed because there is a strong hybridization between d-states of both Fe and Cr atoms. Only a small moment is found in the Cr layer. The Cr moment alignment is determined by a delicate balance between the different magnetic interaction.

  12. Molecular gas in nearby powerful radio galaxies

    CERN Document Server

    Leon, S; Combes, F; Van Trung, D

    2001-01-01

    We report the detection of CO(1-0) and CO(2-1) emission from the central region of nearby 3CR radio galaxies (z$<$ 0.03). Out of 21 galaxies, 8 have been detected in, at least, one of the two CO transitions. The total molecular gas content is below 10$^9$ \\msun. Their individual CO emission exhibit, for 5 cases, a double-horned line profile that is characteristic of an inclined rotating disk with a central depression at the rising part of its rotation curve. The inferred disk or ring distributions of the molecular gas is consistent with the observed presence of dust disks or rings detected optically in the cores of the galaxies. We reason that if their gas originates from the mergers of two gas-rich disk galaxies, as has been invoked to explain the molecular gas in other radio galaxies, then these galaxies must have merged a long time ago (few Gyr or more) but their remnant elliptical galaxies only recently (last 10$^7$ years or less) become active radio galaxies. Instead, we argue the the cannibalism of g...

  13. Effect of O{sub 2} on corrosion of 3Cr steel in high temperature and high pressure CO{sub 2}–O{sub 2} environment

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Xueqiang; Liu, Wei, E-mail: weiliu@ustb.edu.cn; Wu, Fei; Xu, Chuanchuan; Dou, Juanjuan; Lu, Minxu

    2015-02-28

    Highlights: • 3Cr steel suffered severe localized corrosion in CO{sub 2}–O{sub 2} environment. • Fe(OH){sub 3} in CO{sub 2}–O{sub 2} corrosion scale of 3Cr steel caused Cr nonuniform distribution. • A development mechanism of CO{sub 2}–O{sub 2} corrosion pits of 3Cr steel was proposed. - Abstract: The development of corrosion scale of 3Cr steel in an aqueous environment containing 95% CO{sub 2}–5% O{sub 2} was characterized and analyzed by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), X-ray diffraction (XRD) and in situ electrochemical impedance spectroscopy (EIS). The results show that the corrosion of 3Cr steel was promoted by dissolved oxygen. Fe(OH){sub 3} precipitation formed at local areas, leading to the nonuniform distribution of Cr element and pitting corrosion. With the increase of corrosion time, Cr-rich area formed at the bottom of pits, where the pitting corrosion process was inhibited. The importance of Fe(OH){sub 3} and Cr-rich area on the formation of corrosion pits and pits development was emphasized.

  14. Tensile properties and conductivities of a precipitation hardened and cold-rolled Cu-0.3Cr-0.1Zr alloy at cryogenic temperature

    Science.gov (United States)

    Umezawa, O.

    2015-12-01

    Cu-0.3Cr-0.1Zr alloy (in mass%) is one of typical precipitation hardened copper- based alloys, and exhibited an excellent combination of high strength and high conductivities at the temperature range of 4 K to 300 K. The tensile properties, electrical resistivity, thermal conductivity and magnetization of precipitation hardened and cold-rolled Cu-0.3Cr-0.1Zr alloy were measures in comparison with oxygen free copper at cryogenic temperatures. The Cu- 0.3Cr-0.1Zr showed higher yield ratio (yield strength / tensile strength) and lower the ratio of yield strength to electrical resistivity at cryogenic temperature than oxygen free copper. It exhibited high electrical and thermal conductivities, excellent non-magnetic stability and very low magnetic permeability at 4.2 K.

  15. Electron and magnetic properties of three-dimensional magnetic topological insulators Bi2Se3:Cr and Bi2Se3:Fe

    Science.gov (United States)

    Kulatov, E. T.; Men'shov, V. N.; Tugushev, V. V.; Uspenskii, Yu. A.

    2016-09-01

    This letter presents the first-principles study of a three-dimensional (3D) topological insulator (TI) Bi2Se3 doped with magnetic atoms of 3d-transition metal (TM), Cr or Fe. Calculations are performed within the density functional theory (DFT) and a modified potential of Becke and Johnson (MBJ). Using the MBJ scheme, we show that both systems are semiconductors with a direct gap of 0.21 eV (Bi2Se3:Cr) and 0.27 eV (Bi2Se3:Fe), respectively. The magnetic structures of studied materials are, however, different: Bi2Se3:Cr exhibits a clear ferromagnetic (FM) order, while Bi2Se3:Fe has an antiferromagnetic (AFM) order. In view of the great scientific and practical interest to the 3D FMTI systems, the optical and magneto-optical spectra of Bi2Se3:Cr are calculated.

  16. CX3CR1 is expressed by human B lymphocytes and mediates [corrected] CX3CL1 driven chemotaxis of tonsil centrocytes.

    Directory of Open Access Journals (Sweden)

    Anna Corcione

    Full Text Available BACKGROUND: Fractalkine/CX(3CL1, a surface chemokine, binds to CX(3CR1 expressed by different lymphocyte subsets. Since CX(3CL1 has been detected in the germinal centres of secondary lymphoid tissue, in this study we have investigated CX(3CR1 expression and function in human naïve, germinal centre and memory B cells isolated from tonsil or peripheral blood. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrate unambiguously that highly purified human B cells from tonsil and peripheral blood expressed CX(3CR1 at mRNA and protein levels as assessed by quantitative PCR, flow cytometry and competition binding assays. In particular, naïve, germinal centre and memory B cells expressed CX(3CR1 but only germinal centre B cells were attracted by soluble CX(3CL1 in a transwell assay. CX(3CL1 signalling in germinal centre B cells involved PI3K, Erk1/2, p38, and Src phosphorylation, as assessed by Western blot experiments. CX(3CR1(+ germinal centre B cells were devoid of centroblasts and enriched for centrocytes that migrated to soluble CX(3CL1. ELISA assay showed that soluble CX(3CL1 was secreted constitutively by follicular dendritic cells and T follicular helper cells, two cell populations homing in the germinal centre light zone as centrocytes. At variance with that observed in humans, soluble CX(3CL1 did not attract spleen B cells from wild type mice. OVA immunized CX(3CR1(-/- or CX(3CL1(-/- mice showed significantly decreased specific IgG production compared to wild type mice. CONCLUSION/SIGNIFICANCE: We propose a model whereby human follicular dendritic cells and T follicular helper cells release in the light zone of germinal centre soluble CX(3CL1 that attracts centrocytes. The functional implications of these results warrant further investigation.

  17. Star formation rates in Lyman break galaxies: radio stacking of LBGs in the COSMOS field and the sub-$\\mu$Jy radio source population

    CERN Document Server

    Carilli, C L; Capak, P; Schinnerer, E; Lee, K -S; McCraken, H; Yun, M S; Scoville, N; Smolcic, V; Giavalisco, M; Datta, A; Taniguchi, Y; Urry, C Megan

    2008-01-01

    We present an analysis of the radio properties of large samples of Lyman Break Galaxies (LBGs) at $z \\sim 3$, 4, and 5 from the COSMOS field. The median stacking analysis yields a statistical detection of the $z \\sim 3$ LBGs (U-band drop-outs), with a 1.4 GHz flux density of $0.90 \\pm 0.21 \\mu$Jy. The stacked emission is unresolved, with a size $< 1"$, or a physical size $< 8$kpc. The total star formation rate implied by this radio luminosity is $31\\pm 7$ $M_\\odot$ year$^{-1}$, based on the radio-FIR correlation in low redshift star forming galaxies. The star formation rate derived from a similar analysis of the UV luminosities is 17 $M_\\odot$ year$^{-1}$, without any correction for UV dust attenuation. The simplest conclusion is that the dust attenuation factor is 1.8 at UV wavelengths. However, this factor is considerably smaller than the standard attenuation factor $\\sim 5$, normally assumed for LBGs. We discuss potential reasons for this discrepancy, including the possibility that the dust attenuati...

  18. A Three-decade X-band VLBI Study of 3CR Lobe-dominated Quasar Nuclei

    Directory of Open Access Journals (Sweden)

    Hough David H.

    2013-12-01

    Full Text Available We report X-band VLBI observations of several 3CR lobe-dominated quasar nuclei from 1981 to 2010, mostly obtained with the NRAO VLBA. The goal is to follow flux density outbursts and to fully determine the jet morphology and kinematics on 1-100 pc scales. In 3C207, the core region has flux outbursts at mean intervals of ~7 yr; one of these is actually a double outburst from a stationary true core and a swinging component ~0.5 mas apart. The position angle (PA of the swinging component varies by ~40°, while the PA values of the jet components span ~25°. The jet extends to ~25 mas. Average superluminal speeds are ~10c. One component shows apparent acceleration from 7c to 14c at 2-3 mas from the true core, in a jet recollimation zone that redirects the flow toward PA ~90°. Individual jet components expand until reaching the recollimation zone. In 3C263 and other objects, some of the same phenomena are seen, including ejection of jet components over a range in PA, superluminal motion, and apparent acceleration, but to a lesser degree. Possible physical interpretations involving beaming, orientation, projection, precession, and magnetic effects are discussed.

  19. Dengue virus infection elicits highly polarized CX3CR1+ cytotoxic CD4+ T cells associated with protective immunity.

    Science.gov (United States)

    Weiskopf, Daniela; Bangs, Derek J; Sidney, John; Kolla, Ravi V; De Silva, Aruna D; de Silva, Aravinda M; Crotty, Shane; Peters, Bjoern; Sette, Alessandro

    2015-08-04

    Dengue virus (DENV) is a rapidly spreading pathogen with unusual pathogenesis, and correlates of protection from severe dengue disease and vaccine efficacy have not yet been established. Although DENV-specific CD8(+) T-cell responses have been extensively studied, the breadth and specificity of CD4(+) T-cell responses remains to be defined. Here we define HLA-restricted CD4(+) T-cell epitopes resulting from natural infection with dengue virus in a hyperepidemic setting. Ex vivo flow-cytometric analysis of DENV-specific CD4(+) T cells revealed that the virus-specific cells were highly polarized, with a strong bias toward a CX3CR1(+) Eomesodermin(+) perforin(+) granzyme B(+) CD45RA(+) CD4 CTL phenotype. Importantly, these cells correlated with a protective HLA DR allele, and we demonstrate that these cells have direct ex vivo DENV-specific cytolytic activity. We speculate that cytotoxic dengue-specific CD4(+) T cells may play a role in the control of dengue infection in vivo, and this immune correlate may be a key target for dengue virus vaccine development.

  20. Quasicrystalline Al{sub 9}3Fe{sub 3}Cr{sub 2}Ti{sub 2} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Escorial, A.; Natale, E.; Cremaschi, V. J.; Todd, I.; Lieblich, M.

    2015-07-01

    Aluminium alloy powder having a nominal composition of Al{sub 9}3Fe{sub 3}Cr{sub 2}Ti{sub 2} (at%) has been prepared using gas atomisation. The atomised powder present a microstructure of an aluminium matrix reinforced with a spherical quasicrystalline icosahedral phase, in the range of nano metre in size. The powder was consolidated into bars using warm extrusion. The microstructure of the extruded bars retains the quasicrystalline microstructure and the bars present outstanding mechanical properties, i.e. proof stress of 280 MPa at 300 degree centigrade. Upon heating the microstructure evolves towards the equilibrium. The thermal evolution was investigated by means of x-ray diffraction, differential scanning calorimeter, scanning electron microscopy and transmission electron microscopy. According to these observations a transformation in two steps is proposed. A first step consists in the decomposition of the supersaturated solid solution of the matrix and the quasicrystals, and a second step in the transformation of the quasicrystals into the equilibrium phases. (Author)

  1. Ontogeny of CX3CR1-EGFP expressing cells unveil microglia as an integral component of the postnatal subventricular zone

    Directory of Open Access Journals (Sweden)

    Anna Lenice Ribeiro Xavier

    2015-02-01

    Full Text Available The full spectrum of cellular interactions within CNS neurogenic niches is still poorly understood. Only recently has the monocyte counterpart of the nervous system, the microglial cells, been described as an important cellular component in neurogenic niches. The present study sought to characterize the microglial population in the early postnatal subventricular zone (SVZ, the major site of postnatal neurogenesis, and in its anterior extension, the rostral migratory stream (RMS, a pathway for neuroblasts during their transit toward the olfactory bulb (OB layers. Analysis of the transgenic mice strain that has one of the locus of the constitutively expressed fractalkine CX3CR1 receptor replaced by the gene encoding the green fluorescent protein (EGFP circumvented the antigenic plasticity of the microglial cells. Here we show that common phenotypic markers of microglia do not reveal the full complement of these cells within the SVZ/RMS pathway. Remarkably, our analysis show that within the early SVZ/RMS pathway microglia are not proliferative and display a protracted development, retaining a more immature morphology than their counterparts outside germinal layers. Furthermore, during the first postnatal days microglia contact and phagocyte radial glia cells (RGs. Our results unveil microglial cells as a prominent component along the entire SVZ niche, together with neuroblasts and astroglial progenitors.

  2. Ontogeny of CX3CR1-EGFP expressing cells unveil microglia as an integral component of the postnatal subventricular zone.

    Science.gov (United States)

    Xavier, Anna L; Lima, Flavia R S; Nedergaard, Maiken; Menezes, João R L

    2015-01-01

    The full spectrum of cellular interactions within CNS neurogenic niches is still poorly understood. Only recently has the monocyte counterpart of the nervous system, the microglial cells, been described as an integral cellular component of neurogenic niches. The present study sought to characterize the microglia population in the early postnatal subventricular zone (SVZ), the major site of postnatal neurogenesis, as well as in its anterior extension, the rostral migratory stream (RMS), a pathway for neuroblasts during their transit toward the olfactory bulb (OB) layers. Here we show that microglia within the SVZ/RMS pathway are not revealed by phenotypic markers that characterize microglia in other regions. Analysis of the transgenic mice strain that has one locus of the constitutively expressed fractalkine CX3CR1 receptor replaced by the gene encoding the enhanced green fluorescent protein (EGFP) circumvented the antigenic plasticity of the microglia, thus allowing us to depict microglia within the SVZ/RMS pathway during early development. Notably, microglia within the early SVZ/RMS are not proliferative and display a protracted development, retaining a more immature morphology than their counterparts outside germinal layers. Furthermore, microglia contact and phagocyte radial glia cells (RG) processes, thereby playing a role on the astroglial transformation that putative stem cells within the SVZ niche undergo during the first postnatal days.

  3. THz and infrared excitation spectrum below the Jahn-Teller transition in Sr3Cr2O8

    Science.gov (United States)

    Wang, Zhe; Schmidt, Michael; Günther, Axel; Schaile, Sebastian; Pascher, Nikola; Mayr, Franz; Goncharov, Yurii; Krug von Nidda, Hans-Albrecht; Loidl, Alois; Quintero-Castro, Diana; Islam, A. T. M. N.; Lake, Bella; Deisenhofer, Joachim

    2012-02-01

    We report on optical excitations observed recently in Sr3Cr2O8 by THz and infrared spectroscopy. Low-energy excitations below 3 THz are detected by THz time domain spectroscopy. These excitations can be divided into two different classes according to the temperature-dependent properties. One is emergent right below the Jahn-Teller transition temperature, which is determined by specific heat measurement to occur at 285 K [1, 2]. The other appears only below 100 K, where the fluctuations are sufficiently suppressed, consistent with the temperature dependence of low-energy Raman modes [3]. Infrared transmission measurements reveal a broad crystal-field excitation, which can be associated with an electronic transition from E to T2 orbital states. [4pt] [1] Zhe Wang et al., Phys. Rev. B 83, 201102 (2011) [0pt] [2] D. L. Quintero-Castro et al., Phys. Rev. B 81, 014415 (2010) [0pt] [3] D. Wulferding et al., Phys. Rev. B 84, 064419 (2011)

  4. Radio frequency detection assembly and method for detecting radio frequencies

    Science.gov (United States)

    Cown, Steven H.; Derr, Kurt Warren

    2010-03-16

    A radio frequency detection assembly is described and which includes a radio frequency detector which detects a radio frequency emission produced by a radio frequency emitter from a given location which is remote relative to the radio frequency detector; a location assembly electrically coupled with the radio frequency detector and which is operable to estimate the location of the radio frequency emitter from the radio frequency emission which has been received; and a radio frequency transmitter electrically coupled with the radio frequency detector and the location assembly, and which transmits a radio frequency signal which reports the presence of the radio frequency emitter.

  5. The protactive effects and mechanisms of cx3cr1 antibody on retinal neuron in rats with ischemia reperfusion injury by intravitreal injection%Cx3cr1抗体玻璃体腔注射对视网膜缺血-再灌注损伤大鼠视网膜神经元的保护作用及机制

    Institute of Scientific and Technical Information of China (English)

    李娟娟; 李燕; 汤志伟

    2016-01-01

    背景 视网膜小胶质细胞在视网膜缺血-再灌注损伤(IRI)损伤过程中被活化,对视网膜神经节细胞(RGCs)发生损伤作用,cx3cr1表达的上调则是小胶质细胞活化的重要因素,因此阻断cx3cr1的表达从而抑制小胶质细胞活化可成为视网膜IRI过程中神经元保护的治疗靶点.目的 探讨抑制cx3cr1表达对小胶质细胞活化的影响及其对RGCs的保护作用.方法 将90只SD大鼠按照随机数字表法分为4个组,其中正常对照组(15只)未给予任何干预,单纯cx3cr1抗体注射组(30只)于正常大鼠玻璃体腔注射0.2μg/μl的cx3cr1抗体1μl,模型对照组大鼠通过生理盐水前房灌注法制备IRI模型(15只),而模型cx3cr1抗体注射组(30只)于大鼠制备IRI后即刻以同样的方法和剂量注射cx3cr1抗体,右眼为实验眼.于造模后48 h制备视网膜切片,透射电子显微镜下观察各组大鼠视网膜组织中RGCs的形态变化和细胞凋亡情况;采用常规组织病理学方法检测各组大鼠视网膜组织的形态变化,同时计数视网膜中RGCs数目;采用免疫组织化学法检测大鼠视网膜组织中小胶质细胞中CD68的表达,评估各组大鼠视网膜中小胶质细胞的活化状况;采用实时定量PCR法检测cx3cr1、肿瘤坏死因子α(TNF-α)和白细胞介素1β(IL-1β) mRNA在大鼠视网膜组织中的相对表达量.结果 正常对照组和单纯cx3cr1抗体注射组大鼠RGCs细胞核呈圆形或椭圆形,细胞器丰富,光感受器细胞外节膜盘排列整齐,内节线粒体丰富,但模型对照组大鼠视网膜RGCs形态不规则,光感受器细胞外节膜盘断裂,RGCs层可见小胶质细胞,模型cx3cr1抗体注射组大鼠视网膜组织中也可见到光感受器细胞外节膜盘断裂和RGCs减少.正常对照组、单纯cx3cr1抗体注射组、模型对照组和模型cx3cr1抗体注射组大鼠RGCs数目分别为(38.100±3.929)、(37.200±5.266)、(26.700±2.584)和(31.700±2.946)个/视野,

  6. Near-infrared imaging of the host galaxies of three radio-loud quasars at z = 1.5

    CERN Document Server

    Falomo, R; Treves, A; Falomo, Renato; Kotilainen, Jari; Treves, Aldo

    2000-01-01

    We present high spatial resolution near-infrared H-band (1.65 microns) images, taken with ISAAC on UT1 of ESO VLT, of three radio-loud quasars at z = 1.5, as a pilot study for imaging of a larger sample of radio-loud and radio-quiet quasars in the redshift range 1 < z < 2. We are able to clearly detect the host galaxy in two quasars (PKS 0000-177 and PKS 0348-120) and marginally in the third (PKS 0402-362). The host galaxies appear compact (average bulge scale-length R(e) = 4 kpc) and luminous (average M(H) = -27.6+-0.1). They are 2.5 mag more luminous than the typical galaxy luminosity (M*(H) = -25.0+-0.2), and are comparable to the hosts of low redshift radio-loud quasars (M(H) = -26), taking into account passive stellar evolution. Their luminosities are also similar to those of high redshift radio galaxies. All three quasars have at least one close companion galaxy at a projected distance < 50 kpc from the quasar, assuming they are at the same redshift.

  7. AGN Feedback and Evolution of Radio Sources: Discovery of an X-ray Cluster Associated with z=1 Quasar

    CERN Document Server

    Siemiginowska, A; La Massa, S; Burke, D; Aldcroft, T L; Bechtold, J; Elvis, M; Worrall, D M

    2005-01-01

    We report the first significant detection of an X-ray cluster associated with a powerful (L(bol) ~1e47 erg/sec) radio-loud quasar at high redshift (z=1.06). Diffuse X-ray emission is detected out to ~120 kpc from the CSS quasar 3C 186. A strong Fe-line emission at the z(rest)=1.06 confirms its thermal nature. We find that the CSS radio source is highly overpressured with respect to the thermal cluster medium by ~2-3 orders of magnitude. This provides direct observational evidence that the radio source is not thermally confined as posited in the ``frustrated'' scenario for CSS sources. Instead, the radio source may be young and at an early stage of its evolution. This source provides the first detection of the AGN in outburst in the center of a cooling flow cluster. Powerful radio sources are thought to be triggered by the cooling flows. The evidence for the AGN activity and intermittent outbursts comes from the X-ray morphology of low redshift clusters, which usually do not harbour quasars. 3C186 is a young a...

  8. The unification of powerful quasars and radio galaxies and their relation to other massive galaxies

    CERN Document Server

    Podigachoski, P; Haas, M; Leipski, C; Wilkes, B

    2015-01-01

    The unification model for powerful radio galaxies and radio-loud quasars postulates that these objects are intrinsically the same but viewed along different angles. Herschel Space Observatory data permit the assessment of that model in the far-infrared spectral window. We analyze photometry from Spitzer and Herschel for the distant 3CR hosts, and find that radio galaxies and quasars have different mid-infrared, but indistinguishable far-infrared colors. Both these properties, the former being orientation dependent and the latter orientation invariant, are in line with expectations from the unification model. Adding powerful radio-quiet active galaxies and typical massive star-forming galaxies to the analysis, we demonstrate that infrared colors not only provide an orientation indicator, but can also distinguish active from star-forming galaxies.

  9. Sintering and Electronic Conducting Properties of La0.7Ca0.3CrO3 Perovskite Synthesized by a Glycine-nitrate Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    La0.7 Ca0.3 CrO3 powder consisting of superfine and uniform particles (100-200 nm) weresynthesized using a glycine- nitrate process ( GNP ).The sintering and electronic conducting properties of La0.7Ca0.3 CrO3 were investigated in the sintering temperature range of 1 200- 1 450 ℃ .The desired morphology ofthe powder significantly improved its sinterability.La0.7 Ca0.3 CrO3 ceramics sintered at 1 250-1 450 ℃ show high relative densities above 95 % .The ceramics sintered at 1 250- 1 400 ℃ have very similar electronic conducting properties, providing electronic conductivities around 55 Ω- 1 cm-1 at a measuring temperature of 800 ℃ .Further increasing the sintering temperature to 1450 ℃ led to an apparent degradation of electronic conducting properties.This research demonstrates the advantage of the GNP in producing La0.7 Ca0.3 CrO3 with respect to the enhanced sintering properties and superior electronic conducting properties.

  10. Search for an association between V249I and T280M CX3CR1 genetic polymorphisms, endothelial injury and preeclampsia: the ECLAXIR study.

    Directory of Open Access Journals (Sweden)

    Alain Stepanian

    Full Text Available BACKGROUND: Preeclampsia and coronary-artery disease share risk factors, suggesting common pathophysiological mechanisms. CX3CR1/CX3CL1 mediates leukocyte migration and adhesion and has been implicated in the pathophysiology of several inflammatory diseases. M280/I249 variants of CX3CR1 are associated with an atheroprotective effect and reduced endothelial dysfunction. The aim of this study was to search for an association between V249I and T280M polymorphisms of CX3CR1, preeclampsia and endothelial dysfunction. METHODOLOGY/PRINCIPAL FINDINGS: We explored these polymorphisms with real-time polymerase chain reaction in a case-control study (184 white women with preeclampsia and 184 matched normotensive pregnant women. Endothelial dysfunction biomarkers including von Willebrand factor, VCAM-1 and thrombomodulin, as well as the soluble form of CX3CL1 were measured by enzyme-linked immunosorbent assays (ELISA. The I249 and M280 alleles were associated neither with preeclampsia, nor with its more severe form or with endothelial injury. In contrast, we found a trend toward increased CX3CL1 levels in preeclampsia patients, especially in early-onset- preeclampsia as compared to its level in later-onset- preeclampsia. CONCLUSIONS/SIGNIFICANCE: This is the first study to characterize the CX3CR1 gene polymorphisms in patients with preeclampsia. We found no differences in genotype or haplotype frequencies between patients with PE and normal pregnancies, suggesting that maternal CX3CR1 V249I and T280M polymorphisms do not increase susceptibility to preeclampsia. Further studies should be performed to directly evaluate the pathophysiological role of CX3CL1, a molecule abundantly expressed in endometrium, which has been shown to stimulate human trophoblast migration.

  11. Development of a New Class of Fe-3Cr-W(V)Ferritic STeels for Industrial Process Applications

    Energy Technology Data Exchange (ETDEWEB)

    Jawad, M.

    2005-03-31

    The project described in this report dealt with improving the materials performance and fabrication for hydrotreating reactor vessels, heat recovery systems, and other components for the petroleum and chemical industries. The petroleum and chemical industries use reactor vessels that can approach ship weights of approximately 300 tons with vessel wall thicknesses of 3-8 in. These vessels are typically fabricated from Fe-Cr-Mo steels with chromium ranging from 1.25 to 12% and molybdenum from 1 to 2%. Steels in this composition range have great advantages of high thermal conductivity, low thermal expansion, low cost, and good properties obtainable by heat treatment. With all of the advantages of Fe-Cr-Mo steels, several issues are faced in design and fabrication of vessels and related components. These issues include the following: 1. The low strengths of current alloys require thicker sections. 2. Increased thickness causes heat-treatment issues related to nonuniformity across the thickness and thus a failure to achieve optimum properties. 3. Fracture toughness (ductile-to-brittle transition) is a critical safety issue for these vessels, especially in thick sections because of the nonuniformity of the microstructure. 4. The postweld heat treatment (PWHT) needed after welding makes fabrication more timeconsuming with increased cost. 5. PWHT needed after welding also limits any modifications of the large vessels in service. The goal of this project was to reduce the weight of large-pressure-vessel components (ranging from 100 to 300 tons) by approximately 25%, reduce fabrication cost, and improve in-service modification feasibility through development of Fe-3Cr-W(V) steels with a combination of nearly a 50% higher strength, a lower ductile-brittle transition temperature (DBTT), a higher upper-shelf energy, ease of heat treating, and a strong potential for not requiring PWHT.

  12. Development of a New Class of Fe-3Cr-W(V)Ferritic STeels for Industrial Process Applications

    Energy Technology Data Exchange (ETDEWEB)

    Jawad, M.

    2005-03-31

    The project described in this report dealt with improving the materials performance and fabrication for hydrotreating reactor vessels, heat recovery systems, and other components for the petroleum and chemical industries. The petroleum and chemical industries use reactor vessels that can approach ship weights of approximately 300 tons with vessel wall thicknesses of 3-8 in. These vessels are typically fabricated from Fe-Cr-Mo steels with chromium ranging from 1.25 to 12% and molybdenum from 1 to 2%. Steels in this composition range have great advantages of high thermal conductivity, low thermal expansion, low cost, and good properties obtainable by heat treatment. With all of the advantages of Fe-Cr-Mo steels, several issues are faced in design and fabrication of vessels and related components. These issues include the following: 1. The low strengths of current alloys require thicker sections. 2. Increased thickness causes heat-treatment issues related to nonuniformity across the thickness and thus a failure to achieve optimum properties. 3. Fracture toughness (ductile-to-brittle transition) is a critical safety issue for these vessels, especially in thick sections because of the nonuniformity of the microstructure. 4. The postweld heat treatment (PWHT) needed after welding makes fabrication more timeconsuming with increased cost. 5. PWHT needed after welding also limits any modifications of the large vessels in service. The goal of this project was to reduce the weight of large-pressure-vessel components (ranging from 100 to 300 tons) by approximately 25%, reduce fabrication cost, and improve in-service modification feasibility through development of Fe-3Cr-W(V) steels with a combination of nearly a 50% higher strength, a lower ductile-brittle transition temperature (DBTT), a higher upper-shelf energy, ease of heat treating, and a strong potential for not requiring PWHT.

  13. Impact of cognitive radio on radio astronomy

    NARCIS (Netherlands)

    Bentum, M.J.; Boonstra, A.J.; Baan, W.A.

    2010-01-01

    The introduction of new communication techniques requires an increase in the efficiency of spectrum usage. Cognitive radio is one of the new techniques that fosters spectrum efficiency by using unoccupied frequency spectrum for communications. However, cognitive radio will increase the transmission

  14. Resonance and Radio

    Science.gov (United States)

    Starrett, Malin J.

    2008-01-01

    The science and technology of radio receives little attention in contemporary education. This article discusses ways to explore the basic operating principles of radio. (Contains 4 figures, 3 footnotes, and 2 notes.)

  15. Educational Radio in India

    OpenAIRE

    VYAS, R. V.; R. C. Sharma; Kumar, Ashwini

    2002-01-01

    There are a good number of research studies, which indicate that radio has been a good medium of education delivery. Many experiments have been conducted in different countries on the use of radio in education. Radio has been used in conventional education, non-formal education, for agricultural education, for community development, in distance education, so on and so forth. This paper explains various educational radio projects undertaken in India

  16. Commercial Radio as Communication.

    Science.gov (United States)

    Rothenbuhler, Eric W.

    1996-01-01

    Compares the day-to-day work routines of commercial radio with the principles of a theoretical communication model. Illuminates peculiarities of the conduct of communication by commercial radio. Discusses the application of theoretical models to the evaluation of practicing institutions. Offers assessments of commercial radio deriving from…

  17. Ham radio for dummies

    CERN Document Server

    Silver, H Ward

    2013-01-01

    An ideal first step for learning about ham radio Beyond operating wirelessly, today's ham radio operators can transmit data and pictures; use the Internet, laser, and microwave transmitters; and travel to places high and low to make contact. This hands-on beginner guide reflects the operational and technical changes to amateur radio over the past decade and provides you with updated licensing requirements and information, changes in digital communication (such as the Internet, social media, and GPS), and how to use e-mail via radio. Addresses the critical use of ham radio for replacing downe

  18. Development of A New Class of Fe-3Cr-W(V)Ferritic Steels for Industrial Process Applications

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.J.; Jawad, M.H. (Nooter Corp.)

    2005-06-15

    The project, 'Development of a New Class of Fe-Cr-W(V) Ferritic Steels for Industrial Process Applications', was a Cooperative Research and Development Agreement (CRADA) between Oak Ridge National Laboratory (ORNL) and Nooter Corporation. This project dealt with improving the materials performance and fabrication for the hydrotreating reactor vessels, heat recovery systems, and other components for the petroleum and chemical industries. The petroleum and chemical industries use reactor vessels that can approach the ship weights of approximately 300 tons with vessel wall thicknesses of 3 to 8 in. These vessels are typically fabricated from Fe-Cr-Mo steels with chromium ranging from 1.25 to 12% and molybdenum from 1 to 2%. Steels in this composition have great advantages of high thermal conductivity, low thermal expansion, low cost, and properties obtainable by heat treatment. With all of the advantages of Fe-Cr-Mo steels, several issues are faced in design and fabrication of vessels and related components. These issues include the following: (1) low strength properties of current alloys require thicker sections; (2) increased thickness causes heat-treatment issues related to nonuniformity across the thickness and thus not achieving the optimum properties; (3) fracture toughness (ductile-to-brittle transition ) is a critical safety issue for these vessels, and it is affected in thick sections due to nonuniformity of microstructure; (4) PWHT needed after welding and makes fabrication more time-consuming with increased cost; and (5) PWHT needed after welding also limits any modifications of the large vessels in service. The goal of this project was to reduce the weight of large-pressure vessel components (ranging from 100 to 300 tons) by approximately 25% and reduce fabrication cost and improve in-service modification feasibility through development of Fe-3Cr-W(V) steels with combination of nearly a 50% higher strength, a lower DBTT and a higher upper

  19. Radiography of Spanish Radio

    Directory of Open Access Journals (Sweden)

    Dra. Emma Rodero Antón

    2007-01-01

    Full Text Available In its eighty years of existence, radio has been always characterized to adapt to the social, cultural and technological transformations. Thus it has been until this moment. Nevertheless, some years ago, the authors and professionals of this medium have been detecting a stagnation that affects to its structure. At a time in continuous technological evolution, radio demands a deep transformation. For that reason, from the conviction of which the future radio, public and commercial, will necessarily have to renew itself, in this paper we establish ten problems and their possible solutions to the radio crisis in order to draw an x-ray of radio in Spain. Radio has future, but it is necessary to work actively by it. That the radio continues being part of sound of our life, it will depend on the work of all: companies, advertisers, professionals, students, investigators and listeners.

  20. Effect of Bi2O3 Additives on Properties of La0.7Ca0.3CrO3

    Institute of Scientific and Technical Information of China (English)

    Zhong Honghai; Zhou Xiaoliang; Liu Xingqin; Meng Guangyao

    2005-01-01

    Sintering characteristics of Ca-doped lanthanum chromite [La(Ca)CrO3] powder, prepared by gel-casting process were studied by measuring density and the evaluation of micro structural information. Bi2O3 is found to be an effective sintering additive for this material. The amount of Bi2O3 is altered to investigate Bi2O3 effect on the properties of La0.7Ca0.3CrO3. The amount of 10% (mass fraction) Bi2O3 is suitable to increase sinter-ability of La0.7Ca0.3CrO3. Increased concentration of point defects arising form substitution of Bi in La site is the plausible cause of enhanced sintering. Measurement of electrical conductivity and thermal expansion coefficient indicate that the doping of Bi2O3 does not have any significant effect on these properties.

