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Sample records for internal luminosity distribution

  1. Internal Luminosity Distribution of Bright Gamma-Ray Bursts and its Relation to Duration and Spectral Hardness

    NASA Technical Reports Server (NTRS)

    Horack, John M.; Hakkila, Jon

    1997-01-01

    We present first results from a comprehensive investigation into the distribution of luminosity within the 50 brightest cosmic gamma-ray bursts detected by the Burst and Transient Source Experiment (BATSE). The internal luminosity function psi(L) is defined such that the quantity psi(L)dL represents the fraction of total emission time during which the burst possesses a luminosity between L and L + dL. For these brightest bursts, the psi(L) functions are quasi-power-law-like and decrease in amplitude with increasing luminosity. Through investigation of both individual psi(L) distributions and data from the ensemble of bursts, we demonstrate a high probability for correlation between the shape of the internal luminosity function as measured by the average logarithmic slope and the burst duration as measured by the T(sub 90) parameter and, with lower significance, between the shape of psi(L) and the burst photon-fluence spectral index. We furthermore demonstrate a correlation between burst hardness ratio and duration in these brightest bursts which is opposite to that of the entire gamma-ray burst ensemble.

  2. The GRB luminosity function: prediction of the internal shock model and comparison to observations

    NASA Astrophysics Data System (ADS)

    Zitouni, H.; Daigne, F.; Mochkovitch, R.

    2008-05-01

    We compute the expected GRB luminosity function in the internal shock model. We find that if the population of GRB central engines produces all kind of relativistic outflows, from very smooth to highly variable, the luminosity function has to branchs: at low luminosity, the distribution is dominated by low efficiency GRBs and is close to a power law of slope -0.5, whereas at high luminosity, the luminosity function follows the distribution of injected kinetic power. Using Monte Carlo simulations and several observational constrains (BATSE logN-logP diagram, peak energy distribution of bright BATSE bursts, fraction of XRFs in the HETE2 sample), we show that it is currently impossible to distinguish between a single power law or a broken power law luminosity function. However, when the second case is considered, the low-luminosity slope is found to be -0.6+/-0.2, which is compatible with the prediction of the internal shock model.

  3. Luminosity distributions of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Ashall, C.; Mazzali, P.; Sasdelli, M.; Prentice, S. J.

    2016-08-01

    We have assembled a data set of 165 low redshift, z < 0.06, publicly available Type Ia supernovae (SNe Ia). We produce maximum light magnitude (MB and MV) distributions of SNe Ia to explore the diversity of parameter space that they can fill. Before correction for host galaxy extinction we find that the mean MB and MV of SNe Ia are -18.58 ± 0.07 and -18.72 ± 0.05 mag, respectively. Host galaxy extinction is corrected using a new method based on the SN spectrum. After correction, the mean values of MB and MV of SNe Ia are -19.10 ± 0.06 and -19.10 ± 0.05 mag, respectively. After correction for host galaxy extinction, `normal' SNe Ia (Δm15(B) < 1.6 mag) fill a larger parameter space in the width-luminosity relation than previously suggested, and there is evidence for luminous SNe Ia with large Δm15(B). We find a bimodal distribution in Δm15(B), with a pronounced lack of transitional events at Δm15(B) = 1.6 mag. We confirm that faster, low-luminosity SNe tend to come from passive galaxies. Dividing the sample by host galaxy type, SNe Ia from star-forming (S-F) galaxies have a mean MB = -19.20 ± 0.05 mag, while SNe Ia from passive galaxies have a mean MB = -18.57 ± 0.24 mag. Even excluding fast declining SNe, `normal' (MB < -18 mag) SNe Ia from S-F and passive galaxies are distinct. In the V band, there is a difference of 0.4 ± 0.13 mag between the median (MV) values of the `normal' SN Ia population from passive and S-F galaxies. This is consistent with (˜15 ± 10) per cent of `normal' SNe Ia from S-F galaxies coming from an old stellar population.

  4. The GRB luminosity function: predictions from the internal shock model and comparison with observations

    NASA Astrophysics Data System (ADS)

    Zitouni, H.; Daigne, F.; Mochkovich, R.; Zerguini, T. H.

    2008-05-01

    We compute the expected luminosity function of gamma-ray bursts (GRBs) in the context of the internal shock model. We assume that GRB central engines generate relativistic outflows characterized by the respective distributions of injected kinetic power and contrast in Lorentz factor κ = Γmax/Γmin. We find that if the distribution of contrast extends down to values close to unity (i.e. if both highly variable and smooth outflows can exist), then the luminosity function has two branches. At high luminosity it follows the distribution of while at low luminosity it is close to a power law of slope -0.5. We then examine if existing data can constrain the luminosity function. Using the logN-logP curve, the Ep distribution of bright Burst and Transient Source Experiment (BATSE) bursts and the X-ray flash (XRF)/GRB ratio obtained by High Energy Transient Explorer 2 (HETE2), we show that single and broken power laws can provide equally good fits of these data. Present observations are therefore unable to favour one form or the other. However, when a broken power law is adopted they clearly indicate a low-luminosity slope ~= -0.6 +/- 0.2, compatible with the prediction of the internal shock model.

  5. Stellar bars and the spatial distribution of infrared luminosity

    NASA Technical Reports Server (NTRS)

    Devereux, Nicholas

    1987-01-01

    Ground-based 10 micron observations of the central region of over 100 infrared luminous galaxies are presented. A first order estimate of the spatial distribution of infrared emission in galaxies is obtained through a combination of ground-based and Infrared Astronomy Satellite (IRAS) data. The galaxies are nearby and primarily noninteracting, permitting an unbiased investigation of correlations with Hubble type. Approximately 40% of the early-type barred galaxies in this sample are associated with enhanced luminosity in the central (approximately 1 kpc diameter) region. The underlying luminosity source is attributed to both Seyfert and star formation activity. Late-type spirals are different in that the spatial distribution of infrared emission and the infrared luminoisty are not strongly dependent on barred morphology.

  6. THE SIZE-LUMINOSITY DISTRIBUTIONS OF LYMAN-BREAK GALAXIES

    NASA Astrophysics Data System (ADS)

    Huang, Kuang-Han; CANDELS Collaboration

    2014-01-01

    Lyman-break galaxies (LBGs) comprise the largest sample of star-forming galaxies at z>3 and are crucial to our understanding of galaxy formation and evolution. Their luminosity functions allow us to calculate the cosmic star formation history, and their sizes also provide valuable information about the angular momentum content of the galaxies and dark matter halos. However, due to surface brightness dimming effects, galaxies at high redshifts are especially susceptible to selection effects; it is important to understand the selection effects before we can draw conclusions from the statistics of LBG properties. In this work we will investigate the size--luminosity distribution of LBGs between 3 and 6 with careful modeling of selection effects and measurement errors of size and magnitude. Our modeling is more careful than previous studies because it is performed in the two-dimensional size--magnitude space. The results of this work show that (1) the effective radii of star-forming galaxies likely evolve as H(z)^{-2/3} at a fixed luminosity, (2) the widths of the LBG size distribution are larger than expected from the spin parameter distribution of dark matter halos, and (3) the size--luminosity relation slopes of LBGs are similar to those for late-type disk galaxies in the local universe. These results favor the disk formation theory put forward by Fall & Efstathiou (1980) if the majority of LBGs are disks, but more observational evidence is needed to confirm the kinematical structure of LBGs as well as to explain the widths of the size distribution.

  7. LUMINOUS SATELLITES. II. SPATIAL DISTRIBUTION, LUMINOSITY FUNCTION, AND COSMIC EVOLUTION

    SciTech Connect

    Nierenberg, A. M.; Treu, T.; Auger, M. W.; Marshall, P. J.; Fassnacht, C. D.; Busha, Michael T.

    2012-06-20

    We infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies (log{sub 10}[M*{sub h}/M{sub Sun }] > 10.5) between redshifts 0.1 and 0.8 as a function of host stellar mass, redshift, morphology, and satellite luminosity. Exploiting the depth and resolution of the COSMOS Hubble Space Telescope images, we detect satellites up to 8 mag fainter than the host galaxies and as close as 0.3 (1.4) arcsec (kpc). Describing the number density profile of satellite galaxies to be a projected power law such that P(R){proportional_to}R{sup {gamma}{sub p}}, we find {gamma}{sub p} = -1.1 {+-} 0.3. We find no dependency of {gamma}{sub p} on host stellar mass, redshift, morphology, or satellite luminosity. Satellites of early-type hosts have angular distributions that are more flattened than the host light profile and are aligned with its major axis. No significant average alignment is detected for satellites of late-type hosts. The number of satellites within a fixed magnitude contrast from a host galaxy is dependent on its stellar mass, with more massive galaxies hosting significantly more satellites. Furthermore, high-mass late-type hosts have significantly fewer satellites than early-type galaxies of the same stellar mass, possibly indicating that they reside in more massive halos. No significant evolution in the number of satellites per host is detected. The cumulative luminosity function of satellites is qualitatively in good agreement with that predicted using SubHalo Abundance Matching techniques. However, there are significant residual discrepancies in the absolute normalization, suggesting that properties other than the host galaxy luminosity or stellar mass determine the number of satellites.

  8. The Truncated Lognormal Distribution as a Luminosity Function for SWIFT-BAT Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Zaninetti, Lorenzo

    2016-11-01

    The determination of the luminosity function (LF) in gamma ray bursts (GRBs) depends on the adopted cosmology, each one characterized by its corresponding luminosity distance. Here we analyse three cosmologies: the standard cosmology, the plasma cosmology, and the pseudo-Euclidean universe. The LF of the GRBs is firstly modeled by the lognormal distribution and the four broken power law, and secondly by a truncated lognormal distribution. The truncated lognormal distribution fits acceptably the range in luminosity of GRBs as a function of the redshift.

  9. HST Imaging of the Globular Clusters in the Formax Cluster: Color and Luminosity Distributions

    NASA Technical Reports Server (NTRS)

    Grillmair, C. J.; Forbes, D. A.; Brodie, J.; Elson, R.

    1998-01-01

    We examine the luminosity and B - I color distribution of globular clusters for three early-type galaxies in the Fornax cluster using imaging data from the Wide Field/Planetary Camera 2 on the Hubble Space Telescope.

  10. BATSE analysis techniques for probing the GRB spatial and luminosity distributions

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon; Meegan, Charles A.

    1992-01-01

    The Burst And Transient Source Experiment (BATSE) has measured homogeneity and isotropy parameters from an increasingly large sample of observed gamma-ray bursts (GRBs), while also maintaining a summary of the way in which the sky has been sampled. Measurement of both of these are necessary for any study of the BATSE data statistically, as they take into account the most serious observational selection effects known in the study of GRBs: beam-smearing and inhomogeneous, anisotropic sky sampling. Knowledge of these effects is important to analysis of GRB angular and intensity distributions. In addition to determining that the bursts are local, it is hoped that analysis of such distributions will allow boundaries to be placed on the true GRB spatial distribution and luminosity function. The technique for studying GRB spatial and luminosity distributions is direct. Results of BATSE analyses are compared to Monte Carlo models parameterized by a variety of spatial and luminosity characteristics.

  11. Effects of Formation Epoch Distribution on X-Ray Luminosity and Temperature Functions of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Enoki, Motohiro; Takahara, Fumio; Fujita, Yutaka

    2001-07-01

    We investigate statistical properties of galaxy clusters in the context of a hierarchical clustering scenario, taking into account their formation epoch distribution; this study is motivated by the recent finding by Fujita and Takahara that X-ray clusters form a fundamental plane in which the mass and the formation epoch are regarded as two independent parameters. Using the formalism that discriminates between major mergers and accretion, the epoch of a cluster formation is identified with that of the last major merger. Since tiny mass accretion following formation does not much affect the core structure of clusters, the properties of X-ray emission from clusters are determined by the total mass and density at their formation time. Under these assumptions, we calculate X-ray luminosity and temperature functions of galaxy clusters. We find that the behavior of the luminosity function differs from the model that does not take into account formation epoch distribution; the behavior of the temperature function, however, is not much different. In our model, the luminosity function is shifted to a higher luminosity and shows no significant evolution up to z~1, independent of cosmological models. The clusters are populated on the temperature-luminosity plane, with a finite dispersion. Since the simple scaling model in which the gas temperature is equal to the virial temperature fails to reproduce the observed luminosity-temperature relation, we also consider a model that takes into account the effects of preheating. The preheating model reproduces the observations much more accurately.

  12. Spectral Energy Distribution and Bolometric Luminosity of the Cool Brown Dwarf Gliese 229B

    NASA Technical Reports Server (NTRS)

    Matthews, K.; Nakajima, T.; Kulkarni, S. R.; Oppenheimer, B. R.

    1996-01-01

    Infrared broadband photometry of the cool brown dwarf Gliese 229B extending in wavelength from 0.8 to 10.5 micron is reported. These results are derived from both new data and reanalyzed, previously published data. Existing spectral data reported have been rereduced and recalibrated. The close proximity of the bright Gliese 229A to the dim Gliese 229B required the use of special techniques for the observations and also for the data analysis. We describe these procedures in detail. The observed luminosity between 0.8 and 10.5 micron is (4.9 +/- 0.6) x 10(exp -6) solar luminosity. The observed spectral energy distribution is in overall agreement with a dust-free model spectrum by Tsuji et al. for T(eff) approx. equal to 900 K. If this model is used to derive the bolometric correction, the best estimate of the bolometric luminosity is 6.4 x 10(exp -6) solar luminosity and 50% of this luminosity ties between 1 and 2.5 microns. Our best estimate of the effective temperature is 900 K. From the observed near-infrared spectrum and the spectral energy distribution, the brightness temperatures (T(sub B) are estimated. The highest, T(sub B) = 1640 K, is seen at the peak of the J band spectrum, while the lowest, T(sub B) is less than or equal to 600 K, is at 3.4 microns, which corresponds to the location of the fundamental methane band.

  13. The Bivariate Luminosity--HI Mass Distribution Function of Galaxies based on the NIBLES Survey

    NASA Astrophysics Data System (ADS)

    Butcher, Zhon; Schneider, Stephen E.; van Driel, Wim; Lehnert, Matt

    2016-01-01

    We use 21cm HI line observations for 2610 galaxies from the Nançay Interstellar Baryons Legacy Extragalactic Survey (NIBLES) to derive a bivariate luminosity--HI mass distribution function. Our HI survey was selected to randomly probe the local (900 < cz < 12,000 km/s) galaxy population in each 0.5 mag wide bin for the absolute z-band magnitude range of -13.5 < Mz < -24 without regard to morphology or color. This targeted survey allowed more on-source integration time for weak and non-detected sources, enabling us to probe lower HI mass fractions and apply lower upper limits for non-detections than would be possible with the larger blind HI surveys. Additionally, we obtained a factor of four higher sensitivity follow-up observations at Arecibo of 90 galaxies from our non-detected and marginally detected categories to quantify the underlying HI distribution of sources not detected at Nançay. Using the optical luminosity function and our higher sensitivity follow up observations as priors, we use a 2D stepwise maximum likelihood technique to derive the two dimensional volume density distribution of luminosity and HI mass in each SDSS band.

  14. Investigations of the auroral luminosity distribution and the dynamics of discrete auroral forms in a historical retrospective

    NASA Astrophysics Data System (ADS)

    Feldstein, Y. I.; Vorobjev, V. G.; Zverev, V. L.; Förster, M.

    2014-05-01

    Research results about planetary-scale auroral distributions are presented in a historical retrospective, beginning with the first "maps of isochasms" - lines of equal visibility of auroras in the firmament (Fig. 2) - up to "isoaurora maps" - lines of equal occurrence frequency of auroras in the zenith (Fig. 4). The exploration of auroras in Russia from Lomonosov in the 18th century (Fig. 1) until the start of the International Geophysical Year (IGY) in 1957 is shortly summed up. A generalised pattern of discrete auroral forms along the auroral oval during geomagnetically very quiet intervals is presented in Fig. 5. The changes of discrete auroral forms versus local time exhibit a fixed pattern with respect to the sun. The auroral forms comprise rays near noon, homogeneous arcs during the evening, and rayed arcs and bands during the night and in the morning. This fixed auroral pattern is unsettled during disturbances, which occur sometimes even during very quiet intervals. The azimuths of extended auroral forms vary with local time. Such variations in the orientation of extended forms above stations in the auroral zone have been used by various investigators to determine the position of the auroral oval (Fig. 9). Auroral luminosity of the daytime and nighttime sectors differ owing to different luminosity forms, directions of motion of the discrete forms, the height of the luminescent layers, and the spectral composition (predominant red emissions during daytime and green emissions during the night). Schemes that summarise principal peculiarities of daytime luminosity, its structure in MLT (magnetic local time) and MLat (magnetic latitude) coordinates, and the spectral composition of the luminosity are presented in Figs. 15 and 19. We discuss in detail the daytime sector dynamics of individual discrete forms for both quiet conditions and auroral substorms. The most important auroral changes during substorms occur in the nighttime sector. We present the evolution of

  15. Modeling Spiral Galaxy Surface Luminosity to Explain Non-Uniform Inclination Distributions

    NASA Astrophysics Data System (ADS)

    Rozum, Jordan C.; Larson, S. L.

    2014-01-01

    The distribution of spiral and bar galaxy orientations is expected to be uniform. However, analysis of several major galaxy catalogs shows this is not always reflected in data. In an attempt to explain this discrepancy, we have developed a galaxy simulation code to compute the appearance of a spiral type galaxy as a function of its morphological parameters. We examine the dependence of observed brightness upon inclination angle by using smooth luminous mass density and interstellar medium (ISM) density distributions. The luminous mass component is integrated along a particular line of sight, thus producing a mass distribution, from which a surface luminosity profile is derived. The ISM component is integrated alongside the luminous mass component to account for light extinction. Using this model, we present simulated galaxy inclination distributions that account for potential selection effects.

  16. Multiwavelength Energy Distributions and Bolometric Luminosities of the 12 Micron Galaxy Sample

    NASA Astrophysics Data System (ADS)

    Spinoglio, Luigi; Malkan, Matthew A.; Rush, Brian; Carrasco, Luis; Recillas-Cruz, Elsa

    1995-11-01

    Aperture photometry from our own observations and the literature is presented for the 12 microns galaxies in the near-infrared J, H, and K bands and, in some cases, in the L band. These data are corrected to "total" near-infrared magnitudes (with a typical uncertainty of 0.3 mag) for a direct comparison with our IRAS fluxes which apply to the entire galaxy. The corrected data are used to derive integrated total near-infrared and far-infrared luminosities. We then combine these with blue photometry and an estimate of the flux contribution from cold dust at wavelengths longward of 100 microns to derive the first bolometric luminosities for a large sample of galaxies. The presence of nonstellar radiation at 2-3 microns correlates very well with nonstellar IRAS colors. This enables us to identify a universal Seyfert nuclear continuum from near- to far-infrared wavelengths. Thus, there is a sequence of infrared colors which runs from a pure "normal galaxy" to a pure Seyfert/quasar nucleus. Seyfert 2 galaxies fall close to this same sequence, although only a few extreme narrow-line Seyfert galaxies have quasar-like colors, and these show strong evidence of harboring an obscured broad-line region. A corollary is that the host galaxies of Seyfert nuclei have normal near- to far-infrared spectra on average. Starburst galaxies lie significantly off the sequence, having a relative excess of 60 microns emission probably as a result of stochastically heated dust grains. We use these correlations to identify several combinations of infrared colors which discriminate between Seyfert 1 and 2 galaxies, LINERs, and ultraluminous starbursts. In the infrared, Seyfert 2 galaxies are much more like Seyfert 1s than they are like starbursts, presumably because both kinds of Seyferts are heated by a single central source, rather than a distributed region of star formation. Moreover, combining the [25-2.2 mum] color with the [60-12 mum] color, it appears that Seyfert 1 galaxies are

  17. Luminosity distance in ``Swiss cheese'' cosmology with randomized voids. II. Magnification probability distributions

    NASA Astrophysics Data System (ADS)

    Flanagan, Éanna É.; Kumar, Naresh; Wasserman, Ira; Vanderveld, R. Ali

    2012-01-01

    We study the fluctuations in luminosity distances due to gravitational lensing by large scale (≳35Mpc) structures, specifically voids and sheets. We use a simplified “Swiss cheese” model consisting of a ΛCDM Friedman-Robertson-Walker background in which a number of randomly distributed nonoverlapping spherical regions are replaced by mass-compensating comoving voids, each with a uniform density interior and a thin shell of matter on the surface. We compute the distribution of magnitude shifts using a variant of the method of Holz and Wald , which includes the effect of lensing shear. The standard deviation of this distribution is ˜0.027 magnitudes and the mean is ˜0.003 magnitudes for voids of radius 35 Mpc, sources at redshift zs=1.0, with the voids chosen so that 90% of the mass is on the shell today. The standard deviation varies from 0.005 to 0.06 magnitudes as we vary the void size, source redshift, and fraction of mass on the shells today. If the shell walls are given a finite thickness of ˜1Mpc, the standard deviation is reduced to ˜0.013 magnitudes. This standard deviation due to voids is a factor ˜3 smaller than that due to galaxy scale structures. We summarize our results in terms of a fitting formula that is accurate to ˜20%, and also build a simplified analytic model that reproduces our results to within ˜30%. Our model also allows us to explore the domain of validity of weak-lensing theory for voids. We find that for 35 Mpc voids, corrections to the dispersion due to lens-lens coupling are of order ˜4%, and corrections due to shear are ˜3%. Finally, we estimate the bias due to source-lens clustering in our model to be negligible.

  18. Constructing a bivariate distribution function with given marginals and correlation: application to the galaxy luminosity function

    NASA Astrophysics Data System (ADS)

    Takeuchi, Tsutomu T.

    2010-08-01

    We provide an analytic method to construct a bivariate distribution function (DF) with given marginal distributions and correlation coefficient. We introduce a convenient mathematical tool, called a copula, to connect two DFs with any prescribed dependence structure. If the correlation of two variables is weak (Pearson's correlation coefficient |ρ| < 1/3), the Farlie-Gumbel-Morgenstern (FGM) copula provides an intuitive and natural way to construct such a bivariate DF. When the linear correlation is stronger, the FGM copula cannot work anymore. In this case, we propose using a Gaussian copula, which connects two given marginals and is directly related to the linear correlation coefficient between two variables. Using the copulas, we construct the bivariate luminosity function (BLF) and discuss its statistical properties. We focus especially on the far-infrared-far-ulatraviolet (FUV-FIR) BLF, since these two wavelength regions are related to star-formation (SF) activity. Though both the FUV and FIR are related to SF activity, the univariate LFs have a very different functional form: the former is well described by the Schechter function whilst the latter has a much more extended power-law-like luminous end. We construct the FUV-FIR BLFs using the FGM and Gaussian copulas with different strengths of correlation, and examine their statistical properties. We then discuss some further possible applications of the BLF: the problem of a multiband flux-limited sample selection, the construction of the star-formation rate (SFR) function, and the construction of the stellar mass of galaxies (M*)-specific SFR (SFR/M*) relation. The copulas turn out to be a very useful tool to investigate all these issues, especially for including complicated selection effects.

  19. The nearby Abell clusters. II - Luminosity and spatial distribution of galaxies in A2175, A2256, and A2384

    NASA Astrophysics Data System (ADS)

    Oegerle, William R.; Jewison, Michael S.; Hoessel, John G.

    1987-03-01

    A study of the luminosity functions and spatial distributions of galaxies in the clusters A2175, A2256, and A2384 has been carried out, based on data obtained at the Palomar 1.2 m Schmidt and 1.5 m telescopes. The authors have also investigated in detail the accuracy of an automated star/galaxy classifier, by comparing the results obtained from the Schmidt plates of A2175 and A2384 with higher-spatial-resolution results from the 1.5 m telescope. Fits of Schechter functions to the luminosity functions of A2384 and A2256 yield values of Mr* ≡ -22, which is in good agreement with the "universal" value of Mr*. However, for these two clusters, slopes of the faint ends of the luminosity functions are distinctly flatter than the canonical value of α = -1.25. The best fit to the luminosity function of A2175 indicates a fairly steep faint end (α = -1.60). The spatial distributions of galaxies in these three clusters are well described by power laws, with no evidence for constant-density cores. These results, taken together with those reported by Beers and Tonry (1986), indicate a strong correlation between the density distribution of galaxies and the presence of a dominant D or cD galaxy in the cluster.

  20. H II Regions in Spiral Galaxies: Size Distribution, Luminosity Function, and New Isochrone Diagnostics of Density-Wave Kinematics

    DTIC Science & Technology

    2003-11-01

    conjecture to physical galaxies , placing the corotation where the distribution of H ii regions is seen to end. Tremaine & Weinberg (1984) developed an...H ii REGIONS IN SPIRAL GALAXIES : SIZE DISTRIBUTION, LUMINOSITY FUNCTION, AND NEW ISOCHRONE DIAGNOSTICS OF DENSITY-WAVE KINEMATICS M. S. Oey Lowell...Department of Physics and Astronomy, JohnsHopkins University, 3400 North Charles Street, Baltimore, MD 21218 and Xiaolei Zhang Remote Sensing Division

  1. Spectral Energy Distribution Models for Low-Luminosity Active Galactic Nuclei in LINERs

    NASA Technical Reports Server (NTRS)

    Nemmen, Rodrigo S.; Storchi-Bergmann, Thaisa; Eracleous, Michael

    2012-01-01

    Low-luminosity active galactic nuclei (LLAGNs) represent the bulk of the AGN population in the present-day universe and they trace the low-level accreting supermassive black holes. In order to probe the accretion and jet physical properties in LLAGNs as a class, we model the broadband radio to X-rays spectral energy distributions (SEDs) of 21 LLAGNs in low-ionization nuclear emission-line regions (LINERs) with a coupled accretion-jet model. The accretion flow is modeled as an inner ADAF outside of which there is a truncated standard thin disk. We find that the radio emission is severely underpredicted by ADAF models and is explained by the relativistic jet. The origin of the X-ray radiation in most sources can be explained by three distinct scenarios: the X-rays can be dominated by emission from the ADAF, or the jet, or the X-rays can arise from a jet-ADAF combination in which both components contribute to the emission with similar importance. For 3 objects both the jet and ADAF fit equally well the X-ray spectrum and can be the dominant source of X-rays whereas for 11 LLAGNs a jet-dominated model accounts better than the ADAF-dominated model for the data. The individual and average SED models that we computed can be useful for different studies of the nuclear emission of LLAGNs. From the model fits, we estimate important parameters of the central engine powering LLAGNs in LINERs, such as the mass accretion rate and the mass-loss rate in the jet and the jet power - relevant for studies of the kinetic feedback from jets.

  2. The nearby Abell clusters. II - Luminosity and spatial distribution of galaxies in A2175, A2256, and A2384

    NASA Technical Reports Server (NTRS)

    Oegerle, William R.; Jewison, Michael S.; Hoessel, John G.