  1. The disc-dominated host galaxy of FR-I radio source B2 0722+30

    CERN Document Server

    Emonts, B H C; Morganti, R; Oosterloo, T A; Holt, J; Brogt, E; Van Moorsel, G

    2009-01-01

    We present new observational results that conclude that the nearby radio galaxy B2 0722+30 is one of the very few known disc galaxies in the low-redshift Universe that host a classical double-lobed radio source. In this paper we use HI observations, deep optical imaging, stellar population synthesis modelling and emission-line diagnostics to study the host galaxy, classify the Active Galactic Nucleus and investigate environmental properties under which a radio-loud AGN can occur in this system. Typical for spiral galaxies, B2 0722+30 has a regularly rotating gaseous disc throughout which star formation occurs. Dust heating by the ongoing star formation is likely responsible for the high infrared luminosity of the system. The optical emission-line properties of the central region identify a Low Ionization Nuclear Emission-line Region (LINER)-type nucleus with a relatively low [OIII] luminosity, in particular when compared with the total power of the Fanaroff & Riley type-I radio source that is present in t...

  2. THE CHANDRA SURVEY OF EXTRAGALACTIC SOURCES IN THE 3CR CATALOG: X-RAY EMISSION FROM NUCLEI, JETS, AND HOTSPOTS IN THE CHANDRA ARCHIVAL OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Massaro, F. [Dipartimento di Fisica, Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino (Italy); Harris, D. E.; Paggi, A.; Wilkes, B. J.; Kuraszkiewicz, J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Liuzzo, E.; Orienti, M.; Paladino, R. [Istituto di Radioastronomia, INAF, via Gobetti 101, I-40129, Bologna (Italy); Tremblay, G. R. [Yale Center for Astronomy and Astrophysics, Physics Department, Yale University, P.O. Box 208120, New Haven, CT 06520-8120 (United States); Baum, S. A.; O’Dea, C. P. [University of Manitoba, Dept of Physics and Astronomy, Winnipeg, MB R3T 2N2 (Canada)

    2015-09-15

    As part of our program to build a complete radio and X-ray database of all Third Cambridge catalog extragalactic radio sources, we present an analysis of 93 sources for which Chandra archival data are available. Most of these sources have already been published. Here we provide a uniform re-analysis and present nuclear X-ray fluxes and X-ray emission associated with radio jet knots and hotspots using both publicly available radio images and new radio images that have been constructed from data available in the Very Large Array archive. For about 1/3 of the sources in the selected sample, a comparison between the Chandra and radio observations was not reported in the literature: we find X-ray detections of 2 new radio jet knots and 17 hotspots. We also report the X-ray detection of extended emission from the intergalactic medium for 15 galaxy clusters.

  3. Analisis Kendala Perizinan Spektrum Frekuensi Radio untuk Radio Komunitas

    OpenAIRE

    Sri Wahyuningsih

    2014-01-01

    Izin penggunaan spektrum frekuensi radio diatur dalam Undang-undang No.36 tahun 1999 tentang Telekomunikasi. Saat ini masih ditemukan Radio Komunitas yang belum memiliki Izin Stasiun Radio (ISR). Penelitian ini bertujuan untuk menemu kenali kendala-kendala yang dihadapi Radio Komunitas pada proses pengajuan Izin Stasiun Radio (ISR). Teknik pengumpulan data melalui wawancara dengan penanggungjawab Radio Komunitas dan pejabat di lingkungan Balai Monitor Frekuensi Radio (Balmon) di Jakarta, Sema...

  4. Analisis Kendala Perizinan Spektrum Frekuensi Radio untuk Radio Komunitas

    OpenAIRE

    2014-01-01

    Izin penggunaan spektrum frekuensi radio diatur dalam Undang-undang No.36 tahun 1999 tentang Telekomunikasi. Saat ini masih ditemukan Radio Komunitas yang belum memiliki Izin Stasiun Radio (ISR). Penelitian ini bertujuan untuk menemu kenali kendala-kendala yang dihadapi Radio Komunitas pada proses pengajuan Izin Stasiun Radio (ISR). Teknik pengumpulan data melalui wawancara dengan penanggungjawab Radio Komunitas dan pejabat di lingkungan Balai Monitor Frekuensi Radio (Balmon) di Jakarta, Sema...

  5. Study on Two-phase Nanocrystalline Nd8.5Fe74Co5Cu1NblZr3Cr1B6.5 Permanent Magnet

    Institute of Scientific and Technical Information of China (English)

    Jiansen NI; Hui XU; Mingyuan ZHU; Qiang LI; Bangxin ZHOU; Yuanda DONG

    2004-01-01

    Nd8.5Fe74Co5Cu1Nb1Zr3Cr1B6.5 bonded magnets were prepared by melt-spun and subsequent heat treatment. Magnetic properties of Br=0.68 T, JHc=716 Ka/m, (BH)max=77 Kj/m3 were achieved. The addition of Cr element shows to be significantly advantageous in reducing grain size and increasing the intrinsic coercivity.

  6. Mn-Cr intersite independent magnetic behavior and electronic structures of LaMn3Cr4O12: Study from first-principles

    Science.gov (United States)

    Lv, Shuhui; Li, Hongping; Liu, Xiaojuan; Meng, Jian

    2011-07-01

    The magnetic and electronic structures of LaMn3Cr4O12 are investigated using the full-potential linearized augmented plane wave method within both the generalized gradient approximation (GGA) and GGA + U (electronic correlation) methods. The calculated results indicate that LaMn3Cr4O12 is an antiferromagnetic insulator. The magnetic ordering is demonstrated to be G-type within both Mn-site and Cr-site spins. However, there is no obvious magnetic coupling between Mn-site and Cr-site sublattices, which is verified by the separate distribution of their corresponding partial density of states. Moreover, the magnetic coupling constants of JCr-Cr and JMn-Mn are predicted to be - 5.0 (- 2.8) and - 0.83 (- 0.63) meV within GGA (GGA + U), respectively, consistent with the experimentally observed two independent Néel temperatures (TN1 and TN2). The calculated densities of states reveal the experimentally reported charge formula of LaMn3+3Cr3+4O12.

  7. CCR2(+) monocytes infiltrate atrophic lesions in age-related macular disease and mediate photoreceptor degeneration in experimental subretinal inflammation in Cx3cr1 deficient mice.

    Science.gov (United States)

    Sennlaub, Florian; Auvynet, Constance; Calippe, Bertrand; Lavalette, Sophie; Poupel, Lucie; Hu, Shulong J; Dominguez, Elisa; Camelo, Serge; Levy, Olivier; Guyon, Elodie; Saederup, Noah; Charo, Israel F; Rooijen, Nico Van; Nandrot, Emeline; Bourges, Jean-Louis; Behar-Cohen, Francine; Sahel, José-Alain; Guillonneau, Xavier; Raoul, William; Combadiere, Christophe

    2013-11-01

    Atrophic age-related macular degeneration (AMD) is associated with the subretinal accumulation of mononuclear phagocytes (MPs). Their role in promoting or inhibiting retinal degeneration is unknown. We here show that atrophic AMD is associated with increased intraocular CCL2 levels and subretinal CCR2(+) inflammatory monocyte infiltration in patients. Using age- and light-induced subretinal inflammation and photoreceptor degeneration in Cx3cr1 knockout mice, we show that subretinal Cx3cr1 deficient MPs overexpress CCL2 and that both the genetic deletion of CCL2 or CCR2 and the pharmacological inhibition of CCR2 prevent inflammatory monocyte recruitment, MP accumulation and photoreceptor degeneration in vivo. Our study shows that contrary to CCR2 and CCL2, CX3CR1 is constitutively expressed in the retina where it represses the expression of CCL2 and the recruitment of neurotoxic inflammatory CCR2(+) monocytes. CCL2/CCR2 inhibition might represent a powerful tool for controlling inflammation and neurodegeneration in AMD.

  8. CCR2+ monocytes infiltrate atrophic lesions in age-related macular disease and mediate photoreceptor degeneration in experimental subretinal inflammation in Cx3cr1 deficient mice

    Science.gov (United States)

    Sennlaub, Florian; Auvynet, Constance; Calippe, Bertrand; Lavalette, Sophie; Poupel, Lucie; Hu, Shulong J; Dominguez, Elisa; Camelo, Serge; Levy, Olivier; Guyon, Elodie; Saederup, Noah; Charo, Israel F; Van Rooijen, Nico; Nandrot, Emeline; Bourges, Jean-Louis; Behar-Cohen, Francine; Sahel, José-Alain; Guillonneau, Xavier; Raoul, William; Combadiere, Christophe

    2013-01-01

    Atrophic age-related macular degeneration (AMD) is associated with the subretinal accumulation of mononuclear phagocytes (MPs). Their role in promoting or inhibiting retinal degeneration is unknown. We here show that atrophic AMD is associated with increased intraocular CCL2 levels and subretinal CCR2+ inflammatory monocyte infiltration in patients. Using age- and light-induced subretinal inflammation and photoreceptor degeneration in Cx3cr1 knockout mice, we show that subretinal Cx3cr1 deficient MPs overexpress CCL2 and that both the genetic deletion of CCL2 or CCR2 and the pharmacological inhibition of CCR2 prevent inflammatory monocyte recruitment, MP accumulation and photoreceptor degeneration in vivo. Our study shows that contrary to CCR2 and CCL2, CX3CR1 is constitutively expressed in the retina where it represses the expression of CCL2 and the recruitment of neurotoxic inflammatory CCR2+ monocytes. CCL2/CCR2 inhibition might represent a powerful tool for controlling inflammation and neurodegeneration in AMD. PMID:24142887

  9. Ba3(Cr0.97(1)Te0.03(1))2TeO9: in Search of Jahn-Teller Distorted Cr(II) Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Li, Manrong; Deng, Zheng; Lapidus, Saul H.; Stephens, Peter W.; Segre, Carlo U.; Croft, Mark; Sena, Robert Paria; Hadermann, Joke; Walker, David; Greenblatt, Martha

    2016-10-17

    A novel 6H - type hexagonal perovskite Ba 3 (Cr 0.97(1) Te 0.03 (1 ) ) 2 TeO 9 was prepared at high pressure (6 GPa) and temperature ( 1 773 K). Both transmission electron microscopy and synchrotron powder x - ray diffraction data demonstrate that Ba 3 (Cr 0.97(1) Te 0.03(1) ) 2 TeO 9 crystallize s in P6 3 / mmc with face - shared (Cr 0.97(1) Te 0.03(1) )O 6 octahedral pairs interconnected with TeO 6 octahedra via corner - sharing. Structure analysis shows a mixed Cr 2+ /Cr 3+ valence state with ~ 10% Cr 2+ . The existence of Cr 2+ in Ba 3 (Cr 2+ 0.10(1) Cr 3+ 0.87(1) Te 6+ 0.03 ) 2 TeO 9 is further evidenced by x - ray absorption near edge spectr oscopy . Magnetic properties measurements show a paramagnetic response down to 4 K and a small glassy - state curvature at low temperature. In this work, the o ctahedral Cr 2+ O 6 component is stabilized in an oxide material for the first time ; the expected Jahn - Teller distortion of high - spin ( d 4 ) Cr 2+ is not found , which is attributed to the small proportion of Cr 2+ (~ 10%) and the face - sharing arrangement of CrO 6 octahedral pairs, that structu rally dis favor axial distortion.

  10. Deep spectroscopy of z~1 6C radio galaxies - II. Breaking the redshift-radio power degeneracy

    CERN Document Server

    Inskip, K J; Röttgering, H J A; Rawlings, S; Cotter, G; Longair, M S

    2002-01-01

    The results of a spectroscopic analysis of 3CR and 6C radio galaxies at redshift z~1 are contrasted with the properties of lower redshift radio galaxies, chosen to be matched in radio luminosity to the 6C sources studied at z~1, thus enabling the P-z degeneracy to be broken. Partial rank correlations and principal component analysis have been used to determine which of z and P are the critical parameters underlying the observed variation of the ionization state andd kinematics of the emission line gas. [OII]/H-beta is shown to be a useful ionization mechanism diagnostic. Statistical analysis of the data shows that the ionization state of the emission line gas is strongly correlated with radio power, once the effects of other parameters are removed. No dependence of ionization state on z is observed, implying that the ionization state of the emission line gas is solely a function of the AGN properties rather than the hostt galaxy and/or environment. Statistical analysis of the kinematic properties of the emiss...

  11. The Influence of Black Hole Mass and Accretion Rate on the FRI/FRII Radio Galaxy Dichotomy

    Science.gov (United States)

    Wold, M.; Lacy, M.; Armus, L.

    We use medium resolution optical spectra of 3CR radio galaxies to estimate their black hole masses and accretion rates. Black hole masses are found from central stellar velocity dispersions, and accretion rates are derived from narrow emission-line luminosities. The sample covers both Fanaroff-Riley (FR) classes; the more powerful FRIIs and the less powerful FRIs. We find that FRIs and FRIIs separate in diagrams of radio luminosity and narrow-line luminosity versus black hole mass. This suggests that, at a given black hole mass, the FRIIs accrete more efficiently, or accrete more matter, than FRIs.

  12. Senior radio listeners

    DEFF Research Database (Denmark)

    Blaakilde, Anne Leonora

    Radiobroadcasting and the hardware materialization of radio have during the 20th century changed significantly, which means that senior radio listeners have travelled along with this evolution from large, impressive radio furnitures to DAB and small, wireless, mobile devices, and from grave...... and solemn radio voices to lightharted, laughing and chatting speakers. Senior radio listerners have experienced the development and refinements of technique, content and genres. It is now expected of all media users that they are capable of crossing media, combining, juggling and jumping between various...... media platforms, not the least when listening to radio. The elder generation is no exception from this. Recently, for instance, the Danish public broadcast DR has carried out an exodus of programmes targeted for the senior segment. These programmes are removed from regular FM and sent to DAB receivers...

  13. THE UNIFICATION OF POWERFUL QUASARS AND RADIO GALAXIES AND THEIR RELATION TO OTHER MASSIVE GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Podigachoski, Pece; Barthel, Peter [Kapteyn Astronomical Institute, University of Groningen, 9747 AD Groningen (Netherlands); Haas, Martin [Astronomisches Institut, Ruhr Universität, D-44801 Bochum (Germany); Leipski, Christian [Max-Planck Institut für Astronomie (MPIA), D-69117 Heidelberg (Germany); Wilkes, Belinda, E-mail: podigachoski@astro.rug.nl [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2015-06-10

    The unification model for powerful radio galaxies (RGs) and radio-loud quasars postulates that these objects are intrinsically the same but viewed along different angles. Herschel Space Observatory data permit the assessment of that model in the far-infrared spectral window. We analyze photometry from Spitzer and Herschel for the distant 3CR hosts, and find that RGs and quasars have different mid-infrared, but indistinguishable far-infrared colors. Both these properties, the former being orientation dependent and the latter orientation invariant, are in line with expectations from the unification model. Adding powerful radio-quiet active galaxies and typical massive star-forming (SF) galaxies to the analysis, we demonstrate that infrared colors not only provide an orientation indicator, but can also distinguish active from SF galaxies.

  14. Fast Radio Bursts

    Indian Academy of Sciences (India)

    Akshaya Rane; Duncan Lorimer

    2017-09-01

    We summarize our current state of knowledge of fast radio bursts (FRBs) which were first discovered a decade ago. Following an introduction to radio transients in general, including pulsars and rotating radio transients, we discuss the discovery of FRBs. We then discuss FRB follow-up observations in the context of repeat bursts before moving on to review propagation effects on FRB signals, FRB progenitor models and an outlook on FRBs as potential cosmological tools.

  15. A Zynq-based Cluster Cognitive Radio

    OpenAIRE

    Rooks, Kurtis M.

    2014-01-01

    Traditional hardware radios provide very rigid solutions to radio problems. Intelligent software defined radios, also known as cognitive radios, provide flexibility and agility compared to hardware radio systems. Cognitive radios are well suited for radio applications in a changing radio frequency environment, such as dynamic spectrum access. In this thesis, a cognitive radio is demonstrated where the system self reconfigures to dem...

  16. Transformations of Radio Aesthetics

    Directory of Open Access Journals (Sweden)

    Grażyna Stachyra

    2015-09-01

    Full Text Available The paper presents some remarks upon the nature of contemporary radio communications in the context of the terms “aesthetics” and “aesthetisation”. The latter, denoting a process of turning aesthetic phenomena into unaesthetic ones, becomes the dominant strategy of formatted radio. The “surface aesthetisation,” which provides mainly pleasure and entertainment, transcends the simple styling of objects or environment and appears to be a more significant strand of contemporary culture. The article shows several examples of “surface” modelling of radio programming and explains their purpose in radio communication.

  17. STEM on the radio

    Science.gov (United States)

    Showstack, Randy

    2011-10-01

    Looking for an Internet radio station focusing on programing about science, technology, engineering, and math (STEM)? The U.S. National Science Foundation (NSF) announced on 26 September the launch of Science360 Radio, which it says is the first Internet radio stream dedicated to STEM programing. Science360 includes more than 100 radio shows and podcasts that are available on the Web as well as on iPhone and Android devices. The shows originate from a variety of sources, including NSF, other U.S. government agencies, science organizations, universities, and media outlets. For more information, see http://science360.gov/files/.

  18. Enhancing GNU Radio for Hardware Accelerated Radio Design

    OpenAIRE

    Irick, Charles Robert

    2010-01-01

    As technology evolves and new methods for designing radios arise, it becomes necessary to continue the search for fast and flexible development environments. Some of these new technologies include software defined radio (SDR), Field Programmable Gate Arrays (FPGAs), and the open source project GNU Radio. Software defined radio is a concept that GNU Radio has harnessed to allow developers to quickly create flexible radio designs. In terms of hardware, the maturity of FPGAs give ...

  19. Analisis Kendala Perizinan Spektrum Frekuensi Radio untuk Radio Komunitas

    Directory of Open Access Journals (Sweden)

    Sri Wahyuningsih

    2014-03-01

    Full Text Available Izin penggunaan spektrum frekuensi radio diatur dalam Undang-undang No.36 tahun 1999 tentang Telekomunikasi. Saat ini masih ditemukan Radio Komunitas yang belum memiliki Izin Stasiun Radio (ISR. Penelitian ini bertujuan untuk menemu kenali kendala-kendala yang dihadapi Radio Komunitas pada proses pengajuan Izin Stasiun Radio (ISR. Teknik pengumpulan data melalui wawancara dengan penanggungjawab Radio Komunitas dan pejabat di lingkungan Balai Monitor Frekuensi Radio (Balmon di Jakarta, Semarang dan Yogyakarta. Analisis data mengacu pada model Matthew B Miles dan A Michael Huberman. Hasil penelitian menyatakan kendala yang dihadapi terutama pada sertifikasi perangkat Radio Komunitas.

  20. Obscured flat spectrum radio active galactic nuclei as sources of high-energy neutrinos

    Science.gov (United States)

    Maggi, G.; Buitink, S.; Correa, P.; de Vries, K. D.; Gentile, G.; Tavares, J. León; Scholten, O.; van Eijndhoven, N.; Vereecken, M.; Winchen, T.

    2016-11-01

    Active galactic nuclei (AGN) are believed to be one of the main source candidates for the high-energy (TeV-PeV) cosmic neutrino flux recently discovered by the IceCube neutrino observatory. Nevertheless, several correlation studies between AGN and the cosmic neutrinos detected by IceCube show no significance. Therefore, in this article we consider a specific subclass of AGN for which an increased neutrino production is expected. This subclass contains AGN for which their high-energy jet is pointing toward Earth. Furthermore, we impose the condition that the jet is obscured by gas or dust surrounding the AGN. A method is presented to determine the total column density of the obscuring medium, which is probed by determining the relative x-ray attenuation with respect to the radio flux as obtained from the AGN spectrum. The total column density allows us to probe the interaction of the jet with the surrounding matter, which leads to additional neutrino production. Finally, starting from two different source catalogs, this method is applied to specify a sample of low redshift radio galaxies for which an increased neutrino production is expected.

  1. Radio Graceful Hamming Graphs

    Directory of Open Access Journals (Sweden)

    Niedzialomski Amanda

    2016-11-01

    Full Text Available For k ∈ ℤ+ and G a simple, connected graph, a k-radio labeling f : V (G → ℤ+ of G requires all pairs of distinct vertices u and v to satisfy |f(u − f(v| ≥ k + 1 − d(u, v. We consider k-radio labelings of G when k = diam(G. In this setting, f is injective; if f is also surjective onto {1, 2, . . . , |V (G|}, then f is a consecutive radio labeling. Graphs that can be labeled with such a labeling are called radio graceful. In this paper, we give two results on the existence of radio graceful Hamming graphs. The main result shows that the Cartesian product of t copies of a complete graph is radio graceful for certain t. Graphs of this form provide infinitely many examples of radio graceful graphs of arbitrary diameter. We also show that these graphs are not radio graceful for large t.

  2. Radio Emission from Exoplanets

    OpenAIRE

    George, Samuel J.; Stevens, Ian R.

    2008-01-01

    We present results from new low frequency observations of two extrasolar planetary systems (Epsilon Eridani and HD128311) taken at 150 MHz with the Giant Metrewave Radio Telescope (GMRT). We do not detect either system, but are able to place tight upper limits on their low frequency radio emission.

  3. Valuing commercial radio licences

    NARCIS (Netherlands)

    Kerste, M.; Poort, J.; van Eijk, N.

    2015-01-01

    Within the EU regulatory framework, licensees for commercial radio broadcasting may be charged a fee to ensure optimal allocation of scarce resources but not to maximize public revenues. While radio licence renewal occurs in many EU countries, an objective, model-based approach for setting licence f

  4. Modification the Oxalic Co-precipitation Method on a Novel Catalyst Cu/Zn/Al2O3/Cr2O3 for Autothermal Reforming Reaction of Methanol

    Directory of Open Access Journals (Sweden)

    Cheng- Hsin Kuo

    2013-12-01

    Full Text Available This study addresses the catalytic performance of Cu/ZnO/Al2O3/Cr2O3 in low-temperature of autothermal reforming (ATR reaction. Various operating conditions were used to decide the optimum reaction conditions: type of promoter (ZrO2, CeO2, and Cr2O3, precipitation temperature, precipitation pH, operation temperature, molar ratio of O2/CH3OH (O/C, and weight hourly space velocity (WHSV. The catalysts were prepared using the oxalic coprecipitation method. Characterization of the catalyst was conducted using a porosity analyzer, XRD, and SEM. The methanol conversion and volumetric percentage of hydrogen using the best catalyst (Cu/ZnO/Al2O3/Cr2O3 exceeded 93% and 43%, respectively. A catalyst prepared by precipitation at -5 oC and at pH of 1 converted methanol to 40% H2 and less than 3000 ppm CO at reaction temperature of 200 oC. The size and dispersion of copper and the degradation rate and turnover frequency of the catalyst was also calculated. Deactivation of the Cu catalyst at a reaction temperature of 200 oC occurred after 30 h. © 2013 BCREC UNDIP. All rights reservedReceived: 8th May 2013; Revised: 10th August 2013; Accepted: 18th August 2013[How to Cite: Cheng, H.K., Lesmana, D., Wu, H.S. (2013. Modification the Oxalic Co-precipitation Method on a Novel Catalyst Cu/Zn/Al2O3/Cr2O3 for Autothermal Reforming Reaction of Methanol. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (2: 110-124. (doi:10.9767/bcrec.8.2.4844.110-124][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.2.4844.110-124

  5. Intestinal CX3C chemokine receptor 1(high) (CX3CR1(high)) myeloid cells prevent T-cell-dependent colitis.

    Science.gov (United States)

    Kayama, Hisako; Ueda, Yoshiyasu; Sawa, Yukihisa; Jeon, Seong Gyu; Ma, Ji Su; Okumura, Ryu; Kubo, Atsuko; Ishii, Masaru; Okazaki, Taku; Murakami, Masaaki; Yamamoto, Masahiro; Yagita, Hideo; Takeda, Kiyoshi

    2012-03-27

    Adequate activation of CD4(+) T lymphocytes is essential for host defense against invading pathogens; however, exaggerated activity of effector CD4(+) T cells induces tissue damage, leading to inflammatory disorders such as inflammatory bowel diseases. Several unique subsets of intestinal innate immune cells have been identified. However, the direct involvement of innate immune cell subsets in the suppression of T-cell-dependent intestinal inflammation is poorly understood. Here, we report that intestinal CX(3)C chemokine receptor 1(high) (CX(3)CR1(high)) CD11b(+) CD11c(+) cells are responsible for prevention of intestinal inflammation through inhibition of T-cell responses. These cells inhibit CD4(+) T-cell proliferation in a cell contact-dependent manner and prevent T-cell-dependent colitis. The suppressive activity is abrogated in the absence of the IL-10/Stat3 pathway. These cells inhibit T-cell proliferation by two steps. Initially, CX(3)CR1(high) CD11b(+) CD11c(+) cells preferentially interact with T cells through highly expressed intercellular adhesion molecule-1/vascular cell adhesion molecule-1; then, they fail to activate T cells because of defective expression of CD80/CD86. The IL-10/Stat3 pathway mediates the reduction of CD80/CD86 expression. Transfer of wild-type CX(3)CR1(high) CD11b(+) CD11c(+) cells prevents development of colitis in myeloid-specific Stat3-deficient mice. Thus, these cells are regulatory myeloid cells that are responsible for maintaining intestinal homeostasis.

  6. Intestinal CX3C chemokine receptor 1high (CX3CR1high) myeloid cells prevent T-cell-dependent colitis

    Science.gov (United States)

    Kayama, Hisako; Ueda, Yoshiyasu; Sawa, Yukihisa; Jeon, Seong Gyu; Ma, Ji Su; Okumura, Ryu; Kubo, Atsuko; Ishii, Masaru; Okazaki, Taku; Murakami, Masaaki; Yamamoto, Masahiro; Yagita, Hideo; Takeda, Kiyoshi

    2012-01-01

    Adequate activation of CD4+ T lymphocytes is essential for host defense against invading pathogens; however, exaggerated activity of effector CD4+ T cells induces tissue damage, leading to inflammatory disorders such as inflammatory bowel diseases. Several unique subsets of intestinal innate immune cells have been identified. However, the direct involvement of innate immune cell subsets in the suppression of T-cell-dependent intestinal inflammation is poorly understood. Here, we report that intestinal CX3C chemokine receptor 1high (CX3CR1high) CD11b+ CD11c+ cells are responsible for prevention of intestinal inflammation through inhibition of T-cell responses. These cells inhibit CD4+ T-cell proliferation in a cell contact-dependent manner and prevent T-cell-dependent colitis. The suppressive activity is abrogated in the absence of the IL-10/Stat3 pathway. These cells inhibit T-cell proliferation by two steps. Initially, CX3CR1high CD11b+ CD11c+ cells preferentially interact with T cells through highly expressed intercellular adhesion molecule-1/vascular cell adhesion molecule-1; then, they fail to activate T cells because of defective expression of CD80/CD86. The IL-10/Stat3 pathway mediates the reduction of CD80/CD86 expression. Transfer of wild-type CX3CR1high CD11b+ CD11c+ cells prevents development of colitis in myeloid-specific Stat3-deficient mice. Thus, these cells are regulatory myeloid cells that are responsible for maintaining intestinal homeostasis. PMID:22403066

  7. Selective acetone gas sensors using porous WO{sub 3}-Cr{sub 2}O{sub 3} thin films prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Gao Peng; Ji Huiming, E-mail: jihuiming@tju.edu.cn; Zhou Yugui; Li Xiaolei

    2012-01-31

    WO{sub 3}-Cr{sub 2}O{sub 3} semiconducting thin films were prepared by sol-gel method. Acetone gas sensing properties were investigated. Monoclinic phase was obtained as determined by X-ray diffraction after WO{sub 3}-Cr{sub 2}O{sub 3} films were sintered in oxygen atmosphere for 1 h at 500 Degree-Sign C (quenched after sintering). Porous structure was observed by using field emission scanning electron microscopy. Electrical properties were studied by conductivity measurement. The acetone vapor sensing properties of these thin films were found strongly influenced by the porous structure, the content of Cr{sub 2}O{sub 3}, the sintering temperature, and the cooling way. As-prepared WO{sub 3}-Cr{sub 2}O{sub 3} thin films exhibit excellent acetone vapor sensing properties with the maximum sensitivity {approx} 8.91 at 320 Degree-Sign C in air atmosphere with fast response and recovery time. - Highlights: Black-Right-Pointing-Pointer Porous structure was prepared to improve the thin film's gas-sensing properties. Black-Right-Pointing-Pointer Dissymmetrical monoclinic structure was obtained to improve selectivity to acetone. Black-Right-Pointing-Pointer Quenching after sintering enables obtain dissymmetrical structure. Black-Right-Pointing-Pointer Effects of the sintering temperature and the Cr{sub 2}O{sub 3} content were discussed. Black-Right-Pointing-Pointer As prepared sensors can diagnose diabetes based on human breath analysis.

  8. Modification the Oxalic Co-precipitation Method on a Novel Catalyst Cu/Zn/Al2O3/Cr2O3 for Autothermal Reforming Reaction of Methanol

    OpenAIRE

    Cheng- Hsin Kuo; Donny Lesmana; Ho Shing Wu

    2013-01-01

    This study addresses the catalytic performance of Cu/ZnO/Al2O3/Cr2O3 in low-temperature of autothermal reforming (ATR) reaction. Various operating conditions were used to decide the optimum reaction conditions: type of promoter (ZrO2, CeO2, and Cr2O3), precipitation temperature, precipitation pH, operation temperature, molar ratio of O2/CH3OH (O/C), and weight hourly space velocity (WHSV). The catalysts were prepared using the oxalic coprecipitation method. Characterization of the catalyst wa...

  9. Weathering the Largest Storms in the Universe : Understanding environmental effects on extended radio emission in clusters

    Science.gov (United States)

    Dehghan, S.

    2014-05-01

    This thesis presents an investigation of the habitat of extended radio sources, and the way in which the generation and properties of these radio sources are affected by environmental factors. We begin with a detailed structure analysis of the 0.3 deg2 area of the MUSYC-ACES field, generated by applying a density-based clustering method, known as DBSCAN, to our spectroscopic and photometric samples of the field. As a result, we identify 62 over-dense regions across the field. Based on the properties of the detected structures, we classify 13 as clusters, of which 90% are associated with diffuse soft-band X-ray emission. This provides a strong and independent confirmation that both the clustering and classification methodologies are reliable for use in investigation of the environment of the radio sources in the Chandra Deep Field South (CDFS). Using an interpolation-based method followed by a new calibration technique of using clusters of similar mass as standard candles, we are able to estimate the local environmental richness for a desired region. This methodology is applied to a sample of AGNs and star forming galaxies in the CDFS to probe whether or not the radio luminosity of the different radio sources is correlated to their environments. As a result, we do not find a significant correlation between the radio luminosity and the environment of star-forming galaxies and radio-quiet AGNs, however, a weak positive dependency is spotted for radio-loud AGNs. This may indicate that over-populated environments trigger or enhance the radio activity processes in the AGNs. We find that star-forming galaxies, unlike radio-loud AGNs, tend to avoid overpopulated environments especially at low redshifts. However, radio-loud AGN are found in both poor and rich environments. As a result, we find neither of these radio sources suitable for tracing the over-dense regions of the Universe, unlike tailed radio galaxies. It is believed that tailed radio galaxies reside in the dense

  10. The emission line regions of redshift one radio galaxies

    Directory of Open Access Journals (Sweden)

    P. N. Best

    2002-01-01

    Full Text Available Hacemos una rese~na de las ideas corrientes sobre las zonas emisoras de l neas en radio galaxias con corrimientos al rojo de z 1. Primero, consideramos la evoluci on de las propiedades del gas emisor de l neas desde el universo cercano hasta z 1. Luego, consideramos el origen de la ionizaci on y de los estados cinem aticos del gas en poderosas galaxias 3CR a z 1, y en particular mostramos que estas evolucionan fuertemente a lo largo de la vida de la radio fuente como resultado del profundo efecto del pasaje de choques a trav es del medio interestelar de la galaxia. Demostramos que esta dicotom a persiste a z m as bajo y tambi en en una muestra de radio galaxias de menor potencia al mismo z. Finalmente, discutimos las implicaciones de estos resultados para el entendimiento de las propiedades del gas emisor de l neas y del papel m as amplio de las interacciones jet/nube.

  11. VLBI Observations of a Complete Sample of Radio Galaxies. 10 Years Later

    CERN Document Server

    Giovannini, G; Feretti, L; Lara, L; Venturi, T

    2001-01-01

    A complete sample of 27 radio galaxies was selected from the B2 and 3CR catalogs, in order to study their properties on the milliarcsecond scale. In the Appendix of this paper we present new radio images for 12 of them. Thanks to the present data, all the sources in this sample have been imaged at mas resolution. We discuss the general results. In particular we stress the evidence for high velocity jets in low power radio galaxies, we compare high and low power sources, and discuss the source properties in the light of the unified scheme models. We derive that the properties of parsec scale jets are similar in sources with different total radio power and kpc scale morphology. From the core - total radio power correlation, we estimate that relativistic jets with Lorentz factor $\\gamma$ in the range 3 - 10 are present in high and low power radio sources. We discuss also the possible existence of a two velocity structure in the jets (fast spine and lower velocity external shear layer).

  12. Radio source evolution

    CERN Document Server

    Perucho, Manel

    2015-01-01

    Baldwin (1982) wrote that "the distribution of sources in the radio luminosity, P, overall physical size, D, diagram" could be considered as "the radio astronomer's H-R diagram". However, unlike the case of stars, not only the intrinsic properties of the jets, but also those of the host galaxy and the intergalactic medium are relevant to explain the evolutionary tracks of radio radio sources. In this contribution I review the current status of our understanding of the evolution of radio sources from a theoretical and numerical perspective, using the P-D diagram as a framework. An excess of compact (linear size < 10 kpc) sources could be explained by low-power jets being decelerated within the host galaxy, as shown by recent numerical simulations. These decelerated jets could also explain the population of the radio sources that have been recently classified as FR0. I will discuss the possible tracks that radio sources may follow within this diagram, and some of the physical processes that can explain the d...

  13. Microstructural characterization in diffusion bonded TiC–Al2O3/Cr18–Ni8 joint with Ti interlayer

    Indian Academy of Sciences (India)

    Wang Juan; Li Yajiang; Yin Yansheng

    2006-04-01

    Ceramic matrix composite, TiC–Al2O3, and stainless steel, Cr18–Ni8, were joined at 1400 K by solid state diffusion bonding, making use of a Ti foil acting as thermal stress relief interlayer. The microstructure of the joint was thus formed. The diffusion bonded TiC–Al2O3/Cr18–Ni8 joint was investigated by a variety of characterization techniques such as scanning electron microscope (SEM) with energy dispersion spectroscopy (EDS) and X-ray diffraction (XRD). The results indicate that Ti foil is fully fused to react with elements from substrates and Ti3Al, TiC and -Ti are formed in the diffusion bonded TiC–Al2O3/Cr18–Ni8 joint. The interfacial shear strength is up to 99 MPa and the shear fracture occurs close to the ceramic matrix composite due to the application of Ti foil acting as thermal stress relief interlayer.

  14. Influence of secondary carbide precipitation and transformation on abrasion resistance of a 3Cr15Mo1V1.5 white iron

    Institute of Scientific and Technical Information of China (English)

    Haohuai Liu; Jun Wang; Baoluo Shen; Hongshan Yang; Shengji Gao; Sijiu Huang

    2007-01-01

    The relationship between the secondary carbide precipitation and transformation of the 3Cr15Mo1V1.5 white iron and abrasion resistance was investigated by using optical microscope (OM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the properties of secondary carbides precipitated at holding stage play an important role in the abrasion resistance. After certain holding time at 833 K subcritical treatment, the grainy (Fe, Cr)23C6 carbide precipitated and the fresh martensite transformed at the holding stage for 3Cr15Mo1V1.5 white iron improve the bulk hardness and abrasion resistance of the alloy. Prolonging holding time, MoC and (Cr, V)2C precipitations cause the secondary hardening peak and the corresponding better abrasion resistance. Finally, granular (Fe, Cr)23C6 carbide in situ transforms into laminar M3C carbide and the matrix structure transforms into pearlitic matrix. These changes weaken hardness and abrasion resistance of the alloy sharply.

  15. Radio broadcasting via satellite

    Science.gov (United States)

    Helm, Neil R.; Pritchard, Wilbur L.

    1990-10-01

    Market areas offering potential for future narrowband broadcast satellites are examined, including international public diplomacy, government- and advertising-supported, and business-application usages. Technical issues such as frequency allocation, spacecraft types, transmission parameters, and radio receiver characteristics are outlined. Service and system requirements, advertising revenue, and business communications services are among the economic issues discussed. The institutional framework required to provide an operational radio broadcast service is studied, and new initiatives in direct broadcast audio radio systems, encompassing studies, tests, in-orbit demonstrations of, and proposals for national and international commercial broadcast services are considered.

  16. Boom Booom Net Radio

    DEFF Research Database (Denmark)

    Grimshaw, Mark Nicholas; Yong, Louisa; Dobie, Ian

    1999-01-01

    of an existing Internet radio station; Boom Booom Net Radio. Whilst necessity dictates some use of technology-related terminology, wherever possible we have endeavoured to keep such jargon to a minimum and to either explain it in the text or to provide further explanation in the appended glossary.......Internet radio is one of the growth areas of the Internet but, as this article will show, is fraught with difficulties and frustration for both the modestly-funded broadcaster (bitcaster) and the listener. The article will illustrate some of these problems by means of a short case study...

  17. Shoestring Budget Radio Astronomy

    Science.gov (United States)

    Hoot, John E.

    2017-06-01

    The commercial exploitation of microwave frequencies for cellular, WiFi, Bluetooth, HDTV, and satellite digital media transmission has brought down the cost of the components required to build an effective radio telescope to the point where, for the cost of a good eyepiece, you can construct and operate a radio telescope. This paper sets forth a family of designs for 1421 MHz telescopes. It also proposes a method by which operators of such instruments can aggregate and archive data via the Internet. With 90 or so instruments it will be possible to survey the entire radio sky for transients with a 24 hour cadence.

  18. Unlocking radio broadcasts

    DEFF Research Database (Denmark)

    Lykke, Marianne; Skov, Mette

    2012-01-01

    This poster reports the preliminary results of a user study uncovering the information seeking behaviour of humanities scholars dedicated to radio research. The study is part of an interdisciplinary research project on radio culture and auditory resources. The purpose of the study is to inform...... the design of information architecture and interaction design of a research infrastructure that will enable future radio and audio based research. Results from a questionnaire survey on humanities scholars’ research interest and information needs, preferred access points, and indexing levels are reported...

  19. Ionosphere and Radio Communication

    Indian Academy of Sciences (India)

    Saradi Bora

    2017-02-01

    The Earth's ionosphere consists of plasma produced by thephotoionization of thin upper atmospheric gases by UV raysand photons of short wavelength from the sun. The upperionosphere is used for radio communication and navigationas it reflects long, medium, as well as short radio waves. Sincesolar radiation is the main cause of the existence of ionosphere,any variation in the radiations can affect the entireradio communication system. This article attempts to brieflyintroduce the readers to the study of ionosphere in the contextof its use as a radio reflector, with particular reference toIndia.

  20. Radio y elecciones

    Directory of Open Access Journals (Sweden)

    Alma Rosa Alva de la Selva

    2000-01-01

    Full Text Available En este trabajo se analiza el comportamiento de la radio en México ante la contienda electoral de julio de 2000. Se examina el papel de la radio como espacio para la discusión política, así como el tratamiento informativo que hizo del tema. Asimismo, se analiza la posible repercusión de factores de reciente surgimiento en el panorama radiofónico para un manejo más autónomo de la información política en la radio

  1. Unlocking radio broadcasts

    DEFF Research Database (Denmark)

    Skov, Mette; Lykke, Marianne

    2012-01-01

    This poster reports the preliminary results of a user study uncovering the information seeking behaviour of humanities scholars dedicated to radio research. The study is part of an interdisciplinary research project on radio culture and auditory resources. The purpose of the study is to inform...... the design of information architecture and interaction design of a research infrastructure that will enable future radio and audio based research. Results from a questionnaire survey on humanities scholars‟ research interest and information needs, preferred access points, and indexing levels are reported...

  2. Swift observations of unidentified radio sources in the revised Third Cambridge Catalogue

    CERN Document Server

    Maselli, A; Cusumano, G; La Parola, V; Harris, D E; Paggi, A; Liuzzo, E; Tremblay, G R; Baum, S A; O'Dea, C P

    2016-01-01

    We have investigated a group of unassociated radio sources included in the 3CR cat- alogue to increase the multi-frequency information on them and possibly obtain an identification. We have carried out an observational campaign with the Swift satellite to observe with the UVOT and the XRT telescopes the field of view of 21 bright NVSS sources within the positional uncertainty region of the 3CR sources. Furthermore, we have searched in the recent AllWISE Source Catalogue for infrared sources matching the position of these NVSS sources. We have detected significant emission in the soft X-ray band for nine of the investigated NVSS sources. To all of them, and in four cases with no soft X-ray association, we have associated a WISE infrared counterpart. Eight of these infrared candidates have not been proposed earlier in the literature. In the five remaining cases our candidate matches one among a few optical candidates suggested for the same 3CR source in previous studies. No source has been detected in the UVOT ...

  3. Swift observations of unidentified radio sources in the revised Third Cambridge Catalogue

    Science.gov (United States)

    Maselli, A.; Massaro, F.; Cusumano, G.; La Parola, V.; Harris, D. E.; Paggi, A.; Liuzzo, E.; Tremblay, G. R.; Baum, S. A.; O'Dea, C. P.

    2016-08-01

    We have investigated a group of unassociated radio sources included in the Third Cambridge Catalogue (3CR) to increase the multifrequency information on them and possibly obtain an identification. We have carried out an observational campaign with the Swift satellite to observe with the Ultraviolet/Optical Telescope (UVOT) and the X-Ray Telescope (XRT) the field of view of 21 bright NRAO VLA Sky Survey (NVSS) sources within the positional uncertainty region of the 3CR sources. Furthermore, we have searched in the recent AllWISE Source Catalogue for infrared sources matching the position of these NVSS sources. We have detected significant emission in the soft X-ray band for nine of the investigated NVSS sources. To all of them, and in four cases with no soft X-ray association, we have associated a Wide-field Infrared Survey Explorer infrared counterpart. Eight of these infrared candidates have not been proposed earlier in the literature. In the five remaining cases our candidate matches one among a few optical candidates suggested for the same 3CR source in previous studies. No source has been detected in the UVOT filters at the position of the NVSS objects, confirming the scenario that all of them are heavily obscured. With this in mind, a spectroscopic campaign, preferably in the infrared band, will be necessary to establish the nature of the sources that we have finally identified.

  4. A CO-rich merger shaping a powerful and hyper-luminous infrared radio galaxy at z=2: the Dragonfly Galaxy

    CERN Document Server

    Emonts, B H C; Stroe, A; Pentericci, L; Villar-Martin, M; Norris, R P; Miley, G; De Breuck, C; van Moorsel, G A; Lehnert, M D; Carilli, C L; Rottgering, H J A; Seymour, N; Sadler, E M; Ekers, R D; Drouart, G; Feain, I; Colina, L; Stevens, J; Holt, J

    2015-01-01

    In the low-redshift Universe, the most powerful radio sources are often associated with gas-rich galaxy mergers or interactions. We here present evidence for an advanced, gas-rich (`wet') merger associated with a powerful radio galaxy at a redshift of z~2. This radio galaxy, MRC 0152-209, is the most infrared-luminous high-redshift radio galaxy known in the southern hemisphere. Using the Australia Telescope Compact Array, we obtained high-resolution CO(1-0) data of cold molecular gas, which we complement with HST/WFPC2 imaging and WHT long-slit spectroscopy. We find that, while roughly M(H2) ~ 2 x 10$^{10}$ M$_{\\odot}$ of molecular gas coincides with the central host galaxy, another M(H2) ~ 3 x 10$^{10}$ M$_{\\odot}$ is spread across a total extent of ~60 kpc. Most of this widespread CO(1-0) appears to follow prominent tidal features visible in the rest-frame near-UV HST/WFPC2 imaging. Ly$\\alpha$ emission shows an excess over HeII, but a deficiency over L(IR), which is likely the result of photo-ionisation by ...

  5. The digital sport radio.

    Directory of Open Access Journals (Sweden)

    Hilario José ROMERO BEJARANO

    2014-07-01

    Full Text Available Radio has been immersed in recent years in a phase of technological integration and business of multimedia, as well as diversification of systems and channels for broadcasting. In addition, Internet has been consolidated as the platform of digital radio that more has evolved as a result of its continued expansion. However, the merger radio-Internet must be understood as a new form of communication, and not solely as a new complementary medium. In this context, it is of great interest to analyze that transformations in the way of reception, contents, languages, programs and schedules, has brought with it for the radio that integration. To this end is taken as main reference the sports areas, a key aspect and broadly representative of the current broadcasting landscape.

  6. Music, Radio, and Mediatization

    DEFF Research Database (Denmark)

    Krogh, Mads; Michelsen, Morten

    2016-01-01

    Mediatization has become a key concept for understanding the relations between media and other cultural and social fields. Contributing to the discussions related to the concept of mediatization, this article discusses how practices of radio and music(al life) influence each other. We follow Deacon......’s and Stanyer’s advice to supplement the concept of mediatization with ‘a series of additional concepts at lower levels of abstraction’ and suggest, in this respect, the notion of heterogeneous milieus of music– radio. Hereby, we turn away from the all-encompassing perspectives related to the concept...... of mediatization where media as such seem to be ascribed agency. Instead, we consider historical accounts of music–radio in order to address the complex non- linearity of concrete processes of mediatization as they take place in the multiple meetings between a decentred notion of radio and musical life....

  7. Unveiling the radio cosmos

    Science.gov (United States)

    Vanderlinde, Keith

    2017-02-01

    Using a radio telescope with no moving parts, the dark energy speeding up the expansion of the Universe can be probed in unprecedented detail, says Keith Vanderlinde, on behalf of the CHIME collaboration.

  8. Everyday Radio Telescope

    CERN Document Server

    Mandal, Pranshu; Kumar, Pratik; Yelikar, Anjali; Soni, Kanchan; T, Vineeth Krishna

    2016-01-01

    We have developed an affordable, portable college level radio telescope for amateur radio astronomy which can be used to provide hands-on experience with the fundamentals of a radio telescope and an insight into the realm of radio astronomy. With our set-up one can measure brightness temperature and flux of the Sun at 11.2 GHz and calculate the beam width of the antenna. The set-up uses commercially available satellite television receiving system and parabolic dish antenna. We report the detection of point sources like Saturn and extended sources like the galactic arm of the Milky way. We have also developed python pipeline, which are available for free download, for data acquisition and visualization.

  9. Division x: Radio Astronomy

    Science.gov (United States)

    Taylor, Russ; Chapman, Jessica; Rendong, Nan; Carilli, Christopher; Giovannini, Gabriele; Hills, Richard; Hirabayashi, Hisashi; Jonas, Justin; Lazio, Joseph; Morganti, Raffaella; Rubio, Monica; Shastri, Prajval

    2012-04-01

    This triennium has seen a phenomenal investment in development of observational radio astronomy facilities in all parts of the globe at a scale that significantly impacts the international community. This includes both major enhancements such as the transition from the VLA to the EVLA in North America, and the development of new facilities such as LOFAR, ALMA, FAST, and Square Kilometre Array precursor telescopes in Australia and South Africa. These developments are driven by advances in radio-frequency, digital and information technologies that tremendously enhance the capabilities in radio astronomy. These new developments foreshadow major scientific advances driven by radio observations in the next triennium. We highlight these facility developments in section 3 of this report. A selection of science highlight from this triennium are summarized in section 2.

  10. Boom Booom Net Radio

    DEFF Research Database (Denmark)

    Grimshaw, Mark Nicholas; Yong, Louisa; Dobie, Ian

    1999-01-01

    Internet radio is one of the growth areas of the Internet but, as this article will show, is fraught with difficulties and frustration for both the modestly-funded broadcaster (bitcaster) and the listener. The article will illustrate some of these problems by means of a short case study of an exi......Internet radio is one of the growth areas of the Internet but, as this article will show, is fraught with difficulties and frustration for both the modestly-funded broadcaster (bitcaster) and the listener. The article will illustrate some of these problems by means of a short case study...... of an existing Internet radio station; Boom Booom Net Radio. Whilst necessity dictates some use of technology-related terminology, wherever possible we have endeavoured to keep such jargon to a minimum and to either explain it in the text or to provide further explanation in the appended glossary....

  11. Social cognitive radio networks

    CERN Document Server

    Chen, Xu

    2015-01-01

    This brief presents research results on social cognitive radio networks, a transformational and innovative networking paradigm that promotes the nexus between social interactions and cognitive radio networks. Along with a review of the research literature, the text examines the key motivation and challenges of social cognitive radio network design. Three socially inspired distributed spectrum sharing mechanisms are introduced: adaptive channel recommendation mechanism, imitation-based social spectrum sharing mechanism, and evolutionarily stable spectrum access mechanism. The brief concludes with a discussion of future research directions which ascertains that exploiting social interactions for distributed spectrum sharing will advance the state-of-the-art of cognitive radio network design, spur a new line of thinking for future wireless networks, and enable novel wireless service and applications.

  12. Smart Radio Spectrum Management for Cognitive Radio

    Directory of Open Access Journals (Sweden)

    Partha Pratim Bhattacharya

    2011-08-01

    Full Text Available Today’s wireless networks are characterized by fixed spectrum assignment policy. The limited availablespectrum and the inefficiency in the spectrum usage necessitate a new communication paradigm toexploit the existing wireless spectrum opportunistically. Cognitive radio is a paradigm for wirelesscommunication in which either a network or a wireless node changes its transmission or receptionparameters to communicate efficiently avoiding interference with licensed or unlicensed users. It cancapture best available spectrum to meet user communication requirements (spectrum management. Inthis work, a fuzzy logic based system for spectrum management is proposed where the radio can shareunused spectrum depending on parameters like distance, signal strength, node velocity and availabilityof unused spectrum. The system is simulated and is found to give satisfactory results.

  13. Wireless radio a history

    CERN Document Server

    Coe, Lewis

    2006-01-01

    ""Informative...recommended""--Choice; ""interesting...a good read...well worth reading""--Contact Magazine. This history first looks at Marconi's wireless communications system and then explores its many applications, including marine radio, cellular telephones, police and military uses, television and radar. Radio collecting is also discussed, and brief biographies are provided for the major figures in the development and use of the wireless.

  14. Classics in radio astronomy

    CERN Document Server

    Sullivan, Woodruff Turner

    1982-01-01

    Radio techniques were the nrst to lead astronomy away from the quiescent and limited Universe revealed by traditional observations at optical wave­ lengths. In the earliest days of radio astronomy, a handful of radio physicists and engineers made one startling discovery after another as they opened up the radio sky. With this collection of classic papers and the extensive intro­ ductory material, the reader can experience these exciting discoveries, as well as understand the developing techniques and follow the motivations which prompted the various lines of inquiry. For instance he or she will follow in detail the several attempts to detect radio waves from the sun at the turn of the century; the unravelling by Jansky of a "steady hiss type static"; the incredible story of Reber who built a 9 meter dish in his backyard in 1937 and then mapped the Milky Way; the vital discoveries by Hey and colleagues of radio bursts from the Sun and of a discrete source in the constellation of Cygnus; the development of re...

  15. Extreme Gas Kinematics in the z=2.2 Powerful Radio Galaxy MRC1138-262: Evidence for Efficient AGN Feedback in the Early Universe?

    Energy Technology Data Exchange (ETDEWEB)

    Nesvadba, N H; Lehnert, M D; Eisenhauer, F; Gilbert, A M; Tecza, M; Abuter, R

    2007-06-26

    To explain the properties of the most massive low-redshift galaxies and the shape of their mass function, recent models of galaxy evolution include strong AGN feedback to complement starburst-driven feedback in massive galaxies. Using the near-infrared integral-field spectrograph SPIFFI on the VLT, we searched for direct evidence for such a feedback in the optical emission line gas around the z = 2.16 powerful radio galaxy MRC1138-262, likely a massive galaxy in formation. The kpc-scale kinematics, with FWHMs and relative velocities {approx}< 2400 km s{sup -1} and nearly spherical spatial distribution, do not resemble large-scale gravitational motion or starburst-driven winds. Order-of-magnitude timescale and energy arguments favor the AGN as the only plausible candidate to accelerate the gas, with a total energy injection of {approx} few x 10{sup 60} ergs or more, necessary to power the outflow, and relatively efficient coupling between radio jet and ISM. Observed outflow properties are in gross agreement with the models, and suggest that AGN winds might have a similar, or perhaps larger, cosmological significance than starburst-driven winds, if MRC1138-262 is indeed archetypal. Moreover, the outflow has the potential to remove significant gas fractions ({approx}< 50%) from a > L* galaxy within a few 10 to 100 Myrs, fast enough to preserve the observed [{alpha}/Fe] overabundance in massive galaxies at low redshift. Using simple arguments, it appears that feedback like that observed in MRC1138-262 may have sufficient energy to inhibit material from infalling into the dark matter halo and thus regulate galaxy growth as required in some recent models of hierarchical structure formation.

  16. High-level production, solubilization and purification of synthetic human GPCR chemokine receptors CCR5, CCR3, CXCR4 and CX3CR1.

    Directory of Open Access Journals (Sweden)

    Hui Ren

    Full Text Available Chemokine receptors belong to a class of integral membrane G-protein coupled receptors (GPCRs and are responsible for transmitting signals from the extracellular environment. However, the structural changes in the receptor, connecting ligand binding to G-protein activation, remain elusive for most GPCRs due to the difficulty to produce them for structural and functional studies. We here report high-level production in E.coli of 4 human GPCRs, namely chemokine receptors (hCRs CCR5, CCR3, CXCR4 and CX3CR1 that are directly involved in HIV-1 infection, asthma and cancer metastasis. The synthetic genes of CCR5, CCR3, CXCR4 and CX3CR1 were synthesized using a two-step assembly/amplification PCR method and inserted into two different kinds of expression systems. After systematic screening of growth conditions and host strains, TB medium was selected for expression of pEXP-hCRs. The low copy number pBAD-DEST49 plasmid, with a moderately strong promoter tightly regulated by L-arabinose, proved helpful for reducing toxicity of expressed membrane proteins. The synthetic Trx-hCR fusion genes in the pBAD-DEST49 vector were expressed at high levels in the Top10 strain. After a systematic screen of 96 detergents, the zwitterionic detergents of the Fos-choline series (FC9-FC16 emerged as the most effective for isolation of the hCRs. The FC14 was selected both for solubilization from bacterial lysates and for stabilization of the Trx-hCRs during purification. Thus, the FC-14 solubilized Trx-hCRs could be purified using size exclusion chromatography as monomers and dimers with the correct apparent MW and their alpha-helical content determined by circular dichroism. The identity of two of the expressed hCRs (CCR3 and CCR5 was confirmed using immunoblots using specific monoclonal antibodies. After optimization of expression systems and detergent-mediated purification procedures, we achieved large-scale, high-level production of 4 human GPCR chemokine receptor in a

  17. High-level production, solubilization and purification of synthetic human GPCR chemokine receptors CCR5, CCR3, CXCR4 and CX3CR1.

    Science.gov (United States)

    Ren, Hui; Yu, Daoyong; Ge, Baosheng; Cook, Brian; Xu, Zhinan; Zhang, Shuguang

    2009-01-01

    Chemokine receptors belong to a class of integral membrane G-protein coupled receptors (GPCRs) and are responsible for transmitting signals from the extracellular environment. However, the structural changes in the receptor, connecting ligand binding to G-protein activation, remain elusive for most GPCRs due to the difficulty to produce them for structural and functional studies. We here report high-level production in E.coli of 4 human GPCRs, namely chemokine receptors (hCRs) CCR5, CCR3, CXCR4 and CX3CR1 that are directly involved in HIV-1 infection, asthma and cancer metastasis. The synthetic genes of CCR5, CCR3, CXCR4 and CX3CR1 were synthesized using a two-step assembly/amplification PCR method and inserted into two different kinds of expression systems. After systematic screening of growth conditions and host strains, TB medium was selected for expression of pEXP-hCRs. The low copy number pBAD-DEST49 plasmid, with a moderately strong promoter tightly regulated by L-arabinose, proved helpful for reducing toxicity of expressed membrane proteins. The synthetic Trx-hCR fusion genes in the pBAD-DEST49 vector were expressed at high levels in the Top10 strain. After a systematic screen of 96 detergents, the zwitterionic detergents of the Fos-choline series (FC9-FC16) emerged as the most effective for isolation of the hCRs. The FC14 was selected both for solubilization from bacterial lysates and for stabilization of the Trx-hCRs during purification. Thus, the FC-14 solubilized Trx-hCRs could be purified using size exclusion chromatography as monomers and dimers with the correct apparent MW and their alpha-helical content determined by circular dichroism. The identity of two of the expressed hCRs (CCR3 and CCR5) was confirmed using immunoblots using specific monoclonal antibodies. After optimization of expression systems and detergent-mediated purification procedures, we achieved large-scale, high-level production of 4 human GPCR chemokine receptor in a two

  18. High-Level Production, Solubilization and Purification of Synthetic Human GPCR Chemokine Receptors CCR5, CCR3, CXCR4 and CX3CR1

    Science.gov (United States)

    Ren, Hui; Yu, Daoyong; Ge, Baosheng; Cook, Brian; Xu, Zhinan; Zhang, Shuguang

    2009-01-01

    Chemokine receptors belong to a class of integral membrane G-protein coupled receptors (GPCRs) and are responsible for transmitting signals from the extracellular environment. However, the structural changes in the receptor, connecting ligand binding to G-protein activation, remain elusive for most GPCRs due to the difficulty to produce them for structural and functional studies. We here report high-level production in E.coli of 4 human GPCRs, namely chemokine receptors (hCRs) CCR5, CCR3, CXCR4 and CX3CR1 that are directly involved in HIV-1 infection, asthma and cancer metastasis. The synthetic genes of CCR5, CCR3, CXCR4 and CX3CR1 were synthesized using a two-step assembly/amplification PCR method and inserted into two different kinds of expression systems. After systematic screening of growth conditions and host strains, TB medium was selected for expression of pEXP-hCRs. The low copy number pBAD-DEST49 plasmid, with a moderately strong promoter tightly regulated by L-arabinose, proved helpful for reducing toxicity of expressed membrane proteins. The synthetic Trx-hCR fusion genes in the pBAD-DEST49 vector were expressed at high levels in the Top10 strain. After a systematic screen of 96 detergents, the zwitterionic detergents of the Fos-choline series (FC9-FC16) emerged as the most effective for isolation of the hCRs. The FC14 was selected both for solubilization from bacterial lysates and for stabilization of the Trx-hCRs during purification. Thus, the FC-14 solubilized Trx-hCRs could be purified using size exclusion chromatography as monomers and dimers with the correct apparent MW and their alpha-helical content determined by circular dichroism. The identity of two of the expressed hCRs (CCR3 and CCR5) was confirmed using immunoblots using specific monoclonal antibodies. After optimization of expression systems and detergent-mediated purification procedures, we achieved large-scale, high-level production of 4 human GPCR chemokine receptor in a two

  19. THz and infrared excitation spectrum below the Jahn-Teller transition in Sr{sub 3}Cr{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhe; Schmidt, Michael; Guenther, Axel; Mayr, Franz; Krug von Nidda, Hans-Albrecht; Loidl, Alois; Deisenhofer, Joachim [Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg (Germany); Quintero-Castro, Diana; Lake, Bella [Helmholtz-Zentrum Berlin fuer Materialien und Energie, D-14109 Berlin (Germany); Institut fuer Festkoerperphysik, Technische Universitaet Berlin, D-10623 Berlin (Germany); Islam, A.T.M. Nazmul [Helmholtz-Zentrum Berlin fuer Materialien und Energie, D-14109 Berlin (Germany)

    2012-07-01

    We report on optical excitations observed recently in Sr{sub 3}Cr{sub 2}O{sub 8} by THz and infrared spectroscopy. Low-energy excitations below 3 THz are detected by THz time domain spectroscopy. These excitations can be divided into two different classes according to the temperature-dependent properties. One is emergent right below the Jahn-Teller transition temperature, which is determined by specific heat measurement to occur at 285 K. The other appears only below 100 K, where the fluctuations are sufficiently suppressed, consistent with the temperature dependence of low-energy Raman modes. Infrared transmission measurements reveal a broad crystal-field excitation, which can be associated with an electronic transition from E to T{sub 2} orbital states.

  20. Electrochemical impedance spectroscopy study on the corrosion of the weld zone of 3Cr steel welded joints in CO2 environments

    Science.gov (United States)

    Xu, Li-ning; Zhu, Jin-yang; Lu, Min-xu; Zhang, Lei; Chang, Wei

    2015-05-01

    The welded joints of 3Cr pipeline steel were fabricated with commercial welding wire using the gas tungsten arc welding (GTAW) technique. Potentiodynamic polarization curves, linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDS) were used to investigate the corrosion resistance and the growth of a corrosion film on the weld zone (WZ). The changes in electrochemical characteristics of the film were obtained through fitting of the EIS data. The results showed that the average corrosion rate of the WZ in CO2 environments first increased, then fluctuated, and finally decreased gradually. The formation of the film on the WZ was divided into three stages: dynamic adsorption, incomplete-coverage layer formation, and integral layer formation.

  1. Electronic structure and magnetic ordering of the semiconducting chromium trihalides CrCl3, CrBr3, and CrI3

    KAUST Repository

    Wang, Hao

    2011-03-01

    We present results from an electronic structure investigation of the chromium halides CrCl3, CrBr3, and CrI3, as obtained by the linearized augmented plane wave method of density functional theory. Our interest focuses on the chloride. While all three halides display strong ferromagnetic coupling within the halide-Cr-halide triple layers, our emphasis is on differences in the interlayer magnetic coupling. In agreement with experimental results, our calculations indicate ferromagnetic ordering for CrBr3 as well as CrI3. The antiferromagnetic state of CrCl3 can be reproduced by introducing an on-site electron-electron repulsion. However, we observe that the ground state depends critically on the specific approach used. Our results show that a low temperature structural phase transition from monoclinic to trigonal is energetically favourable for CrCl3. © 2011 IOP Publishing Ltd.

  2. Photoluminescence study of LiNbO3:Cr3+; W4+ at high pressure. Pressure dependence of spectroscopic parameters and local structure of Cr3+

    Science.gov (United States)

    Sánchez-Alejo, M. A.; Rodríguez, F.; Barreda-Argüeso, J. A.; Camarillo, I.; Flores J., C.; Murrieta S., H.; Hernández A., J. M.; Jaque, F.; Camarillo, E.

    2016-10-01

    In this study, the photoluminescence properties of congruent codoped LiNbO3:Cr3+; W4+, crystals have been systematically investigated by performing photoluminescence studies at room temperature in the 0-280 kbar pressure range. In particular, we focus on the influence that hydrostatic pressure has on the 2E→ 4A2 (R-lines) transitions of Cr3+. It has been observed that the pressure dependence of the spectral position of the R-lines associated with both Cr3+ centres β and γ shows a bilinear behaviour with an abrupt slope change near 210 kbar. This change is related to the existence of a pressure-induced structural phase transition in the LiNbO3 host. The analysis of experimental results provides the Racah parameters B and C and the crystal field parameter 10Dq and their pressure and volume, through the crystal field theory and equation of state, dependences.

  3. Low cost fabrication of sheet structure using a new beta titanium alloy, Ti-15V-3Cr-3Al-3Sn

    Science.gov (United States)

    Kaneko, R. S.; Davis, G. W.; Woods, C. A.; Royster, D. M.

    1982-01-01

    Development efforts have been undertaken to improve the processing and structural efficiencies of advanced cold-formable beta Ti alloys, using the standard, hot-formed and rivetted construction of Ti-6Al-4V sheet structures as a basis for comparison. Ti-15V-3Cr-3Al-3Sn (Ti-15-3) beta alloy is formable, brazable and weldable in the solution-treated condition, and after aging displays mechanical properties suitable for postulated service in the -65 to 600 F temperature range. A novel methodology using cold-formed Ti-15-3 stringers and Ti-6Al-4V face sheets that are joined by means of an out-of-furnace isothermal brazing process, followed by low temperature aging, can reduce production costs by as much as 28 per cent. Structural efficiency has been demonstrated in room and elevated temperature crippling tests of small skin-stringer assemblies.

  4. Low cost fabrication of sheet structure using a new beta titanium alloy, Ti-15V-3Cr-3Al-3Sn

    Science.gov (United States)

    Kaneko, R. S.; Davis, G. W.; Woods, C. A.; Royster, D. M.

    1982-01-01

    Development efforts have been undertaken to improve the processing and structural efficiencies of advanced cold-formable beta Ti alloys, using the standard, hot-formed and rivetted construction of Ti-6Al-4V sheet structures as a basis for comparison. Ti-15V-3Cr-3Al-3Sn (Ti-15-3) beta alloy is formable, brazable and weldable in the solution-treated condition, and after aging displays mechanical properties suitable for postulated service in the -65 to 600 F temperature range. A novel methodology using cold-formed Ti-15-3 stringers and Ti-6Al-4V face sheets that are joined by means of an out-of-furnace isothermal brazing process, followed by low temperature aging, can reduce production costs by as much as 28 per cent. Structural efficiency has been demonstrated in room and elevated temperature crippling tests of small skin-stringer assemblies.

  5. Electronic structure and magnetic ordering of the semiconducting chromium trihalides CrCl{sub 3}, CrBr{sub 3}, and CrI{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H; Schwingenschloegl, U [PSE Division, KAUST, Thuwal 23955-6900 (Saudi Arabia); Eyert, V, E-mail: udo.schwingenschlogl@kaust.edu.sa [Centre for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg (Germany)

    2011-03-23

    We present results from an electronic structure investigation of the chromium halides CrCl{sub 3}, CrBr{sub 3}, and CrI{sub 3}, as obtained by the linearized augmented plane wave method of density functional theory. Our interest focuses on the chloride. While all three halides display strong ferromagnetic coupling within the halide-Cr-halide triple layers, our emphasis is on differences in the interlayer magnetic coupling. In agreement with experimental results, our calculations indicate ferromagnetic ordering for CrBr{sub 3} as well as CrI{sub 3}. The antiferromagnetic state of CrCl{sub 3} can be reproduced by introducing an on-site electron-electron repulsion. However, we observe that the ground state depends critically on the specific approach used. Our results show that a low temperature structural phase transition from monoclinic to trigonal is energetically favourable for CrCl{sub 3}.

  6. Construction of Giant-Spin Hamiltonians from Many-Spin Hamiltonians by Third-Order Perturbation Theory and Application to an Fe3 Cr Single-Molecule Magnet.