    1987-01-01

    The luminosity and spatial distributions of galaxies in the nearby Abell clusters A2175, A2256, and A2384 have been studied using an automated object detection, classification, and photometry system. Schecter functions have been fit to the observed luminosity functions of these clusters. Values of the characteristic magnitude Mr(asterisk) at the 'break' in the luminosity function (LF) are found that are within about 0.25 mag of the so-called 'universal' value of Mr(asterisk) for A2256 and A2384. The faint ends of the LFs of these two clusters are fairly flat, with a value of -1.6 that is steeper than the universal value of -1.25. The spatial distributions of galaxies in all three clusters seem to be described fairly well by power laws, with no evidence for constant-density cores, when the cluster center is assumed to be the central D or cD galaxy. These results indicate a strong correlation between the density distribution of galaxies and the presence of a dominant D or cD galaxy in the cluster.

  3. Analysis of luminosity distributions and the shape parameters of strong gravitational lensing elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Biernaux, J.; Magain, P.; Sluse, D.; Chantry, V.

    2016-01-01

    Context. The luminosity profiles of galaxies acting as strong gravitational lenses can be tricky to study. Indeed, strong gravitational lensing images display several lensed components, both point-like and diffuse, around the lensing galaxy. Those objects limit the study of the galaxy luminosity to its inner parts. Therefore, the usual fitting methods perform rather badly on such images. Previous studies of strong lenses luminosity profiles using software such as GALFIT or IMFITFITS and various PSF-determining methods have resulted in somewhat discrepant results. Aims: The present work aims at investigating the causes of those discrepancies, as well as at designing more robust techniques for studying the morphology of early-type lensing galaxies with the ability to subtract a lensed signal from their luminosity profiles. Methods: We design a new method to independently measure each shape parameter, namely, the position angle, ellipticity, and half-light radius of the galaxy. Our half-light radius measurement method is based on an innovative scheme for computing isophotes that is well suited to measuring the morphological properties of gravititational lensing galaxies. Its robustness regarding various specific aspects of gravitational lensing image processing is analysed and tested against GALFIT. It is then applied to a sample of systems from the CASTLES database. Results: Simulations show that, when restricted to small, inner parts of the lensing galaxy, the technique presented here is more trustworthy than GALFIT. It gives more robust results than GALFIT, which shows instabilities regarding the fitting region, the value of the Sérsic index, and the signal-to-noise ratio. It is therefore better suited than GALFIT for gravitational lensing galaxies. It is also able to study lensing galaxies that are not much larger than the PSF. New values for the half-light radius of the objects in our sample are presented and compared to previous works. Table 6 is only available

  4. A COMPREHENSIVE STUDY OF GAMMA-RAY BURST OPTICAL EMISSION. III. BRIGHTNESS DISTRIBUTIONS AND LUMINOSITY FUNCTIONS OF OPTICAL AFTERGLOWS

    SciTech Connect

    Wang Xianggao; Liang Enwei; Li Liang; Lu Ruijing; Wei Jianyan; Zhang Bing

    2013-09-10

    We continue our systematic statistical study on optical afterglow data of gamma-ray bursts (GRBs). We present the apparent magnitude distributions of early optical afterglows at different epochs (t = 10{sup 2} s, 10{sup 3} s, and 1 hr) for the optical light curves of a sample of 93 GRBs (the global sample) and for sub-samples with an afterglow onset bump or a shallow decay segment. For the onset sample and shallow decay sample we also present the brightness distribution at the peak time t{sub p} and break time t{sub b}, respectively. All the distributions can be fit with Gaussian functions. We further perform Monte Carlo simulations to infer the luminosity function of GRB optical emission at the rest-frame time 10{sup 3} s, t{sub p}, and t{sub b}. Our results show that a single power-law luminosity function is adequate to model the data with indices -1.40 {+-} 0.10, -1.06 {+-} 0.16, and -1.54 {+-} 0.22. Based on the derived rest-frame 10{sup 3} s luminosity function, we generate the intrinsic distribution of the R-band apparent magnitude M{sub R} at the observed time 10{sup 3} s post-trigger, which peaks at M{sub R} = 22.5 mag. The fraction of GRBs whose R-band magnitude is fainter than 22 mag and 25 mag and at the observer time 10{sup 3} s are {approx}63% and {approx}25%, respectively. The detection probabilities of the optical afterglows with ground-based robotic telescopes and the UV-Optical Telescope on board Swift are roughly consistent with that inferred from this intrinsic M{sub R} distribution, indicating that the variations of the dark GRB fraction among the samples with different telescopes may be due to the observational selection effect, although the existence of an intrinsically dark GRB population cannot be ruled out.

  5. Universities and the International Distribution of Knowledge.

    ERIC Educational Resources Information Center

    Spitzberg, Irving, J., Jr., Ed.

    The role of the universities in the international distribution of knowledge is examined. An introduction by Irving J. Spitzberg, Jr. provides an overview of the volume. Part I: Analytical Context includes: "Universities and the New International Order: A Conceptual Analysis" (Spitzberg); "Knowledge as a Commodity: The Inequities of…

  6. The Protostellar Luminosity Function

    NASA Astrophysics Data System (ADS)

    Offner, Stella S. R.; McKee, Christopher F.

    2011-07-01

    The protostellar luminosity function (PLF) is the present-day luminosity function of the protostars in a region of star formation. It is determined using the protostellar mass function in combination with a stellar evolutionary model that provides the luminosity as a function of instantaneous and final stellar mass. In 2010, McKee & Offner considered three main accretion models: the isothermal sphere (IS) model, the turbulent core (TC) model, and an approximation of the competitive accretion (CA) model. We also consider the effect of an accretion rate that tapers off linearly in time and an accelerating star formation rate. For each model, we characterize the luminosity distribution using the mean, median, maximum, ratio of the median to the mean, standard deviation of the logarithm of the luminosity, and the fraction of very low luminosity objects. We compare the models with bolometric luminosities observed in local star-forming regions and find that models with an approximately constant accretion time, such as the TC and CA models, appear to agree better with observation than those with a constant accretion rate, such as the IS model. We show that observations of the mean protostellar luminosity in these nearby regions of low-mass star formation suggest a mean star formation time of 0.3 ± 0.1 Myr. Such a timescale, together with some accretion that occurs non-radiatively and some that occurs in high-accretion, episodic bursts, resolves the classical "luminosity problem" in low-mass star formation, in which observed protostellar luminosities are significantly less than predicted. An accelerating star formation rate is one possible way of reconciling the observed star formation time and mean luminosity. Future observations will place tighter constraints on the observed luminosities, star formation time, and episodic accretion, enabling better discrimination between star formation models and clarifying the influence of variable accretion on the PLF.

  7. THE PROTOSTELLAR LUMINOSITY FUNCTION

    SciTech Connect

    Offner, Stella S. R.; McKee, Christopher F. E-mail: cmckee@astro.berkeley.edu

    2011-07-20

    The protostellar luminosity function (PLF) is the present-day luminosity function of the protostars in a region of star formation. It is determined using the protostellar mass function in combination with a stellar evolutionary model that provides the luminosity as a function of instantaneous and final stellar mass. In 2010, McKee and Offner considered three main accretion models: the isothermal sphere (IS) model, the turbulent core (TC) model, and an approximation of the competitive accretion (CA) model. We also consider the effect of an accretion rate that tapers off linearly in time and an accelerating star formation rate. For each model, we characterize the luminosity distribution using the mean, median, maximum, ratio of the median to the mean, standard deviation of the logarithm of the luminosity, and the fraction of very low luminosity objects. We compare the models with bolometric luminosities observed in local star-forming regions and find that models with an approximately constant accretion time, such as the TC and CA models, appear to agree better with observation than those with a constant accretion rate, such as the IS model. We show that observations of the mean protostellar luminosity in these nearby regions of low-mass star formation suggest a mean star formation time of 0.3 {+-} 0.1 Myr. Such a timescale, together with some accretion that occurs non-radiatively and some that occurs in high-accretion, episodic bursts, resolves the classical 'luminosity problem' in low-mass star formation, in which observed protostellar luminosities are significantly less than predicted. An accelerating star formation rate is one possible way of reconciling the observed star formation time and mean luminosity. Future observations will place tighter constraints on the observed luminosities, star formation time, and episodic accretion, enabling better discrimination between star formation models and clarifying the influence of variable accretion on the PLF.

  8. The galaxy as the origin of gamma-ray bursts. II - The effect of an intrinsic burst luminosity distribution on log N/greater than S/ versus log S

    NASA Technical Reports Server (NTRS)

    Jennings, M. C.

    1982-01-01

    The effect of intrinsic burst luminosity distributions on log N-log S has been investigated for halo and disk galactic sources, using a power-law burst luminosity distribution characterized by a shape exponent and a luminosity range. Properly chosen burst luminosity distributions are shown to produce the log N-log S relations sufficiently different from those obtained with monoluminosity bursts to yield halo and thick disk geometries which are compatible with the observations. The soft shape of luminosity distributions capable of altering log N-log S has such observable consequences as (1) gamma-ray burst expected repetitions which first become apparent at lower fluences, and (2) the occurrence of most phenomena at luminosities on the order of about 10 to the 39th ergs, and correspondingly lower fluences.

  9. Luminosity dependence of the spatial and velocity distributions of galaxies: semi-analytic models versus the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Jing, Y. P.; Kauffmann, Guinevere; Börner, Gerhard; Kang, Xi; Wang, Lan

    2007-04-01

    By comparing semi-analytic galaxy catalogues with data from the Sloan Digital Sky Survey (SDSS), we show that current galaxy formation models reproduce qualitatively the dependence of galaxy clustering and pairwise peculiar velocities on luminosity, but some subtle discrepancies with the data still remain. The comparisons are carried out by constructing a large set of mock galaxy redshift surveys that have the same selection function as the SDSS Data Release Four (DR4). The mock surveys are based on two sets of semi-analytic catalogues presented by Croton et al. and Kang et al. From the mock catalogues, we measure the redshift-space projected two-point correlation function wp(rp), the power spectrum P(k) and the pairwise velocity dispersion (PVD) in Fourier space σ12(k) and in configuration space σ12(rp), for galaxies in different luminosity intervals. We then compare these theoretical predictions with the measurements derived from the SDSS DR4. On large scales and for galaxies brighter than L*, both sets of mock catalogues agree well with the data. For fainter galaxies, however, both models predict stronger clustering and higher pairwise velocities than observed. We demonstrate that this problem can be resolved if the fraction of faint satellite galaxies in massive haloes is reduced by ~30 per cent compared to the model predictions. A direct look into the model galaxy catalogues reveals that a significant fraction (15 per cent) of faint galaxies (-18 < M0.1r - 5 log10h < -17) reside in haloes with Mvir > 1013 Msolar, and this population is predominantly red in colour. These faint red galaxies are responsible for the high PVD values of low-luminosity galaxies on small scales.

  10. Galaxy And Mass Assembly (GAMA): ugrizYJHK Sérsic luminosity functions and the cosmic spectral energy distribution by Hubble type

    NASA Astrophysics Data System (ADS)

    Kelvin, Lee S.; Driver, Simon P.; Robotham, Aaron S. G.; Graham, Alister W.; Phillipps, Steven; Agius, Nicola K.; Alpaslan, Mehmet; Baldry, Ivan; Bamford, Steven P.; Bland-Hawthorn, Joss; Brough, Sarah; Brown, Michael J. I.; Colless, Matthew; Conselice, Christopher J.; Hopkins, Andrew M.; Liske, Jochen; Loveday, Jon; Norberg, Peder; Pimbblet, Kevin A.; Popescu, Cristina C.; Prescott, Matthew; Taylor, Edward N.; Tuffs, Richard J.

    2014-04-01

    We report the morphological classification of 3727 galaxies from the Galaxy and Mass Assembly survey with Mr < -17.4 mag and in the redshift range 0.025 < z < 0.06 (2.1 × 105 Mpc3) into E, S0-Sa, SB0-SBa, Sab-Scd, SBab-SBcd, Sd-Irr and little blue spheroid classes. Approximately 70 per cent of galaxies in our sample are disc-dominated systems, with the remaining ˜30 per cent spheroid dominated. We establish the robustness of our classifications, and use them to derive morphological-type luminosity functions and luminosity densities in the ugrizYJHK passbands, improving on prior studies that split by global colour or light profile shape alone. We find that the total galaxy luminosity function is best described by a double-Schechter function while the constituent morphological-type luminosity functions are well described by a single-Schechter function. These data are also used to derive the star formation rate densities for each Hubble class, and the attenuated and unattenuated (corrected for dust) cosmic spectral energy distributions, i.e. the instantaneous energy production budget. While the observed optical/near-IR energy budget is dominated 58:42 by galaxies with a significant spheroidal component, the actual energy production rate is reversed, i.e. the combined disc-dominated populations generate ˜1.3 times as much energy as the spheroid-dominated populations. On the grandest scale, this implies that chemical evolution in the local Universe is currently largely confined to mid-type spiral classes like our Milky Way.

  11. THE REDSHIFT DISTRIBUTION OF INTERVENING WEAK Mg II QUASAR ABSORBERS AND A CURIOUS DEPENDENCE ON QUASAR LUMINOSITY

    SciTech Connect

    Evans, Jessica L.; Churchill, Christopher W.; Nielsen, Nikole M.; Klimek, Elizabeth S.; Murphy, Michael T.

    2013-05-01

    We have identified 469 Mg II {lambda}{lambda}2796, 2803 doublet systems having W{sub r} {>=} 0.02 A in 252 Keck/High Resolution Echelle Spectrometer and UVES/Very Large Telescope quasar spectra over the redshift range 0.1 < z < 2.6. Using the largest sample yet of 188 weak Mg II systems (0.02 A {<=}W{sub r} < 0.3 A), we calculate their absorber redshift path density, dN/dz. We find clear evidence of evolution, with dN/dz peaking at z {approx} 1.2, and that the product of the absorber number density and cross section decreases linearly with increasing redshift; weak Mg II absorbers seem to vanish above z {approx_equal} 2.7. If the absorbers are ionized by the UV background, we estimate number densities of 10{sup 6}-10{sup 9} Mpc{sup -3} for spherical geometries and 10{sup 2}-10{sup 5} Mpc{sup -3} for more sheetlike geometries. We also find that dN/dz toward intrinsically faint versus bright quasars differs significantly for weak and strong (W{sub r} {>=} 1.0 A) absorbers. For weak absorption, dN/dz toward bright quasars is {approx}25% higher than toward faint quasars (10{sigma} at low redshift, 0.4 {<=} z {<=} 1.4, and 4{sigma} at high redshift, 1.4 < z {<=} 2.34). For strong absorption the trend reverses, with dN/dz toward faint quasars being {approx}20% higher than toward bright quasars (also 10{sigma} at low redshift and 4{sigma} at high redshift). We explore scenarios in which beam size is proportional to quasar luminosity and varies with absorber and quasar redshifts. These do not explain dN/dz's dependence on quasar luminosity.

  12. The Redshift Distribution of Intervening Weak Mg II Quasar Absorbers and a Curious Dependence on Quasar Luminosity

    NASA Astrophysics Data System (ADS)

    Evans, Jessica L.; Churchill, Christopher W.; Murphy, Michael T.; Nielsen, Nikole M.; Klimek, Elizabeth S.

    2013-05-01

    We have identified 469 Mg II λλ2796, 2803 doublet systems having Wr >= 0.02 Å in 252 Keck/High Resolution Echelle Spectrometer and UVES/Very Large Telescope quasar spectra over the redshift range 0.1 < z < 2.6. Using the largest sample yet of 188 weak Mg II systems (0.02 Å <=Wr < 0.3 Å), we calculate their absorber redshift path density, dN/dz. We find clear evidence of evolution, with dN/dz peaking at z ~ 1.2, and that the product of the absorber number density and cross section decreases linearly with increasing redshift; weak Mg II absorbers seem to vanish above z ~= 2.7. If the absorbers are ionized by the UV background, we estimate number densities of 106-109 Mpc-3 for spherical geometries and 102-105 Mpc-3 for more sheetlike geometries. We also find that dN/dz toward intrinsically faint versus bright quasars differs significantly for weak and strong (Wr >= 1.0 Å) absorbers. For weak absorption, dN/dz toward bright quasars is ~25% higher than toward faint quasars (10σ at low redshift, 0.4 <= z <= 1.4, and 4σ at high redshift, 1.4 < z <= 2.34). For strong absorption the trend reverses, with dN/dz toward faint quasars being ~20% higher than toward bright quasars (also 10σ at low redshift and 4σ at high redshift). We explore scenarios in which beam size is proportional to quasar luminosity and varies with absorber and quasar redshifts. These do not explain dN/dz's dependence on quasar luminosity.

  13. The Swift GRB Host Galaxy Legacy Survey. II. Rest-frame Near-IR Luminosity Distribution and Evidence for a Near-solar Metallicity Threshold

    NASA Astrophysics Data System (ADS)

    Perley, D. A.; Tanvir, N. R.; Hjorth, J.; Laskar, T.; Berger, E.; Chary, R.; de Ugarte Postigo, A.; Fynbo, J. P. U.; Krühler, T.; Levan, A. J.; Michałowski, M. J.; Schulze, S.

    2016-01-01

    We present rest-frame near-IR (NIR) luminosities and stellar masses for a large and uniformly selected population of gamma-ray burst (GRB) host galaxies using deep Spitzer Space Telescope imaging of 119 targets from the Swift GRB Host Galaxy Legacy Survey spanning 0.03 < z < 6.3, and we determine the effects of galaxy evolution and chemical enrichment on the mass distribution of the GRB host population across cosmic history. We find a rapid increase in the characteristic NIR host luminosity between z ˜ 0.5 and z ˜ 1.5, but little variation between z ˜ 1.5 and z ˜ 5. Dust-obscured GRBs dominate the massive host population but are only rarely seen associated with low-mass hosts, indicating that massive star-forming galaxies are universally and (to some extent) homogeneously dusty at high redshift while low-mass star-forming galaxies retain little dust in their interstellar medium. Comparing our luminosity distributions with field surveys and measurements of the high-z mass-metallicity relation, our results have good consistency with a model in which the GRB rate per unit star formation is constant in galaxies with gas-phase metallicity below approximately the solar value but heavily suppressed in more metal-rich environments. This model also naturally explains the previously reported “excess” in the GRB rate beyond z ≳ 2 metals stifle GRB production in most galaxies at z < 1.5 but have only minor impact at higher redshifts. The metallicity threshold we infer is much higher than predicted by single-star models and favors a binary progenitor. Our observations also constrain the fraction of cosmic star formation in low-mass galaxies undetectable to Spitzer to be small at z < 4.

  14. THE SWIFT GRB HOST GALAXY LEGACY SURVEY. II. REST-FRAME NEAR-IR LUMINOSITY DISTRIBUTION AND EVIDENCE FOR A NEAR-SOLAR METALLICITY THRESHOLD

    SciTech Connect

    Perley, D. A.; Tanvir, N. R.; Hjorth, J.; Fynbo, J. P. U.; Krühler, T.; Laskar, T.; Berger, E.; Chary, R.; Postigo, A. de Ugarte; Michałowski, M. J.; Schulze, S.

    2016-01-20

    We present rest-frame near-IR (NIR) luminosities and stellar masses for a large and uniformly selected population of gamma-ray burst (GRB) host galaxies using deep Spitzer Space Telescope imaging of 119 targets from the Swift GRB Host Galaxy Legacy Survey spanning 0.03 < z < 6.3, and we determine the effects of galaxy evolution and chemical enrichment on the mass distribution of the GRB host population across cosmic history. We find a rapid increase in the characteristic NIR host luminosity between z ∼ 0.5 and z ∼ 1.5, but little variation between z ∼ 1.5 and z ∼ 5. Dust-obscured GRBs dominate the massive host population but are only rarely seen associated with low-mass hosts, indicating that massive star-forming galaxies are universally and (to some extent) homogeneously dusty at high redshift while low-mass star-forming galaxies retain little dust in their interstellar medium. Comparing our luminosity distributions with field surveys and measurements of the high-z mass–metallicity relation, our results have good consistency with a model in which the GRB rate per unit star formation is constant in galaxies with gas-phase metallicity below approximately the solar value but heavily suppressed in more metal-rich environments. This model also naturally explains the previously reported “excess” in the GRB rate beyond z ≳ 2; metals stifle GRB production in most galaxies at z < 1.5 but have only minor impact at higher redshifts. The metallicity threshold we infer is much higher than predicted by single-star models and favors a binary progenitor. Our observations also constrain the fraction of cosmic star formation in low-mass galaxies undetectable to Spitzer to be small at z < 4.

  15. THE SPECTRAL ENERGY DISTRIBUTIONS AND INFRARED LUMINOSITIES OF z Almost-Equal-To 2 DUST-OBSCURED GALAXIES FROM Herschel AND Spitzer

    SciTech Connect

    Melbourne, J.; Soifer, B. T.; Desai, Vandana; Armus, Lee; Pope, Alexandra; Alberts, Stacey; Dey, Arjun; Jannuzi, B. T.; Bussmann, R. S. E-mail: bts@submm.caltech.edu E-mail: lee@ipac.caltech.edu E-mail: pope@astro.umass.edu E-mail: jannuzi@noao.edu

    2012-05-15

    Dust-obscured galaxies (DOGs) are a subset of high-redshift (z Almost-Equal-To 2) optically-faint ultra-luminous infrared galaxies (ULIRGs, e.g., L{sub IR} > 10{sup 12} L{sub Sun} ). We present new far-infrared photometry, at 250, 350, and 500 {mu}m (observed-frame), from the Herschel Space Telescope for a large sample of 113 DOGs with spectroscopically measured redshifts. Approximately 60% of the sample are detected in the far-IR. The Herschel photometry allows the first robust determinations of the total infrared luminosities of a large sample of DOGs, confirming their high IR luminosities, which range from 10{sup 11.6} L{sub Sun} 10{sup 13} L{sub Sun }. The rest-frame near-IR (1-3 {mu}m) spectral energy distributions (SEDs) of the Herschel-detected DOGs are predictors of their SEDs at longer wavelengths. DOGs with 'power-law' SEDs in the rest-frame near-IR show observed-frame 250/24 {mu}m flux density ratios similar to the QSO-like local ULIRG, Mrk 231. DOGs with a stellar 'bump' in their rest-frame near-IR show observed-frame 250/24 {mu}m flux density ratios similar to local star-bursting ULIRGs like NGC 6240. None show 250/24 {mu}m flux density ratios similar to extreme local ULIRG, Arp 220; though three show 350/24 {mu}m flux density ratios similar to Arp 220. For the Herschel-detected DOGs, accurate estimates (within {approx}25%) of total IR luminosity can be predicted from their rest-frame mid-IR data alone (e.g., from Spitzer observed-frame 24 {mu}m luminosities). Herschel-detected DOGs tend to have a high ratio of infrared luminosity to rest-frame 8 {mu}m luminosity (the IR8 = L{sub IR}(8-1000 {mu}m)/{nu}L{sub {nu}}(8 {mu}m) parameter of Elbaz et al.). Instead of lying on the z = 1-2 'infrared main sequence' of star-forming galaxies (like typical LIRGs and ULIRGs at those epochs) the DOGs, especially large fractions of

  16. Luminosity monitor at PEP

    SciTech Connect

    Fox, J.D.; Franklin, M.E.B.

    1981-02-01

    The luminosity monitor system utilized by the MKII Detector and by the PEP operators is described. This system processes information from 56 photomultipliers and calculates independent luminosities for each of the 3 colliding bunches in PEP. Design considerations, measurement techniques, and sources of error in the luminosity measurement are discussed.

  17. A Flexible Method of Estimating Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Kelly, Brandon C.; Fan, Xiaohui; Vestergaard, Marianne

    2008-08-01

    We describe a Bayesian approach to estimating luminosity functions. We derive the likelihood function and posterior probability distribution for the luminosity function, given the observed data, and we compare the Bayesian approach with maximum likelihood by simulating sources from a Schechter function. For our simulations confidence intervals derived from bootstrapping the maximum likelihood estimate can be too narrow, while confidence intervals derived from the Bayesian approach are valid. We develop our statistical approach for a flexible model where the luminosity function is modeled as a mixture of Gaussian functions. Statistical inference is performed using Markov chain Monte Carlo (MCMC) methods, and we describe a Metropolis-Hastings algorithm to perform the MCMC. The MCMC simulates random draws from the probability distribution of the luminosity function parameters, given the data, and we use a simulated data set to show how these random draws may be used to estimate the probability distribution for the luminosity function. In addition, we show how the MCMC output may be used to estimate the probability distribution of any quantities derived from the luminosity function, such as the peak in the space density of quasars. The Bayesian method we develop has the advantage that it is able to place accurate constraints on the luminosity function even beyond the survey detection limits, and that it provides a natural way of estimating the probability distribution of any quantities derived from the luminosity function, including those that rely on information beyond the survey detection limits.

  18. THE LUMINOSITY, MASS, AND AGE DISTRIBUTIONS OF COMPACT STAR CLUSTERS IN M83 BASED ON HUBBLE SPACE TELESCOPE/WIDE FIELD CAMERA 3 OBSERVATIONS

    SciTech Connect

    Chandar, Rupali; Whitmore, Bradley C.; Mutchler, Max; Bond, Howard; Kim, Hwihyun; Kaleida, Catherine; Calzetti, Daniela; Saha, Abhijit; O'Connell, Robert; Balick, Bruce; Carollo, Marcella; Disney, Michael; Dopita, Michael A.; Frogel, Jay A.; Hall, Donald; Holtzman, Jon A.; Kimble, Randy A.; McCarthy, Patrick; Paresce, Francesco; Silk, Joe

    2010-08-10

    The newly installed Wide Field Camera 3 (WFC3) on the Hubble Space Telescope has been used to obtain multi-band images of the nearby spiral galaxy M83. These new observations are the deepest and highest resolution images ever taken of a grand-design spiral, particularly in the near-ultraviolet, and allow us to better differentiate compact star clusters from individual stars and to measure the luminosities of even faint clusters in the U band. We find that the luminosity function (LF) for clusters outside of the very crowded starburst nucleus can be approximated by a power law, dN/dL {proportional_to} L {sup {alpha}}, with {alpha} = -2.04 {+-} 0.08, down to M{sub V} {approx} -5.5. We test the sensitivity of the LF to different selection techniques, filters, binning, and aperture correction determinations, and find that none of these contribute significantly to uncertainties in {alpha}. We estimate ages and masses for the clusters by comparing their measured UBVI, H{alpha} colors with predictions from single stellar population models. The age distribution of the clusters can be approximated by a power law, dN/d{tau} {proportional_to} {tau}{sup {gamma}}, with {gamma} = -0.9 {+-} 0.2, for M {approx}> few x 10{sup 3} M {sub sun} and {tau} {approx}< 4 x 10{sup 8} yr. This indicates that clusters are disrupted quickly, with {approx}80%-90% disrupted each decade in age over this time. The mass function of clusters over the same M-{tau} range is a power law, dN/dM {proportional_to} M {sup {beta}}, with {beta} = -1.94 {+-} 0.16, and does not have bends or show curvature at either high or low masses. Therefore, we do not find evidence for a physical upper mass limit, M{sub C} , or for the earlier disruption of lower mass clusters when compared with higher mass clusters, i.e., mass-dependent disruption. We briefly discuss these implications for the formation and disruption of the clusters.