    Science.gov (United States)

    Tabrizi, Shadan Ghassemi; Arbuznikov, Alexei V; Kaupp, Martin

    2016-05-10

    A general giant-spin Hamiltonian (GSH) describing an effective spin multiplet of an exchange-coupled metal cluster with dominant Heisenberg interactions was derived from a many-spin Hamiltonian (MSH) by treating anisotropic interactions at the third order of perturbation theory. Going beyond the existing second-order perturbation treatment allows irreducible tensor operators of rank six (or corresponding Stevens operator equivalents) in the GSH to be obtained. Such terms were found to be of crucial importance for the fitting of high-field EPR spectra of a number of single-molecule magnets (SMMs). Also, recent magnetization measurements on trigonal and tetragonal SMMs have found the inclusion of such high-rank axial and transverse terms to be necessary to account for experimental data in terms of giant-spin models. While mixing of spin multiplets by local zero-field splitting interactions was identified as the major origin of these contributions to the GSH, a direct and efficient microscopic explanation had been lacking. The third-order approach developed in this work is used to illustrate the mapping of an MSH onto a GSH for an S=6 trigonal Fe3 Cr complex that was recently investigated by high-field EPR spectroscopy. Comparisons between MSH and GSH consider the simulation of EPR data with both Hamiltonians, as well as locations of diabolical points (conical intersections) in magnetic-field space. The results question the ability of present high-field EPR techniques to determine high-rank zero-field splitting terms uniquely, and lead to a revision of the experimental GSH parameters of the Fe3 Cr SMM. Indeed, a bidirectional mapping between MSH and GSH effectively constrains the number of free parameters in the GSH. This notion may in the future facilitate spectral fitting for highly symmetric SMMs.

  7. Preparation and Characterization of Ti3+ & Cr3+ :Li2O-LiF-B2O3- ZnO Optical Glasses

    Directory of Open Access Journals (Sweden)

    L. Vijayalakshmi

    2014-06-01

    Full Text Available A transparent base glass in the chemical composition Li2O-LiF-B2O3-ZnO (LBZ has successfully been prepared also a couple of transition metal (Ti3+ & Cr3+ ions doped into this glass matrix have also been done for their further analysis. Structural (XRD, FTIR & Raman and thermal (TG-DTA properties and also absorption spectrum of LBZ glass have been analyzed. Optical absorption, photoluminescence (excitation & emission spectra of Ti3+ & Cr3+:Li2O-LiF- B2O3-ZnO and their spectral assignments, dielectric ( & tan and conductivities (ac & dc have also been undertaken. The XRD profile of the host glass confirms its amorphous nature. Weight loss in the precursor sample powder, glass transition temperature (Tg and crystalline temperature (Tc have been identified from the TG-DTA profiles. FTIR and Raman spectra of the host glass show vibrational bands of B-O from [BO3] and [BO4] units and Li-O. The absorption spectrum of Cr3+: LBZ glass has shown two bands at 412 nm (4A2g (F 4T1g (F and 579 nm (4A2g (F 4T2g (F. In respect of Ti3+: LBZ glass, only one broad band at 490 nm (2B2g2B1g has been measured. From the optical absorption spectral positions, their crystal field (Dq and the Racah (B & C interaction parameters have been evaluated. Dielectric constant and losses (' and tan of all three glasses have been studied in the frequency range from 1Hz to 1M Hz at room temperature and computed conductivities (ac and dc.

  8. Galaxy evolution at low redshift?; 1, optical counts

    CERN Document Server

    Dennefeld, M

    1996-01-01

    We present bright galaxy number counts in the blue (16

  9. The Low Redshift survey at Calar Alto (LoRCA)

    CERN Document Server

    Comparat, J; Rodriguez-Torres, S; Pellejero-Ibanez, M; Prada, F; Yepes, G; Courtois, H M; Zhao, G -B; Wang, Y; Sanchez, J; Maraston, C; Metcalf, R Benton; Peiro-Perez, J; Kitaura, F S; Perez, E; Delgado, R M Gonzalez

    2015-01-01

    The Baryon Acoustic Oscillation (BAO) feature in the power spectrum of galaxies provides a standard ruler to measure the accelerated expansion of the Universe. To extract all available information about dark energy, it is necessary to measure a standard ruler in the local, $z<0.2$, universe where dark energy dominates most the energy density of the Universe. Though the volume available in the local universe is limited, it is just big enough to measure accurately the long 100 $h^{-1}$Mpc wave-mode of the BAO. Using cosmological $N$-body simulations and approximate methods based on Lagrangian perturbation theory, we construct a suite of a thousand light-cones to evaluate the precision at which one can measure the BAO standard ruler in the local universe. We find that using the most massive galaxies on the full sky (34,000 deg$^2$), {\\rm i.e.} a $K_\\mathrm{2MASS}<14$ magnitude-limited sample, one can measure the BAO scale up to a precision of 4\\%. Therefore, we propose a 3-year long observational project, ...

  10. UV spectroscopy of low-redshift active galaxies

    Science.gov (United States)

    Wu, C.-C.; Crenshaw, M.

    1993-01-01

    Ultraviolet spectra of bright Seyfert 1 galaxies will be obtained with the Hubble Space Telescope. Observations will be used to pursue the following goals: (1) Broad and narrow components of the strong emission lines will be deconvolved. (2) Broad-line profiles will be extracted for comparison with kinematic models; line ratios will be determined. (3) Many weak UV and emission lines from optical spectra will be compared for reddening along line of sight and chemical composition. (4) Absorption lines from Galactic halo, intergalactic medium and Seyfert galaxy will be used to establish physical conditions/chemical composition of the gas. (5) Strong emission Fe II in the UV will be used to determine FE II/L-alpha ratios for comparison with photoionization models. Other tasks relating to GTO 1170 program will be performed. It appears that NLR clouds in NGC 5548 experience much higher level of ionizing flux than those Seyfert 2 galaxies. Future observations will determine if this result extends to other Seyfert 1 galaxies.

  11. Dust in the Circumgalactic Medium of Low-Redshift Galaxies

    CERN Document Server

    Peek, J E G; Corrales, Lia

    2014-01-01

    Using spectroscopically selected galaxies from the Sloan Digital Sky Survey we present a detection of reddening due to dust in the circumgalactic medium of galaxies. We detect the mean change in the colors of "standard crayons" correlated with the presence of foreground galaxies at z ~0.05 as a function of angular separation. Following Peek & Graves (2010), we create standard crayons using passively evolving galaxies corrected for Milky Way reddening and color-redshift trends, leading to a sample with as little as 2% scatter in color. We devise methods to ameliorate possible systematic effects related to the estimation of colors, and we find an excess reddening induced by foreground galaxies at a level ranging from 10 to 0.5 millimagnitudes on scales ranging from 30 kpc to 1 Mpc. We attribute this effect to a large-scale distribution of dust around galaxies similar to the findings of Menard et al. 2010. We find that circumgalactic reddening is a weak function of stellar mass over the range $6 \\times 10^9 ...

  12. Observational properties of low redshift pair instability supernovae

    CERN Document Server

    Kozyreva, A; Langer, N; Yoon, S -C

    2014-01-01

    So called superluminous supernovae have been recently discovered in the local Universe. It appears possible that some of them originate from stellar explosions induced by the pair instability mechanism. Recent stellar evolution models also predict pair instability supernovae (PISNe) from very massive stars at fairly high metallicities (i.e. Z~0.004). We provide supernova (SN) models and synthetic light curves for two progenitor models, a 150 Msun red-supergiant and a 250 Msun yellow-supergiant at a metallicity of Z=0.001, for which the evolution from the main sequence to collapse, and the initiation of the PISN itself, has been previously computed in a realistic and self-consistent way. We are using the radiation hydrodynamics code STELLA to describe the SN evolution of both models over a time frame of about 500 days. We describe the shock-breakout phases of both SNe which are characterized by a higher luminosity, a longer duration and a lower effective temperature than those of ordinary SNeIIP. We derive the...

  13. 加巴喷丁对骨癌痛大鼠脊髓CX3CR1受体表达的影响%Effects of gabapentin on the expression of spinal CX3CR1 receptor in a rat model of bone cancer pain

    Institute of Scientific and Technical Information of China (English)

    范钦; 李晶; 程伟; 殷琴; 闫长栋

    2015-01-01

    Objective To explore the effects of administration of gabapentin on the expression of spinal CX3CR1 receptor in rats with tibial bone cancer pain(BCP).Methods Forty female Sprague-Dawley (SD) rats were randomized into 5 groups(n=8):naive group(group N),sham operation+NS control group(group SN),BCP group,BCP+NS control group (group BN),and BCP+ GBP 200 mg·kg-1·d-1 group (group BG 200).The rats in group SN and BN received 5 ml normal saline and the rats in group BG 200 received 5 ml 200 mg·kg-1·d-1 dose of GBP via feeding from day 7 to 14 after operation,respectively.Fifty percent of paw withdrawal mechanical threshold (PWMT) of the right paw and behavioral assays for ambulatory pain (BAAP) were measured just 1 d (T0) before operation and on days 1 (T1),3(T2),5(T3),7(T4),9(T5),11 (T6) and 14(T7) after operation; Western blot assay of CX3CR1 protein expression levels of the spinal cord were carried out.Results PWMT (10.5±0.4) g in rats with BCP decreased on day 3 after operation,and BAAP(2.0±0.8) increased on day 5 after operation,as compared with those in group N[(13.2±1.0) g,0].PWMT (6.1±0.9) g in BG 200 increased and BAAP (1.6±0.7) decreased on day 9 after operation,as compared with those in group BN [(3.0±0.8) g,(2.8 ±0.5)],and the difference was still statistically significant until day 14 (P<0.01).The expression of spinal CX3CR1 increased from day 3 after operation in a rat model of bone cancer pain,as compared with those in group N.The expression of spinal CX3CR1 in group BG 200 decreased as compared with those in group BN (P<0.01).Conclusions Gabapentin attenuates the hyperalgesia in rats of of bone cancer pain,which may be associated with decreased spinal CX3CR1.%目的 观察加巴喷丁(gabapentin,GBP)对骨癌痛(bone cancer pain,BCP)大鼠脊髓CX3CR1受体表达的影响.方法 雌性Sprague-Dawley(SD)大鼠40只,采用随机数字表法将其随机分为5组(每组8只):正常对照组(N组)、假手术组(右侧胫骨骨髓腔内注入

  14. Tools of radio astronomy

    CERN Document Server

    Wilson, Thomas L; Hüttemeister, Susanne

    2013-01-01

    This 6th edition of “Tools of Radio Astronomy”, the most used introductory text in radio astronomy, has been revised to reflect the current state of this important branch of astronomy. This includes the use of satellites, low radio frequencies, the millimeter/sub-mm universe, the Cosmic Microwave Background and the increased importance of mm/sub-mm dust emission. Several derivations and presentations of technical aspects of radio astronomy and receivers, such as receiver noise, the Hertz dipole and  beam forming have been updated, expanded, re-worked or complemented by alternative derivations. These reflect advances in technology. The wider bandwidths of the Jansky-VLA and long wave arrays such as LOFAR and mm/sub-mm arrays such as ALMA required an expansion of the discussion of interferometers and aperture synthesis. Developments in data reduction algorithms have been included. As a result of the large amount of data collected in the past 20 years, the discussion of solar system radio astronomy, dust em...

  15. Radio data archiving system

    Science.gov (United States)

    Knapic, C.; Zanichelli, A.; Dovgan, E.; Nanni, M.; Stagni, M.; Righini, S.; Sponza, M.; Bedosti, F.; Orlati, A.; Smareglia, R.

    2016-07-01

    Radio Astronomical Data models are becoming very complex since the huge possible range of instrumental configurations available with the modern Radio Telescopes. What in the past was the last frontiers of data formats in terms of efficiency and flexibility is now evolving with new strategies and methodologies enabling the persistence of a very complex, hierarchical and multi-purpose information. Such an evolution of data models and data formats require new data archiving techniques in order to guarantee data preservation following the directives of Open Archival Information System and the International Virtual Observatory Alliance for data sharing and publication. Currently, various formats (FITS, MBFITS, VLBI's XML description files and ancillary files) of data acquired with the Medicina and Noto Radio Telescopes can be stored and handled by a common Radio Archive, that is planned to be released to the (inter)national community by the end of 2016. This state-of-the-art archiving system for radio astronomical data aims at delegating as much as possible to the software setting how and where the descriptors (metadata) are saved, while the users perform user-friendly queries translated by the web interface into complex interrogations on the database to retrieve data. In such a way, the Archive is ready to be Virtual Observatory compliant and as much as possible user-friendly.

  16. Galactic radio astronomy

    CERN Document Server

    Sofue, Yoshiaki

    2017-01-01

    This book is a concise primer on galactic radio astronomy for undergraduate and graduate students, and provides wide coverage of galactic astronomy and astrophysics such as the physics of interstellar matter and the dynamics and structure of the Milky Way Galaxy and galaxies. Radio astronomy and its technological development have led to significant progress in galactic astronomy and contributed to understanding interstellar matter and galactic structures. The book begins with the fundamental physics of radio-wave radiation, i.e., black body radiation, thermal emission, synchrotron radiation, and HI and molecular line emissions. The author then gives overviews of ingredients of galactic physics, including interstellar matter such as the neutral (HI), molecular hydrogen, and ionized gases, as well as magnetic fields in galaxies. In addition, more advanced topics relevant to the Galaxy and galaxies are also contained here: star formation, supernova remnants, the Galactic Center and black holes, galactic dynamics...

  17. ANTENNA OF RADIO CONTROL

    Directory of Open Access Journals (Sweden)

    Ludwig Ilnytskyi

    2015-12-01

    Full Text Available The article is devoted to current issues in the field of radio monitoring. In this article was considered the antenna of radio control, which represents a grid from three vibrators. Threelement antenna array provides simultaneous control of two radio electronic devices that radiates at frequencies that are close to each other. Antenna system using simple technical means provides noise suppression, even if noise will have the same frequency as useful signal. This makes it possible to use the antenna system in conditions of multibeam wave propagation under the adjustment on the most intense by the power beam. Antenna system makes it possible to measure the electromagnetic field intensity, congestion of the frequency spectrum, direction of noise electromagnetic waves incidence, noise electric field intensity.

  18. Comets at radio wavelengths

    CERN Document Server

    Crovisier, Jacques; Colom, Pierre; Biver, Nicolas

    2016-01-01

    Comets are considered as the most primitive objects in the Solar System. Their composition provides information on the composition of the primitive solar nebula, 4.6 Gyr ago. The radio domain is a privileged tool to study the composition of cometary ices. Observations of the OH radical at 18 cm wavelength allow us to measure the water production rate. A wealth of molecules (and some of their isotopologues) coming from the sublimation of ices in the nucleus have been identified by observations in the millimetre and submillimetre domains. We present an historical review on radio observations of comets, focusing on the results from our group, and including recent observations with the Nan\\c{c}ay radio telescope, the IRAM antennas, the Odin satellite, the Herschel space observatory, ALMA, and the MIRO instrument aboard the Rosetta space probe.

  19. Mobile radio channels

    CERN Document Server

    Pätzold, Matthias

    2011-01-01

    Providing a comprehensive overview of the modelling, analysis and simulation of mobile radio channels, this book gives a detailed understanding of fundamental issues and examines state-of-the-art techniques in mobile radio channel modelling. It analyses several mobile fading channels, including terrestrial and satellite flat-fading channels, various types of wideband channels and advanced MIMO channels, providing a fundamental understanding of the issues currently being investigated in the field. Important classes of narrowband, wideband, and space-time wireless channels are explored in deta

  20. Saber sobre la radio

    OpenAIRE

    Mata, María Cristina; Universidad Nacional de Córdoba. Argentina

    1998-01-01

    La autora propone en este artículo repensar los fundamentos sobre los cuales se estructuran las asignaturas y talleres de radio en las escuelas de Comunicación Social en Latinoamérica, con el proposito de romper la escisión  entre teoría/práctica y de no violentar su complejidad: en la radio, entendida como práctica comunicativa, se juega en primer lugar una "red de vinculaciones e intercambios" en condiciones privilegiadas para la dialoguicidad. En un segundo lugar, asociado al desarrollo de...

  1. 焊接规范对10Ni3CrMoV药芯焊丝熔敷金属化学成分及力学性能的影响%Influence of Welding Condition on Chemical Composition and Performance of Deposited Metal of 10Ni3CrMoV Flux-cored Wire

    Institute of Scientific and Technical Information of China (English)

    陈爱志; 彭冀湘; 刘健

    2013-01-01

    对焊接电流、焊接速度和道间温度等焊接规范参数的变化对10Ni3CrMoV药芯焊丝熔敷金属化学成分及力学性能的影响进行了研究与量化.结果表明,焊接电流增大时,具有脱氧同时兼具强化作用的合金元素烧损相对多一些,熔敷金属中的针状铁素体略显粗大;焊接速度变大时,熔敷金属中的先共析铁素体含量相对少一些;道间温度控制较高时,熔敷金属中的粒状贝氏体相对多一些.总体来说,当焊接电流在220~260A、焊接速度在25~35 cm/min、道间温度在80~120℃范围内变化时,对10Ni3CrMoV药芯焊丝熔敷金属化学成分和力学性能的影响不大.%The influences of welding conditions such as welding current, welding speed and interpass temperature on the chemical composition and performance of the deposited metal of 10Ni3CrMoV flux-cored wire were studied. The results show that when the welding current increases, the loss of the alloying element with the reinforced and deoxidation effect is relatively more, the acicular ferrite in the deposited metal is slightly large; when the welding speed becomes large, the proeutectoid ferrite content in the deposited metal is relatively less; when the interpass temperature control is high, the granular bainite in the deposited metal is relatively more. When the welding current is 220-260 A,welding speed is 25-35 cm/min, interpass temperature is 80-120 °C , the welding condition has less effects on the chemical composition and mechanical properties of 10Ni3CrMoV flux-cored wire.

  2. e-POP Radio Science Using Amateur Radio Transmissions

    Science.gov (United States)

    Frissell, N. A.; Perry, G. W.; Miller, E. S.; Shovkoplyas, A.; Moses, M. L.; James, H. G.; Yau, A. W.

    2015-12-01

    A major component of the enhanced Polar Outflow Probe (e-POP) Radio Receiver Instrument (RRI) mission is to utilize artificially generated radio emissions to study High Frequency (HF) radio wave propagation in the ionosphere. In the North American and European sectors, communications between amateur radio operators are a persistent and abundant source source of HF transmissions. We present the results of HF radio wave propagation experiments using amateur radio transmissions as an HF source for e-POP RRI. We detail how a distributed and autonomously operated amateur radio network can be leveraged to study HF radio wave propagation as well as the structuring and dynamics of the ionosphere over a large geographic region. In one case, the sudden disappearance of nearly two-dozen amateur radio HF sources located in the midwestern United States was used to detect a enhancement in foF2 in that same region. We compare our results to those from other more conventional radio instruments and models of the ionosphere to demonstrate the scientific merit of incorporating amateur radio networks for radio science at HF.

  3. A reconfigurable radio architecture for Cognitive Radio in emergency networks

    NARCIS (Netherlands)

    Zhang, Q.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2006-01-01

    Cognitive Radio has been proposed as a promising technology to solve today’s spectrum scarcity problem. Cognitive Radio is able to sense the spectrum to find the free spectrum, which can be optimally used by Cognitive Radio without causing interference to the licensed user. In the scope of the

  4. A reconfigurable radio architecture for Cognitive Radio in emergency networks

    NARCIS (Netherlands)

    Zhang, Q.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2006-01-01

    Cognitive Radio has been proposed as a promising technology to solve today’s spectrum scarcity problem. Cognitive Radio is able to sense the spectrum to find the free spectrum, which can be optimally used by Cognitive Radio without causing interference to the licensed user. In the scope of the Adapt

  5. A Reconfigurable Radio Architecture for Cognitive Radio in Emergency Networks

    NARCIS (Netherlands)

    Zhang, Qiwei; Kokkeler, Andre B.J.; Smit, Gerard J.M.

    2006-01-01

    Cognitive Radio has been proposed as a promising technology to solve today's spectrum scarcity problem. Cognitive Radio is able to sense the spectrum to find the free spectrum, which can be optimally used by Cognitive Radio without causing interference to the licensed user. In the scope of the Adapt

  6. Spectrum management and radio resource management considering cognitive radio systems

    NARCIS (Netherlands)

    Haartsen, Jaap C.; Wieweg, Lasse; Huschke, Jörg

    2005-01-01

    International fora and some national administrations define a cognitive radio (CR) as a pioneering radio communication system that would be capable of altering and adapting its transmitter and receiver parameters based on communication and the exchange of information with related detectable radio co

  7. Radio Fatwa : Islamic Tanya-Jawab Programmes on Radio Dakwah

    NARCIS (Netherlands)

    Sunarwoto,

    2012-01-01

    The present article is a study of radio fatwa in Indonesia with special reference to the Tanya-Jawab genres in radio dakwah.The concept of fatwa has changed over time. Such Islamic Tanya-Jawab programmes broadcast on radio dakwah are important to understand how fatwa is disseminated by means of medi

  8. Suppression of Star Formation in the Hosts of Low-Excitation Radio Galaxies

    CERN Document Server

    Pace, Cameron

    2015-01-01

    The feedback from radio-loud active galactic nuclei (R-AGN) may help maintain low star formation (SF) rates in their early-type hosts, but the observational evidence for this mechanism has been inconclusive. We study systematic differences of aggregate spectral energy distributions (SEDs) of various subsets of $\\sim$4000 low-redshift R-AGN from Best & Heckman (2012) with respect to (currently) inactive control samples selected to have matching redshift, stellar mass, population age, axis ratio, and environment. Aggregate SEDs, ranging from the ultraviolet (UV) through mid-infrared (mid-IR, 22 $\\mu$m), were constructed using a Bayesian method that eliminates biases from non-detections in GALEX and WISE. We study rare high-excitation sources separately from low-excitation ones, which we split by environment and host properties. We find that both the UV and mid-IR emission of non-cluster R-AGNs (80% of sample) are suppressed by $\\sim$0.2 dex relative to that of the control group, especially for moderately ma...

  9. The LOFAR radio environment

    CERN Document Server

    Offringa, A R; Zaroubi, S; van Diepen, G; Martinez-Ruby, O; Labropoulos, P; Brentjens, M A; Ciardi, B; Daiboo, S; Harker, G; Jelic, V; Kazemi, S; Koopmans, L V E; Mellema, G; Pandey, V N; Pizzo, R F; Schaye, J; Vedantham, H; Veligatla, V; Wijnholds, S J; Yatawatta, S; Zarka, P; Alexov, A; Anderson, J; Asgekar, A; Avruch, M; Beck, R; Bell, M; Bell, M R; Bentum, M; Bernardi, G; Best, P; Birzan, L; Bonafede, A; Breitling, F; Broderick, J W; Bruggen, M; Butcher, H; Conway, J; de Vos, M; Dettmar, R J; Eisloeffel, J; Falcke, H; Fender, R; Frieswijk, W; Gerbers, M; Griessmeier, J M; Gunst, A W; Hassall, T E; Heald, G; Hessels, J; Hoeft, M; Horneffer, A; Karastergiou, A; Kondratiev, V; Koopman, Y; Kuniyoshi, M; Kuper, G; Maat, P; Mann, G; McKean, J; Meulman, H; Mevius, M; Mol, J D; Nijboer, R; Noordam, J; Norden, M; Paas, H; Pandey, M; Pizzo, R; Polatidis, A; Rafferty, D; Rawlings, S; Reich, W; Rottgering, H J A; Schoenmakers, A P; Sluman, J; Smirnov, O; Sobey, C; Stappers, B; Steinmetz, M; Swinbank, J; Tagger, M; Tang, Y; Tasse, C; van Ardenne, A; van Cappellen, W; van Duin, A P; van Haarlem, M; van Leeuwen, J; van Weeren, R J; Vermeulen, R; Vocks, C; Wijers, R A M J; Wise, M; Wucknitz, O

    2012-01-01

    Aims: This paper discusses the spectral occupancy for performing radio astronomy with the Low-Frequency Array (LOFAR), with a focus on imaging observations. Methods: We have analysed the radio-frequency interference (RFI) situation in two 24-h surveys with Dutch LOFAR stations, covering 30-78 MHz with low-band antennas and 115-163 MHz with high-band antennas. This is a subset of the full frequency range of LOFAR. The surveys have been observed with a 0.76 kHz / 1 s resolution. Results: We measured the RFI occupancy in the low and high frequency sets to be 1.8% and 3.2% respectively. These values are found to be representative values for the LOFAR radio environment. Between day and night, there is no significant difference in the radio environment. We find that lowering the current observational time and frequency resolutions of LOFAR results in a slight loss of flagging accuracy. At LOFAR's nominal resolution of 0.76 kHz and 1 s, the false-positives rate is about 0.5%. This rate increases approximately linear...

  10. Division x: Radio Astronomy

    NARCIS (Netherlands)

    Taylor, Russ; Chapman, Jessica; Rendong, Nan; Carilli, Christopher; Giovannini, Gabriele; Hills, Richard; Hirabayashi, Hisashi; Jonas, Justin; Lazio, Joseph; Morganti, Raffaella; Rubio, Monica; Shastri, Prajval

    This triennium has seen a phenomenal investment in development of observational radio astronomy facilities in all parts of the globe at a scale that significantly impacts the international community. This includes both major enhancements such as the transition from the VLA to the EVLA in North

  11. Educational Broadcasting--Radio.

    Science.gov (United States)

    Ahamed, Uvais; Grimmett, George

    This manual is intended for those who must conduct educational radio broadcasting training courses in Asia-Pacific countries without the resources of experienced personnel, as well as for individuals to use in self-learning situations. The selection of material has been influenced by the need to use broadcasting resources effectively in programs…

  12. Albanian: Basic Radio Communications.

    Science.gov (United States)

    Defense Language Inst., Washington, DC.

    This volume has been designed as a supplement to a course in Albanian developed by the Defense Language Institute. The emphasis in this text is placed on radio communications instruction. The volume is divided into five exercises, each of which contains a vocabulary, dictation, and an air-to-ground communications procedure conducted in Albanian…

  13. Valuing commercial radio licences

    NARCIS (Netherlands)

    Kerste, M.; Poort, J.; van Eijk, N.

    2011-01-01

    Within the EU Regulatory Framework, licensees for commercial radio broadcasting may be charged a fee to ensure optimal allocation of scarce resources but not to maximize public revenues. In this paper, it is described how such a fee can be determined for the purpose of licence renewal or extension.

  14. Zelenchukskaya Radio Astronomical Observatory

    Science.gov (United States)

    Smolentsev, Sergey; Dyakov, Andrei

    2013-01-01

    This report summarizes information about Zelenchukskaya Radio Astronomical Observatory activities in 2012. Last year a number of changes took place in the observatory to improve some technical characteristics and to upgrade some units to the required status. The report provides an overview of current geodetic VLBI activities and gives an outlook for the future.

  15. Svetloe Radio Astronomical Observatory

    Science.gov (United States)

    Smolentsev, Sergey; Rahimov, Ismail

    2013-01-01

    This report summarizes information about the Svetloe Radio Astronomical Observatory activities in 2012. Last year, a number of changes took place in the observatory to improve some technical characteristics and to upgrade some units to their required status. The report provides an overview of current geodetic VLBI activities and gives an outlook for the future.

  16. Dust tori in radio galaxies

    NARCIS (Netherlands)

    van der Wolk, G.; Barthel, P. D.; Peletier, R. F.; Pel, J. W.

    2010-01-01

    Aims: We investigate the quasar - radio galaxy unification scenario and detect dust tori within radio galaxies of various types. Methods: Using VISIR on the VLT, we acquired sub-arcsecond (~0.40 arcsec) resolution N-band images, at a wavelength of 11.85 μm, of the nuclei of a sample of 27 radio gala

  17. Extragalactic radio continuum surveys and the transformation of radio astronomy

    Science.gov (United States)

    Norris, Ray P.

    2017-10-01

    Next-generation radio surveys are about to transform radio astronomy by discovering and studying tens of millions of previously unknown radio sources. These surveys will provide fresh insights for understanding the evolution of galaxies, measuring the evolution of the cosmic star-formation rate, and rivalling traditional techniques in the measurement of fundamental cosmological parameters. By observing a new volume of observational parameter space, they are also likely to discover unexpected phenomena. This Review traces the evolution of extragalactic radio continuum surveys from the earliest days of radio astronomy to the present, and identifies the challenges that must be overcome to achieve this transformational change.

  18. The effects of quercetin in cultured human RPE cells under oxidative stress and in Ccl2/Cx3cr1 double deficient mice

    Science.gov (United States)

    Cao, Xiaoguang; Liu, Melissa; Tuo, Jingsheng; Shen, Defen; Chan, Chi-Chao

    2010-01-01

    Quercetin, a member of the flavonoid family, is one of the most prominent dietary antioxidants. This study investigates the mechanisms for the effects of quercetin on cultured human RPE cells and in Ccl2/Cx3cr1 double knock-out (DKO) mice, which spontaneously develop progressive retinal lesions mimicking age-related macular degeneration (AMD). In the in vitro experiment, cultured ARPE-19 cells were exposed to 1mM H2O2 with or without 50μM quercetin for 2 hours. Cellular viability, mitochondrial function, and apoptosis were assessed using crystal violet staining, MTT assay, and comet assay, respectively. Apoptotic molecular transcripts of BCL-2, BAX, FADD, CASPASE-3 and CASPASE-9 were measured by RQ-PCR. COX activity and nitric oxide (NO) level were determined in the supernatant of the culture medium. Quercetin treatment protected ARPE-19 cells from H2O2-induced oxidative injury, enhanced BCL-2 transcript levels, increased the BCL-2/BAX ratio, suppressed the transcription of pro-apoptotic factors such as BAX, FADD, CASPASE-3 and CASPASE-9, inhibited the transcription of inflammatory factors such as TNF-α, COX-2 and INOS, and decreased the levels of COX and NO in the culture medium. In the in vivo experiment, DKO and C57/B6 mice were treated with 25mg/kg/day quercetin by intraperitoneal injection daily for two months. Funduscopy was performed monthly. After two months, serum was collected to measure NADP+/NADPH, COX, PGE-2, and NO levels. The eyes were harvested for histology and A2E measurement. Ocular transcripts of Bcl-2, Bax, Cox-2, Inos, Tnf-α, Fas, FasL and Caspase-3 were detected by RQ-PCR. Quercetin treatment did not reverse the progression of retinal lesions in DKO mice funduscopically or histologically. Although quercetin treatment could recover systemic anti-oxidative capacity, suppress the systemic expression of NO, COX and PGE-2, and decrease ocular A2E levels, it could not effectively suppress the transcripts of the ocular inflammatory factors Tnf

  19. Designing a dual-mode broadband solar spectral converter: The example of Bi{sup 3+}, Cr{sup 3+}, Yb{sup 3+}-tridoped perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Li-Tian; Wu, Xuan-Ming; Wang, Ting; Chen, Dong-Ju; Deng, Chao; Meng, Jian-Xin, E-mail: tmjx@jnu.edu.cn; Cao, Li-Wei

    2016-07-15

    A promising dual-mode broadband solar spectral converter CaTiO{sub 3}: Bi{sup 3+}, Cr{sup 3+}, Yb{sup 3+} was successfully developed by solid-stated reaction. The structure, photoluminescence (PL), photoluminescence excitation (PLE) and diffuse reflectance (DR) spectra in the UV–vis–NIR region have been systematically investigated. The results show that the as-prepared samples simultaneously exhibit two distinct spectral converting patterns, nonlinear quantum-cutting (QC) involving Bi{sup 3+}–Ti{sup 4+} metal-to-metal charge transfer state (BT-MMCTs) → Yb{sup 3+}: {sup 2}F{sub 5/2} + Yb{sup 3+}: {sup 2}F{sub 5/2} and linear downshift (DS) involving Cr{sup 3+}: {sup 4}T{sub 2} → Yb{sup 3+}: {sup 2}F{sub 5/2}. It deduces that the nonlinear QC is based on a cooperative energy transfer (CET) process while the linear DS belongs to a dipole–dipole mechanism. With the present converter, broadband UV–vis (300–700 nm) photons, which are not fully utilized by the existing c-Si solar cells, can be efficiently harvested and converted into ∼1000 nm NIR photons via the dual-mode mechanism. Moreover, not only the PLE spectrum of CaTiO{sub 3}: Bi{sup 3+}, Cr{sup 3+}, Yb{sup 3+} matched well with that of the solar radiation, but also its NIR emission peak position fell well over the spectral response of the commercial crystalline Si (c-Si) solar cells. This as-prepared dual-mode solar spectral converter with multiple advantages can simultaneously realize high quantum yield and broadband conversion, which offers a new and effective way to boost the conversion efficiency of c-Si solar cells. We believe this novel design of dual-mode solar spectral converters can inspire a direction for the synthesis of more advanced UV–vis–NIR phosphors that can be used in Si solar cells. - Highlights: • A dual-mode broadband solar spectral converter is designed and developed. • The energy transfer mechanism relies on quantum-cutting as well as downshift. • The PLE

  20. INOVASI RADIO KAMPUS (RANCANG BANGUN RADIO UDINUS DENGAN INOVASI TEKNOLOGI @RADIO

    Directory of Open Access Journals (Sweden)

    Wellia Shinta Sari

    2014-08-01

    Full Text Available Perkembangan Teknologi Informasi dan Komunikasi (TIK memaksa industri penyiaran untuk ikut menyesuaikan diri. Radio konvensional bisa jadi akan tertinggal jika tidak melakukan inovasi teknologi yang ada. Begitu juga dengan radio kampus, yang keberadaannya sangat dibutuhkan sebagai wadah kreativitas dan sarana pembelajaran di sebuah universitas, apalagi yang memiliki program studi penyiaran. Radio kampus Suara Dian yang masih konvensional sehingga hampir kehilangan eksistensinya harus segera dibenahi dan dihidupkan kembali dengan mengikuti perkembangan teknologi di era konvergensi. Metode Inovasi teknologi yang bisa dilakukan adalah dengan menggunakan teknologi @Radio Streaming, yang bukan sekedar streaming, tapi juga optimalisasi teknologi yang terintegrasi dinamis melalui RISE (Radio Broadcasting Integrated System. Dengan berbagai fitur unggul dari inovasi teknologi tersebut, maka diharapkan Radio kampus Udinus ”Suara Dian” dapat kembali hidup, berkembang dan lebih kompetitif ditengah industri penyiaran Radio. Kata kunci : radio, kampus, konvergensi, streaming.

  1. Energy Spectra,g Factors and Their Pressure-Induced and/or Thermal Shifts of SrTiO3:Cr3+ and SrTiO3:Mn4+ IV:R-Line Thermal Shifts of SrTiO3:Cr3+

    Institute of Scientific and Technical Information of China (English)

    MA Dong-Ping; ZHANG Ji-Ping

    2001-01-01

    The local impurity-vibration modes (especially,the Iow-frequency one) of SrTiO3 :Cr3+ cause a very large R-line blue-shift;while the Raman term,neighbor-level term and optical-branch term relevant to the lattice vibration cause smallred shifts.The algebraic sum of them gives rise to the observed unusual and large R-line thermal shift (blue-shift) of SrTiOa:Cr3+.By taking into account all the irreducible representations and their components in the electron-phonon interaction (BPI) as well as all the levels and the admixtures of basic wavefunctions within d3 electronic configuration,the values of the parameters in the expressions of thermal shift (TS) from EPI for the ground level,R level and R line of SrTiO3:Cr3+ have been evaluated;the R-line TS and various contributions to it have been calculated in two temperature ranges (30 K ≤ T ≤ 80 K and 130 K ≤ T ≤ 300 K).The contribution to R-line TS from thermal expansion has been approximately neglected in this work.Furthermore,the improvement on simplified approximation of adopting a single low-frequency impurity-mode and neglecting its hardening in Iow-temperature region has been made.``

  2. The importance of Radio Quiet Zone (RQZ) for radio astronomy

    Science.gov (United States)

    Umar, Roslan; Abidin, Zamri Zainal; Ibrahim, Zainol Abidin

    2013-05-01

    Most of radio observatories are located in isolated areas. Since radio sources from the universe is very weak, astronomer need to avoid radio frequency interference (RFI) from active spectrum users and radio noise produced by human made (telecommunication, mobile phone, microwave user and many more. There are many observatories around the world are surrounded by a Radio Quiet Zone (RQZ), which is it was set up using public or state laws. A Radio Quiet Zone normally consists of two areas: an exclusive area in which totally radio emissions are forbidden, with restrictions for residents and business developments, and a larger (radius up to 100 km above) coordination area where the power of radio transmission limits to threshold levels. Geographical Information System (GIS) can be used as a powerful tool in mapping large areas with varying RQZ profiles. In this paper, we report the initial testing of the usage of this system in order to identify the areas were suitable for Radio Quiet Zone. Among the important parameters used to develop the database for our GIS are population density, information on TV and telecommunication (mobile phones) transmitters, road networks (highway), and contour shielding. We will also use other information gathered from on-site RFI level measurements on selected 'best' areas generated by the GIS. The intention is to find the best site for the purpose of establishing first radio quiet zones for radio telescope in Malaysia.

  3. Structural and magnetic properties in the quantum S=1/2 dimer systems Ba3(Cr1-xVx)2O8 with site disorder

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Tao [ORNL; Zhu, L. Y. [Argonne National Laboratory (ANL); Ke, X. [Michigan State University, East Lansing; Garlea, Vasile O [ORNL; Qiu, Y. [National Institute of Standards and Technol/University of Maryland, College Park; Nambu, Y. [Tohoku University, Sendai, Japan; Yoshizawa, H. [University of Tokyo, Tokyo, Japan; Zhu, M. [Michigan State University, East Lansing; Granroth, Garrett E [ORNL; Savici, Andrei T [ORNL; Gai, Zheng [ORNL; Zhou, H. D. [Department of Physics and Astronomy, University of Tennessee

    2013-01-01

    We report a comprehensive study of the DC susceptibility, specific heat, neutron diffraction, and inelastic neutron scattering measurements on the polycrystalline Ba3(Cr1-xVx)2O8 samples, where x=0, 0.06, 0.15, and 0.53. A Jahn-Teller structure transition occurs for x=0, 0.06, and 0.15 samples and the transition temperature is reduced upon vanadium substitution from 70(2) K at x=0 to 60(2) K at x=0.06 and 0.15. The structure becomes less distorted as x increases and such transition disappears at x=0.53. The observed magnetic excitation spectrum indicates that the singlet ground state remains unaltered and spin gap energy =1.3(1) meV is identical within the instrument resolution for all x. In addition, the dispersion bandwidth W decreases with increase of x. At x=0.53, W is reduced to 1.4(1) meV from 2.0(1) meV at x=0.

  4. Characterization of akaganeite synthesized in presence of Al{sup 3+}, Cr{sup 3+}, and Cu{sup 2+} ions and urea

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, K.E. [Instituto de Quimica, Universidad de Antioquia, A.A. 1226, Medellin (Colombia); Grupo de Estado Solido, Sede de Investigacion Universitaria, Universidad de Antioquia, A.A. 1226, Medellin (Colombia)], E-mail: kgarcia@pegasus.udea.edu.co; Barrero, C.A.; Morales, A.L. [Grupo de Estado Solido, Sede de Investigacion Universitaria, Universidad de Antioquia, A.A. 1226, Medellin (Colombia); Greneche, J.M. [Laboratoire de Physique de l' Etat Condense- UMR 6087, Universite du Maine, 72085 Le Mans Cedex 9 (France)

    2008-11-15

    Crystallographic, chemical, and physical properties of akaganeite formed in the presence of Al{sup 3+}, Cr{sup 3+}, and Cu{sup 2+} ions and urea when it is obtained by the hydrolysis of FeCl{sub 3} solutions were investigated by different techniques. X-ray diffraction (XRD), RT and 77 K Moessbauer spectrometry, Fourier transformed infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) demonstrate that akaganeite is the only compound being formed independent of the type and concentration of the metallic cations and urea. Very small differences in some of the crystallographic, Moessbauer and infrared parameters for samples obtained in the presence of Cr, Cu, and Al ions at concentrations less than 10 mol%, were observed. However at 30 mol%, the presence of Al is able to reduce the average grain size of the final products. The presence of urea does not help to incorporate in an appreciable amount the Al into the akaganeite structure at least in the concentration ranges studied here. In contrast, they drastically affect the grain size of the products by reducing them. The present results may suggest that, because the properties of akaganeite are slightly affected by most alloying elements at low concentrations, this compound when formed as corrosion product of weathering and carbon steels should exhibit very similar properties to that of akaganeite obtained synthetically pure.

  5. Hot Deformation Behavior of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe Alloy in α + β Field

    Directory of Open Access Journals (Sweden)

    Zhaoxin Du

    2015-02-01

    Full Text Available The deformation behavior of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe high strength β titanium alloy is systematically investigated by isothermal compression in α + β field with the deformation temperatures ranging from 1003 K to 1078 K, the strain rates ranging from 0.001 s−1 to 1 s−1 and the height reduction is around 50%. Essentially, the flow stress-strain curve of isothermal compression in α + β field exhibits a flow softening feature when the strain rate is higher than 0.1 s−1 as while it exhibits a steady-state feature as the strain rate is lower than 0.1 s−1. The peak stress increases with a decrease in deformation temperature and the increase of strain rate. The activation energy for deformation in α + β field was calculated and the average activation energy of 271.1 kJ/mol. The microstructure observation reveals that the isothermal deformation in the α + β field of the alloy is mainly controlled by the dynamic recovery mechanism accompanied with the secondary dynamic recrystallizitation of β phase. The α phase shows an obvious pinning effect for the movement of dislocations. During deformation, the α phase was elongated and fragmented.

  6. In situ and postradiation analysis of mechanical stress in Al{sub 2}O{sub 3}:Cr induced by swift heavy-ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Skuratov, V.A., E-mail: skuratov@jinr.r [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Bujnarowski, G. [Institute of Physics, Opole University, 45-052 Opole (Poland); Kovalev, Yu.S. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); O' Connell, J. [Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Havanscak, K. [Eoetvoes University, Pazmany P. setany 1/A, H-1117 Budapest (Hungary)

    2010-10-01

    Optical spectroscopy and TEM techniques have been applied to study the radiation damage and correlated mechanical stresses in Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}:Cr single crystals induced by (1-3) MeV/amu Kr, Xe and Bi ion irradiation. Mechanical stresses were evaluated in situ using a piezospectroscopic effect through the shift of the respective lines in ionoluminescence spectra. It was found that dose dependence of the stress level for Xe and Bi ions, when ionization energy loss exceeds the threshold of damage formation via electronic excitations, exhibits several alternate stages showing the build-up and relaxation of stresses. The beginning of relaxation stages is observed at fluences associated with beginning of individual ion track regions overlapping. The residual stress profiles through the ion irradiated layers were deduced from depth-resolved photostimulated spectra using laser confocal scanning microscopy set-up. It was determined that stresses are compressive in basal plane and tensile in perpendicular direction in all samples irradiated with high energy ions.

  7. Thermal and Nonthermal Radio Galaxies

    CERN Document Server

    Antonucci, Robert

    2011-01-01

    Radio galaxies were discovered and mapped in the 1950s. The optical spectra showed little or no nuclear continuum light. Some also revealed powerful high ionization emission lines, while others showed at most weak low-ionization emission lines. Quasars were found in the 1960s, and their spectra were dominated by powerful continuum radiation which was subsequently identified with optically thick thermal radiation from copious accretion flows, as well as high ionization narrow emission lines, and powerful broad permitted lines. By the 1980s, data from optical polarization and statistics of the radio properties required that many radio galaxies contain hidden quasar nuclei, hidden from the line of sight by dusty, roughly toroidal gas distributions. The radio galaxies with hidden quasars are referred to as "thermal." Do all radio galaxies have powerful hidden quasars? We now know the answer using arguments based on radio, infrared, optical and X-ray properties. Near the top of the radio luminosity function, for F...

  8. THE AUGER ENGINEERING RADIO ARRAY

    Directory of Open Access Journals (Sweden)

    Klaus Weidenhaupt

    2013-12-01

    Full Text Available The Auger Engineering Radio Array currently measures MHz radio emission from extensive air showers induced by high energy cosmic rays with 24 self-triggered radio detector stations. Its unique site, embedded into the baseline detectors and extensions of the Pierre Auger Observatory, allows to study air showers in great detail and to calibrate the radio emission. In its final stage AERA will expand to an area of approximately 20km2 to explore the feasibility of the radio-detection technique for future cosmic-ray detectors. The concept and hardware design of AERA as well as strategies to enable self-triggered radio detection are presented. Radio emission mechanisms are discussed based on polarization analysis of the first AERA data.

  9. Radio observations of Planck clusters

    CERN Document Server

    Kale, Ruta

    2012-01-01

    Recently, a number of new galaxy clusters have been detected by the ESA-Planck satellite, the South Pole Telescope and the Atacama Cosmology Telescope using the Sunyaev-Zeldovich effect. Several of the newly detected clusters are massive, merging systems with disturbed morphology in the X-ray surface brightness. Diffuse radio sources in clusters, called giant radio halos and relics, are direct probes of cosmic rays and magnetic fields in the intra-cluster medium. These radio sources are found to occur mainly in massive merging clusters. Thus, the new SZ-discovered clusters are good candidates to search for new radio halos and relics. We have initiated radio observations of the clusters detected by Planck with the Giant Metrewave Radio Telescope. These observations have already led to the detection of a radio halo in PLCKG171.9-40.7, the first giant halo discovered in one of the new Planck clusters.

  10. Distributed Radio Interferometric Calibration

    CERN Document Server

    Yatawatta, Sarod

    2015-01-01

    Increasing data volumes delivered by a new generation of radio interferometers require computationally efficient and robust calibration algorithms. In this paper, we propose distributed calibration as a way of improving both computational cost as well as robustness in calibration. We exploit the data parallelism across frequency that is inherent in radio astronomical observations that are recorded as multiple channels at different frequencies. Moreover, we also exploit the smoothness of the variation of calibration parameters across frequency. Data parallelism enables us to distribute the computing load across a network of compute agents. Smoothness in frequency enables us reformulate calibration as a consensus optimization problem. With this formulation, we enable flow of information between compute agents calibrating data at different frequencies, without actually passing the data, and thereby improving robustness. We present simulation results to show the feasibility as well as the advantages of distribute...

  11. Tools of radio astronomy

    CERN Document Server

    Wilson, Thomas L; Hüttemeister, Susanne

    2009-01-01

    The recent years have seen breathtaking progress in technology, especially in the receiver and digital technologies relevant for radio astronomy, which has at the same time advanced to shorter wavelengths. This is the updated and completely revised 5th edition of the most used introductory text in radio astronomy. It presents a unified treatment of the entire field from centimeter to sub-millimeter wavelengths. Topics covered include instruments, sensitivity considerations, observational methods and interpretations of the data recorded with both single dishes and interferometers. This text is useful to both students and experienced practicing astronomers. Besides making major updates and additions throughout the book, the authors have re-organized a number of chapters to more clearly separate basic theory from rapidly evolving practical aspects. Further, problem sets have been added at the end of each chapter.

  12. Searches for radio transients

    CERN Document Server

    Bhat, N D R

    2011-01-01

    Exploration of the transient Universe is an exciting and fast-emerging area within radio astronomy. Known transient phenomena range in time scales from sub-nanoseconds to years or longer, thus spanning a huge range in time domain and hinting a rich diversity in their underlying physical processes. Transient phenomena are likely locations of explosive or dynamic events and they offer tremendous potential to uncover new physics and astrophysics. A number of upcoming next-generation radio facilities and recent advances in computing and instrumentation have provided a much needed impetus for this field which has remained a relatively uncharted territory for the past several decades. In this paper we focus mainly on the class of phenomena that occur on very short time scales (i.e. from $\\sim$ milliseconds to $\\sim$ nanoseconds), known as {\\it fast transients}, the detections of which involve considerable signal processing and data management challenges, given the high time and frequency resolutions required in the...

  13. Die radio in Afrika

    Directory of Open Access Journals (Sweden)

    S. de Villiers

    1966-03-01

    Full Text Available Omvang van radio-uitsendings in en na Afrika. — Redes vir die versnelde tempo van uitbreiding. — Radio as die geskikste massa-kommunikasiemiddel vir Afrika. — Faktore wat die verspreiding bemoeilik. — Skouspelagtige toename in luistertalle.Toe Plinius, wat in die jaar 79 oorlede is, in sy „Historia Naturalis” verklaar het dat daar altyd iets nuuts uit Afrika afkomstig is, kon hy nouliks voorsien het dat die „iets" negentien eeue later in die lug sou setel wat hierdie reuse-vasteland oorspan — ’n Babelse spraakverwarring en ’n ongekende, verbete woorde-oorlog in die etergolwe, onder meer daarop bereken om die harte en hoofde van derduisendes te verower.

  14. Radio frequency ion source

    CERN Document Server

    Shen Guan Ren; Gao Fu; LiuNaiYi

    2001-01-01

    The study on Radio Frequency Ion Source is mainly introduced, which is used for CIAE 600kV ns Pulse Neutron Generator; and obtained result is also presented. The RF ion source consists of a diameter phi 25 mm, length 200 mm, coefficient of expansion =3.5 mA, beam current on target >=1.5 mA, beam spot =100 h.

  15. Cr3C2及(W,Ti)C对Al2O3/Cr3 C2/(W,Ti)C复合陶瓷材料Vickers硬度的影响%Effect of Cr3C2 and (W,Ti)C on the Vickers Hardness of Al2O3/Cr3 C2/(W, Ti) C Ceramic Composites

    Institute of Scientific and Technical Information of China (English)

    孙德明; 鹿晓阳; 李成美; 薛仲舜; 陈怀明; 岳雪涛; 孙胜

    2005-01-01

    热压烧结制备了Al2O3/Cr3C2/(W,Ti)C复合陶瓷材料(以下简称ACW复合材料),对其Vickers硬度及组织形貌进行了研究,分析了Cr3C2及(W,Ti)C对Vickers硬度的影响.结果表明,(W,Ti)C和Cr3C2的添加利于阻止晶界迁移,抑制晶粒长大,Cr、W、Ti离子在Al2O3基体晶粒中的固溶起强化作用.每一相的添加量在10%~20%(体积分数,下同)为宜,添加总量在30%左右ACW复合材料硬度最佳.

  16. Compact radio cores in radio-quiet AGNs

    CERN Document Server

    Maini, Alessandro; Norris, Ray P; Giovannini, Gabriele; Spitler, Lee R

    2016-01-01

    The mechanism of radio emission in radio-quiet (RQ) active galactic nuclei (AGN) is still debated and might arise from the central AGN, from star formation activity in the host, or from either of these sources. A direct detection of compact and bright radio cores embedded in sources that are classified as RQ can unambiguously determine whether a central AGN significantly contributes to the radio emission. We search for compact, high-surface-brightness radio cores in RQ AGNs that are caused unambiguously by AGN activity. We used the Australian Long Baseline Array to search for compact radio cores in four RQ AGNs located in the Extended Chandra Deep Field South (ECDFS). We also targeted four radio-loud (RL) AGNs as a control sample. We detected compact and bright radio cores in two AGNs that are classified as RQ and in one that is classified as RL. Two RL AGNs were not imaged because the quality of the observations was too poor. We report on a first direct evidence of radio cores in RQ AGNs at cosmological reds...

  17. Extraction of Y2 O3 :Cr(3+) nanophosphor by eco-friendly approach and its suitability for white light-emitting diode applications.

    Science.gov (United States)

    Prasanna Kumar, J B; Ramgopal, G; Sunitha, D V; Prasad, B Daruka; Nagabhushana, H; Vidya, Y S; Anantharaju, K S; Prashantha, S C; Sharma, S C; Prabhakara, K R

    2017-05-01

    Cr(3)(+) -doped Y2 O3 (0.5-9 mol%) was synthesized by a simple solution combustion method using Aloe vera gel as a fuel/surfactant. The final obtained product was calcined at 750°C for 3 h, which is the lowest temperature reported so far for the synthesis of this compound. The calcined product was confirmed for its crystallinity and purity by powder X-ray diffraction (PXRD) studies which showed a single-phase nano cubic phosphor. The particles size estimated by Scherrer formula was in the range of 6-19 nm. The UV-vis spectra showed absorption bands at 198, 272 and 372 nm having band gap energy in the range 4.00-4.26 eV. In order to investigate the possibility of its use in white light emitting display applications, the photoluminescence properties of Cr(3)(+) -doped Y2 O3 nanophosphors were studied at an excitation wavelength in the near ultraviolet (UV) light region (361 nm). The emission spectra consisted of emission peaks in the blue ((4) F9/2  → (6) H15/2 ), orange ((4) F9/2  → (6) H13/2 ) and red ((4) F9/2  → (6) H11/2 ) regions. The CIE coordinates (0.33, 0.33) lie in the white light region. Hence Y2 O3 :Cr(3)(+) can be used for white light-emitting diode (LED) applications. Copyright © 2016 John Wiley & Sons, Ltd.

  18. White light generation from YAG/YAM:Ce{sup 3+}, Pr{sup 3+}, Cr{sup 3+} nanophosphors mixed with a blue dye under 340 nm excitation

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, J. [Centro de Investigaciones en Optica, A.P. 1-948, León, Gto 37150, México (Mexico); De la Rosa, E., E-mail: elder@cio.mx [Centro de Investigaciones en Optica, A.P. 1-948, León, Gto 37150, México (Mexico); Diaz-Torres, L.A [Centro de Investigaciones en Optica, A.P. 1-948, León, Gto 37150, México (Mexico); Torres, A. [Universidad Autónoma de Nuevo León, A.P. 126-F, Monterrey, NL 66450, México (Mexico); Salas, P. [Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, A.P. 1-1010, Juriquilla, Qro. 76000, México (Mexico); Meza, O. [Benemérita Universidad Autónoma de Puebla, 4 Sur 104 Centro Historico, 72000 Puebla, México (Mexico)

    2014-10-15

    The structural and luminescent properties of Y{sub 3}Al{sub 5}O{sub 12}/Y{sub 4}Al{sub 2}O{sub 9}:Ce{sup 3+}(0.1%)–Pr{sup 3+}(0.1%) –Cr{sup 3+} (trace impurities) nanophosphors synthesized by a simple hydrothermal method were studied. The crystalline phase was composed of Yttrium Aluminum Garnet (YAG) and Yttrium Aluminum Monoclinic (YAM) depending on the ammonia concentration and annealing temperature. Ammonia increased the stabilization of YAG from 55 wt% to 63 wt% in the samples annealed at 900 °C, and an increment of 83% of the overall emission under 460 nm excitation was observed. Quenching of the emitted signal after annealing at 1100 °C was observed in spite of single YAG crystalline phase stabilization, due to the formation of Ce{sup 4+}, Pr{sup 4+}, and color centers. In addition to the green–yellow emission from Ce{sup 3+}, all samples present a broad red emission band produced by the relaxations from the broad band {sup 4}T{sub 2} toward the {sup 4}A{sub 2} energy level of Cr{sup 3+} impurities, under 340 nm excitation. By taking advantage of this broad green–yellow–red emission and using a blue dye, white light with CIE coordinates of (0.30, 0.36) under 340 nm excitation was produced. - Highlights: • YAG/YAM:Ce{sup 3+}, Pr{sup 3+}, Cr{sup 3+} nanophosphors were synthesized with a hydrothermal method. • Ammonia introduced during the synthesis increased the emission of nanophosphors. • White light was obtained by combining the emissions of a blue dye and nanophosphors. • The CIE coordinates for this white light are (0.30, 0.36)

  19. Radio emision from supernova remnants

    Science.gov (United States)

    Dubner, G.

    2016-06-01

    The vast majority of supernova remnants (SNRs) in our Galaxy and nearby galaxies have been discovered through radio observations, and only a very small number of the SNRs catalogued in the Milky Way have not been detected in the radio band, or are poorly defined by current radio observations. The study of the radio emission from SNRs is an excellent tool to investigate morphological characteristics, marking the location of shock fronts and contact discontinuities; the presence, orientation and intensity of the magnetic field; the energy spectrum of the emitting particles; and the dynamical consequences of the interaction with the circumstellar and interstellar medium. I will review the present knowledge of different important aspects of radio remnants and their impact on the interstellar gas. Also, new radio studies of the Crab Nebula carried out with the Karl Jansky Very Large Array (JVLA) at 3 GHz and with ALMA at 100 GHz, will be presented.

  20. Flexible Adaptation in Cognitive Radios

    CERN Document Server

    Li, Shujun

    2013-01-01

    This book provides an introduction to software-defined radio and cognitive radio, along with methodologies for applying knowledge representation, semantic web, logic reasoning and artificial intelligence to cognitive radio, enabling autonomous adaptation and flexible signaling. Readers from the wireless communications and software-defined radio communities will use this book as a reference to extend software-defined radio to cognitive radio, using the semantic technology described. Readers with a background in semantic web and artificial intelligence will find in this book the application of semantic web and artificial intelligence technologies to wireless communications. For readers in networks and network management, this book presents a new approach to enable interoperability, collaborative optimization and flexible adaptation of network components. Provides a comprehensive ontology covering the core concepts of wireless communications using a formal language; Presents the technical realization of using a ...

  1. Software defined radio architectures evaluation

    OpenAIRE

    Palomo, Alvaro; Villing, Rudi; Farrell, Ronan

    2008-01-01

    This paper presents an performance evaluation of GNU Radio and OSSIE, two open source Software Defined Radio (SDR) architectures. The two architectures were compared by running implementations of a BPSK waveform utilising a software loopback channel on each. The upper bound full duplex throughput was found to be around 700kbps in both cases, though OSSIE was slightly faster than GNU Radio. CPU and memory loads did not differ significantly.

  2. Uzaybimer Radio Telescope Control System

    Science.gov (United States)

    Balbay, R.; Öz, G. K.; Arslan, Ö.; Özeren, F. F.; Küçük, İ.

    2016-12-01

    A 13 meters former NATO radar is being converted into a radio telescope. The radio telescope is controlled by a system which has been developed at UZAYBİMER. The Telescope Control System(TCS) has been designed using modern industrial systems. TCS has been developed in LabView platform in which works Windows embedded OS. The position feedback used on radio telescopes is an industrial EtherCAT standard. ASCOM library is used for astronomical calculations.

  3. The 1.6 micron near infrared nuclei of 3C radio galaxies: Jets, thermal emission or scattered light?

    CERN Document Server

    Baldi, R D; Capetti, A; Sparks, W; Macchetto, F D; O'Dea, C P; Axon, D J; Baum, S A; Quillen, A C

    2010-01-01

    Using HST NICMOS 2 observations we have measured 1.6-micron near infrared nuclear luminosities of 100 3CR radio galaxies with z<0.3, by modeling and subtracting the extended emission from the host galaxy. We performed a multi-wavelength statistical analysis (including optical and radio data) of the properties of the nuclei following classification of the objects into FRI and FRII, and LIG (low-ionization galaxies), HIG (high-ionization galaxies) and BLO (broad-lined objects) using the radio morphology and optical spectra, respectively. The correlations among near infrared, optical, and radio nuclear luminosity support the idea that the near infrared nuclear emission of FRIs has a non-thermal origin. Despite the difference in radio morphology, the multi-wavelength properties of FRII LIG nuclei are statistically indistinguishable from those of FRIs, an indication of a common structure of the central engine. All BLOs show an unresolved near infrared nucleus and a large near infrared excess with respect to FRI...

  4. Radio-induced brain lesions

    Directory of Open Access Journals (Sweden)

    Gorgan Mircea Radu

    2014-03-01

    Full Text Available Introduction : Radiotherapy, an important tool in multimodal oncologic treatment, can cause radio-induced brain lesion development after a long period of time following irradiation.

  5. Internet Resources for Radio Astronomy

    Science.gov (United States)

    Andernach, H.

    A subjective overview of Internet resources for radio-astronomical information is presented. Basic observing techniques and their implications for the interpretation of publicly available radio data are described, followed by a discussion of existing radio surveys, their level of optical identification, and nomenclature of radio sources. Various collections of source catalogues and databases for integrated radio source parameters are reviewed and compared, as well as the web interfaces to interrogate the current and ongoing large-area surveys. Links to radio observatories with archives of raw (uv-) data are presented, as well as services providing images, both of individual objects or extracts (``cutouts'') from large-scale surveys. While the emphasis is on radio continuum data, a brief list of sites providing spectral line data, and atomic or molecular information is included. The major radio telescopes and surveys under construction or planning are outlined. A summary is given of a search for previously unknown optically bright radio sources, as performed by the students as an exercise, using Internet resources only. Over 200 different links are mentioned and were verified, but despite the attempt to make this report up-to-date, it can only provide a snapshot of the situation as of mid-1998.

  6. Radio Frequency Anechoic Chamber Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Supports the design, manufacture, and test of antenna systems. The facility is also used as an electromagnetic compatibility/radio frequency interference...

  7. Military Mail Radio

    Directory of Open Access Journals (Sweden)

    Bîlbîie Răduţ

    2015-12-01

    Full Text Available Cultural and scientific personalities from the army, military experts and creators of the doctrine have collaborated with the radio from the beginnings of radiophony, the educational role of this new, persuasive communication channel being evident not only for Romania or the Romanian army but also for all the countries that had radiophony services. This happens in the context of the end of the crisis and the start of economic and social development, promoting culture, creating a solid class of peasants with a certain social status, in villages, together with the priest, teacher and gendarme, increasing of the number of subscriptions and development of the Romanian radiophony.

  8. Radio Frequency Identification

    Indian Academy of Sciences (India)

    V Rajaraman

    2017-06-01

    Radio Frequency Identification (RFID) has been around sinceearly 2000. Its use has currently become commonplace as thecost of RFID tags has rapidly decreased. RFID tags have alsobecome more ‘intelligent’ with the incorporation of processorsand sensors in them. They are widely used now in manyinnovative ways. RFIDs are an integral part of Internet ofThings (IOT) and IT systems of smart cities. In this article,we introduce the technology used by RFID systems, illustratetheir use in several applications, and discuss problems of privacyand security when they are used.

  9. Evaluation of GNU Radio Platform Enhanced for Hardware Accelerated Radio Design

    OpenAIRE

    Karve, Mrudula Prabhakar

    2010-01-01

    The advent of software radio technology has enabled radio developers to design and imple- ment radios with great ease and flexibility. Software radios are effective in experimentation and development of radio designs. However, they have limitations when it comes to high- speed, high-throughput designs. This limitation can be overcome by introducing a hardware element to the software radio platform. Enhancing GNU Radio for Hardware Accelerated Radio Design project implements suc...

  10. The coexistence of cognitive radio and radio astronomy

    NARCIS (Netherlands)

    Bentum, Marinus Jan; Boonstra, A.J.; Baan, W.A.

    2009-01-01

    An increase of the efficiency of spectrum usage requires the development of new communication techniques. Cognitive radio may be one of those new technique, which uses unoccupied frequency bands for communications. This will lead to more power in the bands and therefore an increasing level of Radio

  11. The coexistence of cognitive radio and radio astronomy

    NARCIS (Netherlands)

    Bentum, M.J.; Boonstra, A.J.; Baan, W.A.

    2009-01-01

    An increase of the efficiency of spectrum usage requires the development of new communication techniques. Cognitive radio may be one of those new technique, which uses unoccupied frequency bands for communications. This will lead to more power in the bands and therefore an increasing level of Radio

  12. Radio Quiet AGN

    CERN Document Server

    Czerny, B; Karas, V; Ponti, G

    2005-01-01

    Active Galactic Nuclei are powered by accretion onto massive black holes. Although radio-quiet objects are not as spectacular sources of very high energy photons as radio-loud ones this class of objects also represents a challenge for modeling high energy processes close to a black hole. Both a hot optically thin plasma and a cooler optically thick accretion disk are usually thought to be present in the vicinity of a black hole although the details of the accretion flow are still under discussion. The role of the disk seems to decrease with a drop in the Eddington ratio: in sources like quasars and Narrow Line Seyfert 1 galaxies disk flow dominates while in Seyfert galaxies the disk retreats, and in sources like LINERS or Sgr A* a disk is most likely absent. Shocks and reconnections are possibly taking place in an inner hot flow and in the magnetic corona above the cold disk. Uncollimated outflow is also present and it may carry significant fraction of available mass and energy.

  13. Radio astronomy from space

    Science.gov (United States)

    Woan, G.

    2011-04-01

    At frequencies below about 30 MHz, radio astronomy becomes increasingly difficult from the Earth's surface, mainly due to a combination of poor ionospheric seeing and strong terrestrial interference. The obvious move is to space, either as free-flying spacecraft or with a telescope located somewhere on the Moon. All the major space agencies have a renewed interest in the Moon as a site for exploration and science, and low-frequency radio astronomy is probably the strongest of the astronomical objectives put forward in these programmes. Although the Sun is a strong source of interference in extra-solar system work, it is also a prime target for study in itself. A constellation of satellites (as proposed for the SIRA mission) would be able to image both the Sun and the inner heliosphere over the entire low-frequency band. Here we investigate some of the advantages and limitations of astronomy at these very low frequencies, using space- and lunar-based antennas.

  14. 78 FR 32165 - Commercial Radio Operators; Correction

    Science.gov (United States)

    2013-05-29

    ... COMMISSION 47 CFR Part 0 Commercial Radio Operators; Correction AGENCY: Federal Communication Commission...) Administers the Commission's commercial radio operator program (part 13 of this chapter); the Commission's... rules concerning radio operator licenses for maritime and aviation in order to reduce...

  15. Radio Relics in Cosmological Simulations

    Indian Academy of Sciences (India)

    M. Hoeft; S. E. Nuza; S. Gottlöber; R. J. van Weeren; H. J. A. Röttgering; M. Brüggen

    2011-12-01

    Radio relics have been discovered in many galaxy clusters. They are believed to trace shock fronts induced by cluster mergers. Cosmological simulations allow us to study merger shocks in detail since the intra-cluster medium is heated by shock dissipation. Using high resolution cosmological simulations, identifying shock fronts and applying a parametric model for the radio emission allows us to simulate the formation of radio relics. We analyze a simulated shock front in detail. We find a rather broad Mach number distribution. The Mach number affects strongly the number density of relativistic electrons in the downstream area, hence, the radio luminosity varies significantly across the shock surface. The abundance of radio relics can be modeled with the help of the radio power probability distribution which aims at predicting radio relic number counts. Since the actual electron acceleration efficiency is not known, predictions for the number counts need to be normalized by the observed number of radio relics. For the characteristics of upcoming low frequency surveys we find that about thousand relics are awaiting discovery.

  16. Tuning in to pavement radio

    NARCIS (Netherlands)

    Ellis, S.D.K.

    1989-01-01

    This article describes a phenomenon known all over Africa, for which there is no really satisfactory term in English but which is summed up in the French term 'radio trottoir', literally 'pavement radio'. It may be defined as the popular and unofficial discussion of current affairs in Africa,

  17. Cognitive Radio for Emergency Networks

    NARCIS (Netherlands)

    Zhang, Q.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2006-01-01

    In the scope of the Adaptive Ad-hoc Freeband (AAF) project, an emergency network built on top of Cognitive Radio is proposed to alleviate the spectrum shortage problem which is the major limitation for emergency networks. Cognitive Radio has been proposed as a promising technology to solve todayâ?~B

  18. Relics of Double Radio Sources

    CERN Document Server

    Dwarakanath, K S

    2009-01-01

    We have formed a new sample which consists of extended extragalactic radio sources without obvious active galactic nuclei (AGN) in them. Most of these sources appear to be dead double radio sources. These sources with steep spectra ($\\alpha < $ -1.8; S $\\propto \

  19. Cognitive Radio for Emergency Networks

    NARCIS (Netherlands)

    Zhang, Qiwei; Kokkeler, A.B.J.; Smit, G.J.M.