  19. Higher Education and the Distribution of Knowledge: International Perspectives.

    ERIC Educational Resources Information Center

    Altbach, Philip G.

    The relationship between academic institutions and knowledge dissemination is discussed, with attention to new technologies, university presses, the role of scholarly journals, colleges as gatekeepers of knowledge, colleges as both producers and consumers of scholarly products, and an international network of knowledge distribution. New…

  20. 76 FR 32231 - International Business Machines (IBM), Sales and Distribution Business Unit, Global Sales...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-03

    ... Employment and Training Administration International Business Machines (IBM), Sales and Distribution Business... Business Machines (IBM), Sales and Distribution Business Unit, Global Sales Solution Department, off-site... and location is International Business Machines (IBM), Sales and Distribution Business Unit,...

  1. Population studies in groups and clusters of galaxies. IV - Comparison of the luminosity functions and morphological-type distributions in seven nearby groups

    NASA Technical Reports Server (NTRS)

    Ferguson, Henry C.; Sandage, Allan

    1991-01-01

    Published observational data on the Leo, Dorado, NGC 1400, NGC 5044, Antlia, Fornax, and Virgo groups of galaxies are analyzed in terms of the luminosity functions and morphological types of their members. The data sets employed are characterized, and the results are presented in extensive tables and graphs and discussed in detail. While the fractions of early and late galaxies in the groups are similar, the ratio of dwarfs to giants (D/G) in the early galaxies varies monotonically with the richness of the cluster, leading to artificial flattening at the faint end of the total luminosity function in environments with low D/G. The luminosity function for dwarfs in all environments is found to have a slope of about -1.3.

  2. Population studies in groups and clusters of galaxies. IV. Comparison of the luminosity functions and morphological-type distributions in seven nearby groups

    SciTech Connect

    Ferguson, H.C.; Sandage, A. Observatories of the Carnegie Institution, Pasadena, CA Space Telescope Science Institute, Baltimore, MD )

    1991-03-01

    Published observational data on the Leo, Dorado, NGC 1400, NGC 5044, Antlia, Fornax, and Virgo groups of galaxies are analyzed in terms of the luminosity functions and morphological types of their members. The data sets employed are characterized, and the results are presented in extensive tables and graphs and discussed in detail. While the fractions of early and late galaxies in the groups are similar, the ratio of dwarfs to giants (D/G) in the early galaxies varies monotonically with the richness of the cluster, leading to artificial flattening at the faint end of the total luminosity function in environments with low D/G. The luminosity function for dwarfs in all environments is found to have a slope of about -1.3. 54 refs.

  3. Run II luminosity progress

    SciTech Connect

    Gollwitzer, K.; /Fermilab

    2007-06-01

    The Fermilab Tevatron Collider Run II program continues at the energy and luminosity frontier of high energy particle physics. To the collider experiments CDF and D0, over 3 fb{sup -1} of integrated luminosity has been delivered to each. Upgrades and improvements in the Antiproton Source of the production and collection of antiprotons have led to increased number of particles stored in the Recycler. Electron cooling and associated improvements have help make a brighter antiproton beam at collisions. Tevatron improvements to handle the increased number of particles and the beam lifetimes have resulted in an increase in luminosity.

  4. Constraints of the Luminosities of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Hakkila, J.; Meegan, C.; Horack, J.; Pendleton, G.; Briggs, M.; Paciesas, W.; Emslie, G.; Mallozzi, R.

    1995-09-01

    Constraints are found on the gamma-ray burst luminosity function from an analysis of the combined BATSE/PVO intensity distribution. If bursts originate in an extended Galactic halo, then the intrinsic luminosity range is narrow, with bursts spanning only a factor of five or less in luminosity. If bursts originate in a simple Friedmann cosmology with Ω = 1 and Λ = 0, then very few luminosity constraints exist.

  5. Wind Power Forecasting Error Distributions: An International Comparison; Preprint

    SciTech Connect

    Hodge, B. M.; Lew, D.; Milligan, M.; Holttinen, H.; Sillanpaa, S.; Gomez-Lazaro, E.; Scharff, R.; Soder, L.; Larsen, X. G.; Giebel, G.; Flynn, D.; Dobschinski, J.

    2012-09-01

    Wind power forecasting is expected to be an important enabler for greater penetration of wind power into electricity systems. Because no wind forecasting system is perfect, a thorough understanding of the errors that do occur can be critical to system operation functions, such as the setting of operating reserve levels. This paper provides an international comparison of the distribution of wind power forecasting errors from operational systems, based on real forecast data. The paper concludes with an assessment of similarities and differences between the errors observed in different locations.

  6. 76 FR 21033 - International Business Machines (IBM), Sales and Distribution Business Unit, Global Sales...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF LABOR Employment and Training Administration International Business Machines (IBM), Sales and Distribution Business... workers of International Business Machines (IBM), Sales and Distribution Business Unit, Global...

  7. The luminosity function of quasars

    NASA Technical Reports Server (NTRS)

    Pei, Yichuan C.

    1995-01-01

    We propose a new evolutionary model for the optical luminosity function of quasars. Our analytical model is derived from fits to the empirical luminosity function estimated by Hartwick and Schade and Warren, Hewett, and Osmer on the basis of more than 1200 quasars over the range of redshifts 0 approximately less than z approximately less than 4.5. We find that the evolution of quasars over this entire redshift range can be well fitted by a Gaussian distribution, while the shape of the luminosity function can be well fitted by either a double power law or an exponential L(exp 1/4) law. The predicted number counts of quasars, as a function of either apparent magnitude or redshift, are fully consistent with the observed ones. Our model indicates that the evolution of quasars reaches its maximum at z approximately = 2.8 and declines at higher redshifts. An extrapolation of the evolution to z approximately greater than 4.5 implies that quasars may have started their cosmic fireworks at z(sub f) approximately = 5.2-5.5. Forthcoming surveys of quasars at these redshifts will be critical to constrain the epoch of quasar formation. All the results we derived are based on observed quasars and are therefore subject to the bias of obscuration by dust in damped Ly alpha systems. Future surveys of these absorption systems at z approximately greater than 3 will also be important if the formation epoch of quasars is to be known unambiguously.

  8. ROD INTERNAL PRESSURE QUANTIFICATION AND DISTRIBUTION ANALYSIS USING FRAPCON

    SciTech Connect

    Ivanov, Kostadin; Jessee, Matthew Anderson

    2016-01-01

    The discharge rod internal pressure (RIP) and cladding hoop stress (CHS) distributions are quantified forWatts BarNuclearUnit 1 (WBN1) fuel rods by modeling core cycle design data, intercycle assembly movements, operation data (including modeling significant trips and downpowers), and as-built fuel enrichments and densities of each fuel rod in FRAPCON-3.5. An alternate model for the amount of helium released from zirconium diboride (ZrB2) integral fuel burnable absorber (IFBA) layers is derived and applied to FRAPCON output data to quantify the RIP and CHS for these fuel rods. SCALE/Polaris is used to quantify fuel rod-specific spectral quantities and the amount of gaseous fission products produced in the fuel for use in FRAPCON inputs. Fuel rods with ZrB2 IFBA layers (i.e., IFBA rods) are determined to have RIP predictions that are elevated when compared to fuel rod without IFBA layers (i.e., standard rods) despite the fact that IFBA rods often have reduced fill pressures and annular fuel blankets. Cumulative distribution functions (CDFs) are prepared from the distribution of RIP predictions for all standard and IFBA rods. The provided CDFs allow for the determination of the portion of WBN1 fuel rods that exceed a specified RIP limit. Lastly, improvements to the computational methodology of FRAPCON are proposed.

  9. RHIC LUMINOSITY UPGRADE PROGRAM

    SciTech Connect

    Fischer, W.

    2010-05-23

    The Relativistic Heavy Ion Collider (RHIC) operates with either ions or polarized protons. After increasing the heavy ion luminosity by two orders of magnitude since its commissioning in 2000, the current luminosity upgrade program aims for an increase by another factor of 4 by means of 3D stochastic cooling and a new 56 MHz SRF system. An Electron Beam Ion Source is being commissioned that will allow the use of uranium beams. Electron cooling is considered for collider operation below the current injection energy. For the polarized proton operation both luminosity and polarization are important. In addition to ongoing improvements in the AGS injector, the construction of a new high-intensity polarized source has started. In RHIC a number of upgrades are under way to increase the intensity and polarization transmission to 250 GeV beam energy. Electron lenses will be installed to partially compensate the head-on beam-beam effect.

  10. Luminosity enhancements at SLAC

    SciTech Connect

    Coward, D.H.

    1984-04-01

    Several ideas are discussed that have been proposed to improve the luminosity at the SPEAR and PEP electron-positron storage rings and to insure good luminosity at the SLAC Linear Collider. There have been two proposals studied recently for SPEAR: a Microbeta insertion using Samarium Cobalt permanent magnets, and a Minibeta insertion using conventional quadrupole magnets. The notations Microbeta and minibeta used here are somewhat arbitrary since the front faces of the first quadrupole magnets for both insertions are at nearly the same distance from the interaction point.

  11. Internationally educated health professionals and the challenge of workforce distribution.

    PubMed

    Landry, Michel D; Gupta, Neeru; Tepper, Joshua

    2010-01-01

    Internationally educated health professionals (IEHPs) have always been an important part of the Canadian health workforce. A particularly important aspect related to the role of IEHPs is their distribution across different sectors of the healthcare system and various geographical regions. Several provinces and territories have implemented strategies that restrict the initial practice of IEHPs to areas that have long-standing workforce shortages. While the outcomes of these approaches are mixed, some evidence suggests that IEHPs remain in place only as long as their contractual requirements stipulate. However, studies also indicate that IEHPs are increasingly practising in care settings that are perceived to be less attractive by their Canadian-trained counterparts. Whether the contribution of IEHPs is framed in terms of short- or long-term sustainable solutions, their role will continue to be an important component of health service across Canada.

  12. Burst Statistics Using the Lag-Luminosity Relationship

    NASA Technical Reports Server (NTRS)

    Band, D. L.; Norris, J. P.; Bonnell, J. T.

    2003-01-01

    Using the lag-luminosity relation and various BATSE catalogs we create a large catalog of burst redshifts, peak luminosities and emitted energies. These catalogs permit us to evaluate the lag-luminosity relation, and to study the burst energy distribution. We find that this distribution can be described as a power law with an index of alpha = 1.76 +/- 0.05 (95% confidence), close to the alpha = 2 predicted by the original quasi-universal jet model.

  13. High luminosity particle colliders

    SciTech Connect

    Palmer, R.B.; Gallardo, J.C.

    1997-03-01

    The authors consider the high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, p{anti p}), lepton (e{sup +}e{sup {minus}}, {mu}{sup +}{mu}{sup {minus}}) and photon-photon colliders. Technical problems in obtaining increased energy in each type of machine are presented. The machines relative size are also discussed.

  14. Protostellar Luminosity Functions in 11 Diverse Star Forming Environments

    NASA Astrophysics Data System (ADS)

    Kryukova, Erin; Megeath, S. T.; Gutermuth, R.; Pipher, J.; Allen, T. S.; Allen, L. E.; Myers, P. C.; Muzerolle, J.; Cygnus-X Legacy Team

    2012-01-01

    Protostars exist in a variety of environments, ranging from clouds with dispersed low-mass stars, such as Taurus, to clustered regions in clouds forming high-mass stars, like Orion. The effect these different environments have on protostar properties such as mass or luminosity is uncertain. One way to probe the effects of cloud environment on the observable property, protostar luminosity is to compare protostellar luminosity functions of clouds hosting varied populations of protostars. In this dissertation talk I will discuss the protostellar luminosity functions from 11 star forming clouds including Lupus, Chamaeleon, Ophiuchus, Perseus, Serpens, Orion, Cep OB3, Mon R2, Cygnus-X, and Maddalena's Cloud, which encompass a wide range of star forming environments. The luminosity functions are constructed from Spitzer surveys of these molecular clouds. I employ a new technique for estimating the bolometric luminosity from near and mid-IR fluxes alone and for subtracting contamination from galaxies, reddened pre-main sequence stars with disks, and edge-on disk systems. The clouds which are forming massive stars show a significant peak at low luminosity and a tail extending toward luminosities above 10 solar luminosities, while the luminosity functions of clouds which are not forming massive stars have no significant peak down to the sensitivity limit and do not exhibit the tail. I compare these luminosity functions to existing models of protostellar evolution. I also compare the luminosity functions of protostars in distributed and clustered environments, as determined using nearest-neighbor distances. In Orion and Cygnus-X, the clouds which contain the largest populations of protostars there is a clear difference in luminosity functions between protostars incrowded and distributed regions, with the luminosity function biased towards higher luminosities in more luminous regions. I will discuss the implications of these variations and the possibility that the IMF is

  15. Luminosity enhancement in relativistic jets and altered luminosity functions for beamed objects

    NASA Technical Reports Server (NTRS)

    Urry, C. M.; Shafer, R. A.

    1983-01-01

    Due to relativistic effects, the observed emission from relativistic jets is quite different from the rest frame emission. Systematic differences between the observed and intrinsic intensities of sources in which jet phenomena are occurring are discussed. Assuming that jets have a power law luminosity function of a slope B, the observed luminosity distribution as a function of the velocity of the jet, the spectral index of the rest frame emission, and the range of angles of the jets relative to our line of sight are calculated. The results is well-approximated by two power laws, the higher luminosity end having the original power law index X and the lower luminosity end having a flattened exponent independent of B and only slightly greater than 1. A model consisting of beamed emission from a jet and unbeamed emission from a stationary central component is investigated. The luminosity functions for these two-component sources are calculated for two ranges of angles. For sources in which beaming is important, the luminosity function is much flatter. Because of this, the relative numbers of ""beamed'' and ""unbeamed'' sources detected on the sky depend strongly on the luminosity at which the comparison is made.

  16. Rod internal pressure quantification and distribution analysis using Frapcon

    SciTech Connect

    Bratton, Ryan N; Jessee, Matthew Anderson; Wieselquist, William A

    2015-09-01

    This report documents work performed supporting the Department of Energy (DOE) Office of Nuclear Energy (NE) Fuel Cycle Technologies Used Fuel Disposition Campaign (UFDC) under work breakdown structure element 1.02.08.10, ST Analysis. In particular, this report fulfills the M4 milestone M4FT- 15OR0810036, Quantify effects of power uncertainty on fuel assembly characteristics, within work package FT-15OR081003 ST Analysis-ORNL. This research was also supported by the Consortium for Advanced Simulation of Light Water Reactors (http://www.casl.gov), an Energy Innovation Hub (http://www.energy.gov/hubs) for Modeling and Simulation of Nuclear Reactors under U.S. Department of Energy Contract No. DE-AC05-00OR22725. The discharge rod internal pressure (RIP) and cladding hoop stress (CHS) distributions are quantified for Watts Bar Nuclear Unit 1 (WBN1) fuel rods by modeling core cycle design data, operation data (including modeling significant trips and downpowers), and as-built fuel enrichments and densities of each fuel rod in FRAPCON-3.5. A methodology is developed which tracks inter-cycle assembly movements and assembly batch fabrication information to build individual FRAPCON inputs for each evaluated WBN1 fuel rod. An alternate model for the amount of helium released from the zirconium diboride (ZrB2) integral fuel burnable absorber (IFBA) layer is derived and applied to FRAPCON output data to quantify the RIP and CHS for these types of fuel rods. SCALE/Polaris is used to quantify fuel rodspecific spectral quantities and the amount of gaseous fission products produced in the fuel for use in FRAPCON inputs. Fuel rods with ZrB2 IFBA layers (i.e., IFBA rods) are determined to have RIP predictions that are elevated when compared to fuel rod without IFBA layers (i.e., standard rods) despite the fact that IFBA rods often have reduced fill pressures and annular fuel pellets. The primary contributor to elevated RIP predictions at burnups less than and greater than 30 GWd

  17. Classical trajectory study of internal energy distributions in unimolecular processes

    NASA Technical Reports Server (NTRS)

    Mcdonald, J. D.; Marcus, R. A.

    1976-01-01

    Energy flow in a molecular system such as CD3Cl or CD3H representing a chemical activation experiment is studied by the method of classical trajectories. A correlation function method is used to obtain energy distributions before and after the breakup of the activated molecule. The energy distribution in the final product is found to be randomly distributed for a surface with no exit channel barrier or strong intermode couplings. Nonrandom energy distributions result when these special forces are present. Product channel barriers result in an excess of translational energy and exit channel intermode couplings result in nonrandom vibrational distributions.

  18. X-ray luminosity functions of clusters of galaxies

    NASA Technical Reports Server (NTRS)

    Cavaliere, A.; Burg, R.; Giacconi, R.

    1991-01-01

    Clusters of galaxies must have a considerable intrinsic spread in their X-ray luminosities at given mass if they are formed bottom-up by direct gravitational instability. The distributions of luminosities at given mass take on the general form of a flat power law with a sharp upper cutoff, consistent with the recently obtained luminosity functions for Abell clusters of given richness classes. The quantitative features depend on the specific hierarchical cosmogony, with models including mass accretion after first collapse providing the best agreement. The same clustering mechanism, after integrating over mass, yields a steep overall luminosity function consistent with existing measurements.

  19. Evolution of the luminosity function of extragalactic objects

    NASA Technical Reports Server (NTRS)

    Petrosian, V.

    1985-01-01

    A nonparametric procedure for determination of the evolution of the luminosity function of extragalactic objects and use of this for prediction of expected redshift and luminosity distribution of objects is described. The relation between this statistical evolution of the population and their physical evolution, such as the variation with cosmological epoch of their luminosity and formation rate is presented. This procedure when applied to a sample of optically selected quasars with redshifts less than two shows that the luminosity function evolves more strongly for higher luminosities, indicating a larger quasar activity at earlier epochs and a more rapid evolution of the objects during their higher luminosity phases. It is also shown that absence of many quasars at redshifts greater than three implies slowing down of this evolution in the conventional cosmological models, perhaps indicating that this is near the epoch of the birth of the quasar (and galaxies).

  20. LUMINOSITY EVOLUTION OF GAMMA-RAY PULSARS

    SciTech Connect

    Hirotani, Kouichi

    2013-04-01

    We investigate the electrodynamic structure of a pulsar outer-magnetospheric particle accelerator and the resulting gamma-ray emission. By considering the condition for the accelerator to be self-sustained, we derive how the trans-magnetic-field thickness of the accelerator evolves with the pulsar age. It is found that the thickness is small but increases steadily if the neutron-star envelope is contaminated by sufficient light elements. For such a light element envelope, the gamma-ray luminosity of the accelerator is kept approximately constant as a function of age in the initial 10,000 yr, forming the lower bound of the observed distribution of the gamma-ray luminosity of rotation-powered pulsars. If the envelope consists of only heavy elements, on the other hand, the thickness is greater, but it increases less rapidly than a light element envelope. For such a heavy element envelope, the gamma-ray luminosity decreases relatively rapidly, forming the upper bound of the observed distribution. The gamma-ray luminosity of a general pulsar resides between these two extreme cases, reflecting the envelope composition and the magnetic inclination angle with respect to the rotation axis. The cutoff energy of the primary curvature emission is regulated below several GeV even for young pulsars because the gap thickness, and hence the acceleration electric field, is suppressed by the polarization of the produced pairs.

  1. An Analysis of Freight Forwarder Operations in an International Distribution Channel.

    DTIC Science & Technology

    1987-01-01

    44 3. International Marketing Mix ....................... 45 4. Security Assistance Distribution Channel .......... 69 5...an item is ultimately derived from the interaction of variables in the marketing mix . Of those variables, the distribution functions seem to allow the...Component of the Marketing Mix ,"Proceedings, NCPDM Fall Meeting, National council of Physical Distribution Management, San Francisco, CA., 1982. 7

  2. Photoelastic Studies of Internal Stress Distributions of Unidirectional Composites.

    DTIC Science & Technology

    1980-12-01

    Station, Buildling 3, )010 DluKe Street, Alexandria, Virginia 22314 1 ’icc:’ and Ceramics Information Center, Battelle Columbus Laboratories, ,05 K,aig...34verre a, If t nece, e.ry and Identify by block number) ..... ’Io-dimensional phutoelastli, models were used to determine internal taading-. and...OF THIS PAGE(Nla, Dae. ne ted) Block No. 20 -fiber volume ratio and were cured under the same conditions as the models . The transverse strength of

  3. Assessing the contribution of centaur impacts to ice giant luminosities

    NASA Astrophysics Data System (ADS)

    Dodson-Robinson, Sarah E.

    2016-01-01

    Voyager 2 observations revealed that Neptune's internal luminosity is an order of magnitude higher than that of Uranus. If the two planets have similar interior structures and cooling histories, Neptune's luminosity can only be explained by invoking some energy source beyond gravitational contraction. This paper investigates whether centaur impacts could provide the energy necessary to produce Neptune's luminosity. The major findings are (1) that impacts on both Uranus and Neptune are too infrequent to provide luminosities of order Neptune's observed value, even for optimistic impact-rate estimates and (2) that Uranus and Neptune rarely have significantly different impact-generated luminosities at any given time. Uranus and Neptune most likely have structural differences that force them to cool and contract at different rates.

  4. Direct correlation of internal gradients and pore size distributions with low field NMR

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Xiao, Lizhi; Liao, Guangzhi; Blümich, Bernhard

    2016-06-01

    Internal magnetic field gradients Gint, which arise from the magnetic susceptibility difference Δχ between solid matrix and fluid in porous media relate to the pore geometry. However, this relationship is complex and not well understood. Here we correlate internal-gradient distributions to pore-size distributions directly to examine internal gradients in detail at low field NMR. The pore-size distributions were obtained by the method of Decay due to Diffusion in the Internal Field (DDIF), and the internal-gradient distributions were measured with the Carr-Purcell-Meiboom-Gill (CPMG) method. The internal-gradient-pore-size distributions correlation maps were obtained for water in packs of glass beads with different diameter and in a sandstone sample. The relationship between internal gradients and pore structure is analyzed in detail by considering the restricted diffusion of fluids in porous samples. For each case diffusion regimes are assigned by plotting normalized CPMG data and comparing the diffusion lengths, the dephasing lengths and pore diameters. In the free-diffusion limit, the correlation maps reveal the true relationship between pore structure and internal gradients so that Δχ can be approximated from the correlation maps. This limit is met most easily at low field. It provides information about porous media, which is expected to benefit the oil industry, in particular NMR well logging.

  5. Measurement of probability distributions for internal stresses in dislocated crystals

    SciTech Connect

    Wilkinson, Angus J.; Tarleton, Edmund; Vilalta-Clemente, Arantxa; Collins, David M.; Jiang, Jun; Britton, T. Benjamin

    2014-11-03

    Here, we analyse residual stress distributions obtained from various crystal systems using high resolution electron backscatter diffraction (EBSD) measurements. Histograms showing stress probability distributions exhibit tails extending to very high stress levels. We demonstrate that these extreme stress values are consistent with the functional form that should be expected for dislocated crystals. Analysis initially developed by Groma and co-workers for X-ray line profile analysis and based on the so-called “restricted second moment of the probability distribution” can be used to estimate the total dislocation density. The generality of the results are illustrated by application to three quite different systems, namely, face centred cubic Cu deformed in uniaxial tension, a body centred cubic steel deformed to larger strain by cold rolling, and hexagonal InAlN layers grown on misfitting sapphire and silicon carbide substrates.

  6. Corrosion manual for internal corrosion of water distribution systems

    SciTech Connect

    Singley, J.E.; Beaudet, B.A.; Markey, P.H.

    1984-04-01

    Corrosion of distribution piping and of home plumbing and fixtures has been estimated to cost the public water supply industry more than $700 million per year. Two toxic metals that occur in tap water, almost entirely because of corrosion, are lead and cadmium. Three other metals, usually present because of corrosion, cause staining of fixtures, or metallic taste, or both. These are copper (blue stains and metallic taste), iron (red-brown stains and metallic taste), and zinc (metallic taste). Since the Safe Drinking Water Act (P.L. 93-523) makes the supplying utility responsible for the water quality at the customer's tap, it is necessary to prevent these metals from getting into the water on the way to the tap. This manual was written to give the operators of potable water treatment plants and distribution systems an understanding of the causes and control of corrosion.

  7. Luminosity Optimization With Offset, Crossing Angle, and Distortion

    SciTech Connect

    Wu, Juhao; Raubenheimer, T.O.; /SLAC

    2005-06-15

    In a linear collider, sources of beam jitter due to kicker noise, quadrupole vibration and long-range transverse wakefields will lead to beam offsets and tilts at the Intersection Point (IP). In addition, sources of emittance dilution such as short-range transverse wakefields or dispersive errors will lead to internal beam distortions. When the IP disruption parameter is large, these beam imperfections will be amplified by a single bunch kink instability which will lead to luminosity loss. In this paper, we study the luminosity loss and then the optimization required to partially cancel the luminosity loss both analytically and with direct simulation.

  8. A Distributed Perspective on Instructional Leadership in International Baccalaureate (IB) Schools

    ERIC Educational Resources Information Center

    Lee, Moosung; Hallinger, Philip; Walker, Allan

    2012-01-01

    Purpose: The purpose of this study is to provide a better understanding of how instructional leadership responsibilities are distributed in International Baccalaureate (IB) schools in East Asia. Research Design: Case studies were conducted in five international schools located in Thailand, Vietnam, Hong Kong, and China. These schools were selected…

  9. RHIC PLANS TOWARDS HIGHER LUMINOSITY

    SciTech Connect

    FEDOTOV,A.

    2007-06-25

    The Relativistic Heavy Ion Collider (RHIC) is designed to provide luminosity over a wide range of beam energies and species, including heavy ions, polarized protons, and tric beam collisions. In the first seven years of operation there has been a rapid increase in the achieved peak and average luminosity, substantially exceeding design values. Work is presently underway to achieve the Enhanced Design parameters. Planned major upgrades include the Electron Beam Ion Source (EBIS), RHIC-11, and construction of an electron-ion collider (eRHIC). We review the expected RHIC upgrade performance. Electron cooling and its impact on the luminosity both for heavy ions and protons are discussed in detail.

  10. The internal magnetic field distribution, and single exponential magnetic resonance free induction decay, in rocks.

    PubMed

    Chen, Quan; Marble, Andrew E; Colpitts, Bruce G; Balcom, Bruce J

    2005-08-01

    When fluid saturated porous media are subjected to an applied uniform magnetic field, an internal magnetic field, inside the pore space, is induced due to magnetic susceptibility differences between the pore-filling fluid and the solid matrix. The microscopic distribution of the internal magnetic field, and its gradients, was simulated based on the thin-section pore structure of a sedimentary rock. The simulation results were verified experimentally. We show that the 'decay due to diffusion in internal field' magnetic resonance technique may be applied to measure the pore size distribution in partially saturated porous media. For the first time, we have observed that the internal magnetic field and its gradients in porous rocks have a Lorentzian distribution, with an average gradient value of zero. The Lorentzian distribution of internal magnetic field arises from the large susceptibility contrast and an intrinsic disordered pore structure in these porous media. We confirm that the single exponential magnetic resonance free induction decay commonly observed in fluid saturated porous media arises from a Lorentzian internal field distribution. A linear relationship between the magnetic resonance linewidth, and the product of the susceptibility difference in the porous media and the applied magnetic field, is observed through simulation and experiment.