    2006-01-01

    In the scope of the Adaptive Ad-hoc Freeband (AAF) project, an emergency network built on top of Cognitive Radio is proposed to alleviate the spectrum shortage problem which is the major limitation for emergency networks. Cognitive Radio has been proposed as a promising technology to solve todayâ?~B

  20. The Radio Phenomenon in Italy.

    Science.gov (United States)

    Faenza, Roberto

    One in a series of studies of experiments in new audiovisual techniques in Europe and the situations in some member countries, this paper traces the development of radio in Italy. Opposing views about radio broadcasting (public monopoly vs. freedom of broadcasting) are examined, and the various political and legal aspects of communications in…

  1. Radio outburst of BL Lacertae

    Science.gov (United States)

    Buemi, C. S.; Leto, P.; Trigilio, C.; Umana, G.; Giroletti, M.; Orienti, M.; Raiteri, C. M.; Villata, M.; Bach, U.

    2013-04-01

    We report on extremely high radio flux of BL Lacertae at 43 and 8 GHz. Observations at 43 GHz with the 32 m radio telescope in Noto (Italy) revealed a flux density of 10.5 +/- 0.2 Jy on 2013 April 10.65, while observations at 8 GHz with the 32 m radio telescope in Medicina (Italy) detected a flux density of 8.2 +/- 0.7 Jy on April 12.22. These extremely high radio fluxes show that the radio activity likely correlated to the strong optical, near-infrared, and gamma-ray activity of 2011-2012 (see ATels #4028, #4031, #4155, #4271, #4277, #4349, #4565, #4600), and X-ray activity of late 2012 (ATels #4557, #4627), is far to be exhausted.

  2. Radio Emission from Globular Clusters

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Radio emission of globular clusters is studied by analyzing the VLA radio survey data of the NVSS and FIRST. We find that 13 clusters have radio sources within their half-mass radii of clusters. Sources detected previously in NGC 7078and NGC 6440 are identified. Pulsars in NGC 6121, NGC 6440 and NGC 7078cannot be detected because of the insufficient survey sensitivity and resolution.There may be a pulsar in the core of Terzan 1. The nature of the extended radio source near the core of NGC 6440 remains unclear. In the core of a globular cluster,there may be many neutron stars or an intermediate mass black hole, but this cannot be clarified with the current radio observations.

  3. CONSTRAINING RADIO EMISSION FROM MAGNETARS

    Energy Technology Data Exchange (ETDEWEB)

    Lazarus, P.; Kaspi, V. M.; Dib, R. [Department of Physics, Rutherford Physics Building, McGill University, 3600 University Street, Montreal, Quebec H3A 2T8 (Canada); Champion, D. J. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Hessels, J. W. T., E-mail: plazar@physics.mcgill.ca [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo (Netherlands)

    2012-01-10

    We report on radio observations of five magnetars and two magnetar candidates carried out at 1950 MHz with the Green Bank Telescope in 2006-2007. The data from these observations were searched for periodic emission and bright single pulses. Also, monitoring observations of magnetar 4U 0142+61 following its 2006 X-ray bursts were obtained. No radio emission was detected for any of our targets. The non-detections allow us to place luminosity upper limits of L{sub 1950} {approx}< 1.60 mJy kpc{sup 2} for periodic emission and L{sub 1950,single} {approx}< 7.6 Jy kpc{sup 2} for single pulse emission. These are the most stringent limits yet for the magnetars observed. The resulting luminosity upper limits together with previous results are discussed, as is the importance of further radio observations of radio-loud and radio-quiet magnetars.

  4. Constraining Radio Emission from Magnetars

    CERN Document Server

    Lazarus, Patrick; Champion, David J; Hessels, Jason W T; Dib, Rim

    2011-01-01

    We report on radio observations of five magnetars and two magnetar candidates carried out at 1950 MHz with the Green Bank Telescope in 2006-2007. The data from these observations were searched for periodic emission and bright single pulses. Also, monitoring observations of magnetar 4U0142+61 following its 2006 X-ray bursts were obtained. No radio emission was detected was detected for any of our targets. The non-detections allow us to place luminosity upper limits (at 1950 MHz) of approximately L < 1.60 mJy kpc^2 for periodic emission and L < 7.6 Jy kpc^2 for single pulse emission. These are the most stringent limits yet for the magnetars observed. The resulting luminosity upper limits together with previous results are discussed, as is the importance of further radio observations of radio-loud and radio-quiet magnetars.

  5. Radio propagation measurement and channel modelling

    CERN Document Server

    Salous, Sana

    2013-01-01

    While there are numerous books describing modern wireless communication systems that contain overviews of radio propagation and radio channel modelling, there are none that contain detailed information on the design, implementation and calibration of radio channel measurement equipment, the planning of experiments and the in depth analysis of measured data. The book would begin with an explanation of the fundamentals of radio wave propagation and progress through a series of topics, including the measurement of radio channel characteristics, radio channel sounders, measurement strategies

  6. OPTIMIZATION OF SPECTRUM UTILIZATION IN COGNITIVE RADIO SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Li Hongjiang; Zhu Qi

    2011-01-01

    In Cognitive Radio (CR) networks,CR user has to detect the spectrum channel periodically to make sure that the channel is idle during data transmission frame in order to avoid the collisions to the primary users.Hence recent research has been focused on the interference avoidance problem.Quality of Service (QoS) requirement of CR user will affect the time of data transmission in each frame.In this paper,in order to solve the interference avoidance and spectrum utilization problems without cooperation among CR users,a new scheme to obtain the optimal duration of data transmission frame is proposed to maximize the spectrum utilization and guarantee the protection to the primary users.The main advantages of our proposed scheme include the followings:(1) QoS requirement of CR user is concerned; (2) p-persistent Media Access Control (MAC) random access is used to avoid the collisions among CR users; (3) CR network system capacity is considered.We develop a Markov chain of the primary spectrum channel states and an exponential distribution of the CR user's traffic model to analyze the performance of our proposed scheme.Computer simulation shows that there is an optimal data transmission time to maximize the spectrum utilization.However,the regulatory constraint of the collision rate to the primary users has to be satisfied at the expense of spectrum utilization.And also the tradeoff between the spectrum utilization and the capacity of the CR system is taken into account.

  7. CURIE: Cubesat Radio Interferometry Experiment

    Science.gov (United States)

    Sundkvist, D. J.; Saint-Hilaire, P.; Bain, H. M.; Bale, S. D.; Bonnell, J. W.; Hurford, G. J.; Maruca, B.; Martinez Oliveros, J. C.; Pulupa, M.

    2016-12-01

    The CUbesat Radio Interferometry Experiment (CURIE) is a proposed two-element radio interferometer, based on proven and developed digital radio receivers and designed to fit within a Cubesat platform. CURIE will launch as a 6U Cubesat and then separate into two 3U Cubesats once in orbit. CURIE measures radio waves from 0.1-19MHz, which must be measured from space, as those frequencies fall below the cutoff imposed by Earth's ionosphere. The principal science objective for CURIE is to use radio interferometry to study radio burst emissions from solar eruptive events such as flares and coronal mass ejections (CMEs) in the inner heliosphere, providing observations important for our understanding of the heliospheric space weather environment. The influence of space weather can be felt at Earth and other planets, as radiation levels increase and lead to auroral activity and geomagnetic effects. CURIE will be able to determine the location and size of radio burst source regions and then to track their movement outward from the Sun. In addition to the primary objective CURIE will measure the gradients of the local ionospheric density and electron temperature on the spatial scale of a few kilometers, as well as create an improved map of the radio sky at these unexplored frequencies. A space based radio interferometry observatory has long been envisioned, in orbit around the Earth or the Moon, or on the far side of the Moon. Beyond its important science objectives, CURIE will prove that the concept of a dedicated space-based interferometer can be realized by using relatively cheap Cubesats. CURIE will therefore not only provide new important science results but also serve as a pathfinder in the development of new space-based radio observation techniques for helio- and astro-physics.

  8. 激光硬化和渗氮复合处理W9Mo3Cr4V高速钢组织与性能%Microstructure and Properties of W9Mo3Cr4V High Speed Steel Treated by Laser Hardening and Nitriding

    Institute of Scientific and Technical Information of China (English)

    赵宪; 王存山

    2012-01-01

    采用激光硬化与渗氮复合表面改性技术,对W9Mo3Cr4V高速钢表面进行了强化处理.利用X射线衍射仪、扫描电子显微镜、电子探针、显微硬度计和摩擦磨损试验机,分别对复合处理试样的相组成、微观组织、成分、显微硬度和耐磨性进行了分析.研究结果表明,复合处理表面改性层主要是回火马氏体、残余奥氏体、Fe3N、Cr7C3、M2C型碳化物所构成.由于激光硬化的晶粒细化作用,以及大量位错、孪晶、空位等微观缺陷的产生,致使氮化层的深度得到明显提高.与单一的激光硬化和渗氮工艺相比,复合处理工艺有效地提高了高速钢的硬度和耐磨性能.%W9Mo3Cr4V high speed steel is treated by composite technology of laser hardening and nitriding. The microstructure and properties of the sample after the composite treatment are investigated by means of X-ray diffraction, scanning electron microscopy, electron probe micro-analyzer, Vickers hardness tester, and friction wear testing machine. The results show that the surface modification layer consists of tempered martensite, retained austenite, Fe3N, Cr7C3, and M2C phases. Laser hardening obviously increases the depth of the nitrided layer, as a result of grain refinement, as well as production of high concentration microscopic defects. Compared to laser hardening and nitriding technologies, respectively, the composite treatment technology can effectively increase the hardness and wear resistance of the high speed steel.

  9. The faint radio sky: radio astronomy becomes mainstream

    Science.gov (United States)

    Padovani, Paolo

    2016-09-01

    Radio astronomy has changed. For years it studied relatively rare sources, which emit mostly non-thermal radiation across the entire electromagnetic spectrum, i.e. radio quasars and radio galaxies. Now, it is reaching such faint flux densities that it detects mainly star-forming galaxies and the more common radio-quiet active galactic nuclei. These sources make up the bulk of the extragalactic sky, which has been studied for decades in the infrared, optical, and X-ray bands. I follow the transformation of radio astronomy by reviewing the main components of the radio sky at the bright and faint ends, the issue of their proper classification, their number counts, luminosity functions, and evolution. The overall "big picture" astrophysical implications of these results, and their relevance for a number of hot topics in extragalactic astronomy, are also discussed. The future prospects of the faint radio sky are very bright, as we will soon be flooded with survey data. This review should be useful to all extragalactic astronomers, irrespective of their favourite electromagnetic band(s), and even stellar astronomers might find it somewhat gratifying.

  10. A Radio Astronomy Science Education Partnership - GAVRT and Radio JOVE

    Science.gov (United States)

    Higgins, C. A.; Thieman, J. R.; Bunnell, K.; Soholt, G.

    2009-12-01

    The planet Jupiter provides an excellent subject to educate, engage, and inspire students and teachers to learn science. The Goldstone Apple-Valley Radio Telescope (GAVRT) program (http://www.lewiscenter.org/gavrt) and The Radio JOVE project (http://radiojove.gsfc.nasa.gov) each have a long history of allowing students and teachers to interact with scientists and real radio telescopes. The upcoming Juno mission to Jupiter (2011 launch) allows both GAVRT and Radio JOVE to combine efforts and engage with the NASA Juno mission, thus increasing the excitement and learning potential for teachers, students, and the general public. Teachers can attend workshops for training to operate a 34-meter radio telescope and/or build their own simple radio telescope, both of which can be used directly in the classroom. We will overview some classroom activities and highlight some teacher-student experiences. In addition, we will update our efforts on greater Web-based control of the radio telescopes, as well as highlight our upcoming workshops to allow better access for teachers in different parts of the Country.

  11. The faint radio sky: radio astronomy becomes mainstream

    CERN Document Server

    Padovani, Paolo

    2016-01-01

    Radio astronomy has changed. For years it studied relatively rare sources, which emit mostly non-thermal radiation across the entire electromagnetic spectrum, i.e. radio quasars and radio galaxies. Now it is reaching such faint flux densities that it detects mainly star-forming galaxies and the more common radio-quiet active galactic nuclei. These sources make up the bulk of the extragalactic sky, which has been studied for decades in the infrared, optical, and X-ray bands. I follow the transformation of radio astronomy by reviewing the main components of the radio sky at the bright and faint ends, the issue of their proper classification, their number counts, luminosity functions, and evolution. The overall "big picture" astrophysical implications of these results, and their relevance for a number of hot topics in extragalactic astronomy, are also discussed. The future prospects of the faint radio sky are very bright, as we will soon be flooded with survey data. This review should be useful to all extragalac...

  12. The Radio Language Arts Project: adapting the radio mathematics model.

    Science.gov (United States)

    Christensen, P R

    1985-01-01

    Kenya's Radio Language Arts Project, directed by the Academy for Educational Development in cooperation with the Kenya Institute of Education in 1980-85, sought to teach English to rural school children in grades 1-3 through use of an intensive, radio-based instructional system. Daily 1/2 hour lessons are broadcast throughout the school year and supported by teachers and print materials. The project further was aimed at testing the feasibility of adaptation of the successful Nicaraguan Radio Math Project to a new subject area. Difficulties were encountered in articulating a language curriculum with the precision required for a media-based instructional system. Also a challenge was defining the acceptable regional standard for pronunciation and grammar; British English was finally selected. An important modification of the Radio Math model concerned the role of the teacher. While Radio Math sought to reduce the teacher's responsibilities during the broadcast, Radio Language Arts teachers played an important instructional role during the English lesson broadcasts by providing translation and checks on work. Evaluations of the Radio language Arts Project suggest significant gains in speaking, listening, and reading skills as well as high levels of satisfaction on the part of parents and teachers.

  13. NICMOS observations of high redshift radio galaxies witnessing the formation of bright elliptical galaxies?

    CERN Document Server

    Pentericci, L; Röttgering, H J A; Miley, G K; Van Breugel, W; Fosbury, R A E

    2001-01-01

    We present the results of a near infrared imaging program of a sample of 19 radio galaxies with redshift between 1.7 and 3.2, using the NICMOS Camera 2 on the Hubble Space Telescope. The galaxies were observed in H-band which, for 18 of the 19 targets, samples the rest-frame optical emission longwards of the 4000 A break. The images show a wide range of morphologies, from unresolved to compact systems, to systems with substructures such as multiple emission peaks, to systems comprised of several components spread over large areas. The morphologies of 5 of the lowest redshift targets are well represented by a de Vaucouleurs profile, consistent with them being elliptical galaxies. Their average effective radius is a factor of 2 smaller than that of z=1 3CR radio galaxies at similar restframe wavelengths. The near infrared continuum light is generally well aligned with the radio axis and the aligned light has typical V-H colors of around 3.5-4. For several galaxies where WFPC2 images were available, we computed ...

  14. Implementing Software Defined Radio

    CERN Document Server

    Grayver, Eugene

    2013-01-01

    Software Defined Radio makes wireless communications easier, more efficient, and more reliable. This book bridges the gap between academic research and practical implementation. When beginning a project, practicing engineers, technical managers, and graduate students can save countless hours by considering the concepts presented in these pages. The author covers the myriad options and trade-offs available when selecting an appropriate hardware architecture. As demonstrated here, the choice between hardware- and software-centric architecture can mean the difference between meeting an aggressive schedule and bogging down in endless design iterations. Because of the author’s experience overseeing dozens of failed and successful developments, he is able to present many real-life examples. Some of the key concepts covered are: Choosing the right architecture for the market – laboratory, military, or commercial Hardware platforms – FPGAs, GPPs, specialized and hybrid devices Standardization efforts to ens...

  15. Correlation radio range finder

    Directory of Open Access Journals (Sweden)

    A. Sorochan

    2012-10-01

    Full Text Available In work widely known methods of range measuring are short characterized. The basic attention is given features of signal processing in a correlation method of range measuring. The signal with angular modulation with one-voice-frequency fluctuation is used as a probing signal. The absence of Doppler effect on the formation of the correlation integral, the frequency instability of the transmitter, the phase change on reflection from the target is presented. It is noticed that the result of signal processing in the range measuring instrument is reduced to formation on an exit one-voice-frequency harmonious fluctuation equal to modulating frequency that provides high characteristics of a radio range finder.

  16. MUSIC RADIO-JOURNALISM

    Directory of Open Access Journals (Sweden)

    Dubovtceva Ludmila I.

    2014-04-01

    Full Text Available The article is based on years of practical experience, the author highlights the main radio genres in which music correspondent, music reviewer, music commentator, and music leading and a disc jockey work. Theoretical principles of their creative activities are analyzed in common journalistic genres, such as interview, reportage, talk show, live broadcast, radiofilm, as well as specialized genres like concert on demand and music competition. Journalist’ speech is seen as a logical element, the incoming with music in art-structural relationships. However, it does not become the predominant sound layer and aims to harmonious correlation or local penetration into music opus. In addition, important links in music journalism are defined the auxiliary "offscreen" editor's job and keeping the original sound archive. The author cites a number of own work examples on the air.

  17. Teaching radio astronomy with Affordable Small Radio Telescope (ASRT)

    Science.gov (United States)

    Joshi, Bhal Chandra

    A simple, easy to build and portable radio telescope, called Affordable Small Radio Telescope (ASRT), has been developed by the Radio Physics Laboratory (RPL), a radio astronomy teaching unit associated with the National Centre for Radio Astrophysics (TIFR) and Inter-University Centre for Astronomy and Astrophysics (IUCAA), which are two premier astronomy institutes in India. ASRT consists of off-the-shelf available Direct to Home television dishes and is easy to assemble. Our design is scalable from simple very low cost telescope to more complex yet moderately costing instrument. ASRT provides a platform for demonstrating radio physics concepts through simple hands-on experiment as well as for carrying out solar monitoring by college/University students. The presentation will highlight the concept of ASRT and the different experiments that can be carried out using it. The solar monitoring observations will be discussed along-with details of methods for calibrating these measurements. The pedagogical usefulness of ASRT in introducing undergraduatephysics students to astrophysics, measurements and analysis methods used in radio astronomy will also be discussed. Use of ASRT in the last three years in the programs of RPL, namely the annual Radio Astronomy Winter School for College students (RAWSC) and Pulsar Observing for Students (POS) is also presented. This year a new program was initiated to form a virtual group of an ASRT community, which will not only share their measurements, but also think of improving the pedagogical usefulness of ASRT by innovative experiments. This initiative is presented with the best practices drawn from our experience in using ASRT as a tool for student training in space sciences. The talk will also point out future ideas in involving a larger body of students in simple radio astronomy experiments with the ASRT, which RPL is likely to nucleate as part of its mandate.

  18. South African Radio League Introduction to Amateur Radio: A study guide for the Radio Amateur Examination

    CSIR Research Space (South Africa)

    Burger, Chris

    2016-01-01

    Full Text Available recognition of amateur radio licences. South African radio amateurs can exercise their privileges in more than 80 countries and territories with minimal paperwork. In exchange, we have an obligation to ensure that all licence holders possess a minimum level...

  19. Energy Spectra, g Factors and Their Pressure-Induced and/or Thermal Shifts of SrTiO3:Cr3+ and SrTiO3:Mn4+ I: Energy Spectra and g Factors at Normal Pressure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ji-Ping; MA Dong-Ping

    2001-01-01

    With the strong-field scheme and cubic bases, the complete d3 energy matrix in a tctragonally distorted cubic-field has been constructed. By diagonalizing this matrix, the energy spectra of Sr TiO3 :Cr3+ and Sr TiO3 :Mn4+ at normal pressure and various temperatures have been calculated. Correspondingly, the FORTRAN program calculating the g factor of the ground state has been worked out. By using the program and the wavefunction obtained from diagonalizing the complete energy matrix, the g factors of the ground state of SrTiO3 :Cr3+ and SrTiO3 :Mn4+ at normal pressure and room temperature have been evaluated. The calculated results are in good agreement with the optical spectral and EPR experimental data. The comparison and analysis of the results of two crystals have been made. It is demonstrated that the covalency of the bonding between Mn4+ and ligands (O2 ) in SrTiO3:Mn4+ is stronger than the one of the bonding between Cr3+ and ligands (O2 ) in SrTiO3:Cr3+. It is shown that the obtained wavefunctions and values of parameters are reasonable.

  20. Radio Astronomy Explorer /RAE/. I - Observations of terrestrial radio noise.

    Science.gov (United States)

    Herman, J. R.; Caruso, J. A.; Stone, R. G.

    1973-01-01

    Radio Astronomy Explorer (RAE) I data are analyzed to establish characteristics of HF terrestrial radio noise at an altitude of about 6000 km. Time and frequency variations in amplitude of the observed noise well above cosmic noise background are explained on the basis of temporal and spatial variations in ionospheric critical frequency coupled with those in noise source distributions. It is shown that terrestrial radio noise regularly breaks through the ionosphere and reaches RAE with magnitudes 15 dB and more above cosmic noise background, on frequencies above the F-layer critical frequency.

  1. Influence of CeO2 on the Performance of Stainless Steel - based SiO2 - BaO - Al2O3 - Cr2O3 Ceramic Coating%CeO2对不锈钢基SiO2-BaO-Al2O3-Cr2O3陶瓷涂层性能的影响

    Institute of Scientific and Technical Information of China (English)

    吕晶; 樊旭峰; 康勇; 陈彪; 郑君刚

    2012-01-01

    采用高温熔烧法于1Cr18 Ni9Ti不锈钢基材表面制备掺CeO2的SiO2 - BaO - Al2O3 - Cr2O3陶瓷涂层,研究了不同含量CeO2对涂层的抗氧化性、抗热震性和硬度的影响.研究结果表明,含CeO2的不锈钢基SiO2 - BaO- Al2O3 - Cr2O3陶瓷涂层能有效阻止不锈钢基体的氧化增重,提高涂层的抗热震性能及硬度.本实验条件下,CeO2含量2.8%时,涂层具有最好的抗氧化性能和抗热震性能.%SiO2 - BaO - A12O3 - Cr2O3 ceramic coating with CeO2 was fabricated on the substrate of an austenitic stainless steel lCrl8Ni9Ti by high temperature melting process. Influence of CeO2 on oxidation resistance, thermal shock resistance and hardness of the coating was investigated. The results show that SiO2 - BaO - A12O3 - Cr2O3 ceramic coating with CeO2 can effectively prevent oxidation weight gain of stainless steel substrate, improve the thermal shock resistance and hardness of coating. Under this experimental condition, when the amount of CeO2 is 2.8% , the coating has the best oxidation resistance and thermal shock resistance.

  2. Dust tori in radio galaxies

    CERN Document Server

    van der Wolk, G; Peletier, R F; Pel, J W

    2009-01-01

    We investigate the validity of the quasar - radio galaxy unification scenario and determine the presence of dust tori among radio galaxies of various types. Actively accreting supermassive black holes in the centres of radio galaxies may be uncovered through their dust tori reradiating the optical and ultraviolet continuum in mid-infrared bands. Using VISIR on the VLT, we have obtained sub-arcsecond (~0.40") resolution N-band images, at a wavelength of 11.85 micron, of the nuclei of a sample of 27 radio galaxies of four types in the redshift range z=0.006-0.156. The sample consists of 8 edge-darkened, low-power Fanaroff-Riley class I (FR-I) radio galaxies, 6 edge-brightened, class II (FR-II) radio galaxies displaying low-excitation optical emission, 7 FR-IIs displaying high-excitation optical emission, and 6 FR-II broad emission line radio galaxies. Out of the sample of 27 objects, 10 nuclei are detected and several have constraining non-detections at 10 sigma sensitivities of 7 mJy. On the basis of the core ...

  3. W4Mo3Cr4VSiN低合金高速钢中马氏体二次硬化的研究%Martensite Secondary Hardening of W4Mo3Cr4VSiN Low Alloy High Speed Steel

    Institute of Scientific and Technical Information of China (English)

    郑立允; 赵立新; 吴炳胜; 罗建民

    2002-01-01

    通过透射电子显微镜分析研究了W4Mo3Cr4VSiN(F205)低合金高速钢在1160℃淬火,250~700℃不同温度下回火时马氏体二次硬化的原因、碳化物析出机理.结果表明:在回火温度为350℃时,F205钢从基体中析出大量的Fe3C;520℃时Fe3C消失、重溶;540℃时有类似于Al-Cu合金中的GP区的W、Mo等合金元素与碳原子组成的复合偏聚区存在;560℃时,有面心立方的Mo2C和Cr7C3从基体中弥散析出,与此同时W、Mo等合金元素与碳原子组成的复合偏聚区逐渐减少,使得F205钢二次硬化效应达到了最大值;在700℃左右,Mo2C晶格发生变化(Mo2C(fcc)Mo2C(hcp)).

  4. Radio emission in Mercury magnetosphere

    Science.gov (United States)

    Varela, J.; Reville, V.; Brun, A. S.; Pantellini, F.; Zarka, P.

    2016-10-01

    Context. Active stars possess magnetized wind that has a direct impact on planets that can lead to radio emission. Mercury is a good test case to study the effect of the solar wind and interplanetary magnetic field (IMF) on radio emission driven in the planet magnetosphere. Such studies could be used as proxies to characterize the magnetic field topology and intensity of exoplanets. Aims: The aim of this study is to quantify the radio emission in the Hermean magnetosphere. Methods: We use the magnetohydrodynamic code PLUTO in spherical coordinates with an axisymmetric multipolar expansion for the Hermean magnetic field, to analyze the effect of the IMF orientation and intensity, as well as the hydrodynamic parameters of the solar wind (velocity, density and temperature), on the net power dissipated on the Hermean day and night side. We apply the formalism derived by Zarka et al. (2001, Astrophys. Space Sci., 277, 293), Zarka (2007, Planet. Space Sci., 55, 598) to infer the radio emission level from the net dissipated power. We perform a set of simulations with different hydrodynamic parameters of the solar wind, IMF orientations and intensities, that allow us to calculate the dissipated power distribution and infer the existence of radio emission hot spots on the planet day side, and to calculate the integrated radio emission of the Hermean magnetosphere. Results: The obtained radio emission distribution of dissipated power is determined by the IMF orientation (associated with the reconnection regions in the magnetosphere), although the radio emission strength is dependent on the IMF intensity and solar wind hydro parameters. The calculated total radio emission level is in agreement with the one estimated in Zarka et al. (2001, Astrophys. Space Sci., 277, 293) , between 5 × 105 and 2 × 106 W.

  5. The SINFONI survey of powerful radio galaxies at z 2: Jet-driven AGN feedback during the Quasar Era

    Science.gov (United States)

    Nesvadba, N. P. H.; De Breuck, C.; Lehnert, M. D.; Best, P. N.; Collet, C.

    2017-03-01

    We present VLT/SINFONI imaging spectroscopy of the rest-frame optical emission lines of warm ionized gas in 33 powerful radio galaxies at redshifts z ≳ 2, which are excellent sites to study the interplay of rapidly accreting active galactic nuclei and the interstellar medium of the host galaxy in the very late formation stages of massive galaxies. Our targets span two orders of magnitude in radio size (2-400 kpc) and kinetic jet energy (a few 1046- almost 1048 erg s-1). All sources have complex gas kinematics with broad line widths up to 1300 km s-1. About half have bipolar velocity fields with offsets up to 1500 km s-1 and are consistent with global back-to-back outflows. The others have complex velocity distributions, often with multiple abrupt velocity jumps far from the nucleus of the galaxy, and are not associated with a major merger in any obvious way. We present several empirical constraints that show why gas kinematics and radio jets seem to be physically related in all galaxies of the sample. The kinetic energy in the gas from large scale bulk and local outflow or turbulent motion corresponds to a few 10-3 to 10-2 of the kinetic energy output of the radio jet. In galaxies with radio jet power ≳ 1047 erg s-1, the kinetic energy in global back-to-back outflows dominates the total energy budget of the gas, suggesting that bulk motion of outflowing gas encompasses the global interstellar medium. This might be facilitated by the strong gas turbulence, as suggested by recent analytical work. We compare our findings with recent hydrodynamic simulations, and discuss the potential consequences for the subsequent evolution of massive galaxies at high redshift. Compared with recent models of metal enrichment in high-z AGN hosts, we find that the gas-phase metallicities in our galaxies are lower than in most low-z AGN, but nonetheless solar or even super-solar, suggesting that the ISM we see in these galaxies is very similar to the gas from which massive low-redshift

  6. Technology, Empowerment and Community Radio

    OpenAIRE

    Scifo, Salvatore

    2015-01-01

    This article will provide an overview of the conceptual contours of community media and community radio, highlighting some of the key questions shaping the debate and, with the help of a case study, show how digital media in the context of community radio can help local groups to get a voice in their local media systems, and how a university-based radio station, and its students and volunteers, play an important role for a more diverse and vibrant media content available in their area.

  7. Radio Search For Extrasolar Planets

    Science.gov (United States)

    Zarka, P.

    Theoretical justification and ongoing observational efforts in view of detecting radio emissions from extrasolar planets will be presented. On the "prediction" side, a heuris- tic scaling law has been established relating the radio output of any magnetized flow- obstacle system to the incident magnetic energy flux on the obstacle. Its confirmation by the observation of radio emission from extrasolar planets would help to understand the energy budget of such a system. On the "detection" side, specific procedures have been developed for interference mitigation and weak burst detection.

  8. Advanced Radio Resource Management for Multi Antenna Packet Radio Systems

    OpenAIRE

    Stanislav Nonchev; Mikko Valkama

    2010-01-01

    In this paper, we propose fairness-oriented packet scheduling (PS) schemes with power-efficientcontrol mechanism for future packet radio systems. In general, the radio resource managementfunctionality plays an important role in new OFDMA based networks. The control of the networkresource division among the users is performed by packet scheduling functionality based on maximizingcell coverage and capacity satisfying, and certain quality of service requirements. Moreover, multiantennatransmit-r...

  9. Recent Radio Monitoring of Microquasars with RATAN-600 Radio Telescope

    CERN Document Server

    Trushkin, S A; Kotani, T; Nizhelskij, N A; Namiki, M; Tsuboi, M; Voitsik, P A

    2007-01-01

    We report about the multi-frequency (1-30 GHz) daily monitoring of the radio flux variability of the three microquasars: SS433, GRS1915+105 and Cyg X-3 during the period from September 2005 to May 2006. 1. We detected clear correlation of the flaring radio fluxes and X-rays 'spikes' at 2-12 keV emission detected in RXTE ASM from GRS1915+105 during eight relatively bright (200-600 mJy) radio flares in October 2005. The 1-22 GHz spectra of these flares in maximum were optically thick at frequencies lower 2.3 GHz and optically thin at the higher frequencies. During the radio flares the spectra of the X-ray spikes become softer than those of the quiescent phase. Thus these data indicated the transitions from very high/hard states to high/soft ones during which massive ejections are probably happened. These ejections are visible as the detected radio flares. 2. After of the quiescent radio emission we have detected a drop down of the fluxes (~20 mJy) from Cyg X-3. That is a sign of the following bright flare. Inde...

  10. Radio frequency integrated circuit design for cognitive radio systems

    CERN Document Server

    Fahim, Amr

    2015-01-01

    This book fills a disconnect in the literature between Cognitive Radio systems and a detailed account of the circuit implementation and architectures required to implement such systems.  Throughout the book, requirements and constraints imposed by cognitive radio systems are emphasized when discussing the circuit implementation details.  In addition, this book details several novel concepts that advance state-of-the-art cognitive radio systems.  This is a valuable reference for anybody with background in analog and radio frequency (RF) integrated circuit design, needing to learn more about integrated circuits requirements and implementation for cognitive radio systems. ·         Describes in detail cognitive radio systems, as well as the circuit implementation and architectures required to implement them; ·         Serves as an excellent reference to state-of-the-art wideband transceiver design; ·         Emphasizes practical requirements and constraints imposed by cognitive radi...

  11. Innovativeness and the Public Radio Audience.

    Science.gov (United States)

    Williams, Wenmouth, Jr.; Krugman, Dean M.

    1981-01-01

    A public radio audience was surveyed to test the hypothesis that a relationship exists between innovativeness and public radio listening. Rather than supporting the hypothesis, findings indicate that the entertainment and information elements of public radio are the primary attractions for the public radio audience. (MER)

  12. On the evaluation of Web Radio

    NARCIS (Netherlands)

    Field, A.N.; Hartel, Pieter H.

    We develop an evaluation method for Web radio, and perform it to see what we can be learnt about seven prominent Web radio sites. We also evaluate a commercial FM radio station for control purposes. We present a taxonomy of Web radio, and we give our observations and conclusions on this evaluation.

  13. On the evaluation of Web Radio

    NARCIS (Netherlands)

    Field, A.N.; Hartel, P.H.

    2001-01-01

    We develop an evaluation method for Web radio, and perform it to see what we can be learnt about seven prominent Web radio sites. We also evaluate a commercial FM radio station for control purposes. We present a taxonomy of Web radio, and we give our observations and conclusions on this evaluation.

  14. On the evaluation of Web Radio

    NARCIS (Netherlands)

    Field, A.N.; Hartel, Pieter H.

    2001-01-01

    We develop an evaluation method for Web radio, and perform it to see what we can be learnt about seven prominent Web radio sites. We also evaluate a commercial FM radio station for control purposes. We present a taxonomy of Web radio, and we give our observations and conclusions on this evaluation.