  11. Study on temperature distribution effect on internal charging by computer simulation

    NASA Astrophysics Data System (ADS)

    Yi, Zhong

    2016-07-01

    Internal charging (or deep dielectric charging) is a great threaten to spacecraft. Dielectric conductivity is an important parameter for internal charging and it is sensitive to temperature. Considering the exposed dielectric outside a spacecraft may experience a relatively large temperature range, temperature effect can't be ignored in internal charging assessment. We can see some reporters on techniques of computer simulation of internal charging, but the temperature effect has not been taken into accounts. In this paper, we realize the internal charging simulation with consideration of temperature distribution inside the dielectric. Geant4 is used for charge transportation, and a numerical method is proposed for solving the current reservation equation. The conductivity dependences on temperature, radiation dose rate and intense electric field are considered. Compared to the case of uniform temperature, the internal charging with temperature distribution is more complicated. Results show that temperature distribution can cause electric field distortion within the dielectric. This distortion refers to locally considerable enlargement of electric field. It usually corresponds to the peak electric field which is critical for dielectric breakdown judgment. The peak electric field can emerge inside the dielectric, or appear on the boundary. This improvement of internal charging simulation is beneficial for the assessment of internal charging under multiple factors.

  12. Populations of High-Luminosity Density-Bounded HII Regions in Spiral Galaxies? Evidence and Implications

    NASA Technical Reports Server (NTRS)

    Beckman, J. E.; Rozas, M.; Zurita, A.; Watson, R. A.; Knapen, J. H.

    2000-01-01

    In this paper we present evidence that the H II regions of high luminosity in disk galaxies may be density bounded, so that a significant fraction of the ionizing photons emitted by their exciting OB stars escape from the regions. The key piece of evidence is the presence, in the Ha luminosity functions (LFs) of the populations of H iI regions, of glitches, local sharp peaks at an apparently invariant luminosity, defined as the Stromgren luminosity Lstr), LH(sub alpha) = Lstr = 10(sup 38.6) (+/- 10(sup 0.1)) erg/ s (no other peaks are found in any of the LFs) accompanying a steepening of slope for LH(sub alpha) greater than Lstr This behavior is readily explicable via a physical model whose basic premises are: (a) the transition at LH(sub alpha) = Lstr marks a change from essentially ionization bounding at low luminosities to density bounding at higher values, (b) for this to occur the law relating stellar mass in massive star-forming clouds to the mass of the placental cloud must be such that the ionizing photon flux produced within the cloud is a function which rises more steeply than the mass of the cloud. Supporting evidence for the hypothesis of this transition is also presented: measurements of the central surface brightnesses of H II regions for LH(sub alpha) less than Lstr are proportional to L(sup 1/3, sub H(sub alpha)), expected for ionization bounding, but show a sharp trend to a steeper dependence for LH(sub alpha) greater than Lstr, and the observed relation between the internal turbulence velocity parameter, sigma, and the luminosity, L, at high luminosities, can be well explained if these regions are density bounded. If confirmed, the density-bounding hypothesis would have a number of interesting implications. It would imply that the density-bounded regions were the main sources of the photons which ionize the diffuse gas in disk galaxies. Our estimates, based on the hypothesis, indicate that these regions emit sufficient Lyman continuum not only to

  13. On the Radio and Optical Luminosity Evolution of Quasars

    SciTech Connect

    Singal, J.; Petrosian, V.; Lawrence, A.; Stawarz, L.; /JAXA, Sagamihara /Jagiellonian U., Astron. Observ.

    2011-05-20

    We calculate simultaneously the radio and optical luminosity evolutions of quasars, and the distribution in radio loudness R defined as the ratio of radio and optical luminosities, using a flux limited data set containing 636 quasars with radio and optical fluxes from White et al. We first note that when dealing with multivariate data it is imperative to first determine the true correlations among the variables, not those introduced by the observational selection effects, before obtaining the individual distributions of the variables. We use the methods developed by Efron and Petrosian which are designed to obtain unbiased correlations, distributions, and evolution with redshift from a data set truncated due to observational biases. It is found that as expected the population of quasars exhibits strong positive correlation between the radio and optical luminosities and that this correlation deviates from a simple linear relation in a way indicating that more luminous quasars are more radio loud. We also find that there is a strong luminosity evolution with redshift in both wavebands, with significantly higher radio than optical evolution. We conclude that the luminosity evolution obtained by arbitrarily separating the sources into radio loud (R > 10) and radio quiet (R < 10) populations introduces significant biases that skew the result considerably. We also construct the local radio and optical luminosity functions and the density evolution. Finally, we consider the distribution of the radio loudness parameter R obtained from careful treatment of the selection effects and luminosity evolutions with that obtained from the raw data without such considerations. We find a significant difference between the two distributions and no clear sign of bi-modality in the true distribution. Our results indicate therefore, somewhat surprisingly, that there is no critical switch in the efficiency of the production of disk outflows/jets between very radio quiet and very radio

  14. The AGN Luminosity Fraction in Galaxy Mergers

    NASA Astrophysics Data System (ADS)

    Dietrich, Jeremy; Weiner, Aaron; Ashby, Matthew; Martinez-Galarza, Juan Rafael; Smith, Howard Alan

    2017-01-01

    Galaxy mergers are key events in galaxy evolution, generally triggering massive starbursts and AGNs. However, in these chaotic systems, it is not yet known what fraction each of these two mechanisms contributes to the total luminosity. Here we measure and model spectral energy distributions (SEDs) using the Code for Investigating Galaxy Emission (CIGALE) in up to 33 broad bands from the UV to the far-IR for 23 IR-luminous galaxies to estimate the fraction of the bolometric IR luminosity that can be attributed to the AGN. The galaxies are split nearly evenly into two subsamples: late-stage mergers, found in the IRAS Revised Bright Galaxy Sample or Faint Source Catalog, and early-stage mergers found in the Spitzer Interacting Galaxy Sample. We find that the AGN contribution to the total IR luminosity varies greatly from system to system, from 0% up to ~90%, but is substantially greater in the later-stage and brighter mergers. This is consistent with what is known about galaxy evolution and the triggering of AGNs.The SAO REU program is funded in part by the National Science Foundation REU and Department of Defense ASSURE programs under NSF Grant no. 1262851, and by the Smithsonian Institution.

  15. Multiwavelength Luminosity Functions of Galaxies

    NASA Technical Reports Server (NTRS)

    Gardner, Jonathan; Oegerle, William R. (Technical Monitor)

    2002-01-01

    I have developed a technique for measuring multi-variate luminosity functions of galaxies. Multivariate or multi-wavelength luminosity functions will reveal the interplay between star formation, chemical evolution, and absorption and re-emission of dust within evolving galaxy populations. By using principle component analysis to reduce the dimensionality of the problem, I optimally extract the relevant photometric information from large galaxy catalogs. As a demonstration of the technique, I derive the multiwavelength luminosity function for the galaxies in the released SDSS catalog, and show that the results are consistent with those obtained by traditional methods. This technique will be applicable to catalogs of galaxies from datasets obtained by the SIRTF and GALEX missions.

  16. 76 FR 2711 - Cinram Distribution, LLC, a Subsidiary of Cinram International, Simi Valley Distribution Center...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-14

    ... Valley Distribution Center, Including On-Site Leased Workers From Labor Ready Southwest, Inc. and Select... Southwest, Inc., and Select Remedy Staffing Services, Simi Valley, California. The notice was published in... workers from Labor Ready Southwest, Inc., and Select Remedy Staffing Services, Simi Valley,...

  17. Evolutionary variations of solar luminosity

    NASA Technical Reports Server (NTRS)

    Endal, A. S.

    1981-01-01

    Theoretical arguments for a 30% increase in the solar luminosity over the past 4.7 billion years are reviewed. A scaling argument shows that this increase can be predicted without detailed numerical calculations. The magnitude of the increase is independent of nuclear reaction rates, as long as conversion of hydrogen to helium provides the basic energy source of the Sun. The effect of the solar luminosity increase on the terrestrial climate is briefly considered. It appears unlikely that an enhanced greenhouse effect, due to reduced gases (NH3, CH4), can account for the long-term paleoclimatic trends.

  18. AMMONIA AND CO OBSERVATIONS TOWARD LOW-LUMINOSITY 6.7 GHz METHANOL MASERS

    SciTech Connect

    Wu, Y. W.; Xu, Y.; Yang, J.; Zhang, S. B.; Pandian, J. D.; Henkel, C.; Menten, K. M.

    2010-09-01

    To investigate whether distinctions exist between low- and high-luminosity Class II 6.7 GHz methanol masers, we have undertaken multi-line mapping observations of various molecular lines, including the NH{sub 3} (1,1), (2,2), (3,3), (4,4), and {sup 12}CO (1-0) transitions, toward a sample of nine low-luminosity 6.7 GHz masers and {sup 12}CO (1-0) observations toward a sample of eight high-luminosity 6.7 GHz masers, for which we already had NH{sub 3} spectral line data. Emission in the NH{sub 3} (1,1), (2,2), and (3,3) transitions was detected in eight out of nine low-luminosity maser sources, in which 14 cores were identified. We derive densities, column densities, temperatures, core sizes, and masses of both low- and high-luminosity maser regions. A comparative analysis of the physical quantities reveals marked distinctions between the low-luminosity and high-luminosity groups: in general, cores associated with high-luminosity 6.7 GHz masers are larger and more massive than those traced by low-luminosity 6.7 GHz masers; regions traced by the high-luminosity masers have larger column densities but lower densities than those of the low-luminosity maser regions. Further, strong correlations between 6.7 GHz maser luminosity and NH{sub 3} (1,1) and (2,2) line widths are found, indicating that internal motions in high-luminosity maser regions are more energetic than those in low-luminosity maser regions. A {sup 12}CO (1-0) outflow analysis also shows distinctions in that outflows associated with high-luminosity masers have wider line wings and larger sizes than those associated with low-luminosity masers.

  19. Dijet spectroscopy at high luminosity

    SciTech Connect

    Green, D.

    1990-07-01

    A study of the dijet mass resolution has been made appropriate to high luminosity operation. As a benchmark, the mass resolution of W {yields} jj for a Higgs boson of 800 GeV has been optimized for no, eight, and sixteen overlapping minbias events. A factor of 2.5 degradation in M{sub jj} width is seen. 6 refs., 10 figs.

  20. Characterization of the Vertical Energy Distribution of the Internal Wave Field in the Upper Ocean

    NASA Astrophysics Data System (ADS)

    Bruch, Jeremy

    2013-11-01

    A method to simulate internal waves in the upper ocean is proposed by defining the vertical energy distribution as a function of mode number with the associated vertical structure functions as an appropriate set of orthogonal basis functions. An internal wave simulation is shown for a case with a stylized BV peak profile, using the Garrett and Munk internal wave model (GM) as the input energy distribution. The resulting simulated spectra are shown to be self-consistent with the proposed definition of the vertical energy distribution. Application of the GM model requires many assumptions, including the requirement that the internal waves are modeled strictly in deep water where there is little variation in the stratification. Given the typical non-uniformity of the stratification profile in the upper ocean, it may be of interest to relax this restriction of the GM model but the obvious non-stationary properties near the thermocline are incompatible with the calculation of the vertical spectrum of the internal wave field. The method described in this presentation suggests a means to reconcile this incompatibility. Membership pending.

  1. The Effect of Internal Salary Increment Distributions on Retention Behaviors of Western New York Teachers

    ERIC Educational Resources Information Center

    Patterson, Michele M.

    2013-01-01

    This is a study of district internal salary distribution practices and its effect on retention. The study is a replication study as recommended by Jacobson (1986) and Lankford and Wyckoff (1997) whereby their research shows the prevalence of "back loading" and ineffectiveness relative to retention. In the case of this study, the…

  2. In-Situ Measurement of Internal Temperature Distribution of Sintered Materials Using Ultrasonic Technique

    NASA Astrophysics Data System (ADS)

    Ihara, I.; Tomomatsu, T.

    2011-03-01

    It is often required to measure internal temperature distribution of a heated material because it is closely related to the materials properties and behavior. In this work, an effective ultrasonic method has been applied to the monitoring of internal temperature distributions of an alumina being heated. The principle of the method is based on the temperature dependence of the velocity of ultrasound propagating through a heated material. In the method, a combined technique of ultrasonic pulse-echo measurements and a finite difference calculation is employed to determine the one-dimensional temperature distribution in a heated material. Shear wave is used for the ultrasonic measurements to improve the accuracy in determining temperature. To verify the feasibility of the method, pulse-echo measurements with a shear wave transducer have been performed for an alumina rod of 14 mm diameter and 25 mm length whose single-end is being heated. The internal temperature distribution and its variation of the alumina are then measured during the heating. The temperature distributions determined by the ultrasonic method almost agree with those obtained by an infrared method. Thus, it is demonstrated that the ultrasonic method has the potential for in-process monitoring of the transient temperature variation of ceramics being processed at high temperatures.

  3. Effect of Internal Clearance on Load Distribution and Life of Radially Loaded Ball and Roller Bearings

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2012-01-01

    The effect of internal clearance on radially loaded deepgroove ball and cylindrical roller bearing load distribution and fatigue life was determined for four clearance groups defined in the bearing standards. The analysis was extended to negative clearance (interference) conditions to produce a curve of life factor versus internal clearance. Rolling-element loads can be optimized and bearing life maximized for a small negative operating clearance. Life declines gradually with positive clearance and rapidly with increasing negative clearance. Relationships were found between bearing life and internal clearance as a function of ball or roller diameter, adjusted for load. Results are presented as life factors for radially loaded bearings independent of bearing size or applied load. In addition, a modified Stribeck Equation is presented that relates the maximum rolling-element load to internal bearing clearance.

  4. PROPERTIES OF THE MOLECULAR CORES OF LOW LUMINOSITY OBJECTS

    SciTech Connect

    Hsieh, Tien-Hao; Lai, Shih-Ping; Belloche, Arnaud; Wyrowski, Friedrich; Hung, Chao-Ling E-mail: shawinchone@gmail.com

    2015-04-01

    We present a survey toward 16 low luminosity objects (LLOs with an internal luminosity, L{sub int}, lower than 0.2 L{sub ⊙}) with N{sub 2}H{sup +} (1–0), N{sub 2}H{sup +} (3–2), N{sub 2}D{sup +} (3–2), HCO{sup +} (3–2), and HCN (3–2) using the Arizona Radio Observatory Kitt Peak 12 m Telescope and Submillimeter Telescope. Our goal is to probe the nature of these faint protostars which are believed to be either very low mass or extremely young protostars. We find that the N{sub 2}D{sup +}/N{sub 2}H{sup +} column density ratios of LLOs are similar to those of typical starless cores and Class 0 objects. The N{sub 2}D{sup +}/N{sub 2}H{sup +} column density ratios are relatively high (>0.05) for LLOs with kinetic temperatures less than 10 K in our sample. The distribution of N{sub 2}H{sup +} (1–0) line widths spreads between that of starless cores and young Class 0 objects. If we use the line width as a dynamic evolutionary indicator, LLOs are likely young Class 0 protostellar sources. We further use the optically thick tracers, HCO{sup +} (3–2) and HCN (3–2), to probe the infall signatures of our targets. We derive the asymmetry parameters from both lines and estimate the infall velocities by fitting the HCO{sup +} (3–2) spectra with two-layer models. As a result, we identify eight infall candidates based on the infall velocities and seven candidates have infall signatures supported by asymmetry parameters from at least one of HCO{sup +} (3–2) and HCN (3–2)

  5. Internal energy distribution of peptides in electrospray ionization : ESI and collision-induced dissociation spectra calculation.

    PubMed

    Pak, Alireza; Lesage, Denis; Gimbert, Yves; Vékey, Károly; Tabet, Jean-Claude

    2008-04-01

    The internal energy of ions and the timescale play fundamental roles in mass spectrometry. The main objective of this study is to estimate and compare the internal energy distributions of different ions (different nature, degree of freedom 'DOF' and fragmentations) produced in an electrospray source (ESI) of a triple-quadrupole instrument (Quattro I Micromass). These measurements were performed using both the Survival Yield method (as proposed by De Pauw) and the MassKinetics software (kinetic model introduced by Vékey). The internal energy calibration is the preliminary step for ESI and collision-induced dissociation (CID) spectra calculation. meta-Methyl-benzylpyridinium ion and four protonated peptides (YGGFL, LDIFSDF, LDIFSDFR and RLDIFSDF) were produced using an electrospray source. These ions were used as thermometer probe compounds. Cone voltages (V(c)) were linearly correlated with the mean internal energy values () carried by desolvated ions. These mean internal energy values seem to be slightly dependent on the size of the studied ion. ESI mass spectra and CID spectra were then simulated using the MassKinetics software to propose an empirical equation for the mean internal energy () versus cone voltage (V(c)) for different source temperatures (T): < E(int) > = [405 x 10(-6) - 480 x 10(-9) (DOF)] V(c)T + E(therm)(T). In this equation, the E(therm)(T) parameter is the mean internal energy due to the source temperature at 0 V(c).

  6. Internal energy distributions from nitrogen dioxide fluorescence. 1. Cumulative sum method

    SciTech Connect

    Johnston, H.S.; Miller, C.E.; Oh, B.Y.; Patten, K.O. Jr.; Sisk, W.N. Lawrence Berkeley Lab., CA )

    1993-09-30

    This article describes a method of obtaining information about the internal energy (E) distribution of a fluorescing population of nitrogen dioxide, NO[sub 2]*, from its dispersed spectrum between 400 and 840 nm. We show that two fluorescing populations of the same average energy but different energy spread give statistically significant differences in their observed cumulative sum spectra, although the differences are small. Broadly spread distributions of NO[sub 2]* internal energy are produced by photolysis of RNO[sub 2] molecules and by collisional deactivation of monoenergetically excited NO[sub 2]. The cumulative sum fluorescence spectrum from a broadly distributed internal energy population is represented as a weighted combination of monoenergetically excited cumulative sum fluorescence spectra. A cumulative sum spectrum utilizes all of the data, is positive and single valued, and smoothly, monotonically increases with decreasing observation energy. By differentiation of the cumulative sum spectrum, the original spectrum is recovered undistorted. Unlike a structured monoenergetic fluorescence spectrum, the cumulative sum is well approximated by a simple algebraic expression, I(E,X), where E is the internal energy of NO[sub 2]* and X are the photon energies of the observed spectrum. 14 refs., 18 figs., 3 tabs.

  7. The neuronal extracellular matrix restricts distribution and internalization of aggregated Tau-protein.

    PubMed

    Suttkus, A; Holzer, M; Morawski, M; Arendt, T

    2016-01-28

    Alzheimer's disease (AD) is a chronic degenerative disorder characterized by fibrillary aggregates of Aß and Tau-protein. Formation and progression of these pathological hallmarks throughout the brain follow a specific spatio-temporal pattern which provides the basis for neuropathological staging. Previously, we could demonstrate that cortical and subcortical neurons are less frequently affected by neurofibrillary degeneration if they are enwrapped by a specialized form of the hyaluronan-based extracellular matrix (ECM), the so called 'perineuronal net' (PN). PNs are composed of large aggregating chondroitin sulfate proteoglycans connected to a hyaluronan backbone, stabilized by link proteins and cross-linked via tenascin-R. Recently, PN-associated neurons were shown to be better protected against iron-induced neurodegeneration compared to neurons without PN, indicating a neuroprotective function. Here, we investigated the role of PNs in distribution and internalization of exogenous Tau-protein by using organotypic slice cultures of wildtype mice as well as mice lacking the ECM-components aggrecan, HAPLN1 or tenascin-R. We could demonstrate that PNs restrict both distribution and internalization of Tau. Accordingly, PN-ensheathed neurons were less frequently affected by Tau-internalization, than neurons without PN. Finally, the PNs as well as their three investigated components were shown to modulate the processes of distribution as well as internalization of Tau.

  8. Glycoprotein Ib Is Homogeneously Distributed on External and Internal Membranes of Resting Platelets

    PubMed Central

    White, James G.; Krumwiede, Marlys D.; Escolar, Gines

    1999-01-01

    Recent ultrastructural studies have suggested that Glycoprotein Ib (GPIb) has a different distribution on external (surface) versus internal (open canalicular system) membranes in resting discoid platelets. The differential distribution proposed for GPIb differs from that reported for the fibrinogen receptor, GPIIb-IIIa, and could have profound physiological significance when platelets are activated by surfaces. The present study explored the distribution of GPIb on external and internal membranes of resting platelets. Immunogold cytochemical techniques were applied to ultrathin cryosections of washed platelets. Polyclonal antibodies or mixtures of monoclonal antibodies (AP1 and 6D1) were used for labeling. To avoid the technical problem posed by limited accessibility of antigens located in very narrow portions of the open canalicular system (OCS) to antibodies, the same methods were applied to patients with giant platelets syndromes. The OCS of normal resting platelets was also dilated by exposure of platelets to hypertonic conditions or to cytochalasin-B, an agent that prevents assembly of actin, and, reportedly, movement of GPIb. Morphometric analysis revealed that rates of labeling on internal versus external membranes of giant platelets does not differ significantly (0.93 ± 0.20), provided the OCS is sufficiently dilated. Platelets exposed to cytochalasin B (1.01 ± 0.31) or to hypertonic conditions (0.96 ± 0.20) revealed similar ratios for immunogold particles on external and internal membranes. Results of our study indicate that membranes of the exposed surface and lining OCS channels of resting platelets are continuous, identical structures and GPIb is homogeneously distributed on external and internal membranes. PMID:10595941

  9. Accelerator Science: Luminosity vs. Energy

    ScienceCinema

    Lincoln, Don

    2016-09-28

    In the world of high energy physics there are several parameters that are important when one constructs a particle accelerator. Two crucial ones are the energy of the beam and the luminosity, which is another word for the number of particles in the beam. In this video, Fermilab’s Dr. Don Lincoln explains the differences and the pros and cons. He even works in an unexpected sporting event.

  10. Accelerator Science: Luminosity vs. Energy

    SciTech Connect

    Lincoln, Don

    2016-09-19

    In the world of high energy physics there are several parameters that are important when one constructs a particle accelerator. Two crucial ones are the energy of the beam and the luminosity, which is another word for the number of particles in the beam. In this video, Fermilab’s Dr. Don Lincoln explains the differences and the pros and cons. He even works in an unexpected sporting event.

  11. Impact of internal waves on the spatial distribution of Planktothrix rubescens (cyanobacteria) in an alpine lake.

    PubMed

    Cuypers, Yannis; Vinçon-Leite, Brigitte; Groleau, Alexis; Tassin, Bruno; Humbert, Jean-François

    2011-04-01

    The vertical and horizontal distribution of the cyanobacterium, Planktothrix rubescens, was studied in a deep alpine lake (Lac du Bourget) in a 2-year monitoring program with 11 sampling points, and a 24-h survey at one sampling station. This species is known to proliferate in the metalimnic layer of numerous deep mesotrophic lakes in temperate areas, and also to produce hepatotoxins. When looking at the distribution of P. rubescens at the scale of the entire lake, we found large variations (up to 10  m) in the depth of the biomass peak in the water column. These variations were closely correlated to isotherm displacements. We also found significant variations in the distribution of the cyanobacterial biomass in the northern and southern parts of the lake. We used a physical modeling approach to demonstrate that two internal wave modes can explain these variations. Internal waves are generated by wind events, but can still be detected several days after the end of these events. Finally, our 24-h survey at one sampling point demonstrated that the V1H1 sinusoidal motion could evolve into nonlinear fronts. All these findings show that internal waves have a major impact on the distribution of P. rubescens proliferating in the metalimnic layer of a deep lake, and that this process could influence the growth of this species by a direct impact on light availability.

  12. Voltage Distribution of Internal Windings of Pole-Mounted Distribution Transformer by Lightning Surge and Measures for Voltage Reduction

    NASA Astrophysics Data System (ADS)

    Honda, Hideki; Asakawa, Akira; Yokoyama, Shigeru

    When steep lightning surge enters a pole-mounted distribution transformer, the voltage distribution of the internal windings is unbalanced. It is known that a layer-to-layer short or a turn-to-turn short occurs where the voltage distribution of windings is high. In this paper, the voltage distribution of the windings was measured at the primary and secondary sides of the transformer using a testing transformer. The point of the windings where the highest voltage occurred was clarified. At the primary windings, large voltage occurs at the layer nearest the primary bushing, and the possibility of breakdown at this point is high. By field test using several types of surge arrestor, it is found that the lower the operating voltage of the surge arrestor installed in the primary side, the lower the voltage occurring at the primary windings. At the secondary windings, large voltage occurs at the layer closer to the neutral terminal, and the possibility of breakdown at this point is high. The lower the operating voltage of the surge arrestor installed in the primary side, the lower the voltage occurring at the secondary windings, too. Adding the surge arrestor in the secondary side, although effectively reduce line-to-line voltage, does not effectively reduce the voltage of the secondary windings.

  13. Internal stress distribution for generating closure domains in laser-irradiated Fe–3%Si(110) steels

    SciTech Connect

    Iwata, Keiji; Imafuku, Muneyuki; Orihara, Hideto; Sakai, Yusuke; Ohya, Shin-Ichi; Suzuki, Tamaki; Shobu, Takahisa; Akita, Koichi; Ishiyama, Kazushi

    2015-05-07

    Internal stress distribution for generating closure domains occurring in laser-irradiated Fe–3%Si(110) steels was investigated using high-energy X-ray analysis and domain theory based on the variational principle. The measured triaxial stresses inside the specimen were compressive and the stress in the rolling direction became more dominant than stresses in the other directions. The calculations based on the variational principle of magnetic energy for closure domains showed that the measured triaxial stresses made the closure domains more stable than the basic domain without closure domains. The experimental and calculation results reveal that the laser-introduced internal stresses result in the occurrence of the closure domains.

  14. Spatiotemporal modeling of internal states distribution for lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Wang, Mingliang; Li, Han-Xiong

    2016-01-01

    Electrochemical properties of the battery are described in partial differential equations that are impossible to compute online. These internal states are spatially distributed and thus difficult to measure in the battery operation. A space-time separation method is applied to model the electrochemical properties of the battery with the help of the extended Kalman filter. The model is efficiently optimized by using LASSO adaptation method and can be updated through data-based learning. The analytical model derived is able to offer a fast estimation of internal states of the battery, and thus has potential to become a prediction model for battery management system.