  15. SUPPRESSION OF STAR FORMATION IN THE HOSTS OF LOW-EXCITATION RADIO GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Pace, Cameron; Salim, Samir, E-mail: cameronpace@suu.edu, E-mail: salims@indiana.edu [Indiana University, Department of Astronomy, Swain Hall West 319, Bloomington, IN 47405-7105 (United States)

    2016-02-10

    The feedback from radio-loud active galactic nuclei (R-AGNs) may help maintain low star-formation (SF) rates in their early-type hosts, but the observational evidence for this mechanism has been inconclusive. We study systematic differences of aggregate spectral energy distributions (SEDs) of various subsets of ∼4000 low-redshift R-AGNs from Best and Heckman with respect to (currently) inactive control samples selected to have matching redshift, stellar mass, population age, axis ratio, and environment. Aggregate SEDs, ranging from the ultraviolet (UV) through mid-infrared (mid-IR, 22 μm), were constructed using a Bayesian method that eliminates biases from non-detections in Galaxy Evolution Explorer and Wide-field Infrared Survey Explorer. We study rare high-excitation sources separately from low-excitation ones, which we split by environment and host properties. We find that both the UV and mid-IR emission of non-cluster R-AGNs (80% of sample) are suppressed by ∼0.2 dex relative to that of the control group, especially for moderately massive galaxies (log M{sub *} ≲ 11). The difference disappears for high-mass R-AGNs and for R-AGNs in clusters, where other, non-AGN quenching/maintenance mechanisms may dominate, or where the suppression of SF due to AGNs may persist between active phases of the central engine, perhaps because of the presence of a hot gaseous halo storing AGN energy. High-excitation (high accretion rate) sources, which make up 2% of the R-AGN sample, do not show any evidence of SF suppression (their UV is the same as in controls), but they exhibit a strong mid-IR excess due to AGN dust heating.

  16. Reconfigurable, Digital EVA Radio Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The nature of human exploration missions to the Moon and Mars demands a frequency-agile, reconfigurable, durable digital radio delivering telemetry, ranging, voice,...

  17. Reconfigurable, Digital EVA Radio Project

    Data.gov (United States)

    National Aeronautics and Space Administration — AeroAstro proposes to develop a low-power, low-volume and lightweight, state-of-the-art digital radio capable of operating in a wide variety of bands, from VHF...

  18. The Concept of 'Radio Music'

    DEFF Research Database (Denmark)

    Fjeldsøe, Michael

    2016-01-01

    In the late 1920s, young composers and musicians turned towards new fields of activity and new media in order to reach a larger audience. In Germany, this effort was part of the movement of Neue Sachlichkeit, and for a short period of time, Radiomusik was considered the ideal means for a democratic......, as discussed by Kurt Weill and Paul Hindemith, was at first greeted with great expectations, but soon a more realistic attitude prevailed. Weill, himself a radio critic as well, composed Der Lindberghflug (1929) as a piece of ‘radio music theatre’, but then changed some of its features in order to turn...... it into a didactical play for amateurs, a so-called Lehrstück. The article will present the concept of ‘radio music’ developed within German Neue Sachlichkeit and discuss the relevance of such a concept for current research in the field of radio and music....

  19. Miniaturized Digital EVA Radio Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Bennett Aerospace and Team Partners propose to develop a small, lightweight, and very power-efficient mobile radio for use on the Lunar surface. Our Team will...

  20. RADIO NOISE ADVANCES SEXUAL MATURITY

    African Journals Online (AJOL)

    ansistf-lewis

    Supplementary radio noise advances sexual maturity in domestic pullets exposed .... non-stimulatory photoperiod in some way provides a stimulus for initiating rapid gonadal development. However, the ..... Congress, New Delhi, India. Vol II ...

  1. Coherent Radio Emission from Pulsars

    CERN Document Server

    Mitra, Dipanjan; Gil, Janusz

    2015-01-01

    We review a physical model where the high brightness temperature of 10$^{25}-10^{30}$ K observed in pulsar radio emission is explained by coherent curvature radiation excited in the relativistic electron-positron plasma in the pulsar magnetosphere.

  2. SETI and International Radio Law

    Science.gov (United States)

    Lyall, F.

    2010-04-01

    The use of radio in SETI is subject to international rules agreed through the International Telecommunication Union. These are summarised. An opportunity for their revision will arise in 2012. Suggestions may be made.

  3. Radio Implementation of a Testbed For Cognitive Radio Source Localization Using USRPS and GNU Radio

    Science.gov (United States)

    2014-09-01

    pp. 116–130, 2009. [4] R.A. Rashid , M.A. Sarijari, N. Fisal, S.K.S. Yusof and N.H. Mahalin, “Spectrum sensing measurement using GNU Radio and...USRP software radio platform,” in Proc. 7th Int. Conf. Wireless and Mobile Commun., Luxembourg, 2011. [5] R.A. Rashid , M.A. Sarijari, N. Fisal...Sarijari, A. Marwanto, N. Fisal, S.K.S. Yusof and R.A Rashid , “Energy detection sensing based on GNU Radio and USRP: An analysis study,” in Proc

  4. Radio and line transmission 2

    CERN Document Server

    Roddy, Dermot

    2013-01-01

    Radio and Line Transmission, Volume 2 gives a detailed treatment of the subject as well as an introduction to additional advanced subject matter. Organized into 14 chapters, this book begins by explaining the radio wave propagation, signal frequencies, and bandwidth. Subsequent chapters describe the transmission lines and cables; the aerials; tuned and coupled circuits; bipolar transistor amplifiers; field-effect transistors and circuits; thermionic valve amplifiers; LC oscillators; the diode detectors and modulators; and the superheterodyne receiver. Other chapters explore noise and interfere

  5. Radio interferometry and satellite tracking

    CERN Document Server

    Kawase, Seiichiro

    2012-01-01

    Worldwide growth of space communications has caused a rapid increase in the number of satellites operating in geostationary orbits, causing overcrowded orbits. This practical resource is designed to help professionals overcome this problem. This timely book provides a solid understanding of the use of radio interferometers for tracking and monitoring satellites in overcrowded environments. Practitioners learn the fundamentals of radio interferometer hardware, including antennas, receiving equipment, signal processing and phase detection, and measurement accuracies. This in-depth volume describ

  6. A zero-power radio receiver.

    Energy Technology Data Exchange (ETDEWEB)

    Brocato, Robert Wesley

    2004-09-01

    This report describes both a general methodology and some specific examples of passive radio receivers. A passive radio receiver uses no direct electrical power but makes sole use of the power available in the radio spectrum. These radio receivers are suitable as low data-rate receivers or passive alerting devices for standard, high power radio receivers. Some zero-power radio architectures exhibit significant improvements in range with the addition of very low power amplifiers or signal processing electronics. These ultra-low power radios are also discussed and compared to the purely zero-power approaches.

  7. The radio properties of infrared-faint radio sources

    Science.gov (United States)

    Middelberg, E.; Norris, R. P.; Hales, C. A.; Seymour, N.; Johnston-Hollitt, M.; Huynh, M. T.; Lenc, E.; Mao, M. Y.

    2011-02-01

    Context. Infrared-faint radio sources (IFRS) are objects that have flux densities of several mJy at 1.4 GHz, but that are invisible at 3.6 μm when using sensitive Spitzer observations with μJy sensitivities. Their nature is unclear and difficult to investigate since they are only visible in the radio. Aims: High-resolution radio images and comprehensive spectral coverage can yield constraints on the emission mechanisms of IFRS and can give hints to similarities with known objects. Methods: We imaged a sample of 17 IFRS at 4.8 GHz and 8.6 GHz with the Australia Telescope Compact Array to determine the structures on arcsecond scales. We added radio data from other observing projects and from the literature to obtain broad-band radio spectra. Results: We find that the sources in our sample are either resolved out at the higher frequencies or are compact at resolutions of a few arcsec, which implies that they are smaller than a typical galaxy. The spectra of IFRS are remarkably steep, with a median spectral index of -1.4 and a prominent lack of spectral indices larger than -0.7. We also find that, given the IR non-detections, the ratio of 1.4 GHz flux density to 3.6 μm flux density is very high, and this puts them into the same regime as high-redshift radio galaxies. Conclusions: The evidence that IFRS are predominantly high-redshift sources driven by active galactic nuclei (AGN) is strong, even though not all IFRS may be caused by the same phenomenon. Compared to the rare and painstakingly collected high-redshift radio galaxies, IFRS appear to be much more abundant, but less luminous, AGN-driven galaxies at similar cosmological distances.

  8. The radio properties of infrared-faint radio sources

    CERN Document Server

    Middelberg, Enno; Hales, Christopher A; Seymour, Nick; Johnston-Hollitt, Melanie; Huynh, Minh T; Lenc, Emil; Mao, Minnie Y

    2010-01-01

    Infrared-faint radio sources (IFRS) are objects that have flux densities of several mJy at 1.4GHz, but that are invisible at 3.6um when using sensitive Spitzer observations with uJy sensitivities. Their nature is unclear and difficult to investigate since they are only visible in the radio. High-resolution radio images and comprehensive spectral coverage can yield constraints on the emission mechanisms of IFRS and can give hints to similarities with known objects. We imaged a sample of 17 IFRS at 4.8GHz and 8.6GHz with the Australia Telescope Compact Array to determine the structures on arcsecond scales. We added radio data from other observing projects and from the literature to obtain broad-band radio spectra. We find that the sources in our sample are either resolved out at the higher frequencies or are compact at resolutions of a few arcsec, which implies that they are smaller than a typical galaxy. The spectra of IFRS are remarkably steep, with a median spectral index of -1.4 and a prominent lack of spec...

  9. The Excess Radio Background and Fast Radio Transients

    CERN Document Server

    Kehayias, John; Weiler, Thomas J

    2015-01-01

    In the last few years ARCADE 2, combined with older experiments, has detected an additional radio background, measured as a temperature and ranging in frequency from 22 MHz to 10 GHz, not accounted for by known radio sources and the cosmic microwave background. One type of source which has not been considered in the radio background is that of fast transients (those with event times much less than the observing time). We present a simple estimate, and a more detailed calculation, for the contribution of radio transients to the diffuse background. As a timely example, we estimate the contribution from the recently-discovered fast radio bursts (FRBs). Although their contribution is likely 6 or 7 orders of magnitude too small (though there are large uncertainties in FRB parameters) to account for the ARCADE~2 excess, our development is general and so can be applied to any fast transient sources, discovered or yet to be discovered. We estimate parameter values necessary for transient sources to noticeably contrib...

  10. Solar Imaging Radio Array (SIRA): Radio Aperture Synthesis from Space

    Science.gov (United States)

    MacDowall, R.; Kaiser, M.; Gopalswamy, N.

    2003-05-01

    SIRA, the Solar Imaging Radio Array, will be a constellation of about 16 microsats designed to image radio sources in the solar corona and heliosphere using aperture synthesis techniques. These images will permit the mapping and tracking of CME-driven shocks (type II radio bursts) and solar flare electrons (type III radio bursts) as a function of time from near the sun to 1 AU. Two dimensional imaging of the CME-driven shock front is important for determination of space weather effects of CMEs, whereas imaging of the ubiquitous type III bursts will permit the derivation of density maps in the outer corona and solar wind. This will be the first mission to image the heliosphere (and the celestial sphere) with good angular resolution at frequencies below the ionospheric cutoff ( 10 MHz). The radio images are intrinsically complementary to white-light coronograph data, such as those of SDO, and can play a valuable role in the NASA Living with a Star program.

  11. Crystal structure and magnetic properties of Li,Cr-containing molybdates Li 3Cr(MoO 4) 3, LiCr(MoO 4) 2 and Li 1.8Cr 1.2(MoO 4) 3

    Science.gov (United States)

    Sarapulova, A.; Mikhailova, D.; Senyshyn, A.; Ehrenberg, H.

    2009-12-01

    Single crystals of LiCr(MoO 4) 2, Li 3Cr(MoO 4) 3 and Li 1.8Cr 1.2(MoO 4) 3 were grown by a flux method during the phase study of the Li 2MoO 4-Cr 2(MoO 4) 3 system at 1023 K. LiCr(MoO 4) 2 and Li 3Cr(MoO 4) 3 single phases were synthesized by solid-state reactions. Li 3Cr(MoO 4) 3 adopts the same structure type as Li 3In(MoO 4) 3 despite the difference in ionic radii of Cr 3+ and In 3+ for octahedral coordination. Li 3Cr(MoO 4) 3 is paramagnetic down to 7 K and shows a weak ferromagnetic component below this temperature. LiCr(MoO 4) 2 is isostructural with LiAl(MoO 4) 2 and orders antiferromagnetically below 20 K. The magnetic structure of LiCr(MoO 4) 2 was determined from low-temperature neutron diffraction and is based on the propagation vektor k⇒=({1}/{2},{1}/{2},0). The ordered magnetic moments were refined to 2.3(1) μ B per Cr-ion with an easy axis close to the [1 1 1¯] direction. A magnetic moment of 4.37(3) μ B per Cr-ion was calculated from the Curie constant for the paramagnetic region. The crystal structures of the hitherto unknown Li 1.8Cr 1.2(MoO 4) 3 and LiCr(MoO 4) 2 are compared and reveal a high degree of similarity: In both structures MoO 4-tetrahedra are isolated from each other and connected with CrO 6 and LiO 5 via corners. In both modifications there are Cr 2O 10 fragments of edge-sharing CrO 6-octahedra.

  12. Radio Halos in future surveys in the radio continuum

    CERN Document Server

    Cassano, R; Norris, Ray P; Roettgering, H J A; Johnston-Hollitt, M; Trasatti, M

    2012-01-01

    Giant radio halos (RH) are Mpc-scale synchrotron sources detected in a significant fraction of massive and merging galaxy clusters.Their statistical properties can be used to discriminate among various models for their origin. Theoretical predictions are important as new radio telescopes are about to begin to survey the sky at low and high frequencies with unprecedented sensitivity. We carry out Monte Carlo simulations to model the formation and evolution of RH in a cosmological framework by assuming that RH are either generated in turbulent merging clusters, or are purely hadronic sources generated in more relaxed clusters, "off-state" halos. The models predict that the luminosity function of RH at high radio luminosities is dominated by the contribution of RH generated in turbulent clusters. The generation of these RH becomes less efficient in less massive systems causing a flattening of the luminosity function at lower luminosities. This flattening is compensated by the contribution of "off-state" RH that ...

  13. IA-Regional-Radio - Social Network for Radio Recommendation

    Science.gov (United States)

    Dziczkowski, Grzegorz; Bougueroua, Lamine; Wegrzyn-Wolska, Katarzyna

    This chapter describes the functions of a system proposed for the music hit recommendation from social network data base. This system carries out the automatic collection, evaluation and rating of music reviewers and the possibility for listeners to rate musical hits and recommendations deduced from auditor's profiles in the form of regional Internet radio. First, the system searches and retrieves probable music reviews from the Internet. Subsequently, the system carries out an evaluation and rating of those reviews. From this list of music hits, the system directly allows notation from our application. Finally, the system automatically creates the record list diffused each day depending on the region, the year season, the day hours and the age of listeners. Our system uses linguistics and statistic methods for classifying music opinions and data mining techniques for recommendation part needed for recorded list creation. The principal task is the creation of popular intelligent radio adaptive on auditor's age and region - IA-Regional-Radio.

  14. Reconfigurable radio systems network architectures and standards

    CERN Document Server

    Iacobucci, Maria Stella

    2013-01-01

    This timely book provides a standards-based view of the development, evolution, techniques and potential future scenarios for the deployment of reconfigurable radio systems.  After an introduction to radiomobile and radio systems deployed in the access network, the book describes cognitive radio concepts and capabilities, which are the basis for reconfigurable radio systems.  The self-organizing network features introduced in 3GPP standards are discussed and IEEE 802.22, the first standard based on cognitive radio, is described. Then the ETSI reconfigurable radio systems functional ar

  15. Unseen cosmos the universe in radio

    CERN Document Server

    Graham-Smith, Francis

    2013-01-01

    Radio telescopes have transformed our understanding of the Universe. Pulsars, quasars, Big Bang cosmology: all are discoveries of the new science of radio astronomy. Here, Francis Graham-Smith describes the birth, development, and maturity of radio astronomy, from the first discovery of cosmic radio waves to its present role as a major part of modern astronomy. Radio is part of the electromagnetic spectrum, covering infra-red, visible light, ultraviolet, X-rays, and gamma-rays, and Graham-Smith explains why it is that radio waves give us a unique view of the Universe. Tracing the development o

  16. The radio properties of bright Seyfert galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Giuricin, G.; Mardirossian, F.; Mezzetti, M.; Bertotti, G. (Centro Interuniversitario Regionale per l' Astrofisica e la Cosmologia (Italy) Centre for Advanced Research in Space Optics (Italy))

    1990-03-01

    The radio properties of a sample of 69 bright spectroscopically selected Seyfert galaxies, which suffers from little bias toward Markarian galaxies with strong UV excess. At variance with most of the earlier results, generally based on galaxy samples which are strongly biased toward the inclusion of Markarian objects, there is no clear evidence of a significant difference in the major radio properties (radio power, radio-to-optical luminosity ratio, radio spectral index and radio size) of type 1 and type 2 Seyferts. The resulting observational scenario appears now to be more consistent than before with the idea that Seyfert 2 galaxies are simply Seyfert 1 obscured objects. 70 refs.

  17. Expected Number Counts of Radio Galaxy Clusters

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Clusters of galaxies may contain radio sources if they still experience successive mergers at present. This has been confirmed by radio observations that about 30% of nearby clusters possess radio halos. We present a theoretical prediction of radio cluster counts using a semi-analytic approach which incorporates the empirical correlation between radio power and dynamical mass of clusters, and the cluster mass function described by the Press-Schechter formalism. The total population of radio clusters over the whole sky and their redshift distribution are given.

  18. Radio-Optical Imaging of ATLBS Survey

    Indian Academy of Sciences (India)

    Kshitij Thorat

    2011-12-01

    We present the radio-optical imaging of ATLBS, a sensitive radio survey (Subrahmanyan et al. 2010). The primary aim of the ATLBS survey is to image low-power radio sources which form the bulk of the radio source population to moderately high red-shifts ( ∼ 1.0). The accompanying multiband optical and near infra-red observations provide information about the hosts and environments of the radio sources. We give here details of the imaging of the radio data and optical data for the ATLBS survey.

  19. Modular Software-Defined Radio

    Directory of Open Access Journals (Sweden)

    Rhiemeier Arnd-Ragnar

    2005-01-01

    Full Text Available In view of the technical and commercial boundary conditions for software-defined radio (SDR, it is suggestive to reconsider the concept anew from an unconventional point of view. The organizational principles of signal processing (rather than the signal processing algorithms themselves are the main focus of this work on modular software-defined radio. Modularity and flexibility are just two key characteristics of the SDR environment which extend smoothly into the modeling of hardware and software. In particular, the proposed model of signal processing software includes irregular, connected, directed, acyclic graphs with random node weights and random edges. Several approaches for mapping such software to a given hardware are discussed. Taking into account previous findings as well as new results from system simulations presented here, the paper finally concludes with the utility of pipelining as a general design guideline for modular software-defined radio.

  20. A Repeating Fast Radio Burst

    CERN Document Server

    Spitler, L G; Hessels, J W T; Bogdanov, S; Brazier, A; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J; Ferdman, R D; Freire, P C C; Kaspi, V M; Lazarus, P; Lynch, R; Madsen, E C; McLaughlin, M A; Patel, C; Ransom, S M; Seymour, A; Stairs, I H; Stappers, B W; van Leeuwen, J; Zhu, W W

    2016-01-01

    Fast Radio Bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measures (i.e. integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of the fast radio bursts has led several authors to hypothesise that they originate in cataclysmic astrophysical events. Here we report the detection of ten additional bursts from the direction of FRB121102, using the 305-m Arecibo telescope. These new bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and wh...

  1. Phenomenology of magnetospheric radio emissions

    Science.gov (United States)

    Carr, T. D.; Desch, M. D.; Alexander, J. K.

    1983-01-01

    Jupiter has now been observed over 24 octaves of the radio spectrum, from about 0.01 MHz to 300,000 MHz. Its radio emissions fill the entire spectral region where interplanetary electromagnetic propagation is possible at wavelengths longer than infrared. Three distinct types of radiation are responsible for this radio spectrum. Thermal emission from the atmosphere accounts for virtually all the radiation at the high frequency end. Synchrotron emission from the trapped high-energy particle belt deep within the inner magnetosphere is the dominant spectral component from about 4000 to 40 MHz. The third class of radiation consists of several distinct components of sporadic low frequency emission below 40 MHz. The decimeter wavelength emission is considered, taking into account the discovery of synchrotron emission, radiation by high-energy electrons in a magnetic field, and the present status of Jovian synchrotron phenomenology. Attention is also given to the decameter and hectometer wavelength emission, and emissions at kilometric wavelengths.

  2. An Update on Radio Supernovae

    Science.gov (United States)

    van Dyk, Schuyler D.; Sramek, Richard A.; Weiler, Kurt W.; Montes, Marcos J.; Panagia, Nino

    The radio emission from supernovae (SNe) is nonthermal synchrotron radiation of high brightness temperature, with a ``turn-on'' delay at longer wavelengths, power-law decline after maximum with index beta, and spectral index alpha asymptotically decreasing with time to a final, optically thin value. Radio supernovae (RSNe) are best described by the Chevalier (1982) ``mini-shell'' model, with modifications by Weiler \\etal\\ (1990). RSNe observations provide a valuable probe of the SN circumstellar environment and constraints on progenitor masses. We present a progress report on a number of recent RSNe, as well as on new behavior from RSNe 1979C and 1980K, and on RSNe as potential distance indicators. In particular, we present updated radio light curves for SN 1993J in M81.

  3. Radio Context Awareness and Applications

    Directory of Open Access Journals (Sweden)

    Luca Reggiani

    2013-01-01

    Full Text Available The context refers to “any information that can be used to characterize the situation of an entity, where an entity can be a person, place, or physical object.” Radio context awareness is defined as the ability of detecting and estimating a system state or parameter, either globally or concerning one of its components, in a radio system for enhancing performance at the physical, network, or application layers. In this paper, we review the fundamentals of context awareness and the recent advances in the main radio techniques that increase the context awareness and smartness, posing challenges and renewed opportunities to added-value applications in the context of the next generation of wireless networks.

  4. Miniature EVA Software Defined Radio

    Science.gov (United States)

    Pozhidaev, Aleksey

    2012-01-01

    As NASA embarks upon developing the Next-Generation Extra Vehicular Activity (EVA) Radio for deep space exploration, the demands on EVA battery life will substantially increase. The number of modes and frequency bands required will continue to grow in order to enable efficient and complex multi-mode operations including communications, navigation, and tracking applications. Whether conducting astronaut excursions, communicating to soldiers, or first responders responding to emergency hazards, NASA has developed an innovative, affordable, miniaturized, power-efficient software defined radio that offers unprecedented power-efficient flexibility. This lightweight, programmable, S-band, multi-service, frequency- agile EVA software defined radio (SDR) supports data, telemetry, voice, and both standard and high-definition video. Features include a modular design, an easily scalable architecture, and the EVA SDR allows for both stationary and mobile battery powered handheld operations. Currently, the radio is equipped with an S-band RF section. However, its scalable architecture can accommodate multiple RF sections simultaneously to cover multiple frequency bands. The EVA SDR also supports multiple network protocols. It currently implements a Hybrid Mesh Network based on the 802.11s open standard protocol. The radio targets RF channel data rates up to 20 Mbps and can be equipped with a real-time operating system (RTOS) that can be switched off for power-aware applications. The EVA SDR's modular design permits implementation of the same hardware at all Network Nodes concept. This approach assures the portability of the same software into any radio in the system. It also brings several benefits to the entire system including reducing system maintenance, system complexity, and development cost.

  5. Microwave radio transmission design guide

    CERN Document Server

    Manning, Trevor

    2009-01-01

    This newly revised second edition provides a current, comprehensive treatment of the subject with a focus on applying practical knowledge to real-world networks. It includes a wealth of important updates, including discussions on backhaul capacity limitations, ethernet over radio, details on the latest cellular radio standards (2.5G, 3G, and 4G). You also learn about recent changes in spectrum management, including the availability of unlicensed bands and new mm band frequencies between 70 and 90 GHz. Additionally, you find more details on the fundamentals of antennas, especially at VHF/UHF le

  6. Synthesis and Crystal Structure of a Cyano-bridged Bimetallic Complex[La(DMSO)3(H2O)3Cr(CN)6]·H2O (DMSO = Dimethylsulfoxide) with One-dimensional Chain Molecular Structure

    Institute of Scientific and Technical Information of China (English)

    梁淑惠; 车云霞; 郑吉民

    2004-01-01

    The title complex [La(DMSO)3(H2O)3Cr(CN)6](H2O was obtained by the reaction of LaCl3(7H2O, DMSO and K3[Cr(CN)6] in aqueous solution on a hot water bath. The crystal crystallizes in orthorhombic, space group P212121 with a = 9.827(3), b = 15.037(4), c = 17.633(5)A, C12H26CrLaN6O7S3, Mr = 653.48, Z = 4, V = 2605.7(13) A3, Dc = 1.666 g/m3, μ (MoKα) = 2.314 mm-1, F(000) = 1300, R = 0.0205 and wR = 0.0481 for 5038 observed reflections (I > 2σ(I)). La3+ ion is eight-coordinated by three DMSO molecules, three H2O molecules and two [Cr(CN)6]3- units. The structure of the title complex possesses a cyano-bridged onedimensional zigzag chain structure with alternating La(DMSO)3(H2O)3 and Cr(CN)6 moieties, which are linked by some hydrogen bonds to form a 3D network structure.

  7. Temperature affecting the magnetic properties of the Co{sub 79−x}Fe{sub 3}Cr{sub 3}Si{sub 15}B{sub x} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tsepelev, Vladimir, E-mail: v.s.tsepelev@urfu.ru [Boris Yeltzin Ural Federal University, Mira 19, Ekaterinburg 620002 (Russian Federation); Starodubtsev, Yuri [Boris Yeltzin Ural Federal University, Mira 19, Ekaterinburg 620002 (Russian Federation); Research and Production Enterprise «Gammamet», Kirov 28, Ekaterinburg 620028 (Russian Federation); Zelenin, Viktor; Belozerov, Vladimir [Research and Production Enterprise «Gammamet», Kirov 28, Ekaterinburg 620028 (Russian Federation); Konashkov, Viktor [Boris Yeltzin Ural Federal University, Mira 19, Ekaterinburg 620002 (Russian Federation)

    2015-09-15

    The paper studies the effect the temperature has on the magnetic properties of the Co{sub 79−x}Fe{sub 3}Cr{sub 3}Si{sub 15}B{sub x} amorphous alloy with different boron content. Magnetic saturation induction B{sub s} and Curie temperature T{sub C} decrease as the boron content increases. Within the range of relatively high temperatures, magnetic saturation induction B{sub s} = μ{sub 0}M{sub s} is related to the temperature by B{sub s}(T) ∼ (T{sub C} − T){sup 0.38}. In the Co{sub 79−x}Fe{sub 3}Cr{sub 3}Si{sub 15}B{sub x} amorphous alloys with the Curie temperature of lower than 180 °C the initial permeability of 200,000 and the coercive force of 0.1 A/m were obtained. The high initial permeability of the amorphous alloy is attributed to the absence of the crystalline, magnetoelastic and induced magnetic anisotropy in this alloy. Low Curie temperature near which the permeability appreciably increases (Hopkinson effect) is another approach to the ideal magnetic softness.

  8. Nucleation and growth kinetics of La0.7Sr0.3Cr0.4Mn0.6O3-δ SOFC perovskite: Symmetry alteration evolution induced by Cu2+ and Ni2+ impregnation

    Directory of Open Access Journals (Sweden)

    A. Concha-Balderrama

    2016-12-01

    Full Text Available La0.7Sr0.3Cr0.4Mn0.6O3-δ perovskite nanoparticles have been synthetized using an ethylene glycol modified sol-gel method and impregnated by Cu0.75Ni0.25 nanoparticles. The phase transitions and nucleation kinetics were studied by time resolved x-ray diffraction, Rietveld, Raman spectroscopy and high resolution transmission electron microscopy. Findings have shown that, an atomic disorder dominates from room temperature to 400 °C. Nanoparticles with crystal size <26 nm start through nuclei formation of La0.7Sr0.3Cr0.4Mn0.6O3-δ and SrCrO4 solid solutions with Pm3¯m cubic and P21/n monoclinic symmetry respectively in the range of 600–650 °C. Symmetry reduction from the Pm3¯m⟶R3¯c space group had been obtained at a lower temperature (750 °C than those reported in the literature in oxygen atmosphere and it was confirmed by an octahedral distortion, which takes place in the crystallographic direction[22̅1]/(12̅2. The Johnson-Mehl-Avrami model had described the whole process, where the existence of two phases was shown before it reached its complete D3d6 point group symmetry.

  9. Magnetism on quasi-1-D lattices in novel non-centrosymmetric Ba3CrVS4O3 and in centrosymmetric La3TMWS3O6 (TM = Cr, Fe, Co)

    Science.gov (United States)

    Kim, Jinkwang; Lai, Kwing To; Valldor, Martin

    2017-08-01

    La3TMWS3O6 (TM = Fe, Co) and novel Ba3CrVS4O3 can be obtained as pure polycrystalline samples by mineralizer aided solid-state reactions and a solid-state reaction with further purification by water, respectively. In contrast, La3CrWS3O6 needs a standard solid-state reaction to form but the final product contains observable impurities. All four compounds contain similar quasi-1-D magnetic lattices although La-based ones are centrosymmetric (P63/m) and the Ba-containing one is polar and non-centrosymmetric (P63). Strong antiferromagnetic couplings are observed along the magnetic chains in the Fe and Cr containing compounds. As a result, short-range magnetic order is suggested at low temperatures for the Fe-chain, which can be related to magneto-electric couplings. The Co3+-homologue shows typical diamagnetic behavior, as supported by its insulating nature, which is due to a low-spin state. The polar Cr3+-compound exhibits very different magnetic behavior compared to its corresponding non-polar relative. This proves a strong influence on the physical properties from the crystallographic symmetry.

  10. Intelligent Cognitive Radio Models for Enhancing Future Radio Astronomy Observations

    Directory of Open Access Journals (Sweden)

    Ayodele Abiola Periola

    2016-01-01

    Full Text Available Radio astronomy organisations desire to optimise the terrestrial radio astronomy observations by mitigating against interference and enhancing angular resolution. Ground telescopes (GTs experience interference from intersatellite links (ISLs. Astronomy source radio signals received by GTs are analysed at the high performance computing (HPC infrastructure. Furthermore, observation limitation conditions prevent GTs from conducting radio astronomy observations all the time, thereby causing low HPC utilisation. This paper proposes mechanisms that protect GTs from ISL interference without permanent prevention of ISL data transmission and enhance angular resolution. The ISL transmits data by taking advantage of similarities in the sequence of observed astronomy sources to increase ISL connection duration. In addition, the paper proposes a mechanism that enhances angular resolution by using reconfigurable earth stations. Furthermore, the paper presents the opportunistic computing scheme (OCS to enhance HPC utilisation. OCS enables the underutilised HPC to be used to train learning algorithms of a cognitive base station. The performances of the three mechanisms are evaluated. Simulations show that the proposed mechanisms protect GTs from ISL interference, enhance angular resolution, and improve HPC utilisation.

  11. Radio access selection in multi-radio access systems

    NARCIS (Netherlands)

    Jorgušeski, L.; Litjens, R.; Zhiyi, C.; Nikookar, H.

    2007-01-01

    Future wireless access systems will be characterized by their heterogeneity from technological point of view. It is envisaged that in certain areas end-users will have a choice between various radio accesses (RAs) such as e.g. classical cellular networks (GSM, UMTS, WiMAX, etc), WLAN hot-spots, or o

  12. Cosmic downsizing of powerful radio galaxies to low radio luminosities

    CERN Document Server

    Rigby, E E; Best, P N; Rosario, D; Röttgering, H J A

    2015-01-01

    At bright radio powers ($P_{\\rm 1.4 GHz} > 10^{25}$ W/Hz) the space density of the most powerful sources peaks at higher redshift than that of their weaker counterparts. This paper establishes whether this luminosity-dependent evolution persists for sources an order of magnitude fainter than those previously studied, by measuring the steep--spectrum radio luminosity function (RLF) across the range $10^{24} 10^{26}$ W/Hz the redshift of the peak space density increases with luminosity, whilst at lower radio luminosities the position of the peak remains constant within the uncertainties. This `cosmic downsizing' behaviour is found to be similar to that seen at optical wavelengths for quasars, and is interpreted as representing the transition from radiatively efficient to inefficient accretion modes in the steep-spectrum population. This conclusion is supported by constructing simple models for the space density evolution of these two different radio galaxy classes; these are able to successfully reproduce the ...

  13. RADIO FATWA Islamic Tanya-Jawab Programmes on Radio Dakwah

    Directory of Open Access Journals (Sweden)

    Sunarwoto S.

    2012-07-01

    Full Text Available The present article is a study of radio fatwa in Indonesia with special referenceto the Tanya-Jawab genres in radio dakwah.The concept of fatwa haschanged over time. Such Islamic Tanya-Jawab programmes broadcast onradio dakwah are important to understand how fatwa is disseminated bymeans of media, since Islamic Tanya-Jawab programmes can be consideredas part of fatwa. These programmes give not only information about Islam,but also become a forum in which interpretation of Islam takes place. Thiscan be seen in the discussion on the Islamic ruling on eating “dog meat”, inwhich interpretation of Islamic law is highly contested.[Artikel ini mendisukusikan radio fatwa di Indonesia, utamanya tentangprogram tanya-jawab yang disiarkan radio dakwah. Konsep fatwa terusberubah dan program tanya-jawab merupakan salah satu cara bagaimanafatwa disebarluaskan melalui berbagai media. Penulis berpendapat bahwaprogram Tanya-Jawab dapat disebut sebagai salah satu bentuk fatwa. Inikarena program tersebut tidak saja mengetengahkan informasi mengenaiIslam, namun juga interpretasi mengenai Islam. Pedebatan mengenai hukummemakan daging anjing merupakan salah satu contoh isu kontrovesial yang akan dijelaskan melalui artikel ini.