  15. Systematic properties of CO emission from galaxies. I - Luminosity function

    NASA Technical Reports Server (NTRS)

    Verter, Frances

    1987-01-01

    A sensitive survey of normal galaxies covering a wide range of luminosities and morphological types is combined with galaxy observations in the literature to provide a sample for statistical study. The global CO emission of these galaxies is extrapolated by modeling the galaxies with an exponential radial profile. The maximum-likelihood distribution functions of CO luminosity and CO/H I flux ratio are similar in behavior. Both have long tails of bright galaxies. However, the typical galaxy has a CO luminosity of about 10 to the 6th Jy km/s Mpc-squared or less and a CO/H I ratio of the order of 10 or less. Averages of the distributions of CO luminosity and CO/H I flux ratio are higher for galaxies of Hubble type Sb-Sbc than for groups of earlier or later types. Quantitative estimates of the possible error sources in the conversion of CO luminosity to molecular mass indicates that the peaking of CO emission at intermediate types is a fairly confident result.

  16. Clamping stiffness and its influence on load distribution between paired internal spinal fixation devices.

    PubMed

    Rohlmann, A; Calisse, J; Bergmann, G; Radvan, J; Mayer, H M

    1996-06-01

    The load distribution between two internal spinal fixation devices depends, besides other factors, on their stiffness. The stiffness ranges were determined experimentally for the clamps of the AO internal fixator with lateral nut and with posterior nut as well as for the clamps of the SOCON fixator. The stiffness of eight devices each differed by a factor of 3.1 for the clamp with lateral nut, by a factor of 1.5 for the clamp with posterior nut, and by a factor of 1.4 for the clamp of the SOCON fixator. For the AO clamp with lateral nut, the influence of the nut-tightening torque on the stiffness was determined. Using instrumented internal spinal fixation devices mounted to plastic vertebrae and simulating a corpectomy, the load distribution between the implants was measured for different tightening torques. It could be shown that, for the AO internal fixator whose clamps have a lateral nut, a nut-tightening torque > 5 Nm has only a negligible influence on load-sharing between the implants. Tooth damage occurs when the teeth of the clamp body and clamping jaw of the clamp with lateral nut do not gear together exactly, which leads to changes in the clamping stiffness and load-sharing between the two implants.

  17. The Local [CII] Emission Line Luminosity Function

    NASA Astrophysics Data System (ADS)

    Hemmati, Shoubaneh

    2017-01-01

    I present, for the first time, the local [CII]158 $\\mu$m emission line luminosity function measured using a sample of more than 500 galaxies from the RBGS. [CII] luminosities are measured from the Herschel PACS observations of the LIRGs in the GOALS survey and estimated for the rest of the sample based on the far-IR luminosity and color. The sample covers 91.3% of the sky and is complete at $S_{60\\mu m} > 5.24 Jy$. We calculated the completeness as a function of [CII] line luminosity and distance, based on the far-IR color and flux densities. The [CII] luminosity function is constrained in the range $\\sim 10^{7-9} \\ L_{\\odot}$ from both the 1/Vmax and the STY maximum likelihood methods. The shape of our derived [CII] emission line luminosity function agrees well with the IR luminosity function. For the CO(1-0) and [CII] luminosity functions to agree, we propose a varying ratio of [CII]/CO(1-0) as a function of CO luminosity, with larger ratios for fainter CO luminosities. Limited [CII] high redshift observations as well as estimates based on the IR and UV luminosity functions, are suggestive of an evolution in the [CII] luminosity function similar to the evolution trend of the cosmic star formation rate density. ALMA with full capability will be able to confirm this prediction.

  18. THE LUMINOSITY PROFILES OF BRIGHTEST CLUSTER GALAXIES

    SciTech Connect

    Donzelli, C. J.; Muriel, H.; Madrid, J. P.

    2011-08-01

    We have derived detailed R-band luminosity profiles and structural parameters for a total of 430 brightest cluster galaxies (BCGs), down to a limiting surface brightness of 24.5 mag arcsec{sup -2}. Light profiles were initially fitted with a Sersic's R {sup 1/n} model, but we found that 205 ({approx}48%) BCGs require a double component model to accurately match their light profiles. The best fit for these 205 galaxies is an inner Sersic model, with indices n {approx} 1-7, plus an outer exponential component. Thus, we establish the existence of two categories of the BCG luminosity profiles: single and double component profiles. We found that double profile BCGs are brighter ({approx}0.2 mag) than single profile BCGs. In fact, the Kolmogorov-Smirnov test applied to these subsamples indicates that they have different total magnitude distributions, with mean values M{sub R} = -23.8 {+-} 0.6 mag for single profile BCGs and M{sub R} = -24.0 {+-} 0.5 mag for double profile BCGs. We find that partial luminosities for both subsamples are indistinguishable up to r = 15 kpc, while for r > 20 kpc the luminosities we obtain are on average 0.2 mag brighter for double profile BCGs. This result indicates that extra-light for double profile BCGs does not come from the inner region but from the outer regions of these galaxies. The best-fit slope of the Kormendy relation for the whole sample is a = 3.13 {+-} 0.04. However, when fitted separately, single and double profile BCGs show different slopes: a{sub single} = 3.29 {+-} 0.06 and a{sub double} = 2.79 {+-} 0.08. Also, the logarithmic slope of the metric luminosity {alpha} is higher in double profile BCGs ({alpha}{sub double} = 0.65 {+-} 0.12) than in single profile BCGs ({alpha}{sub single} = 0.59 {+-} 0.14). The mean isophote outer ellipticity (calculated at {mu} {approx} 24 mag arcsec{sup -2}) is higher in double profile BCGs (e{sub double} = 0.30 {+-} 0.10) than in single profile BCGs (e{sub single} = 0.26 {+-} 0.11). Similarly

  19. Internal energy distributions from nitrogen dioxide fluorescence. 2. Collisional energy transfer from excited nitrogen dioxide

    SciTech Connect

    Patten, K.O. Jr.; Johnston, H.S. Lawrence Berkeley Lab., CA )

    1993-09-30

    We follow the collisional deactivation of laser-excited nitrogen dioxide through its dispersed fluorescence. The energy acceptor gases are NO[sub 2] at four excitation energies ranging from 18828 to 24989 cm[sup [minus]1] and five monatomic gases, four diatomic gases, and three polyatomic gases with 18828-cm[sup [minus]1] excitation energy. The nominal products are the shapes of the internal energy distributions, which are obtained and plotted for several representative cases. From these distributions, the first three moments of the internal energy distributions are derived as a function of molecular collisions and tabulated as (i) the average internal energy, (ii) energy spread, and (iii) skewness. These quantities are plotted against c(M)t, the product of buffer gas concentration c(M) and delay time after laser excitation t(0.5-2 [mu]s), which is a quantity proportional to number of collisions. The negative slope of average energy vs c(M)t is the macroscopic energy-transfer rate constant, k[sub [epsilon

  20. Using internal discharge data in a distributed conceptual model to reduce uncertainty in streamflow simulations

    NASA Astrophysics Data System (ADS)

    Guerrero, J.; Halldin, S.; Xu, C.; Lundin, L.

    2011-12-01

    Distributed hydrological models are important tools in water management as they account for the spatial variability of the hydrological data, as well as being able to produce spatially distributed outputs. They can directly incorporate and assess potential changes in the characteristics of our basins. A recognized problem for models in general is equifinality, which is only exacerbated for distributed models who tend to have a large number of parameters. We need to deal with the fundamentally ill-posed nature of the problem that such models force us to face, i.e. a large number of parameters and very few variables that can be used to constrain them, often only the catchment discharge. There is a growing but yet limited literature showing how the internal states of a distributed model can be used to calibrate/validate its predictions. In this paper, a distributed version of WASMOD, a conceptual rainfall runoff model with only three parameters, combined with a routing algorithm based on the high-resolution HydroSHEDS data was used to simulate the discharge in the Paso La Ceiba basin in Honduras. The parameter space was explored using Monte-Carlo simulations and the region of space containing the parameter-sets that were considered behavioral according to two different criteria was delimited using the geometric concept of alpha-shapes. The discharge data from five internal sub-basins was used to aid in the calibration of the model and to answer the following questions: Can this information improve the simulations at the outlet of the catchment, or decrease their uncertainty? Also, after reducing the number of model parameters needing calibration through sensitivity analysis: Is it possible to relate them to basin characteristics? The analysis revealed that in most cases the internal discharge data can be used to reduce the uncertainty in the discharge at the outlet, albeit with little improvement in the overall simulation results.

  1. Pinhole Luminosity Monitor with Feedback

    SciTech Connect

    Spencer, J

    2004-05-17

    Previously, the generalized luminosity L was defined and calculated for all incident channels based on an NLC e{sup +}e{sup -} design. Alternatives were then considered to improve the differing beam-beam e{sup -}e{sup -} e{gamma} and {gamma}{gamma} channels. Regardless of the channel, there was a large flux of outgoing, high energy photons that were produced from the beam-beam interaction e.g. beamsstrahlung that needs to be disposed of and whose flux depended on L. One approach to this problem is to consider it a resource and attempt to take advantage of it by disposing of these straight-ahead photons in more useful ways than simply dumping them. While there are many options for monitoring the luminosity, any method that allows feedback and optimization in real time and in a non-intercepting and non-interfering way during normal data taking is extremely important--especially if it provides other capabilities such as high resolution tuning of spot sizes and can be used for all incident channels without essential modifications to their setup. Our ''pin-hole'' camera appears to be such a device if it can be made to work with high energy photons in ways that are compatible with the many other constraints and demands on space around the interaction region. The basis for using this method is that it has, in principle, the inherent resolution and bandwidth to monitor the very small spot sizes and their stabilities that are required for very high, integrated luminosity. While there are many possible, simultaneous uses of these outgoing photon beams, we limit our discussion to a single, blind, proof-of-principle experiment that was done on the FFTB line at SLAC to certify the concept of a camera obscura for high energy photons.

  2. Interpreting the H II Region Luminosity Function

    NASA Astrophysics Data System (ADS)

    Oey, M. S.; Clarke, C. J.

    1998-12-01

    We construct Monte Carlo simulations of the H II region luminosity function (H II LF), drawing ionizing stars from a constant stellar IMF, and the number of ionizing stars from a power-law distribution of constant slope. We find that observed variations in the form of the H II LF across the Hubble sequence can be explained by a trend in the maximum number of ionizing stars per nebula. In addition, variations in the form of the H II LF between arm and interarm populations of spiral galaxies can be explained by evolutionary effects. The H II LF can thus reveal features in the most recent (< 10 Myr) star formation history of the host galaxies.

  3. The consequences of internal waves for phytoplankton focusing on the distribution and production of Planktothrix rubescens.

    PubMed

    Hingsamer, Peter; Peeters, Frank; Hofmann, Hilmar

    2014-01-01

    Consequences of internal wave motion for phytoplankton and in particular for the distribution and production of the harmful and buoyant cyanobacterium Planktothrix rubescens were investigated based on data from two field campaigns conducted in Lake Ammer during summer 2009 and 2011. In both years, P. rubescens dominated the phytoplankton community and formed a deep chlorophyll maximum (DCM) in the metalimnion. Internal wave motions caused vertical displacement of P. rubescens of up to 6 m and 10 m, respectively. Vertical displacements of isotherms and of iso-concentration lines of P. rubescens from the same depth range coincided, suggesting that P. rubescens did not or could not regulate its buoyancy to prevent wave-induced vertical displacements. Diatoms dominated the phytoplankton community in the epilimnion and were vertically separated from P. rubescens. The thickness of the diatom layer, but not the diatom concentrations within the layer, changed in phase with the changes in the thickness of the epilimnion caused by internal wave motions. Seiche induced vertical displacements of P. rubescens caused fluctuations in the light intensity available at the depth of the P. rubescens layer. The interplay between seiche induced vertical displacements of the P. rubescens layer and the daily cycle of incident light lead to differences in the daily mean available light intensity between lake ends by up to a factor of ∼3. As a consequence, the daily mean specific oxygen production rate of P. rubescens differed by up to a factor of ∼7 between lake ends. The horizontal differences in the specific oxygen production rate of P. rubescens were persistent over several days suggesting that the associated production of P. rubescens biomass may lead to phytoplankton patchiness. The effect of internal seiches on the spatial heterogeneity and the persistence of horizontal differences in production, however, depend on the timing and the synchronization between internal wave motion

  4. Significance of major international seaports in the distribution of murine typhus in Taiwan

    PubMed Central

    Wardrop, Nicola; Chang, Chung-Te; Wang, Hsi-Chieh; Atkinson, Peter M.

    2017-01-01

    Background International seaports are hotspots for disease invasion and pathogens can persist in seaports even after ports are abandoned. Transmitted by fleas infected by Rickettsia typhi, murine typhus, a largely neglected and easily misdiagnosed disease, is known to occur primarily in large seaports. However, the significance of seaports in the occurrence of murine typhus has never been validated quantitatively. Methodology/Principal findings We studied the spatial distribution of murine typhus, a notifiable disease, in Taiwan. We investigated whether risk of infection was correlated with distance to international seaports and a collection of environmental and socioeconomic factors, using a Bayesian negative binomial conditionally autoregressive model, followed with geographically weighted regression. Seaports that are currently in use and those that operated in the 19th century for trade with China, but were later abandoned due to siltation were analyzed. A total of 476 human cases of murine typhus were reported during 2000–2014 in the main island of Taiwan, with spatial clustering in districts in southwest and central-west Taiwan. A higher incidence rate (case/population) was associated with a smaller distance to currently in-use international seaports and lower rainfall and temperature, but was uncorrelated with distance to abandoned ports. Geographically weighted regression revealed a geographic heterogeneity in the importance of distance to in-use seaports near the four international seaports of Taiwan. Conclusions/Significance Our study suggests that murine typhus is associated with international seaports, especially for those with large trading volume. Thus, one of the costs of global trade in Taiwan might be elevated risks of murine typhus. Globalization has accelerated the spread of infectious diseases, but the burden of disease varies geographically, with regions surrounding major international seaports warranting particular surveillance. PMID

  5. The galaxy luminosity function and the redshift-distance controversy (A Review)

    PubMed Central

    Salpeter, E. E.; Hoffman, G. L.

    1986-01-01

    The mean relation between distance and redshift for galaxies is reviewed as an observational question. The luminosity function for galaxies is an important ingredient and is given explicitly. We discuss various observational selection effects that are important for comparison of the linear and quadratic distance-redshift laws. Several lines of evidence are reviewed, including the distribution of galaxy luminosities in various redshift ranges, the luminosities of brightest galaxies in groups and clusters at various redshifts, and the Tully-Fisher correlation between neutral hydrogen velocity widths and luminosity. All of these strongly favor the linear law over the quadratic. PMID:16593693

  6. Implications of the Observed Ultraluminous X-Ray Source Luminosity Function

    NASA Technical Reports Server (NTRS)

    Swartz, Douglas A.; Tennant, Allyn; Soria, Roberto; Yukita, Mihoko

    2012-01-01

    We present the X-ray luminosity function (XLF) of ultraluminous X-ray (ULX) sources with 0.3-10.0 keV luminosities in excess of 10(sup 39) erg/s in a complete sample of nearby galaxies. The XLF shows a break or cut-off at high luminosities that deviates from its pure power law distribution at lower luminosities. The cut-off is at roughly the Eddington luminosity for a 90-140 solar mass accretor. We examine the effects on the observed XLF of sample biases, of small-number statistics (at the high luminosity end) and of measurement uncertainties. We consider the physical implications of the shape and normalization of the XLF. The XLF is also compared and contrasted to results of other recent surveys.

  7. Internal distribution of uranium and associated genotoxic damages in the chronically exposed bivalve Corbicula fluminea.

    PubMed

    Simon, Olivier; Floriani, Magali; Cavalie, Isabelle; Camilleri, Virginie; Adam, Christelle; Gilbin, Rodolphe; Garnier-Laplace, Jacqueline

    2011-08-01

    Uranium (U) internal distribution and involved effects in the bivalve Corbicula fluminea have been studied after direct chronic exposure (90 d, 10 μg.L-1). U distribution was assessed at the subcellular level (Metal Rich Granules -MRG-, pellets and cytosol fractions) in two main organs of the bivalve (gills and visceral mass). Micro-localisation was investigated by TEM-EDX analysis in the gills epithelium. DNA damage in gill and hemolymph samples was measured by the Comet assay. The 90-d exposure period led to a significant increase of U concentration in gills over time (× 5) and a large U quantity in subcellular granules in gills. Finally, a significant increase (× 2) in DNA damage was noted in exposed gills and haemocytes. This study shows that the accumulation levels and consequently the potential toxicity cannot be successfully predicted only on the basis of concentration in water or in tissues and subcellular fractions after chronic exposure.

  8. Composition and distribution of internal resistance in three types of microbial fuel cells.

    PubMed

    Liang, Peng; Huang, Xia; Fan, Ming-Zhi; Cao, Xiao-Xin; Wang, Cheng

    2007-12-01

    High internal resistance is a key problem limiting the power output of the microbial fuel cell (MFC). Therefore, more knowledge about the internal resistance is essential to enhance the performance of the MFC. However, different methods are used to determine the internal resistance, which makes the comparison difficult. In this study, three different types of MFCs were constructed to study the composition and distribution of internal resistance. The internal resistance (R(i)) is partitioned into anodic resistance (R(a)), cathodic resistance (R(c)), and ohmic resistance (R(Omega)) according to their origin and the design of the MFCs. These three resistances were then evaluated by the "current interrupt" method and the "steady discharging" method based on the proposed equivalent circuits for MFCs. In MFC-A, MFC-B, and MFC-C, the R(i) values were 3.17, 0.35, and 0.076 Omega m(2), the R(Omega) values were 2.65, 0.085, and 0.008 Omega m(2), the R(a) values were 0.055, 0.115, and 0.034 Omega m(2), and the R(c) values were 0.466, 0.15, and 0.033 Omega m(2), respectively. For MFC-B and MFC-C, the remarkable decrease in R(i) compared with the two-chamber MFC was mainly ascribed to the decline in R(Omega) and R(c). In MFC-C, the membrane electrodes' assembly lowered the ohmic resistance and facilitated the mass transport through the anode and cathode electrodes, resulting in the lowest R(i) among the three types.

  9. Characterizing luminosity evolution in the Tevatron

    SciTech Connect

    Shiltsev, V.; McCrory, E.; /Fermilab

    2005-05-01

    We derive an approximate form of a luminosity evolution in a high intensity hadron collider taking into account the most important phenomena of intrabeam scattering (IBS), beam burn-up due to luminosity and beam-beam effects. It is well known that an exponential decay does not describe luminosity evolution very well unless the lifetime is allowed to vary with time. However, a ''1/time'' evolution, which this derivation shows is a good approximation, fits data from the Tevatron well.

  10. Construction of luminosity function for galaxy clusters

    NASA Astrophysics Data System (ADS)

    Godłowski, Włodzimierz; Popiela, Joanna; Bajan, Katarzyna; Biernacka, Monika; Flin, Piotr; Panko, Elena

    2015-02-01

    The luminosity function is an important quantity for analysis of large scale structure statistics, interpretation of galaxy counts (Lin & Kirshner 1996). We investigate the luminosity function of galaxy clusters. This is performed by counting the brightness of galaxies belonging to clusters in PF Catalogue. The obtained luminosity function is significantly different than that obtained both for optical and radiogalaxies (Machalski & Godowski 2000). The implications of this result for theories of galaxy formation are discussed as well.

  11. The spectral energy distribution of compact jets powered by internal shocks

    NASA Astrophysics Data System (ADS)

    Malzac, Julien

    2014-09-01

    Internal shocks caused by fluctuations of the outflow velocity are likely to power the radio-to-IR emission of the compact jets of X-ray binaries. The dynamics of internal shocks and the resulting spectral energy distribution (SED) of the jet are very sensitive to the time-scales and amplitudes of the velocity fluctuations injected at the base of the jet. I present a new code designed to simulate the synchrotron emission of a compact jet powered by internal shocks. I also develop a semi-analytical formalism allowing one to estimate the observed SED of the jet as a function of the Power Spectral Density (PSD) of the assumed fluctuations of the Lorentz factor. I discuss the cases of a sine modulation of the Lorentz factor and Lorentz factor fluctuations with a power-law PSD shape. Independently of the details of the model, the observed nearly flat SEDs are obtained for PSDs of Lorentz factor fluctuations that are close to a flicker noise spectrum (i.e. P(f ) ∝ 1/f ). The model also presents a strong wavelength-dependent variability that is similar to that observed in these sources.

  12. Baroclinic internal wave energy distribution in the Baltic Sea derived from 45 years of circulation simulations

    NASA Astrophysics Data System (ADS)

    Rybin, Artem; Soomere, Tarmo; Kurkina, Oxana; Kurkin, Andrey; Rouvinskaya, Ekaterina; Markus Meier, H. E.

    2016-04-01

    Internal waves and internal tides are an essential component of the functioning of stratified shelf seas. They carry substantial amounts of energy through the water masses, drive key hydrophysical processes such as mixing and overturning and support the functioning of marine ecosystem in many ways. Their particular impact becomes evident near and at the bottom where they often create substantial loads to engineering structures and exert a wide range of impacts on the bottom sediments and evolution of the seabed. We analyse several properties of spatio-temporal distributions of energy of relatively long-period large-scale internal wave motions in the Baltic Sea. The analysis is based on numerically simulated pycnocline variations that are extracted from the hydrographic data calculated by the Rossby Centre Ocean circulation model (RCO) for the entire Baltic Sea for 1961-2005. This model has a horizontal resolution of 2 nautical miles and uses 41 vertical layers with a thickness between 3 m close to the surface and 12 m in 250 m depth. The model is forced with atmospheric data derived from the ERA-40 re-analysis using a regional atmosphere model with a horizontal resolution of 25 km. It also accounts for river inflow and water exchange through the Danish Straits. See (Meier, H.E.M., Höglund, A., 2013. Studying the Baltic Sea circulation with Eulerian tracers, in Soomere, T., Quak, E., eds., Preventive Methods for Coastal Protection, Springer, Cham, Heidelberg, 101-130) for a detailed description of the model and its forcing. The resolution of the model output used in this study (once in 6 hours) is sufficient for estimates of spectral amplitudes of the displacements of isopycnal surfaces with a typical period of 2-12 days. We provide the analysis of kinetic and potential energy of motions with these periods. The resulting maps of the maxima of energy and spatial distributions of near-bottom velocities have been evaluated for the entire simulation interval of 45

  13. Higher luminosities via alternative incident channels

    SciTech Connect

    Spencer, J.E.

    1985-04-01

    We show that PEP provides some unique opportunities for one and two photon physics with real photons as well as for QCD studies with internal targets. Photon beams would avoid the major limitation on the luminosity of present machines and could provide PEP an ideal b-physics factory producing the full range of J/sub c//sup PC/ and J/sub b//sup PC/ states that may not be observable otherwise as well as allow a whole new class of ''missing-mass'' experiments. These latter particles are the pseudo-Goldstone bosons and their supersymmetric counterparts. These and related possibilities like a single-pass, ''free electron laser'' facility or even synchrotron radiation beam lines all favor a mini-maxi configuration for the low-beta insertions in PEP. This allows more diverse experiments without excluding any ongoing experimental programs. Such possibilities have interesting implications for a number of proposed facilities including the SSC. Some systematic machine physics studies over a range of energies are suggested. 24 refs., 6 figs.

  14. Wind Variability in Intermediate Luminosity B Supergiants

    NASA Technical Reports Server (NTRS)

    Massa, Derck

    1996-01-01

    This study used the unique spectroscopic diagnostics of intermediate luminosity B supergiants to determine the ubiquity and nature of wind variability. Specifically, (1) A detailed analysis of HD 64760 demonstrated massive ejections into its wind, provided the first clear demonstration of a 'photospheric connection' and ionization shifts in a stellar wind; (2) The international 'IUE MEGA campaign' obtained unprecedented temporal coverage of wind variability in rapidly rotating stars and demonstrated regularly repeating wind features originating in the photosphere; (3) A detailed analysis of wind variability in the rapidly rotating B1 Ib, gamma Ara demonstrated a two component wind with distinctly different mean states at different epochs; (4) A follow-on campaign to the MEGA project to study slowly rotating stars was organized and deemed a key project by ESA/NASA, and will obtain 30 days of IUE observations in May-June 1996; and (5) A global survey of archival IUE time series identified recurring spectroscopic signatures, identified with different physical phenomena. Items 4 and 5 above are still in progress and will be completed this summer in collaboration with Raman Prinja at University College, London.

  15. Measurement and Data Distribution for Microgravity Accelerations on the International Space Station

    NASA Technical Reports Server (NTRS)

    McPherson, Kevin; Hrovat, Kenneth

    1999-01-01

    Two accelerometer systems will be available on the International Space Station to support microgravity payloads with information about the quasi-steady and vibratory acceleration environment of the research facilities. The Microgravity Acceleration Measurement System will record contributions to the quasi-steady microgravity environment, including the influences of aerodynamic drag, vehicle rotation, and venting effects. The Space Acceleration Measurement System-II will measure vibratory disturbances on-board due to vehicle, crew, and equipment disturbances. Due to the dynamic nature of the microgravity environment and its potential to influence sensitive experiments, NASA's Principal Investigator Microgravity Services project has initiated a plan through which the data from these instruments will be distributed to researchers in a timely and meaningful fashion. Beyond the obvious benefit of correlation between accelerations and the scientific phenomena being studied, such information is also useful for hardware developers who can gain qualitative and quantitative feedback about their facility acceleration output to station.

  16. Internal shocks at the origin of the flat spectral energy distribution of compact jets

    NASA Astrophysics Data System (ADS)

    Malzac, Julien

    2013-02-01

    An internal shock model is proposed to interpret the radio to infrared (IR) emission of the compact jets observed in the hard spectral state of X-ray binaries. Assuming that the specific bulk Lorentz factor of the jet at its base varies with a flicker noise power spectrum [i.e. P(f) ∝ 1/f], we estimate the energy dissipation profile along the jet and the resulting partially self-absorbed synchrotron emission. For this type of velocity fluctuations, and a conical jet geometry, the shock dissipation at large distance from the black hole balances exactly the adiabatic losses. This leads to a flat radio to IR spectral energy distribution similar to that observed in compact jets.

  17. Cosmological tests with the FSRQ gamma-ray luminosity function

    NASA Astrophysics Data System (ADS)

    Zeng, Houdun; Melia, Fulvio; Zhang, Li

    2016-11-01

    The extensive catalogue of gamma-ray selected flat-spectrum radio quasars (FSRQs) produced by Fermi during a four-year survey has generated considerable interest in determining their gamma-ray luminosity function (GLF) and its evolution with cosmic time. In this paper, we introduce the novel idea of using this extensive database to test the differential volume expansion rate predicted by two specific models, the concordance Λ cold dark matter (ΛCDM) and Rh = ct cosmologies. For this purpose, we use two well-studied formulations of the GLF, one based on pure luminosity evolution (PLE) and the other on a luminosity-dependent density evolution (LDDE). Using a Kolmogorov-Smirnov test on one-parameter cumulative distributions (in luminosity, redshift, photon index and source count), we confirm the results of earlier works showing that these data somewhat favour LDDE over PLE; we show that this is the case for both ΛCDM and Rh = ct. Regardless of which GLF one chooses, however, we also show that model selection tools very strongly favour Rh = ct over ΛCDM. We suggest that such population studies, though featuring a strong evolution in redshift, may none the less be used as a valuable independent check of other model comparisons based solely on geometric considerations.

  18. Using Distributed Operations to Enable Science Research on the International Space Station

    NASA Technical Reports Server (NTRS)

    Bathew, Ann S.; Dudley, Stephanie R. B.; Lochmaier, Geoff D.; Rodriquez, Rick C.; Simpson, Donna

    2011-01-01

    In the early days of the International Space Station (ISS) program, and as the organization structure was being internationally agreed upon and documented, one of the principal tenets of the science program was to allow customer-friendly operations. One important aspect of this was to allow payload developers and principle investigators the flexibility to operate their experiments from either their home sites or distributed telescience centers. This telescience concept was developed such that investigators had several options for ISS utilization support. They could operate from their home site, the closest telescience center, or use the payload operations facilities at the Marshall Space Flight Center in Huntsville, Alabama. The Payload Operations Integration Center (POIC) processes and structures were put into place to allow these different options to its customers, while at the same time maintain its centralized authority over NASA payload operations and integration. For a long duration space program with many scientists, researchers, and universities expected to participate, it was imperative that the program structure be in place to successfully facilitate this concept of telescience support. From a payload control center perspective, payload science operations require two major elements in order to make telescience successful within the scope of the ISS program. The first element is decentralized control which allows the remote participants the freedom and flexibility to operate their payloads within their scope of authority. The second element is a strong ground infrastructure, which includes voice communications, video, telemetry, and commanding between the POIC and the payload remote site. Both of these elements are important to telescience success, and both must be balanced by the ISS program s documented requirements for POIC to maintain its authority as an integration and control center. This paper describes both elements of distributed payload

  19. Effects of internal mass distribution and its isolation on the acoustic characteristics of a submerged hull

    NASA Astrophysics Data System (ADS)

    Peters, Herwig; Kinns, Roger; Kessissoglou, Nicole

    2014-03-01

    The primary aim of machinery isolation in marine vessels is to isolate structural vibration of the onboard machinery from the hull and to reduce far-field radiation of underwater noise. A substantial proportion of the total submarine mass is on flexible mounts that isolate supported masses from the hull at frequencies above the mounting system resonant frequency. This reduces the dynamically effective mass of the hull and affects the signature of the marine vessel due to propeller excitation. A fully coupled finite element/boundary element (FE/BE) model has been developed to investigate the effect of mass distribution and isolation in a submerged hull. The finite element model of the structure includes internal structures to represent the machinery and other flexibly mounted components. Changes in the radiated sound power demonstrate the effect of machinery isolation on the acoustic signature of the submerged hull due to the external propeller forces. Results are also presented to show how the arrangement of flexible mounts for a large internal structure can influence the radiation due to machinery forces.

  20. LUMINOSITY FUNCTIONS OF SPITZER-IDENTIFIED PROTOSTARS IN NINE NEARBY MOLECULAR CLOUDS

    SciTech Connect

    Kryukova, E.; Megeath, S. T.; Allen, T. S.; Gutermuth, R. A.; Pipher, J.; Allen, L. E.; Myers, P. C.; Muzerolle, J.

    2012-08-15

    We identify protostars in Spitzer surveys of nine star-forming (SF) molecular clouds within 1 kpc: Serpens, Perseus, Ophiuchus, Chamaeleon, Lupus, Taurus, Orion, Cep OB3, and Mon R2, which combined host over 700 protostar candidates. These clouds encompass a variety of SF environments, including both low-mass and high-mass SF regions, as well as dense clusters and regions of sparsely distributed star formation. Our diverse cloud sample allows us to compare protostar luminosity functions in these varied environments. We combine near- and mid-infrared photometry from the Two Micron All Sky Survey and Spitzer to create 1-24 {mu}m spectral energy distributions (SEDs). Using protostars from the c2d survey with well-determined bolometric luminosities, we derive a relationship between bolometric luminosity, mid-IR luminosity (integrated from 1-24 {mu}m), and SED slope. Estimations of the bolometric luminosities for protostar candidates are combined to create luminosity functions for each cloud. Contamination due to edge-on disks, reddened Class II sources, and galaxies is estimated and removed from the luminosity functions. We find that luminosity functions for high-mass SF clouds (Orion, Mon R2, and Cep OB3) peak near 1 L{sub Sun} and show a tail extending toward luminosities above 100 L{sub Sun }. The luminosity functions of the low-mass SF clouds (Serpens, Perseus, Ophiuchus, Taurus, Lupus, and Chamaeleon) do not exhibit a common peak, however the combined luminosity function of these regions peaks below 1 L{sub Sun }. Finally, we examine the luminosity functions as a function of the local surface density of young stellar objects. In the Orion molecular clouds, we find a significant difference between the luminosity functions of protostars in regions of high and low stellar density, the former of which is biased toward more luminous sources. This may be the result of primordial mass segregation, although this interpretation is not unique. We compare our luminosity

  1. Selected papers from Middleware'98: The IFIP International Conference on Distributed Systems Platforms and Open Distributed Processing

    NASA Astrophysics Data System (ADS)

    Davies, Nigel; Raymond, Kerry; Blair, Gordon

    1999-03-01

    In recent years the distributed systems community has witnessed a growth in the number of conferences, leading to difficulties in tracking the literature and a consequent loss of awareness of work done by others in this important research domain. In an attempt to synthesize many of the smaller workshops and conferences in the field, and to bring together research communities which were becoming fragmented, IFIP staged Middleware'98: The IFIP International Conference on Distributed Systems Platforms and Open Distributed Processing. The conference was widely publicized and attracted over 150 technical submissions including 135 full paper submissions. The final programme consisted of 28 papers, giving an acceptance ratio of a little over one in five. More crucially, the programme accurately reflected the state of the art in middleware research, addressing issues such as ORB architectures, engineering of large-scale systems and multimedia. The traditional role of middleware as a point of integration and service provision was clearly intact, but the programme stressed the importance of emerging `must-have' features such as support for extensibility, mobility and quality of service. The Middleware'98 conference was held in the Lake District, UK in September 1998. Over 160 delegates made the journey to one of the UK's most beautiful regions and contributed to a lively series of presentations and debates. A permanent record of the conference, including transcripts of the panel discussions which took place, is available at: http://www.comp.lancs.ac.uk/computing/middleware98/ Based on their original reviews and the reactions of delegates to the ensuing presentations we have selected six papers from the conference for publication in this special issue of Distributed Systems Engineering. The first paper, entitled `Jonathan: an open distributed processing environment in Java', by Dumant et al describes a minimal, modular ORB framework which can be used for supporting real

  2. Investigation of Spectral Lag and Epeak as Joint Luminosity Indicators in GRBs

    NASA Technical Reports Server (NTRS)

    White, Nicholas E. (Technical Monitor); Norris, Jay P.

    2003-01-01

    Models for gamma-ray bursts which invoke jetted, colliding shells would appear to have at least two determinants for luminosity, e.g., observer viewing angle and Lorentz factor, or possibly shell mass. The latter two internal physical parameters may vary from pulse to pulse within a burst, and such variation might be reflected in evolution of observables such as spectral lag and peak in the spectral energy distribution. We analyze bright BATSE bursts using the 16-channel medium energy resolution (MER) data, with time resolutions of 16 and 64 ms, measuring spectral lags and peak energies for significant pulse structures within a burst, identified using a Bayesian block algorithm. We then explore correlations between the measured parameters and total flux for the individual pulse structures.

  3. The internal energy distribution of NO and N 2 scattering from defective surfaces

    NASA Astrophysics Data System (ADS)

    Pierro, William; Castejón, Henry J.

    2008-11-01

    The internal energy distribution of NO and N 2 scattering from a defective surfaces has been studied using classical molecular dynamics. Stochastic trajectory simulations were used to calculate the final rotational excitation, angular distribution and trapping probabilities of N 2 and NO scattering from clean Ag(1 1 1) surfaces, with adatoms and with vacancies. Calculations reproduce well the experimental results for NO and N 2 scattering from clean surfaces. NO undergoes more extensive rotational excitation than N 2 on clean and defective surfaces. Scattering is more inelastic on defective surfaces and adatoms defects appear to promote rotational excitation more efficiently than vacancies. Trapping exhibits a complex behavior. Dynamical corrugation causes trapping of NO on clean Ag(1 1 1) to exhibit a "crossover" behavior. That is, the value of n in the standard functional dependence of trapping on the incident energy, Eicos nθi, switches sign as the incident energy increases. This behavior is also observed in the case of N 2 scattering from a surface with adatoms, but in this case is caused by the static corrugation. It appears that the breaking of the 2-D symmetry of the surface (i.e. static corrugation) compensates for the lack of anisotropy in the interaction potential (i.e. dynamical corrugation) for N 2/Ag(1 1 1). Adatom defects increase trapping for NO molecules impinging on the surface with glancing trajectories while vacancies have the opposite effect.

  4. Inhomogeneous longitudinal distribution of Ni atoms on graphene induced by layer-number-dependent internal diffusion

    NASA Astrophysics Data System (ADS)

    Hasegawa, M.; Tashima, K.; Kotsugi, M.; Ohkochi, T.; Suemitsu, M.; Fukidome, H.

    2016-09-01

    The intrinsic transport properties, such as carrier mobility and saturation velocity, of graphene are the highest among materials owing to its linear band dispersion and weak backscattering. However, the reported field-effect mobility of transistors using graphene as a channel is much lower than the intrinsic channel mobility. One of the reasons for this low mobility is the high contact resistance between graphene and metals used for the source and drain electrodes, which results from the interfacial roughness. Even Ni, which is a promising contact metal for many materials because of its high adhesion and lower contact resistance, does not meet the requirement as a contact metal for graphene. Noticing that the interfacial roughness between the a metal and graphene is strongly related to the onset of the contact resistance, we performed transmission electron microscopy and photoemission electron microscopy measurements to evaluate the microscopic lateral and longitudinal distributions of Ni atoms at the Ni/graphene interface formed on epitaxial graphene (EG) on 4H-SiC(0001). Our data revealed that the deposited Ni atoms diffused into the EG layers, but they did not reach the EG/SiC interface, and the diffusion was stronger on bilayered graphene than on monolayered graphene. We thus ascribe the layer-number-dependent internal diffusion of Ni atoms in EG as a cause of the microscopic interfacial roughness between graphene and the metal. Ensuring homogeneous distribution of the number of EG layers should be key to lowering the contact resistance.

  5. Preparation of ring-shaped composite bonded magnets with continuously controlled anisotropy distribution for internal space

    NASA Astrophysics Data System (ADS)

    Yamashita, F.; Yamada, O.; Ohya, S.; Kobayashi, O.; Nakano, M.; Fukunaga, H.

    2010-01-01

    We have already reported an advanced method for producing a radially-anisotropic rare earth composite bonded magnet with continuously controlled direction of anisotropy. The magnet has been applied to an inner rotor as a practical usage. In this study, the outstanding preparation method was adopted into the preparation of a magnet applied for an outer rotor. An optimized condition of extrusion and compaction at an elevated temperature could be obtained. In addition, a low pressure configuration to the ring-shaped magnet from plural preformed magnets was carried out, which had specific distribution of magnetic anisotropy for internal space for a small motor, by using self recoverability based on the viscous deformation without an alignment field. No deterioration of magnetic properties was detected through the process even if those magnets were miniaturized. Resultantly, the (BH)max of a ring-shaped magnet with the continuously controlled direction of magnetic anisotropy attained the value of 186 kJ/m3, and we obtained sine-wave magnetic anisotropy distribution, even if those magnets were miniaturized.

  6. Phylogenetic structure of European Salmonella Enteritidis outbreak correlates with national and international egg distribution network

    PubMed Central

    Inns, Thomas; Jombart, Thibaut; Ashton, Philip; Loman, Nicolas; Chatt, Carol; Messelhaeusser, Ute; Rabsch, Wolfgang; Simon, Sandra; Nikisins, Sergejs; Bernard, Helen; le Hello, Simon; Jourdan da-Silva, Nathalie; Kornschober, Christian; Mossong, Joel; Hawkey, Peter; de Pinna, Elizabeth; Grant, Kathie; Cleary, Paul

    2016-01-01

    Outbreaks of Salmonella Enteritidis have long been associated with contaminated poultry and eggs. In the summer of 2014 a large multi-national outbreak of Salmonella Enteritidis phage type 14b occurred with over 350 cases reported in the United Kingdom, Germany, Austria, France and Luxembourg. Egg supply network investigation and microbiological sampling identified the source to be a Bavarian egg producer. As part of the international investigation into the outbreak, over 400 isolates were sequenced including isolates from cases, implicated UK premises and eggs from the suspected source producer. We were able to show a clear statistical correlation between the topology of the UK egg distribution network and the phylogenetic network of outbreak isolates. This correlation can most plausibly be explained by different parts of the egg distribution network being supplied by eggs solely from independent premises of the Bavarian egg producer (Company X). Microbiological sampling from the source premises, traceback information and information on the interventions carried out at the egg production premises all supported this conclusion. The level of insight into the outbreak epidemiology provided by whole-genome sequencing (WGS) would not have been possible using traditional microbial typing methods. PMID:28348865

  7. Magnetic Coulomb fields of monopoles in spin ice and their signatures in the internal field distribution.

    PubMed

    Sala, G; Castelnovo, C; Moessner, R; Sondhi, S L; Kitagawa, K; Takigawa, M; Higashinaka, R; Maeno, Y

    2012-05-25

    Fractionalization-the breaking up of an apparently indivisible microscopic degree of freedom-is one of the most counterintuitive phenomena in many-body physics. Here we study its most fundamental manifestation in spin ice, the only known fractionalized magnetic compound in 3D: we directly visualize the 1/r(2) magnetic Coulomb field of monopoles that emerge as the atomic magnetic dipoles fractionalize. We analyze the internal magnetic field distribution, relevant for local experimental probes. In particular, we present new zero-field NMR measurements that exhibit excellent agreement with the calculated line shapes, noting that this experimental technique can in principle measure directly the monopole density in spin ice. The distribution of field strengths is captured by a simple analytical form that exhibits a low density of low-field sites-in apparent disagreement with reported muon spin rotation results. Counterintuitively, the density of low-field locations decreases as the local ferromagnetic correlations imposed by the ice rules weaken.

  8. Cross-cultural differences in color preferences: implication for international film distribution

    NASA Astrophysics Data System (ADS)

    Lee, Kyung Jae

    2002-06-01

    This paper proposes the necessity of manipulating colors of movie contents to fit diverse audiences around the world. Since films are highly color-dependent messages, it is critical to understand how people in different cultures respond differently to color. In recent years, the international market for filmed entertainment has grown more than the U.S. market. However, a lack of research on audience preferences shows no constant guide for the motion picture industry. The film production stage is often disregarded to deliver the appropriate visual color contents for local audience when U.S. films are distributed to foreign markets. Therefore, it is assumed that it would cause distractions for local audiences and it could result in poor ticket sales. When the U.S. produced films are distributed in Asia, colors of original films are always shown without manipulation. It is common that when a U.S. manufactured car is imported to Japan, a driver seat is installed on the right side and also other parts are modified for local customers. Film development is also significantly dependent on audience behavior, so film content also needs to be localized for the different culture. This paper will only address a hypothesis of the implementation of color marketing methodology present in motion pictures.

  9. Phylogenetic structure of European Salmonella Enteritidis outbreak correlates with national and international egg distribution network.

    PubMed

    Dallman, Tim; Inns, Thomas; Jombart, Thibaut; Ashton, Philip; Loman, Nicolas; Chatt, Carol; Messelhaeusser, Ute; Rabsch, Wolfgang; Simon, Sandra; Nikisins, Sergejs; Bernard, Helen; le Hello, Simon; Jourdan da-Silva, Nathalie; Kornschober, Christian; Mossong, Joel; Hawkey, Peter; de Pinna, Elizabeth; Grant, Kathie; Cleary, Paul

    2016-08-01

    Outbreaks of Salmonella Enteritidis have long been associated with contaminated poultry and eggs. In the summer of 2014 a large multi-national outbreak of Salmonella Enteritidis phage type 14b occurred with over 350 cases reported in the United Kingdom, Germany, Austria, France and Luxembourg. Egg supply network investigation and microbiological sampling identified the source to be a Bavarian egg producer. As part of the international investigation into the outbreak, over 400 isolates were sequenced including isolates from cases, implicated UK premises and eggs from the suspected source producer. We were able to show a clear statistical correlation between the topology of the UK egg distribution network and the phylogenetic network of outbreak isolates. This correlation can most plausibly be explained by different parts of the egg distribution network being supplied by eggs solely from independent premises of the Bavarian egg producer (Company X). Microbiological sampling from the source premises, traceback information and information on the interventions carried out at the egg production premises all supported this conclusion. The level of insight into the outbreak epidemiology provided by whole-genome sequencing (WGS) would not have been possible using traditional microbial typing methods.

  10. Impact of Internal Metallic Ports in Temporary Tissue Expanders on Postmastectomy Radiation Dose Distribution

    SciTech Connect

    Chen, Susie A.; Ogunleye, Tomiwa; Dhabbaan, Anees; Huang, Eugene H.; Losken, Albert; Gabram, Sheryl; Davis, Lawrence; Torres, Mylin A.

    2013-03-01

    Purpose: Temporary tissue expanders (TTE) with an internal magnetic metal port (IMP) have been increasingly used for breast reconstruction in post-mastectomy patients who receive radiation therapy (XRT). We evaluated XRT plans of patients with IMP to determine its effect on XRT dose distribution. Methods and Materials: Original treatment plans with CT simulation scans of 24 consecutive patients who received XRT (ORI), planned without heterogeneity corrections, to a reconstructed breast containing an IMP were used. Two additional treatment plans were then generated: one treatment plan with the IMP assigned the electron density of the rare earth magnet, nickel plated neodymium-iron-boron (HET), and a second treatment plan with the IMP assigned a CT value of 1 to simulate a homogeneous breast without an IMP (BRS). All plans were prescribed 50 Gy to the reconstructed breast (CTV). Results: CTV coverage by 50 Gy was significantly lower in the HET (mean 87.7% CTV) than in either the ORI (mean 99.7% CTV, P<.001) or BRS plans (mean 95.0% CTV, P<.001). The effect of the port was more pronounced on CT slices containing the IMP with prescription dose coverage of the CTV being less in the HET than in either ORI (mean difference 33.6%, P<.01) or BRS plans (mean difference 30.1%, P<.001). HET had a less homogeneous and conformal dose distribution than BRS or ORI. Conclusion: IMPs increase dose heterogeneity and reduce dose to the breast CTV through attenuation of the beam. For optimal XRT treatment, heterogeneity corrections should be used in XRT planning for patients with TTE with IMP, as the IMP impacts dose distribution.

  11. Finding and characterising WHIM structures using the luminosity density method

    NASA Astrophysics Data System (ADS)

    Nevalainen, Jukka; Liivamägi, L. J.; Tempel, E.; Branchini, E.; Roncarelli, M.; Giocoli, C.; Heinämäki, P.; Saar, E.; Bonamente, M.; Einasto, M.; Finoguenov, A.; Kaastra, J.; Lindfors, E.; Nurmi, P.; Ueda, Y.

    2016-10-01

    We have developed a new method to approach the missing baryons problem. We assume that the missing baryons reside in a form of Warm Hot Intergalactic Medium, i.e. the WHIM. Our method consists of (a) detecting the coherent large scale structure in the spatial distribution of galaxies that traces the Cosmic Web and that in hydrodynamical simulations is associated to the WHIM, (b) mapping its luminosity into a galaxy luminosity density field, (c) using numerical simulations to relate the luminosity density to the density of the WHIM, (d) applying this relation to real data to trace the WHIM using the observed galaxy luminosities in the Sloan Digital Sky Survey and 2dF redshift surveys. In our application we find evidence for the WHIM along the line of sight to the Sculptor Wall, at redshifts consistent with the recently reported X-ray absorption line detections. Our indirect WHIM detection technique complements the standard method based on the detection of characteristic X-ray absorption lines, showing that the galaxy luminosity density is a reliable signpost for the WHIM. For this reason, our method could be applied to current galaxy surveys to optimise the observational strategies for detecting and studying the WHIM and its properties. Our estimates of the WHIM hydrogen column density N H in Sculptor agree with those obtained via the X-ray analysis. Due to the additional N H estimate, our method has potential for improving the constrains of the physical parameters of the WHIM as derived with X-ray absorption, and thus for improving the understanding of the missing baryons problem.

  12. Bolometric Luminosities of 3 New Bright Lensed Galaxies

    NASA Astrophysics Data System (ADS)

    Rigby, Jane; Chen, Hsiao-Wen; Gladders, Mike; Papovich, Casey

    2008-08-01

    We propose DDT observations of three recently--discovered, very bright, lensed galaxies. We propose IRAC, 24, and 70 um photometry and IRS LL1 spectra for SDSS1226+2152, an extremely bright UV--selected galaxy at z=2.93. Because this galaxy is a full magnitude brighter in g-band than cB58 (the longstanding Rosetta Stone), its optical spectrum provides a resolved, high-S/N window into stellar populations, star formation, and star formation history at high redshift. Spitzer observations will constrain the stellar mass, measure the bolometric luminosity, and measure the 7.7um aromatic luminosity. Because this galaxy was not discovered until Jan 2008, it could not have been proposed in Cycle 5. We also propose 70um photometry for two UV-selected lensed galaxies at z=1.7 and z=2.73, RCS0327-1326 and SDSS1527+0652. These galaxies were discovered in late 2007. Photometry at 70um will measure the bolometric luminosities of these three galaxies. LL1 spectroscopy for S1226 will accurately measure the 7.7um aromatic luminosity. Together, these observations will enable us to: * determine the spectral energy distributions of Lyman break galaxies; * test whether the strange SED of cB58 is anomalous or typical; * test whether the aromatic--to--bolometric luminosity ratios of these galaxies evolve with redshift (as do IR--selected lensed galaxies); compare near-IR, mid-IR, and optical diagnostics of star formation rate; * and work to understand the relationship between IR--selected and UV--selected star--forming galaxies.

  13. The effect of anisotropic emission from thick accretion disks on the luminosity functions of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Urry, C. M.; Marziani, P.; Calvani, M.

    1991-01-01

    High-luminosity active galactic nuclei (AGNs) powered by accretion onto a massive black hole (or other compact object) may have bolometric luminosities dominated by thermal emission from a geometrically thick accretion disk. Radiation from these disks is strongly anisotropic, which has important consequences for the observed luminosity distribution, and therefore for systematic biases in flux-limited samples. The effect of anisotropic emission from an ensemble of AGNs with random oriented thick disks radiating at or near the Eddington limit is calculated. Because of their higher luminosities, it is predicted face-on disks should constitute an increasing fraction of observed high-redshift, high-luminosity AGNs. Comparison of the results with observed quasar luminosity functions suggests a narrow mass distribution with an upper limit of about a billion solar masses for high-redshift quasars.

  14. Size dependence of the radio-luminosity-mechanical-power correlation in radio galaxies

    SciTech Connect

    Shabala, S. S.; Godfrey, L. E. H.

    2013-06-01

    We examine the relationship between source radio luminosity and kinetic power in active galactic nucleus jets. We show that neglecting various loss processes can introduce a systematic bias in the jet powers inferred from radio luminosities for a sample of radio galaxies. This bias can be corrected for by considering source size as well as radio luminosity; effectively the source size acts as a proxy for source age. Based on a sample of Fanaroff-Riley Type II radio sources with jet powers derived from the measured hotspot parameters, we empirically determine a new expression for jet power that accounts for the source size, (Q{sub jet}/10{sup 36} W)=1.5{sub −0.8}{sup +1.8}(L{sub 151}/10{sup 27} W Hz{sup −1}){sup 0.8}(1+z){sup 1.0}(D/kpc){sup 0.58±0.17}, where D is source size and L {sub 151} the 151 MHz radio luminosity. By comparing a flux-limited and volume-limited sample, we show that any derived radio-luminosity-jet-power relation depends sensitively on sample properties, in particular the source size distribution and the size-luminosity correlation inherent in the sample. Such bias will affect the accuracy of the kinetic luminosity function derived from lobe radio luminosities and should be treated with caution.

  15. Lessons Learned In Developing Multiple Distributed Planning Systems for the International Space Station

    NASA Technical Reports Server (NTRS)

    Maxwell, Theresa G.; McNair, Ann R. (Technical Monitor)

    2002-01-01

    The planning processes for the International Space Station (ISS) Program are quite complex. Detailed mission planning for ISS on-orbit operations is a distributed function. Pieces of the on-orbit plan are developed by multiple planning organizations, located around the world, based on their respective expertise and responsibilities. The "pieces" are then integrated to yield the final detailed plan that will be executed onboard the ISS. Previous space programs have not distributed the planning and scheduling functions to this extent. Major ISS planning organizations are currently located in the United States (at both the NASA Johnson Space Center (JSC) and NASA Marshall Space Flight Center (MSFC)), in Russia, in Europe, and in Japan. Software systems have been developed by each of these planning organizations to support their assigned planning and scheduling functions. Although there is some cooperative development and sharing of key software components, each planning system has been tailored to meet the unique requirements and operational environment of the facility in which it operates. However, all the systems must operate in a coordinated fashion in order to effectively and efficiently produce a single integrated plan of ISS operations, in accordance with the established planning processes. This paper addresses lessons learned during the development of these multiple distributed planning systems, from the perspective of the developer of one of the software systems. The lessons focus on the coordination required to allow the multiple systems to operate together, rather than on the problems associated with the development of any particular system. Included in the paper is a discussion of typical problems faced during the development and coordination process, such as incompatible development schedules, difficulties in defining system interfaces, technical coordination and funding for shared tools, continually evolving planning concepts/requirements, programmatic

  16. Lessons Learned in Developing Multiple Distributed Planning Systems for the International Space Station

    NASA Technical Reports Server (NTRS)

    Maxwell, Theresa G.