  14. 75 FR 10439 - Cognitive Radio Technologies and Software Defined Radios

    Science.gov (United States)

    2010-03-08

    ... clarification filed by Cisco Systems, Inc. (``Cisco'') requesting that the Commission clarify: (1) The... of software that controls security measures in software defined radios. 3. In responding to the Cisco... response to the Cisco petition for reconsideration that raised the issue of using open source software...

  15. Structure and denitrification behaviors of Fe2O3-Cr2O3/TiO2 catalysts%Fe2O3-Cr2O3/TiO2系列催化剂的结构和脱硝性能

    Institute of Scientific and Technical Information of China (English)

    任晓光; 任超; 李富霞; 李鹏; 宋永吉

    2012-01-01

    研究以纳米TiO2为载体,浸渍负载过渡金属氧化物,以CO为还原剂的脱硝催化剂的脱硝性能。实验中以计算量的Ni(NO3)2和Fe(NO3)3混合溶液浸渍纳米TiO2粉末,室温下搅拌30 min至混合均匀,放入旋转蒸发器中,70℃下至水分蒸干为止;所得粉末在550℃下、空气气氛中焙烧4 h即得所需催化剂。用以上方法分别制备2%Fe2O3-10%Cr2O3/TiO2、4%Fe2O3-8%Cr2O3/TiO2、6%Fe2O3-6%Cr2O3/TiO2、8%Fe2O3-4%Cr2O3/TiO2与10%Fe2O3-2%Cr2O3/TiO2等5种催化剂样品。实验结果表明,制备的催化剂具有较好的结构,分散较为均匀。对于CO+NO反应,Fe2O3-Cr2O3/TiO2系列催化剂具有较好的催化活性,NO的转化率都达到了100%。其中,10%Fe2O3-2%Cr2O3/TiO2样品具有最好的低温活性,H2-TPR结果表明,这是由于10%Fe2O3-2%Cr2O3/TiO2催化剂更易于被CO预还原。%This work aimed to investigate the performance of a denitration catalyst,which uses nanometer TiO2 as support,transition metal oxides as active component and CO as reducer.Nanometer TiO2 powder was dipped by the mixture of Fe(NO3)3 and Cr(NO3)3,kept stirring for 30 min until well mixed at room temperature,and then it was evaporated to dryness in rotary evaporator at 70℃.The samples obtained with this process were calcined at 550℃ for 4 h in air atmosphere to prepare the catalysts.In this experiment,five catalysts produced by this method,2%Fe2O3-10%Cr2O3/TiO2,4%Fe2O3-8%Cr2O3/TiO2,6%Fe2O3-6%Cr2O3/TiO2,8%Fe2O3-4%Cr2O3/TiO2 and 10%Fe2O3-2%Cr2O3/TiO2,were investigated.Experimental results indicate that the Fe2O3-Cr2O3/TiO2 catalysts series,with excellent structure and dispersity,have great catalytic activity to the reaction NO+ CO and the conversion of NO reaches 100%.Of all the prepared catalysts,10%Fe2O3-2%Cr2O3/TiO2 catalyst shows the best activity at lower temperature,due to fact that it could more easily be pre-reduced by CO,which is proved by the H2-TPR results.

  16. Symmetry breaking and electrical conductivity of La{sub 0.7}Sr{sub 0.3}Cr{sub 0.4}Mn{sub 0.6}O{sub 3-{delta}} perovskite as SOFC anode material

    Energy Technology Data Exchange (ETDEWEB)

    Reyes-Rojas, A., E-mail: armando.reyes@cimav.edu.mx [Centro de investigacion en Materiales Avanzados S.C. (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Cd. de Chihuahua, Chihuahua (Mexico); Alvarado-Flores, J.; Esparza-Ponce, H.; Esneider-Alcala, M. [Centro de investigacion en Materiales Avanzados S.C. (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Cd. de Chihuahua, Chihuahua (Mexico); Espitia-Cabrera, I. [Facultad de Ingenieria Quimica, Universidad Michoacana de San Nicolas de Hidalgo, Zodiaco no. 81, Fraccionamiento Cosmos, Morelia, Michoacan CP 58040 (Mexico); Torres-Moye, E. [Centro de investigacion en Materiales Avanzados S.C. (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Cd. de Chihuahua, Chihuahua (Mexico)

    2011-04-15

    Research highlights: {yields} Perovskite-type La{sub 0.7}Sr{sub 0.3}Cr{sub 0.4}Mn{sub 0.6}O{sub 3-{delta}}-NiO nucleation kinetics. Symmetry-breaking by introducing Ni{sup 2+} cations at 1050 deg. C. Phase transition from high temperature aristotype R3-bar c to hettotype I4/mmm. At low Ni concentration {rho} resistivity decreases when increasing the temperature. For Ni concentration higher than 25% {rho} resistivity increases. - Abstract: This work is focused on nanocrystalline solid oxide fuel cell synthesis and characterization (SOFC) anodes of La{sub 0.7}Sr{sub 0.3}Cr{sub 0.4}Mn{sub 0.6}O{sub 3-{delta}} (perovskite-type) with Nickel. Perovskite-type oxide chemical reactivity, nucleation kinetics and phase composition related with La{sub 0.7}Sr{sub 0.3}Cr{sub 0.4}Mn{sub 0.6}O{sub 3-{delta}}-NiO to La{sub 0.7}Sr{sub 0.3}Cr{sub 0.4}Mn{sub 0.6}O{sub 3-{delta}}-Ni transformation have been analyzed. SOFC anode powders were obtained by sol-gel synthesis, using polyvinyl alcohol as an organic precursor to get a porous cermet electrode after sintering at 1365 deg. C and oxide reduction by hydrogen at 800 deg. C/1050 deg. C for 8 h in a horizontal tubular reactor furnace under 10% H{sub 2}/N{sub 2} atmosphere. Composite powders were compressed into 10-mm diameter discs with 25-75 wt% Ni. Electrical and structural characterization by four-point probe method for conductivity, scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Rietveld method were carried out. Symmetry-breaking by phase transition from high temperature aristotype R3-bar c to hettotype I4/mmm has been identified and confirmed by XRD and Rietveld method which can be produced by introducing Ni{sup 2+} cations in the perovskite solid solution. Rietveld analysis suggests that Ni contents are directly proportional to La{sub 0.7}Sr{sub 0.3}Cr{sub 0.4}Mn{sub 0.6}NiO{sub 3.95} tetragonal structure cell volume and inversely proportional to Ni cubic structure

  17. Cosmological measurements with forthcoming radio continuum surveys

    CSIR Research Space (South Africa)

    Raccanelli, A

    2012-08-01

    Full Text Available -correlation between radio sources and cosmic microwave background (CMB) maps (the integrated Sachs–Wolfe effect), the crosscorrelation of radio sources with foreground objects resulting from cosmic magnification, and a joint analysis together with the CMB power...

  18. Newnes radio and electronics engineer's pocket book

    CERN Document Server

    Moorshead, H W; Perry, J

    1978-01-01

    Newnes Radio and Electronics Engineer's Pocket Book, Fifteenth Edition provides reference of the information relevant in radio and electronics engineering. The book presents tables, illustrations, and diagrams of various data used in radio and electronics engineering. The coverage of the text includes abbreviations and symbols, electrical equations, and code conversions. The text will be useful to engineers, technicians, and other professionals who require a reference about the different aspects of radio and electronics.

  19. Sensitive Radio Survey of Obscured Quasar Candidates

    CERN Document Server

    Alexandroff, Rachael M; van Velzen, Sjoert; Greene, Jenny E; Strauss, Michael A

    2016-01-01

    We study the radio properties of moderately obscured quasars over a range of redshifts to understand the role of radio activity in accretion using the Jansky Very Large Array (JVLA) at 6.0GHz and 1.4GHz. Our z~2.5 sample consists of optically-selected obscured quasar candidates, all of which are radio-quiet, with typical radio luminosities of $\

  20. Low Frequency Radio Experiment (LORE)

    Science.gov (United States)

    Manoharan, P. K.; Naidu, Arun; Joshi, B. C.; Roy, Jayashree; Kate, G.; Pethe, Kaiwalya; Galande, Shridhar; Jamadar, Sachin; Mahajan, S. P.; Patil, R. A.

    2016-03-01

    In this paper, we present a case study of Low Frequency Radio Experiment (LORE) payload to probe the corona and the solar disturbances at solar offsets greater than 2 solar radii, i.e., at frequencies below 30 MHz. The LORE can be complimentary to the planned Indian solar mission, “Aditya-L1” and its other payloads as well as synergistic to ground-based interplanetary scintillation (IPS) observations, which are routinely carried out by the Ooty Radio Telescope. We discuss the baseline design and technical details of the proposed LORE and its particular suitability for providing measurements on the detailed time and frequency structure of fast drifting type-III and slow drifting type-II radio bursts with unprecedented time and frequency resolutions. We also brief the gonio-polarimetry, which is possible with better-designed antennas and state-of-the-art electronics, employing FPGAs and an intelligent data management system. These would enable us to make a wide range of studies, such as nonlinear plasma processes in the Sun-Earth distance, in-situ radio emission from coronal mass ejections (CMEs), interplanetary CME driven shocks, nature of ICMEs driving decelerating IP shocks and space weather effects of solar wind interaction regions.

  1. Radio properties of local AGN

    NARCIS (Netherlands)

    Nagar, NM; Falcke, H; Wilson, AS; Mujica, R; Maiolino, R

    2004-01-01

    This article focuses on the radio properties of the similar to 470 nearby bright (northern) galaxies of the Palomar spectroscopic sample. Almost half the sample's galaxies have nuclei with emission-lines characteristic of AGN but with L-H alpha = 50% of all LLAGNs; there is no evidence against all L

  2. Radio observations of massive stars

    CERN Document Server

    Blomme, Ronny

    2011-01-01

    Detectable radio emission occurs during almost all phases of massive star evolution. I will concentrate on the thermal and non-thermal continuum emission from early-type stars. The thermal radio emission is due to free-free interactions in the ionized stellar wind material. Early ideas that this would lead to an easy and straightforward way of measuring the mass-loss rates were thwarted by the presence of clumping in the stellar wind. Multi-wavelength observations provide important constraints on this clumping, but do not allow its full determination. Non-thermal radio emission is associated with binarity. This conclusion was already known for some time for Wolf-Rayet stars and in recent years it has become clear that it is also true for O-type stars. In a massive-star binary, the two stellar winds collide and around the shocks a fraction of the electrons are accelerated to relativistic speeds. Spiralling in the magnetic field these electrons emit synchrotron radiation, which we detect as non-thermal radio em...

  3. Radio emission in Mercury magnetosphere

    CERN Document Server

    Varela, J; Brun, A S; Pantellini, F; Zarka, P

    2016-01-01

    Context: Active stars possess magnetized wind that has a direct impact on planets that can lead to radio emission. Mercury is a good test case to study the effect of the solar wind and interplanetary magnetic field on radio emission driven in the planet magnetosphere. Such studies could be used as proxies to characterize the magnetic field topology and intensity of exoplanets. Aims: The aim of this study is to quantify the radio emission in the Hermean magnetosphere. Methods: We use the MHD code PLUTO in spherical coordinates with an axisymmetric multipolar expansion for the Hermean magnetic field, to analyze the effect of the interplanetary magnetic field (IMF) orientation and intensity, as well as the hydrodynamic parameters of the solar wind (velocity, density and temperature), on the net power dissipated on the Hermean day and night side. We apply the formalism derived by Zarka [2001, 2007] to infer the radio emission level from the net dissipated power. We perform a set of simulations with different hydr...

  4. Radio frequency propagation made easy

    CERN Document Server

    Faruque, Saleh

    2015-01-01

    This book introduces Radio Frequency Propagation to a broad audience.  The author blends theory and practice to bring readers up-to-date in key concepts, underlying principles and practical applications of wireless communications.  The presentation is designed to be easily accessible, minimizing mathematics and maximizing visuals.

  5. Radio Frequency Solid State Amplifiers

    CERN Document Server

    Jacob, J

    2015-01-01

    Solid state amplifiers are being increasingly used instead of electronic vacuum tubes to feed accelerating cavities with radio frequency power in the 100 kW range. Power is obtained from the combination of hundreds of transistor amplifier modules. This paper summarizes a one hour lecture on solid state amplifiers for accelerator applications.

  6. LEP radio-frequency cavity

    CERN Multimedia

    1991-01-01

    One of the copper radio-frequency accelerating cavities installed for the first phase of LEP (1989-1995). Bunches of electrons and positrons circulated in LEP in opposite directions and were accelerated in eight different sets of 16 cavities (situated on either side of the four experiments), gaining 400 million volts of accelerating power per turn.

  7. Utrecht and Galactic Radio Astronomy

    NARCIS (Netherlands)

    van Woerden, H.

    Important roles in early Dutch Galactic radio astronomy were played by several Utrecht astronomers: Van de Hulst, Minnaert and Houtgast. The poster announcing the conference contained a number of pictures referring to scientific achievements of the Astronomical Institute Utrecht. One of these

  8. Young Radio Amateurs Speak English.

    Science.gov (United States)

    Freund, Bilha

    1997-01-01

    In an Israeli elementary school program to stimulate students' development of oral English skills, students write dialogs and conversation themes in areas of interest, then practice and conduct the conversations with amateur radio operators around the world. Challenges and successes are detailed. (MSE)

  9. Public safety and cognitive radio

    NARCIS (Netherlands)

    Heskamp, Marnix; Schiphorst, Roel; Slump, Kees; Wyglinsk, Alexander M.; Nekovee, Maziar; Hou, Y. Thomas

    2009-01-01

    This book gives comprehensive and balanced coverage of the principles of cognitive radio communications, cognitive networks, and details of their implementation, including the latest developments in the standards and spectrum policy. Case studies, end-of-chapter questions, and descriptions of variou

  10. Radio Monitoring of Protoplanetary Discs

    Science.gov (United States)

    Ubach, C.; Maddison, S. T.; Wright, C. M.; Wilner, D. J.; Lommen, D. J. P.; Koribalski, B.

    2017-01-01

    Protoplanetary disc systems observed at radio wavelengths often show excess emission above that expected from a simple extrapolation of thermal dust emission observed at short millimetre wavelengths. Monitoring the emission at radio wavelengths can be used to help disentangle the physical mechanisms responsible for this excess, including free-free emission from a wind or jet, and chromospheric emission associated with stellar activity. We present new results from a radio monitoring survey conducted with Australia Telescope Compact Array over the course of several years with observation intervals spanning days, months and years, where the flux variability of 11 T Tauri stars in the Chamaeleon and Lupus star forming regions was measured at 7 and 15 mm and 3 and 6 cm. Results show that for most sources are variable to some degree at 7 mm, indicating the presence of emission mechanisms other than thermal dust in some sources. Additionally, evidence of grain growth to cm-sized pebbles was found for some sources that also have signs of variable flux at 7 mm. We conclude that multiple processes contributing to the emission are common in T Tauri stars at 7 mm and beyond, and that a detection at a single epoch at radio wavelengths should not be used to determine all processes contributing to the emission.

  11. Radio frequency modulation made easy

    CERN Document Server

    Faruque, Saleh

    2017-01-01

    This book introduces Radio Frequency Modulation to a broad audience. The author blends theory and practice to bring readers up-to-date in key concepts, underlying principles and practical applications of wireless communications. The presentation is designed to be easily accessible, minimizing mathematics and maximizing visuals.

  12. China's Largest Radio Antenna System

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ After three-and-half-year efforts, the National Astronomical Observatories at CAS (NAOC) has constructed two arrays of radio antennae: a 50m antenna at Miyun Station in Beijing and a 40m antenna in Kunming, capital of southwest China's Yunnan Province.

  13. Hybrid spread spectrum radio system

    Science.gov (United States)

    Smith, Stephen F [London, TN; Dress, William B [Camas, WA

    2010-02-09

    Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.

  14. Constraining Radio Emission from Magnetars

    NARCIS (Netherlands)

    Lazarus, P.; Kaspi, V.M.; Champion, D.; Hessels, J.W.T.; Dib, R.

    2012-01-01

    We report on radio observations of five magnetars and two magnetar candidates carried out at 1950 MHz with the Green Bank Telescope in 2006-2007. The data from these observations were searched for periodic emission and bright single pulses. Also, monitoring observations of magnetar 4U 0142+61 follow

  15. Radio Properties of Pinwheel Nebulae

    CERN Document Server

    Monnier, J D; Tuthill, P G; Danchi, W C

    2002-01-01

    A small number of dusty Wolf-Rayet stars have been resolved into pinwheel nebulae, defined by their ``rotating'' spiral dust shells observed in the infrared. This morphology is naturally explained by dust formation associated with colliding winds in a binary system. In order to confirm and further explore this hypothesis, we have observed the known pinwheel nebulae (WR 104 and WR 98a) as well as the suspected binary WR 112 at multiple radio wavelengths with the Very Large Array to search for non-thermal radio emission from colliding winds. The spectrum of each target is nearly flat between 5 and 22 GHz, consistent with the presence of non-thermal emission that is reduced at low frequencies by free-free absorption. This emission must lie outside the radio ``photosphere,'' leading us to estimate a lower limit to the physical size of the non-thermal emitting region that is larger than expected from current theory. Based on a radio and infrared comparison to WR 104 and 98a, we conclude that WR 112 is a likely can...

  16. Near-infrared Hubble Space Telescope polarimetry of a complete sample of narrow-line radio galaxies

    CERN Document Server

    Ramírez, E A; Axon, D; Batcheldor, D; Packham, C; Lopez-Rodriguez, E; Sparks, W; Young, S

    2014-01-01

    We present an analysis of 2.05 $\\mu$m Hubble Space Telescope (HST) polarimetric data for a sample of 13 nearby Fanaroff-Riley type II (FRII) 3CR radio sources ($0.03radio galaxies (NLRG) at optical wavelengths. We find that the compact cores of the NLRG in our sample are intrinsically highly polarised in the near-IR ($6 < P_{2.05\\mu m} < 60$ per cent), with the electric-vector (E-vector) perpendicular to the radio axis in 54 per cent of the sources. The levels of extinction required to produce near-infrared polarisation by the dichroic extinction mechanism are consistent with the measured values reported in Ram\\'irez et al. (2014), provided that this mechanism has its maximum efficiency. This consistency suggests that the nuclear polarisation could be due to dichroic extinction. In this case, toroidal magnetic fields that are highly coherent would be required in the circumnuclear tori to align the elongated dust grains responsible for the dichroic extin...

  17. 47 CFR 90.185 - Multiple licensing of radio transmitting equipment in the mobile radio service.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Multiple licensing of radio transmitting equipment in the mobile radio service. 90.185 Section 90.185 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES...

  18. 62. The Return of Educational Radio?

    Science.gov (United States)

    Berman, Sally D.

    2008-01-01

    This paper examines one of the traditional technologies of distance education, radio, and presents examples of educational and community radio usage in Asia and Africa. Instead of merely transposing western approaches to distance education in developing countries, it is suggested that the developed world can learn from uses of radio in developing…

  19. Radio Broadcasting and Public Education in Africa.

    Science.gov (United States)

    Perraton, Hilary

    1981-01-01

    The strengths and weaknesses of radio for distance learning in the Third World are determined through an examination of its use for upgrading teachers, to support education and development broadly, for mass education through radio campaigns, and through the radio schools of Latin America. Eighteen references are listed. (CHC)

  20. Radio labeling with pre-assigned frequencies

    NARCIS (Netherlands)

    Bodlaender, H.L.; Broersma, H.J.; Fomin, F.V.; Pyatkin, A.V.; Woeginer, G.J.

    2007-01-01

    A radio labeling of a graph G is an assignment of pairwise distinct, positive integer labels to the vertices of G such that labels of adjacent vertices differ by at least 2. The radio labeling problem (RL) consists in determining a radio labeling that minimizes the maximum label that is used (the so

  1. Classic Radio Theatre in Contemporary Education.

    Science.gov (United States)

    West, Keith

    Radio theater production has been a component of secondary and post-secondary education since the late 1920s. Since the reduction in radio theater in the 1950s, such courses have been used to prepare students for other fields--television, film, etc. Radio theater production can be approached in two ways: classic production and modern production.…

  2. Fast radio flashes observed with LOFAR prototypes

    NARCIS (Netherlands)

    Nigl, A.

    2008-01-01

    This thesis consists of a detailed analysis of several observations with prototype stations of the Low Frequency Array (LOFAR). Chapter 1 introduces the field of radio astronomy, briefly describes the radio telescopes which were used and discusses radio frequency interference (RFI) and important too

  3. New trends in meteor radio receivers

    Science.gov (United States)

    Rault, Jean-Louis

    2014-01-01

    Recent progresses in low cost—but performing—SDR (software defined radio) technology presents a major breakthrough in the domain of meteor radio observations. Their performances are now good enough for meteor work and should therefore encourage newcomers to join the meteor radio community.

  4. 78 FR 23150 - Commercial Radio Operators

    Science.gov (United States)

    2013-04-18

    ... COMMISSION 47 CFR Parts 0, 1, 13, 80 and 87 Commercial Radio Operators AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: This document amends our rules concerning commercial radio operator... hold an appropriate commercial radio operator license. The Commission initiated this proceeding...

  5. 46 CFR 169.715 - Radio.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Radio. 169.715 Section 169.715 Shipping COAST GUARD..., Miscellaneous Systems, and Equipment § 169.715 Radio. (a) Radiotelegraph and radiotelephone installations are... Regulations, part 83. (b) A valid certificate issued by the FCC is evidence that the radio installation is...

  6. Radio labeling with pre-assigned frequencies

    NARCIS (Netherlands)

    Bodlaender, H.L.; Broersma, H.J.; Fomin, F.V.; Pyatkin, A.V.; Woeginer, G.J.

    2002-01-01

    A radio labeling of a graph G is an assignment of pairwise distinct, positive integer labels to the vertices of G such that labels of adjacent vertices differ by at least 2. The radio labeling problem (RL) consists in determining a radio labeling that minimizes the maximum label that is used (the

  7. Radio labeling with pre-assigned frequencies

    NARCIS (Netherlands)

    Bodlaender, H.L.; Broersma, Haitze J.; Fomin, F.V.; Pyatkin, A.V.; Woeginger, Gerhard

    2002-01-01

    A radio labeling of a graph $G$ is an assignment of pairwise distinct, positive integer labels to the vertices of $G$ such that labels of adjacent vertices differ by at least $2$. The radio labeling problem (\\mbox{\\sc RL}) consists in determining a radio labeling that minimizes the maximum label

  8. The Dynamics of Radio Galaxies and Double–Double Radio Galaxies

    Indian Academy of Sciences (India)

    C. Konar; M. Jamrozy; M. J. Hardcastle; J. H. Croston; S. Nandi; D. J. Saikia; J. Machalski

    2011-12-01

    Relativistic and magnetized plasma ejected by radio loud AGNs through jets form the diffuse lobes of radio galaxies. The radiating particles (electron/electron–positron) in lobes emit in radio via the synchrotron process and X-ray via inverse-Compton scattering of cosmic microwave background photons. The thermal environment around radio galaxies emits X-rays via the thermal bremsstrahlung process. By combining information from these processes we can measure physical conditions in and around the radio lobes and thus study the dynamics of radio galaxies, including double–double radio galaxies.

  9. Radio responding media. Prosumers, media innovation in web-based radio

    OpenAIRE

    Brundu, Gabriella

    2015-01-01

    After a century of traditional broadcasting, this is the history of how the radio as a medium entered the web world, becoming web-based radios. Our case is based on an Italian web-radio, Radio Casa Bertallot, which started to make radio programmes using the possibilities of new media technology and the internet to create a platform for interacting with the users. The founder Alessio Bertallot, expressed his view on the radio production by describing the radio as, a place, as a home, a room, ...

  10. The Role of Alternative Programming in College Radio.

    Science.gov (United States)

    Sauls, Samuel J.

    College radio is quite often viewed as the true alternative to commercial radio. However, what is alternative radio and how does college radio factor into the ideal? To further understand this concept, this paper focuses on the role of alternative programming in college radio. Areas discussed include alternative radio as a non-mainstream form of…

  11. Synthesis, structural and magnetic properties of the nanocomposite Fe{sub 63}B{sub 23}Nd{sub 7}Y{sub 3}Nb{sub 3}Cr{sub 1} magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Zubair [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Institute of Industrial Control System, P. Box 1398, Rawalpindi (Pakistan); Ma Tianyu, E-mail: maty@zju.edu.cn [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Tao Shan [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Yan Mi, E-mail: mse_yanmi@zju.edu.cn [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2012-04-15

    The Fe{sub 63}B{sub 23}Nd{sub 7}Y{sub 3}Nb{sub 3}Cr{sub 1} nanocomposite magnets in the form of sheets have been prepared by copper mold casting technique. The phase evolution, crystal structure, microstructural and magnetic properties have been investigated in the as-cast and annealed states. The as-cast sheets show magnetically soft behaviors which become magnetically hard by thermal annealing. The optimal annealed microstructure was composed of nanosize soft magnetic {alpha}-Fe (19-29 nm) and hard magnetic Nd{sub 2}Fe{sub 14}B (45-55 nm) grains. The best hard magnetic properties such as intrinsic coercivity, {sub j}H{sub c} of 1119 kA/m, remanence, B{sub r} of 0.44 T, magnetic induction to saturation magnetization ratio, M{sub r}/M{sub s}=0.61 and maximum energy product, (BH){sub max} of 55 kJ/m{sup 3} was obtained after annealing at 680 Degree-Sign C for 15 min. The annealing treatment above 680 Degree-Sign C results in non-ideal phase grains growth, which degrade the magnetic properties. - Highlights: Black-Right-Pointing-Pointer Synthesis of Fe{sub 63}B{sub 23}Nd{sub 7}Y{sub 3}Nb{sub 3}Cr{sub 1} amorphous sheets by copper mold injection casting technique. Black-Right-Pointing-Pointer Development of high coercivity nanocomposite permanent magnet based on Fe{sub 63}B{sub 23}Nd{sub 7}Y{sub 3}Nb{sub 3}Cr{sub 1} alloy. Black-Right-Pointing-Pointer Microstructural and magnetic properties are affected by alloy constitution magnetic phases. Black-Right-Pointing-Pointer Magnet exhibited promising magnetic properties such as: {sub j}H{sub c} of 1119 kA/m, B{sub r} of 0.44 T, (BH){sub max} of 55 kJ/m{sup 3}.

  12. De radio en radio: el escenario radiofónico

    Directory of Open Access Journals (Sweden)

    Lic. Dulce María García Dávila

    1999-01-01

    Full Text Available Este artículo discierne sobre concepciones modernas de programación radiofónica y presenta los resultados que arrojó el estudio del escenario radiofónico de la ciudad de Maracaibo, con el uso de la técnica de la audiografía. Nos ofrece una descripción de los tipos de programación, la música, los programas informativos y de opinión, las estrategias de promoción y publicitarias más utilizadas por las emisoras de amplitud modulada en la ciudad. Este estudio forma parte de una primera etapa del proyecto de investigación titulado "Hacia un modelo de radio educativa y popular para el Occidente del país, a partir de la experiencia de Radio Fe y Alegría 850 AM".

  13. Radio Astronomy Explorer (RAE) 1 observations of terrestrial radio noise

    Science.gov (United States)

    Herman, J. R.; Caruso, J. A.

    1971-01-01

    Radio Astonomy Explorer (RAE) 1 data are analyzed to establish characteristics of HF terrestrial radio noise at an altitude of about 6000 km. Time and frequency variations in amplitude of the observed noise well above cosmic noise background are explained on the basis of temporal and spatial variations in ionospheric critical frequency coupled with those in noise source distributions. It is shown that terrestrial noise regularly breaks through the ionosphere and reaches RAE with magnitudes 15 or more db higher than cosmic noise background. Maximum terrestrial noise is observed when RAE is over the dark side of the Earth in the neighborhood of equatorial continental land masses where thunderstorms occur most frequently. The observed noise level is 30-40 db lower with RAE over oceans.

  14. Advanced Radio Resource Management for Multi Antenna Packet Radio Systems

    CERN Document Server

    Nonchev, Stanislav; 10.5121/ijwmn.2010.2201

    2010-01-01

    In this paper, we propose fairness-oriented packet scheduling (PS) schemes with power-efficient control mechanism for future packet radio systems. In general, the radio resource management functionality plays an important role in new OFDMA based networks. The control of the network resource division among the users is performed by packet scheduling functionality based on maximizing cell coverage and capacity satisfying, and certain quality of service requirements. Moreover, multiantenna transmit-receive schemes provide additional flexibility to packet scheduler functionality. In order to mitigate inter-cell and co-channel interference problems in OFDMA cellular networks soft frequency reuse with different power masks patterns is used. Stemming from the earlier enhanced proportional fair scheduler studies for single-input multiple-output (SIMO) and multiple-input multipleoutput (MIMO) systems, we extend the development of efficient packet scheduling algorithms by adding transmit power considerations in the ove...

  15. K. C. Yeh: Radio Science Editor

    Science.gov (United States)

    Advances in satellite technology and computer science have had the greatest impact on radio science in the last quarter century, according to Kung Chie Yeh, the new editor of Radio Science. Yeh, whose term began July 1 (Eos, April 12, 1983, p. 137, February 22, 1983, p. 73), is a professor in the electrical engineering department at the University of Illinois at Urbana-Champaign.An international authority on ionospheric radio physics, Yeh also is known for his work on trans-ionospheric radio wave propagation as it affects earth-space communications and satellite navigation. Hehas been studying radio science for nearly 30 years.

  16. Radio Frequency Interference Mitigation at the WSRT

    CERN Document Server

    Fridman, P A; Millenaar, R P

    2010-01-01

    The sensitivity of radio astronomical stations is often limited by man-made radio frequency interference (RFI) due to a variety of terrestrial activities. An RFI mitigation subsystem (RFIMS) based on real-time digital signalprocessing is proposed here for the Westerbork Synthesis Radio Telescope based on a powerful field programmable gate array processor. In this system the radio astronomy signals polluted by RFI are "cleaned" with the RFIMS before routine back-end correlation processing takes place. The high temporal and frequency resolution of RFIMS allows the detection and excision of RFI better than do standard radio telescope back-end configurations.

  17. Fast Radio Bursts and Radio Transients from Black Hole Batteries

    CERN Document Server

    Mingarelli, Chiara M F; Lazio, T Joseph W

    2015-01-01

    Most black holes (BHs) will absorb a neutron star (NS) companion fully intact, without tidal disruption, suggesting the pair will remain dark to telescopes. Even without tidal disruption, electromagnetic luminosity is generated from the battery phase of the binary when the BH interacts with the NS magnetic field. Originally the luminosity was expected in high-energy X-rays or gamma-rays, however we conjecture that some of the battery power is emitted in the radio bandwidth. While the luminosity and timescale are suggestive of fast radio bursts (FRBs; millisecond-scale radio transients) NS--BH coalescence rates are too low to make these a primary FRB source. Instead, we propose the transients form a FRB sub-population, distinguishable by a double peak with a precursor. The rapid ramp-up in luminosity manifests as a precursor to the burst which is $20\\%-80\\%$ as luminous, given 0.5~ms timing resolution. The main burst is from the peak luminosity before merger. The post-merger burst follows from the NS magnetic ...

  18. 47 CFR 95.201 - (R/C Rule 1) What is the Radio Control (R/C) Radio Service?

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false (R/C Rule 1) What is the Radio Control (R/C) Radio Service? 95.201 Section 95.201 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Radio Control (R/C) Radio Service...

  19. Radio-quiet Fast Coronal Mass Ejections

    Science.gov (United States)

    Gopalswamy, N.; Aguilar-Rodriguez, E.; Kaiser, M. L.; Howard, R. A.

    2004-12-01

    Coronal mass ejections (CMEs) drive shocks in the interplanetary medium that produce type II radio emission. These CMEs are faster and wider on the average, than the general population of CMEs. However, when we start from fast (speed > 900 km/s) and wide (angular width > 60 degrees), more than half of them are not associated with radio bursts. In order to understand why these CMEs are radio quiet, we collected all the fast and wide (FW) CMEs detected by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) and isolated those without associated type II radio bursts. The radio bursts were identified in the dynamic spectra of the Radio and Plasma Wave (WAVES) Experiment on board the Wind spacecraft. We also checked the list against metric type II radio bursts reported in Solar Geophysical Data and isolated those without any radio emission. This exercise resulted in about 140 radio-quiet FW CMEs. We identified the source regions of these CMEs using the Solar Geophysical Data listings, cross-checked against the eruption regions in the SOHO/EIT movies. We explored a number of possibilities for the radio-quietness: (i) Source region being too far behind the limb, (ii) flare size, (iii) brightness of the CME, and (iv) the density of the ambient medium. We suggest that a combination of CME energy and the Alfven speed profile of the ambient medium is primarily responsible for the radio-quietness of these FW CMEs.

  20. Relic Radio Bubbles and Cluster Cooling Flows

    CERN Document Server

    De Young, D S

    2003-01-01

    Recent suggestions that buoyant radio emitting cavities in the intracluster medium can cause significant reheating of cooling flows are re-examined when the effects of the intracluster magnetic field are included. Expansion of the cavity creates a tangential magnetic field in the ICM around the radio source, and this field can suppress instabilities that mix the ICM and the radio source. The onset of instability can be delayed for ~100 million years, and calculation of the actual reheating time shows that this may not occur until about 1Gy after creation of the cavity. These results may explain why the relic radio bubbles are still intact at such late times, and it may imply that the role of radio sources in reheating the ICM should be re-examined. In addition, the existence of relic radio cavities may also imply that the particle content of radio source lobes is primarily electrons and protons rather than electrons and positrons.