    2002-01-01

    The planning processes for the International Space Station (ISS) Program are quite complex. Detailed mission planning for ISS on-orbit operations is a distributed function. Pieces of the on-orbit plan are developed by multiple planning organizations, located around the world, based on their respective expertise and responsibilities. The pieces are then integrated to yield the final detailed plan that will be executed onboard the ISS. Previous space programs have not distributed the planning and scheduling functions to this extent. Major ISS planning organizations are currently located in the United States (at both the NASA Johnson Space Center (JSC) and NASA Marshall Space Flight Center (MSFC)), in Russia, in Europe, and in Japan. Software systems have been developed by each of these planning organizations to support their assigned planning and scheduling functions. Although there is some cooperative development and sharing of key software components, each planning system has been tailored to meet the unique requirements and operational environment of the facility in which it operates. However, all the systems must operate in a coordinated fashion in order to effectively and efficiently produce a single integrated plan of ISS operations, in accordance with the established planning processes. This paper addresses lessons learned during the development of these multiple distributed planning systems, from the perspective of the developer of one of the software systems. The lessons focus on the coordination required to allow the multiple systems to operate together, rather than on the problems associated with the development of any particular system. Included in the paper is a discussion of typical problems faced during the development and coordination process, such as incompatible development schedules, difficulties in defining system interfaces, technical coordination and funding for shared tools, continually evolving planning concepts/requirements, programmatic and

  17. Results From the DAFNE High Luminosity Test

    SciTech Connect

    Milardi, C.; Alesini, D.; Biagini, M.E.; Boni, R.; Boscolo, M.; Bossi, F.; Buonomo, B.; Clozza, A.; Delle Monache, G.; Demma, T.; Di Pasquale, E.; Di Pirro, G.; Drago, A.; Gallo, A.; Ghigo, A.; Guiducci, S.; Ligi, C.; Marcellini, F.; Mazzitelli, G.; Murtas, F.; Pellegrino, L.; /Frascati /Novosibirsk, IYF /CERN /INFN, Cosenza /INFN, Rome /KEK, Tsukuba /Orsay, LAL /Rome U. /Pisa U. /INFN, Pisa /INFN, Rome3 /SLAC

    2012-04-11

    The DAPHNE collider, based on a new collision scheme including Large Piwinsky angle and Crab-Waist, has been successfully commissioned and is presently delivering luminosity to the SIDDHARTA detector. Large crossing angle and Crab-Waist scheme proved to be effective in: (1) Increasing luminosity, now a factor 2.7 higher than in the past; and (2) controlling transverse beam blow-up due to the beam-beam. Work is in progress to reach the ultimate design luminosity goal 5.0 {center_dot} 10{sup 32} cm{sup -2}s{sup -1}. The new collision scheme is the main design concept for a new project aimed at building a Super-B factory that is expected to achieve a luminosity of the order of 10{sup 36} cm{sup -2} s{sup -1} and it has been also taken into account to upgrade one of the LHC interaction regions.

  18. Calibration of a Physically-Based Semi-Distributed Hydrologic Model: The Importance of Internal Justification

    NASA Astrophysics Data System (ADS)

    Tasdighi, A.; Arabi, M.

    2014-12-01

    Calibration of physically-based distributed hydrologic models has always been a challenging task and subject of controversy in the literature. This study is aimed to investigate how different physiographic characteristics of watersheds call for adaption of the methods used in order to have more robust and internally justifiable simulations. Haw Watershed (1300 sq. mi.) is located in the piedmont region of North Carolina draining into B. Everett Jordan Lake located in west of Raleigh. Major land covers in this watershed are forest (50%), urban/suburban (21%) and agriculture (25%) of which a large portion is pasture. Different hydrologic behaviors are observed in this watershed based on the land use composition and size of the sub-watersheds. Highly urbanized sub-watersheds show flashier hydrographs and near instantaneous hydrologic responses. This is also the case with smaller sub-watersheds with relatively lower percentage of urban areas. The Soil and Water Assessment Tool (SWAT) has been widely used in the literature for hydrologic simulation on daily basis using Soil Conservation Service Curve Number method (SCS CN). However, it has not been used as frequently using the sub-daily routines. In this regard there are a number of studies in the literature which have used coarse time scale (daily) precipitation with methods like SCS CN to calibrate SWAT for watersheds containing different types of land uses and soils reporting satisfying results at the outlet of the watershed. This is while for physically-based distributed models, the more important concern should be to check and analyze the internal processes leading to those results. In this study, the watershed is divided into several sub-watersheds to compare the performance of SCS CN and Green & Ampt (GA) methods on different land uses at different spatial scales. The results suggest better performance of GA compared to SCS CN for smaller and highly urbanized sub-watersheds although GA predominance is not very

  19. Novel method of determination of the internal enzyme distribution within porous solid supports and the deactivation rate constant

    SciTech Connect

    Do, D.D.; Hossain, M.M.

    1986-04-01

    This article presents a method for determining the rate constant for deactivation and the internal distribution of immobilized enzyme. This method makes use of the parallel deactivation process in a diffusion-controlled regime, in which the internal activity profile behaves like a penetration front. This front basically traces through the initial active enzymatic profile, and one can determine the internal profile and the rate constant for deactivation from the experimentally observable bulk concentration versus time. This method is applied to the experimental data of the system of hydrogen peroxide-immobilized catalase on controlled pore glas and Si-Al particles. 26 references.

  20. The luminosity of Population III star clusters

    NASA Astrophysics Data System (ADS)

    DeSouza, Alexander L.; Basu, Shantanu

    2015-06-01

    We analyse the time evolution of the luminosity of a cluster of Population III protostars formed in the early Universe. We argue from the Jeans criterion that primordial gas can collapse to form a cluster of first stars that evolve relatively independently of one another (i.e. with negligible gravitational interaction). We model the collapse of individual protostellar clumps using non-axisymmetric numerical hydrodynamics simulations. Each collapse produces a protostar surrounded by a massive disc (i.e. Mdisc /M* ≳ 0.1), whose evolution we follow for a further 30-40 kyr. Gravitational instabilities result in the fragmentation and the formation of gravitationally bound clumps within the disc. The accretion of these fragments by the host protostar produces accretion and luminosity bursts on the order of 106 L⊙. Within the cluster, we show that a simultaneity of such events across several protostellar cluster members can elevate the cluster luminosity to 5-10 times greater than expected, and that the cluster spends ˜15 per cent of its star-forming history at these levels. This enhanced luminosity effect is particularly enabled in clusters of modest size with ≃10-20 members. In one such instance, we identify a confluence of burst events that raise the luminosity to nearly 1000 times greater than the cluster mean luminosity, resulting in L > 108 L⊙. This phenomenon arises solely through the gravitational-instability-driven episodic fragmentation and accretion that characterizes this early stage of protostellar evolution.

  1. The relationship of internalized racism to body fat distribution and insulin resistance among African adolescent youth.

    PubMed

    Chambers, Earle C; Tull, Eugene S; Fraser, Henry S; Mutunhu, Nyasha R; Sobers, Natasha; Niles, Elisa

    2004-12-01

    This study examined the relationship of internalized racism (INR) and hostility to body fat distribution and insulin resistance in black adolescent children age 14-16 years on the Caribbean island of Barbados. Questionnaire data on psychosocial variables and anthropometric measurements, together with a fasting blood sample, were obtained from 53 low-birthweight and 119 normal-birthweight adolescents. Insulin resistance was calculated using the homeostasis model assessment (HOMA). Spearman correlation analyses showed that both INR (r = 0.244) and hostility (r = 0.204) were significantly (p < 0.05) correlated with waist circumference in girls but not boys. Among girls, age- and birthweight-adjusted mean levels of BMI and waist circumference were greater for those with high levels of INR and hostility compared to those with low levels of both variables. In multiple logistic regression analyses, a high INR remained independently associated [odds ratio = 3.30 (95% CI = 1.30-8.36); p = 0.012] with having an elevated HOMA value in models that included age, income, birthweight, hostility, physical activity and family history of diabetes. The results of the current study show that the positive relationship between INR and metabolic health risk seen in African-Caribbean adults also exists in African Caribbean adolescent youth independent of birthweight.

  2. Operational results from the LHC luminosity monitors

    SciTech Connect

    Miyamoto, R.; Ratti, A.; Matis, H.S.; Stezelberger, T.; Turner, W.C.; Yaver, H.; Bravin, E.

    2011-03-28

    The luminosity monitors for the high luminosity regions in the LHC have been operating to monitor and optimize the luminosity since 2009. The device is a gas ionization chamber inside the neutral particle absorber 140 m from the interaction point and monitors showers produced by high energy neutral particles from the collisions. It has the ability to resolve the bunch-by-bunch luminosity as well as to survive the extreme level of radiation in the nominal LHC operation. We present operational results of the device during proton and lead ion operations in 2010 and make comparisons with measurements of experiments. The Large Hadron Collider (LHC) at CERN can accelerate proton and lead ion beams to 7 TeV and 547 TeV and produce collisions of these particles. Luminosity measures performance of the LHC and is particularly important for experiments in high luminosity interaction points (IPs), ATLAS (IP1) and CMS (IP5). To monitor and optimize the luminosities of these IPs, BRAN (Beam RAte Neutral) detectors [1, 2] have been installed and operating since the beginning of the 2009 operation [3]. A neutral particle absorber (TAN) protects the D2 separation dipole from high energy forward neutral particles produced in the collisions [4]. These neutral particles produce electromagnetic and hadronic showers inside the TAN and their energy flux is proportional to the collision rate and hence to the luminosity. The BRAN detector is an Argon gas ionization chamber installed inside the TANs on both sides of the IP1 and IP5 and monitors the relative changes in the luminosity by detecting the ionization due to these showers. When the number of collisions per bunch crossing (multiplicity) is small, the shower rate inside the TAN is also proportional to the luminosity. Hence, the detector is designed to operate by measuring either the shower rate (counting mode for low and intermediate luminosities) or the average shower flux (pulse height mode for high luminosities). The detector is

  3. Modeling of the internal fields distribution in human inner hearing system exposed to 900 and 1800 MHz.

    PubMed

    Parazzini, Marta; Tognola, Gabriella; Franzoni, Claudia; Grandori, Ferdinando; Ravazzani, Paolo

    2007-01-01

    This paper investigates the internal electric and magnetic field distribution and the specific absorption rate (SAR) values in a magnetic resonance imaging-based model of the inner hearing system exposed to 900 and 1800 MHz. The internal fields distributions were calculated using the Finite Integration Technique. The estimation of the field values was evaluated along lines passing through that target organ, specifically from the vestibular to the cochlear region and from the apex to the base of the cochlea. The specific findings are: 1) higher internal fields strength and SAR value in the vestibular region rather than in the auditory region, especially for the inner ear closer to the external source; 2) higher internal fields strength in the basal and apical region of the cochlea than in the middle one; 3) local differences in the internal fields distribution and SAR value, comparing the head models including or not the inner auditory system model; 4) results' variability evaluated by changing the head-source mutual position and the dielectric properties of the inner hearing system.

  4. Non-thermal internal energy distribution of ions observed in an electrospray source interfaced with a sector mass spectrometer.

    PubMed

    Rondeau, David; Galland, Nicolas; Zins, Emilie-Laure; Pepe, Claude; Drahos, László; Vékey, Károly

    2011-02-01

    The internal energy distribution P(E(int)) of ions emitted in an electrospray (ESI) source interfaced with a sector mass spectrometer is evaluated by using the experimental survival yield (SY) method including the kinetic shift. This method is based on the relationship between the degree of fragmentation of an ion and its amount of internal energy and uses benzylpyridinium cations due to their simple fragmentation scheme. Quantum chemical calculations are performed, namely at G3(MP2)//B3LYP and QCISD/MP2 levels of theory. The results show that the internal energy distribution of the ions emitted in the ESI source interfaced with a sector analyzer is very narrow. The MassKinetics software is used to confirm these observations. The P(E(int)) is the parameter that allows to fit the experimental SY of each substituted benzylpyridinium cation with theoretical mass spectra generated by the MassKinetics software. The resulting internal energy distributions are similar to the ones obtained with the experimental SY method. This indicates that in the present experimental conditions, P(E(int)) cannot be compared with a 'thermal-like' Boltzmann distribution. In addition, it appears that with the sector analyzer, increasing the collision energy in the first pumping stage of the ESI source does not correspond to a warm-up of the produced ions.

  5. Mapping fluorophore distributions in three dimensions by quantitative multiple angle-total internal reflection fluorescence microscopy.

    PubMed Central

    Olveczky, B P; Periasamy, N; Verkman, A S

    1997-01-01

    The decay of evanescent field intensity beyond a dielectric interface depends upon beam incident angle, enabling the 3-d distribution of fluorophores to be deduced from total internal reflection fluorescence microscopy (TIRFM) images obtained at multiple incident angles. Instrumentation was constructed for computer-automated multiple angle-TIRFM (MA-TIRFM) using a right angle F2 glass prism (n(r) 1.632) to create the dielectric interface. A laser beam (488 nm) was attenuated by an acoustooptic modulator and directed onto a specified spot on the prism surface. Beam incident angle was set using three microstepper motors controlling two rotatable mirrors and a rotatable optical flat. TIRFM images were acquired by a cooled CCD camera in approximately 0.5 degree steps for >15 incident angles starting from the critical angle. For cell studies, cells were grown directly on the glass prisms (without refractive index-matching fluid) and positioned in the optical path. Images of the samples were acquired at multiple angles, and corrected for angle-dependent evanescent field intensity using "reference" images acquired with a fluorophore solution replacing the sample. A theory was developed to compute fluorophore z-distribution by inverse Laplace transform of angle-resolved intensity functions. The theory included analysis of multiple layers of different refractive index for cell studies, and the anisotropic emission from fluorophores near a dielectric interface. Instrument performance was validated by mapping the thickness of a film of dihexyloxacarbocyanine in DMSO/water (n(r) 1.463) between the F2 glass prism and a plano-convex silica lens (458 mm radius, n(r) 1.463); the MA-TIRFM map accurately reproduced the lens spherical surface. MA-TIRFM was used to compare with nanometer z-resolution the geometry of cell-substrate contact for BCECF-labeled 3T3 fibroblasts versus MDCK epithelial cells. These studies establish MA-TIRFM for measurement of submicroscopic distances between

  6. A SYSTEMATIC SEARCH FOR MOLECULAR OUTFLOWS TOWARD CANDIDATE LOW-LUMINOSITY PROTOSTARS AND VERY LOW LUMINOSITY OBJECTS

    SciTech Connect

    Schwarz, Kamber R.; Shirley, Yancy L.; Dunham, Michael M.

    2012-10-01

    We present a systematic single-dish search for molecular outflows toward a sample of nine candidate low-luminosity protostars and 30 candidate very low luminosity objects (VeLLOs; L{sub int} {<=} 0.1 L{sub Sun }). The sources are identified using data from the Spitzer Space Telescope cataloged by Dunham et al. toward nearby (D < 400 pc) star-forming regions. Each object was observed in {sup 12}CO and {sup 13}CO J = 2 {yields} 1 simultaneously using the sideband separating ALMA Band-6 prototype receiver on the Heinrich Hertz Telescope at 30'' resolution. Using five-point grid maps, we identify five new potential outflow candidates and make on-the-fly maps of the regions surrounding sources in the dense cores B59, L1148, L1228, and L1165. Of these new outflow candidates, only the map of B59 shows a candidate blue outflow lobe associated with a source in our survey. We also present larger and more sensitive maps of the previously detected L673-7 and the L1251-A-IRS4 outflows and analyze their properties in comparison to other outflows from VeLLOs. The accretion luminosities derived from the outflow properties of the VeLLOs with detected CO outflows are higher than the observed internal luminosity of the protostars, indicating that these sources likely had higher accretion rates in the past. The known L1251-A-IRS3 outflow is detected but not re-mapped. We do not detect clear, unconfused signatures of red and blue molecular wings toward the other 31 sources in the survey indicating that large-scale, distinct outflows are rare toward this sample of candidate protostars. Several potential outflows are confused with the kinematic structure in the surrounding core and cloud. Interferometric imaging is needed to disentangle large-scale molecular cloud kinematics from these potentially weak protostellar outflows.

  7. The pulse luminosity function of Swift gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Amaral-Rogers, A.; Willingale, R.; O'Brien, P. T.

    2017-01-01

    The complete Swift Burst Alert Telescope and X-Ray Telescope light curves of 118 gamma-ray bursts (GRBs) with known redshifts were fitted using the physical model of GRB pulses by Willingale et al. to produce a total of 607 pulses. We compute the pulse luminosity function utilizing three GRB formation rate models: a progenitor that traces the cosmic star formation rate density (CSFRD) with either a single population of GRBs, coupled to various evolutionary parameters, or a bimodal population of high- and low-luminosity GRBs; and a direct fit to the GRB formation rate excluding any a priori assumptions. We find that a single population of GRB pulses with an evolving luminosity function is preferred over all other univariate evolving GRB models, or bimodal luminosity functions in reproducing the observed GRB pulse L-z distribution and that the magnitude of the evolution in brightness is consistent with studies that utilize only the brightest GRB pulses. We determine that the appearance of a GRB formation rate density evolution component is an artefact of poor parametrization of the CSFRD at high redshifts rather than indicating evolution in the formation rate of early epoch GRBs. We conclude that the single brightest region of a GRB light curve holds no special property; by incorporating pulse data from the totality of GRB emission we boost the GRB population statistics by a factor of 5, rule out some models utilized to explain deficiencies in GRB formation rate modelling, and constrain more tightly some of the observed parameters of GRB behaviour.

  8. Radio luminosity function of brightest cluster galaxies

    NASA Astrophysics Data System (ADS)

    Yuan, Z. S.; Han, J. L.; Wen, Z. L.

    2016-08-01

    By cross-matching the currently largest optical catalogue of galaxy clusters and the NVSS radio survey data base, we obtain a large complete sample of brightest cluster galaxies (BCGs) in the redshift range of 0.05 < z ≤ 0.45, which have radio emission and redshift information. We confirm that more powerful radio BCGs tend to be these optically very bright galaxies located in more relaxed clusters. We derived the radio luminosity functions of the largest sample of radio BCGs, and find that the functions depend on the optical luminosity of BCGs and the dynamic state of galaxy clusters. However, the radio luminosity function does not show significant evolution with redshift.

  9. Stellar luminosity variations and global warming.

    PubMed

    Foukal, P

    1994-04-08

    Recent studies indicate that variation in the sun's luminosity is less than that observed in many other stars of similar magnetic activity. Current findings also indicate that in more active stars, the attenuation by faculae of sunspot luminosity modulation is less effective than in the sun at present. The sun could thus become photometrically more variable (and dimmer) if its magnetic activity exceeded present levels. But the levels of solar activity required for this to occur are not observed in carbon-14 and beryllium-10 records over the past several millennia, which indicates that such an increase in amplitude of surface magnetism-driven variations in solar luminosity is unlikely in the present epoch.

  10. The BRAN luminosity detectors for the LHC

    NASA Astrophysics Data System (ADS)

    Matis, H. S.; Placidi, M.; Ratti, A.; Turner, W. C.; Bravin, E.; Miyamoto, R.

    2017-03-01

    This paper describes the several phases which led, from the conceptual design, prototyping, construction and tests with beam, to the installation and operation of the BRAN (Beam RAte of Neutrals) relative luminosity monitors for the LHC. The detectors have been operating since 2009 to contribute, optimize and maintain the accelerator performance in the two high luminosity interaction regions (IR), the IR1 (ATLAS) and the IR5 (CMS). The devices are gas ionization chambers installed inside a neutral particle absorber 140 m away from the Interaction Points in IR1 and IR5 and monitor the energy deposited by electromagnetic showers produced by high-energy neutral particles from the collisions. The detectors have the capability to resolve the bunch-by-bunch luminosity at the 40 MHz bunch rate, as well as to survive the extreme level of radiation during the nominal LHC operation. The devices have operated since the early commissioning phase of the accelerator over a broad range of luminosities reaching 1.4×1034 cm-2 s-1 with a peak pileup of 45 events per bunch crossing. Even though the nominal design luminosity of the LHC has been exceeded, the BRAN is operating well. After describing how the BRAN can be used to monitor the luminosity of the collider, we discuss the technical choices that led to its construction and the different tests performed prior to the installation in two IRs of the LHC. Performance simulations are presented together with operational results obtained during p-p operations, including runs at 40 MHz bunch rate, Pb-Pb operations and p-Pb operations.

  11. Multi-wavelength Luminosity Functions of Galaxies

    NASA Technical Reports Server (NTRS)

    Gardner, J. P.; Miller, N. A.

    2002-01-01

    Multivariate or multi-wavelength luminosity functions will reveal the interplay between star formation, chemical evolution, and absorption and re-emission of dust within evolving galaxy populations. By using principal component analysis to reduce the dimensionality of the problem, we optimally extract the relevant photometric information from large galaxy catalogs. As a demonstration of the technique, we derive the multi-wavelength luminosity function for the galaxies in the released SDSS catalog, and compare the results with those obtained by traditional methods. This technique will be applicable to catalogs of galaxies from datasets obtained by 2MASS, and the SIRTF and GALEX missions.

  12. Multi-Wavelength Luminosity Functions of Galaxies

    NASA Technical Reports Server (NTRS)

    Gardner, Jonathan P.

    2002-01-01

    Multivariate or multi-wavelength luminosity functions will reveal the interplay between star formation, chemical evolution, and ab- sorption and re-emission of dust within evolving galaxy populations. By using principal component analysis to reduce the dimensionality of the problem, I optimally extract the relevant photometric information from large galaxy catalogs. As a demonstration of the technique, I derive the multi-wavelength luminosity function for the galaxies in the released SDSS catalog, and compare the results with those obtained by traditional methods. This technique will be applicable to catalogs of galaxies from datasets obtained by 2MASS, and the SIRTF and GALEX missions.

  13. Feedback from AGN: The Kinetic/Radio Luminosity Function

    NASA Astrophysics Data System (ADS)

    Melini, Gabriele; La Franca, Fabio; Fiore, Fabrizio

    2010-05-01

    We have measured the probability distribution function of the ratio RX = log L1.4/LX, where L1.4/LX = ν Lν(1.4 GHz)/LX(2-10 keV), between the 1.4 GHz and the unabsorbed 2-10 keV luminosities and its dependence on LX and z. We have used a complete sample of ~1800 hard X-ray selected AGN, observed in the 1.4 GHz band, cross-correlated in order to exclude FR II-type objects, and thus obtain a contemporaneous measure of the radio and X-ray emission. The distribution P(RX|LX,z) is shown in Figure 1. Convolution of the distribution P(RX|LX,z) with the 2-10 keV X-ray AGN luminosity function from La Franca et al. (2005) and the relations between radio power and kinetic energy from Best et al. (2006) and Willott et al. (1999) allows us to derive the AGN kinetic power and its evolution. As shown in Figure 1, our results are in good agreement with the predictions of the most recent models of galaxy formation and evolution (e.g., Croton et al. 2006), where AGN radio feedback is required to quench the star formation.

  14. Recent improvements in luminosity at PEP

    SciTech Connect

    Helm, R.; Allen, M.; Chao, A.

    1983-03-01

    We will describe improvements which have led to new records for peak and average luminosity at PEP. Comparison of recent results with several earlier lattice and optical modifications shows rather good correlation with the predictions of a beam-beam simulation program.

  15. RHIC Proton Luminosity and Polarization Improvement

    SciTech Connect

    Zhang, S. Y.

    2014-01-17

    The RHIC proton beam polarization can be improved by raising the Booster scraping, which also helps to reduce the RHIC transverse emittance, and therefore to improve the luminosity. By doing this, the beam-beam effect would be enhanced. Currently, the RHIC working point is constrained between 2/3 and 7/10, the 2/3 resonance would affect intensity and luminosity lifetime, and the working point close to 7/10 would enhance polarization decay in store. Run 2013 shows that average polarization decay is merely 1.8% in 8 hours, and most fills have the luminosity lifetime better than 14 hours, which is not a problem. Therefore, even without beam-beam correction, there is room to improve for RHIC polarization and luminosity. The key to push the Booster scraping is to raise the Booster input intensity; for that, two approaches can be used. The first is to extend the LINAC tank 9 pulse width, which has been successfully applied in run 2006. The second is to raise the source temperature, which has been successfully applied in run 2006 and run 2012.

  16. The Luminosity Function of QSO Host Galaxies

    NASA Technical Reports Server (NTRS)

    Hamilton, Timothy S.; Casertano, Stefano; Turnshek, David A.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present some results from our HST archival image study of 71 QSO host galaxies. The objects are selected to have z less than or equal to 0.46 and total absolute magnitude M(sub v) less than or equal to -23 in our adopted cosmology (H(sub 0) = 50 kilometers per second Mpc(sup-1), q(sub 0) = 0.5, lambda = 0)). The aim of this initial study is to investigate the composition of the sample with respect to host morphology and radio loudness, as well as derive the QSO host galaxy luminosity function. We have analyzed available WFPC2 images in R or I band (U in one case), using a uniform set of procedures. The host galaxies span a narrow range of luminosities and are exceptionally bright, much more so than normal galaxies, usually L greater than L*(sub v). The QSOs are almost equally divided among three subclasses: radio-loud QSOs with elliptical hosts, radio-quiet QSOs with elliptical hosts, and radio-quiet QSOs with spiral hosts. Radio-loud QSOs with spiral hosts are extremely rare. Using a weighting procedure, we derive the combined luminosity function of QSO host galaxies. We find that the luminosity function of QSO hosts differs in shape from that of normal galaxies but that they coincide at the highest luminosities. The ratio of the number of quasar hosts to the number of normal galaxies at a luminosity L*(sub v) is R = (Lv/11.48L*(sub v))(sup 2.46), where L*(sub v) corresponds to M*(sub v)= -22.35, and a QSO is defined to be an object with total nuclear plus host light M(sub v) less than or equal to -23. This ratio can be interpreted as the probability that a galaxy with luminosity L(sub V) will host a QSO at redshift z approximately equal to 0.26.

  17. Distribution of heavy metals in muscles and internal organs of Korean cephalopods and crustaceans: risk assessment for human health.

    PubMed

    Mok, Jong Soo; Kwon, Ji Young; Son, Kwang Tae; Choi, Woo Seok; Shim, Kil Bo; Lee, Tae Seek; Kim, Ji Hoe

    2014-12-01

    Samples of seven species of cephalopods and crustaceans were collected from major fish markets on the Korean coast and analyzed for mercury (Hg) using a direct Hg analyzer and for the metals cadmium (Cd), lead (Pb), chromium, silver, nickel, copper, and zinc using inductively coupled plasma mass spectrometry. The distributions of heavy metals in muscles, internal organs, and whole tissues were determined, and a risk assessment was conducted to provide information concerning consumer safety. The heavy metals accumulated to higher levels (P < 0.05) in internal organs than in muscles for all species. The mean concentrations of Cd, which had the highest concentrations of the three hazardous metals (Cd, Pb, and Hg), in all internal organs (except those of blue crab) exceeded the regulatory limits set by Korea and the European Union. The Cd concentrations in all whole tissues of squid and octopus (relatively large cephalopods), red snow crab, and snow crab exceeded the European Union limits. The estimated dietary intake of Cd, Pb, and Hg for each part of all species accounted for 1.73 to 130.57%, 0.03 to 0.39%, and 0.93 to 1.67%, respectively, of the provisional tolerable daily intake adopted by the Joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives; the highest values were found in internal organs. The hazard index (HI) is recognized as a reasonable parameter for assessing the risk of heavy metal consumption associated with contaminated food. Because of the high HI (>1.0) of the internal organs of cephalopods and the maximum HI for whole tissue of 0.424, consumers eating internal organs or whole tissues of cephalopods could be at risk of high heavy metal exposure. Therefore, the internal organs of relatively large cephalopods and crabs (except blue crab) are unfit for consumption. However, consumption of flesh after removing internal organs is a suitable approach for decreasing exposure to harmful metals.

  18. A Solar-luminosity Model and Climate

    NASA Technical Reports Server (NTRS)

    Perry, Charles A.

    1990-01-01

    Although the mechanisms of climatic change are not completely understood, the potential causes include changes in the Sun's luminosity. Solar activity in the form of sunspots, flares, proton events, and radiation fluctuations has displayed periodic tendencies. Two types of proxy climatic data that can be related to periodic solar activity are varved geologic formations and freshwater diatom deposits. A model for solar luminosity was developed by using the geometric progression of harmonic cycles that is evident in solar and geophysical data. The model assumes that variation in global energy input is a result of many periods of individual solar-luminosity variations. The 0.1-percent variation of the solar constant measured during the last sunspot cycle provided the basis for determining the amplitude of each luminosity cycle. Model output is a summation of the amplitudes of each cycle of a geometric progression of harmonic sine waves that are referenced to the 11-year average solar cycle. When the last eight cycles in Emiliani's oxygen-18 variations from deep-sea cores were standardized to the average length of glaciations during the Pleistocene (88,000 years), correlation coefficients with the model output ranged from 0.48 to 0.76. In order to calibrate the model to real time, model output was graphically compared to indirect records of glacial advances and retreats during the last 24,000 years and with sea-level rises during the Holocene. Carbon-14 production during the last millenium and elevations of the Great Salt Lake for the last 140 years demonstrate significant correlations with modeled luminosity. Major solar flares during the last 90 years match well with the time-calibrated model.

  19. High frequency (hourly) variation in vertical distribution and abundance of meroplanktonic larvae in nearshore waters during strong internal tidal forcing

    NASA Astrophysics Data System (ADS)

    Liévana MacTavish, A.; Ladah, L. B.; Lavín, M. F.; Filonov, A.; Tapia, Fabian J.; Leichter, J.

    2016-04-01

    We related the vertical distribution and abundance of nearshore meroplankton at hourly time scales with internal tidal wave events. We proposed that significant changes in plankter abundance would occur across internal tidal fronts, and that surface and bottom strata would respond in opposite fashions. First-mode internal tidal bores propagating in the alongshore direction were detected in water-column currents and baroclinic temperature changes. Surface and bottom currents always flowed in opposite directions, and abrupt flow reversals coincided with large temperature changes during arrival of bores. Crab zoeae and barnacle cyprids were more abundant in the bottom strata, whereas barnacle nauplii showed the opposite pattern. Significant changes in vertical distribution and abundance of target meroplankters occurred across internal tidal fronts, especially for crabs at depth, with surface and bottom organisms responding in opposite fashions. Changes in plankter abundance were significantly correlated with current flows in the strata where they were most abundant. The manner in which plankters were affected (increasing or decreasing abundance) appeared to be modulated by their vertical position within the water column. The significant differences found at the high frequencies of this study, maintained across sampling days, suggest that nearshore meroplankton populations may have greater and more consistent temporal and vertical variability than previously considered.

  20. Mapping luminosity-redshift relationship to Lemaitre-Tolman-Bondi cosmology

    SciTech Connect

    Chung, Daniel J. H.; Romano, Antonio Enea

    2006-11-15

    We derive a direct general map from the luminosity distance D{sub L}(z) to the inhomogeneous matter distribution M(r) in the Lemaitre-Tolman-Bondi (LTB) cosmology and compute several examples. One of our examples explicitly demonstrates that it is possible to tune the LTB cosmological solution to approximately reproduce the luminosity distance curve of a flat Friedmann-Robertson-Walker universe with a cosmological constant. We also discuss how smooth matter distributions can evolve into naked singularities due to shell crossing when the inhomogeneous 'curvature' E(r) is a function which changes sign.

  1. The luminosity-bias relation from filaments in the Sloan Digital Sky Survey Data Release Four

    NASA Astrophysics Data System (ADS)

    Pandey, Biswajit; Bharadwaj, Somnath

    2007-05-01

    We compare quantitative estimates of the filamentarity of the galaxy distribution in seven nearly two-dimensional sections from the survey against the predictions of Λ cold dark matter (ΛCDM) N-body simulations. The filamentarity of the actual galaxy distribution is known to be luminosity-dependent. It is also known that the filamentarity of the simulated galaxy distribution is highly sensitive to the bias, and the simulations are consistent with the data for only a narrow range of bias. We apply this feature to several volume-limited subsamples with different luminosities to determine a luminosity-bias relation. The relative bias b/b* as a function of the luminosity ratio L/L* is found to be well described by a straight line b/b* = A + B(L/L*) with A = 0.833 +/- 0.009 and B = 0.171 +/- 0.009. Comparing with the earlier works, all of which use ratios of the two-point statistics, we find that our results are consistent with Norberg et al. and Tegmark et al., while a steeper luminosity dependence found by Benoist et al. is inconsistent.

  2. Extra-galactic high-energy transients: event rate density and luminosity function

    NASA Astrophysics Data System (ADS)

    Sun, Hui; Zhang, Bing; Li, Zhuo

    2015-08-01

    Several types of extra-galactic high-energy transients have been discovered, which include high-luminosity and low-luminosity long-duration gamma-ray bursts (GRBs), short-duration GRBs, supernova shock breakouts (SBOs), and tidal disruption events (TDEs) without or with a relativistic jet. In this paper, we apply a unified method to systematically study the reshift-dependent event rate densities and luminosity functions of these extra-galactic high-energy transients. We consider star formation history as the tracer of the redshift distribution for long GRBs and SBOs. For short GRBs, we consider the compact star merger model to introduce several possible merger delay time distribution models. For TDEs, we consider the mass distribution of supermassive black holes as a function of redshift. We derive some empirical formulae for the redshift-dependent event rate density for different types of transients. Based on the observed events, we derive the local specific event rate density, ρ0,L ∝ dρ0/dL for each type of transient, which represents its luminosity function. All the transients are consistent with having a single power law luminosity function, except the high luminosity long GRBs (HL-lGRBs), whose luminosity function can be well described by a broken power law. The total event rate density for a particular transient depends on the luminosity threshold, and we obtain the following values in units of Gpc-3 yr-1: 2.82^{+0.41}_{-0.36} for HL-lGRBs above 4×1049 erg s-1 218^{+130}_{-86} for low luminosity long GRBs above 6×1046 erg s-1 3.18^{+0.88}_{-0.70}, 2.87^{+0.80}_{-0.64}, and 6.25^{+1.73}_{-1.38} above 5×1049 erg s-1 for short GRBs with three different merger delay models (Gaussian, log-normal, and power law); 2.0^{+2.6}_{-1.3}×104 above 9×1043 erg s-1 for SBOs, 3.0^{+1.0}_{-0.8}×105 for normal TDEs above 1042 erg s-1 and 6.2^{+8.2}_{-4.0} above 3×1047 erg s-1for TDE jets as discovered by Swift. Intriguingly, the global specific event rate densities

  3. The faint end of the 250 μm luminosity function at z < 0.5

    NASA Astrophysics Data System (ADS)

    Wang, L.; Norberg, P.; Bethermin, M.; Bourne, N.; Cooray, A.; Cowley, W.; Dunne, L.; Dye, S.; Eales, S.; Farrah, D.; Lacey, C.; Loveday, J.; Maddox, S.; Oliver, S.; Viero, M.

    2016-08-01

    Aims: We aim to study the 250 μm luminosity function (LF) down to much fainter luminosities than achieved by previous efforts. Methods: We developed a modified stacking method to reconstruct the 250 μm LF using optically selected galaxies from the SDSS survey and Herschel maps of the GAMA equatorial fields and Stripe 82. Our stacking method not only recovers the mean 250 μm luminosities of galaxies that are too faint to be individually detected, but also their underlying distribution functions. Results: We find very good agreement with previous measurements in the overlapping luminosity range. More importantly, we are able to derive the LF down to much fainter luminosities (~ 25 times fainter) than achieved by previous studies. We find strong positive luminosity evolution L*250(z)∝(1+z)4.89±1.07 and moderate negative density evolution Φ*250(z)∝(1+z)-1.02±0.54 over the redshift range 0.02

  4. RF TECHNIQUES FOR IMPROVED LUMINOSITY IN RHIC.

    SciTech Connect

    BRENNAN,J.M.BLASKIEWICZ,J.BUTLER,J.DELONG,J.FISCHER,W.HAYES,T.

    2004-07-05

    The luminosity of the Relativistic Heavy Ion Collider has improved significantly [1] over the first three physics runs. A number of special rf techniques have been developed to facilitate higher luminosity. The techniques described herein include: an ultra low-noise rf source for the 197 MHz storage rf system, a frequency shift switch-on technique for transferring bunches from the acceleration to the storage system, synchronizing the rings during the energy ramp (including crossing the transition energy) to avoid incidental collisions, installation of dedicated 200 MHZ cavities to provide longitudinal Landau damping on the ramp, and the development of a bunch merging scheme in the Booster to increase the available bunch intensity from the injectors.

  5. Optimization of integrated luminosity in the Tevatron

    SciTech Connect

    Gattuso, C.; Convery, M.; Syphers, M.; /Fermilab

    2009-04-01

    We present the strategy which has been used recently to optimize the performance of the Fermilab Tevatron proton-antiproton collider. We use a relatively simple heuristic model based on the antiproton production rate, which optimizes the number of antiprotons in a store in order to maximize the integrated luminosity. A store is terminated as soon as the target number of antiprotons is reached and the Tevatron quickly resets to load another store. Since this procedure was implemented, the integrated luminosity has improved by {approx} 35%. Other recent operational improvements include decreasing the shot setup time, and reducing beam-beam effects by making the proton and antiproton brightness more compatible, for example by scraping protons to smaller emittances.

  6. RR Lyrae period luminosity relations with Spitzer

    NASA Astrophysics Data System (ADS)

    Neeley, Jillian R.; Marengo, Massimo; CRRP Team

    2017-01-01

    RR Lyrae variable stars have long been known to be valuable distance indicators, but only recently has a well defined period luminosity relationship been utilized at infrared wavelengths. In my thesis, I am combining Spitzer Space Telescope data of RR Lyrae stars obtained as part of the Carnegie RR Lyrae Program with ground based NIR data to characterize the period-luminosity-metallicity (PLZ) relation and provide an independent Population II calibration of the cosmic distance scale. I will discuss the ongoing efforts to calibrate this relation using objects such as M4 and NGC 6441 and how the first data release from the Gaia mission impacts our findings. I will also compare my preliminary empirical relations to theoretical PLZ relations derived from stellar pulsation models.

  7. Luminosity limitations for Electron-Ion Collider

    SciTech Connect

    Valeri Lebedev

    2000-09-01

    The major limitations on reaching the maximum luminosity for an electron ion collider are discussed in application to the ring-ring and linac-ring colliders. It is shown that with intensive electron cooling the luminosity of 10{sup 33} cm{sup -2} s{sup -1} is feasible for both schemes for the center-of-mass collider energy above approximately 15 GeV. Each scheme has its own pros and cons. The ring-ring collider is better supported by the current accelerator technology while the linac-ring collider suggests unique features for spin manipulations of the electron beam. The article addresses a general approach to a choice of collider scheme and parameters leaving details for other conference publications dedicated to particular aspects of the ring-ring and linac-ring colliders.

  8. School Leadership for the Future: Heroic or Distributed? Translating International Discourses in Norwegian Policy Documents

    ERIC Educational Resources Information Center

    Abrahamsen, Hedvig; Aas, Marit

    2016-01-01

    School leadership as a key for school reforms has become a dominant theme in education, as demonstrated by a growing body of research during the last 15 years. Still, little attention has been paid to how changing international discourses on school leadership are translated into national public policy documents during the last decade. As such,…

  9. Radio variability survey of very low luminosity protostars

    SciTech Connect

    Choi, Minho; Kang, Miju; Lee, Jeong-Eun

    2014-07-01

    Ten very low luminosity objects were observed multiple times in the 8.5 GHz continuum in search of protostellar magnetic activities. A radio outburst of IRAM 04191+1522 IRS was detected, and the variability timescale was about 20 days or shorter. The results of this survey and archival observations suggest that IRAM 04191+1522 IRS is in active states about half the time. Archival data show that L1014 IRS and L1148 IRS were detectable previously and suggest that at least 20%-30% of very low luminosity protostars are radio variables. Considering the variability timescale and flux level of IRAM 04191+1522 IRS and the previous detection of the circular polarization of L1014 IRS, the radio outbursts of these protostars are probably caused by magnetic flares. However, IRAM 04191+1522 IRS is too young and small to develop an internal convective dynamo. If the detected radio emission is indeed coming from magnetic flares, the discovery implies that the flares may be caused by the fossil magnetic fields of interstellar origin.

  10. EVOLUTION OF THE Halpha LUMINOSITY FUNCTION

    SciTech Connect

    Westra, Eduard; Geller, Margaret J.; Kurtz, Michael J.; Fabricant, Daniel G.; Dell'Antonio, Ian

    2010-01-01

    The Smithsonian Hectospec Lensing Survey (SHELS) is a window on the star formation history over the last 4 Gyr. SHELS is a spectroscopically complete survey for R{sub tot} < 20.3 over 4 square{sup 0}. We use the 10k spectra to select a sample of pure star-forming galaxies based on their Halpha emission line. We use the spectroscopy to determine extinction corrections for individual galaxies and to remove active galaxies in order to reduce systematic uncertainties. We use the large volume of SHELS with the depth of a narrowband survey for Halpha galaxies at z approx 0.24 to make a combined determination of the Halpha luminosity function at z approx 0.24. The large area covered by SHELS yields a survey volume big enough to determine the bright end of the Halpha luminosity function from redshift 0.100 to 0.377 for an assumed fixed faint-end slope alpha = -1.20. The bright end evolves: the characteristic luminosity L* increases by 0.84 dex over this redshift range. Similarly, the star formation density increases by 0.11 dex. The fraction of galaxies with a close neighbor increases by a factor of 2-5 for L{sub Ha}lpha approx> L* in each of the redshift bins. We conclude that triggered star formation is an important influence for star-forming galaxies with Halpha emission.

  11. Luminosity segregation in three clusters of galaxies (A119, A2443, A2218)

    NASA Astrophysics Data System (ADS)

    Pracy, Michael B.; Driver, Simon P.; De Propris, Roberto; Couch, Warrick J.; Nulsen, Paul E. J.

    2005-12-01

    We use deep wide-field V-band imaging obtained with the Wide Field Camera at the prime focus of the Issac Newton Telescope to study the spatial and luminosity distribution of galaxies in three low redshift (0.04 < z < 0.2) clusters: Abell 119, Abell 2443 and Abell 2218. The absolute magnitude limits probed in these clusters are MV- 5 logh0.7=-13.3, -15.4 and -16.7mag, respectively. The galaxy population, at all luminosities, along the line-of-sight to the clusters can be described by the linear combination of a King profile and a constant surface density of field galaxies. We find that, for these three clusters, the core radius is invariant with intrinsic luminosity of the cluster population to the above limits and thus there is no evidence for luminosity segregation in these clusters. The exception is the brightest galaxies in A2218 which exhibit a more compact spatial distribution. We find that the total projected luminosity distribution (within 1h-10.7Mpc of the cluster centre) can be well represented by a single Schechter function with moderately flat faint-end slopes: α=-1.22+0.07-0.06 (A119), α=-1.11+0.10-0.09 (A2443) and α=-1.14+0.08-0.07 (A2218). We perform a geometric deprojection of the cluster galaxy population and confirm that no `statistically significant' evidence of a change in the shape of the luminosity distribution with cluster-centric radius exists. Again, the exception being A2218 which exhibits a core region with a flatter faint-end slope.

  12. International Comparison of Labor Productivity Distribution for Manufacturing and Non-Manufacturing Firms

    NASA Astrophysics Data System (ADS)

    Ikeda, Y.; Souma, W.

    Labor productivity was studied at the microscopic level in terms of distributions based on individual firm financial data from Japan and the US. A power-law distribution in terms of firms and sector productivity was found in both countries' data. The labor productivities were not equal for nation and sectors, in contrast to the prevailing view in the field of economics. It was found that the low productivity of the Japanese non-manufacturing sector reported in macro-economic studies was due to the low productivity of small firms.

  13. Tissue distribution of Thorotrast and role of internal irradiation in carcinogenesis.

    PubMed

    Yamasaki, Kyoko; Yamasaki, Aiichi; Tosaki, Mitsuo; Isozumi, Yasuto; Hiai, Hiroshi

    2004-10-01

    Carcinogenesis in Thorotrastosis has been assumed due to direct bombardment by alpha-particle with high linear energy transfer during decay of 232Th. To revisit the mechanism of carcinogenesis by Thorotrast (THR), we examined the tissue distribution of THR granules and two-dimensional distribution of radioactivity in the organs of Thorotrastosis patients and studied their spatial relationship to histopathological changes. The high radioactivity in the patients' organ was predominantly derived from decay of Thorium series and showed unique distribution, while the far lower natural radioactivity was mainly from Uranium series decay and fairly evenly distributed. It was found that a large majority of THR granules were phagocytized by macrophages and were embedded in extensive fibrosis. Cancer was rarely in the center of THR deposition but rather at a distance from the deposits. These observations may indicate that the predominant feature of THR deposition is the tissue damage by direct hit of alpha-particles and subsequent fibrosis. The effect of THR resembles action of toxic chemical agents, as several authors have pointed out. We therefore assume that carcinogenesis in Thorotrastosis is a combination of events, such as regeneration of liver tissue after radiation damage, emission of secondary electrons, ionization of the surrounding tissue, and beta- or gamma-ray from daughter nuclei of Thorium (Th). In this context, the role of alpha-particle is important but more intriguing.

  14. A Distributed Model for Managing Academic Staff in an International Online Academic Programme

    ERIC Educational Resources Information Center

    Kalman, Yoram M.; Leng, Paul H.

    2007-01-01

    Online delivery of programmes of Higher Education typically involves a distributed community of students interacting with a single university site, at which the teachers, learning resources and administration of the programme are located. The alternative model, of a fully "Virtual University", which assumes no physical campus, poses…

  15. Calibration of gamma-ray burst luminosity indicators

    NASA Astrophysics Data System (ADS)

    Liang, Enwei; Zhang, Bing

    2006-06-01

    Several gamma-ray burst (GRB) luminosity indicators have been proposed which can be generally written in the form of , where c is the coefficient, xi is the ith observable, and ai is its corresponding power-law index. Unlike in Type Ia supernovae, calibration of GRB luminosity indicators using a low-redshift sample is difficult. This is because the GRB rate drops rapidly at low redshifts, and some nearby GRBs may be different from their cosmological brethren. Calibrating the standard candles using GRBs in a narrow redshift range (Δz) near a fiducial redshift has been proposed recently. Here we elaborate such a possibility and propose to calibrate {ai} based on the Bayesian theory and to marginalize the c value over a reasonable range of cosmological parameters. We take our newly discovered multivariable GRB luminosity indicator, Eiso=cEa1pta2b, as an example and test the validity of this approach through simulations, where Eiso is the isotropic energy of prompt gamma-rays, Ep is the spectral break energy, and tb is the temporal break time of the optical afterglow light curve. We show that while c strongly depends on the cosmological parameters, neither a1 nor a2 does as long as Δz is small enough. The selection of Δz for a particular GRB sample could be judged according to the size and the observational uncertainty of the sample. There is no preferable redshift to perform the calibration of the indices {ai}, while a lower redshift is preferable for c-marginalization. The best strategy would be to collect GRBs within a narrow redshift bin around a fiducial intermediate redshift (e.g. zc~ 1 or zc~ 2), as the observed GRB redshift distribution is found to peak around this range. Our simulation suggests that with the current observational precisions of measuring Eiso, Ep and tb, 25 GRBs within a redshift bin of Δz~ 0.30 would give fine calibration to the Liang-Zhang luminosity indicator.

  16. The Next Generation Virgo Cluster Survey. VII. The Intrinsic Shapes of Low-luminosity Galaxies in the Core of the Virgo Cluster, and a Comparison with the Local Group

    NASA Astrophysics Data System (ADS)

    Sánchez-Janssen, Rubén; Ferrarese, Laura; MacArthur, Lauren A.; Côté, Patrick; Blakeslee, John P.; Cuillandre, Jean-Charles; Duc, Pierre-Alain; Durrell, Patrick; Gwyn, Stephen; McConnacchie, Alan W.; Boselli, Alessandro; Courteau, Stéphane; Emsellem, Eric; Mei, Simona; Peng, Eric; Puzia, Thomas H.; Roediger, Joel; Simard, Luc; Boyer, Fred; Santos, Matthew

    2016-03-01

    samples of more massive quiescent systems, and with field, star-forming galaxies of similar luminosities. We find that the intrinsic flattening in this low-luminosity regime is almost independent of the environment in which the galaxy resides, but there is a hint that objects may be slightly rounder in denser environments. The comparable flattening distributions of low-luminosity galaxies that have experienced very different degrees of environmental effects suggest that internal processes are the main drivers of galaxy structure at low masses, with external mechanisms playing a secondary role.

  17. FORCAST Spectroscopy of Orion Protostars: Probing Intermediate Luminosities

    NASA Astrophysics Data System (ADS)

    Megeath, Tom

    2015-10-01

    We propose FORECAST low resolution spectroscopy of seven protostars in the Orion molecular clouds. These protostars have luminosities between those of low mass protostars which were the primary focus of the Herschel Orion Protostar Survey (HOPS) and those of the high mass protostars in the Orion Nebula. Although we have constructed 1-870 micron SEDs from 2MASS, Spitzer, Herschel and APEX photometry of these intermediate (40-600 Lsun) luminosity protostars, we do not have Spitzer IRS spectra showing the shape and depth of the 10 micron silicate features and the slope of the mid-IR spectral energy distribution (SED). Given the importance of such spectra for constraining the properties of the protostars through radiative transfer modeling, we request time to obtain FORCAST FOR-G111 (8.4-13.7 micron) and FOR-G227 (17.6-27.7 micron) grism spectra. With these data, we can extend our study of protostars in Orion to include a sample of more luminous protostar which are expected to include both intermediate mass protostars and low mass protostars undergoing outbursts. To investigate potential variability between Spitzer and WISE epochs, we also request photomety of a protostar potentially undergoing an episodic outburst.

  18. Dark and luminous properties of low-luminosity spiral galaxies

    NASA Astrophysics Data System (ADS)

    Kogoshvili, N.; Borchkhadze, T.

    2012-08-01

    On the basis of data in our Merged Catalogue of Galaxies (MERCG), for which an online version is now available, we have analysed some properties of spiral galaxies that are members of pairs or small groups of galaxies. Our sample consists of a total of approximately 300 pairs and groups, distributed over the entire sky. In this context, low-luminosity spirals (LLS), here defined as those with an absolute magnitude of MB ≥ -20.6, are of particular interest, since they are thought to harbour dark matter. We find that the mean distance between the two components in LLS/LLS pairs of galaxies is significantly smaller than in LLS/elliptical (E), LLS/high-luminosity spiral (HLS) and HLS/HLS pairs, as well as in groups with at least one LLS. Moreover, LLS from this sample in the mean have larger central surface densities μo and smaller values of the full angular momentum K than HLS. In the second part, we investigate the relative frequencies of LLS galaxies, single as well as in pairs/groups. We find that they are 4-5 times more frequent inside and around three major clusters of galaxies (Virgo, Pegasus I and Perseus) than in the general field. Our findings all support the assumption that LLS galaxies are indeed carriers of dark matter.

  19. NLC Luminosity as a Function of Beam Parameters

    SciTech Connect

    Nosochkov, Yuri

    2002-06-06

    Realistic calculation of NLC luminosity has been performed using particle tracking in DIMAD and beam-beam simulations in GUINEA-PIG code for various values of beam emittance, energy and beta functions at the Interaction Point (IP). Results of the simulations are compared with analytic luminosity calculations. The optimum range of IP beta functions for high luminosity was identified.

  20. An Investigation of X-ray Luminosity versus Crystalline Powder Granularity

    SciTech Connect

    Borade, Ramesh; Bourret-Courchesne, Edith; ,

    2012-03-07

    At the High-throughput Discovery of Scintillator Materials Facility at Lawrence Berkeley National Laboratory, scintillators are synthesized by solid-state reaction or melt mixing, forming crystalline powders. These powders are formed in various granularity and the crystal grain size affects the apparent luminosity of the scintillator. To accurately predict a "full-size" scintillator's crystal luminosity, the crystal luminosity as a function of crystal granularity size has to be known. In this study, we examine Bi{sub 4}Ge{sub 3}O{sub 12} (BGO), Lu{sub 2}SiO{sub 5}:Ce (LSO), YAlO{sub 3}:Ce (YAP:Ce), and CsBa{sub 2}I{sub 5}:Eu{sup 2+} (CBI) luminosities as a function of crystalline grain size. The highest luminosities were measured for 600- to 1000-{micro}m crystal grain sizes for BGO and LSO, for 310- to 600-{micro}m crystal grain sizes for CBI, and for crystal grains larger than 165{micro}m for YAP:Ce. Crystal grains that were larger than 1 mm had a lower packing fraction, and smaller grains were affected by internal scattering. We measured a 34% decrease in luminosity for BGO when decreasing from the 600- to 1000- {micro}m crystal grain size range down to the 20- to 36-{micro}m range. The corresponding luminosity decrease for LSO was 44% for the same grain size decrease. YAP:Ce exhibited a luminosity decrease of 47% when the grain size decreased from the 165- to 310-{micro}m crystal grains to the 20- to 36-{micro}m range, and CBI exhibited a luminosity decrease of 98% when the grain size decreased from the 310- to 600-{micro}m crystal grain range to the 36- to 50-{micro}m range. We were able to very accurately estimate full-size crystal luminosities from crystalline grains that are larger than 90 {micro}m.

  1. Human resources for health in southeast Asia: shortages, distributional challenges, and international trade in health services.

    PubMed

    Kanchanachitra, Churnrurtai; Lindelow, Magnus; Johnston, Timothy; Hanvoravongchai, Piya; Lorenzo, Fely Marilyn; Huong, Nguyen Lan; Wilopo, Siswanto Agus; dela Rosa, Jennifer Frances

    2011-02-26

    In this paper, we address the issues of shortage and maldistribution of health personnel in southeast Asia in the context of the international trade in health services. Although there is no shortage of health workers in the region overall, when analysed separately, five low-income countries have some deficit. All countries in southeast Asia face problems of maldistribution of health workers, and rural areas are often understaffed. Despite a high capacity for medical and nursing training in both public and private facilities, there is weak coordination between production of health workers and capacity for employment. Regional experiences and policy responses to address these challenges can be used to inform future policy in the region and elsewhere. A distinctive feature of southeast Asia is its engagement in international trade in health services. Singapore and Malaysia import health workers to meet domestic demand and to provide services to international patients. Thailand attracts many foreign patients for health services. This situation has resulted in the so-called brain drain of highly specialised staff from public medical schools to the private hospitals. The Philippines and Indonesia are the main exporters of doctors and nurses in the region. Agreements about mutual recognition of professional qualifications for three groups of health workers under the Association of Southeast Asian Nations Framework Agreement on Services could result in increased movement within the region in the future. To ensure that vital human resources for health are available to meet the needs of the populations that they serve, migration management and retention strategies need to be integrated into ongoing efforts to strengthen health systems in southeast Asia. There is also a need for improved dialogue between the health and trade sectors on how to balance economic opportunities associated with trade in health services with domestic health needs and equity issues.

  2. Distribution of heavy metals in internal organs and tissues of Korean molluscan shellfish and potential risk to human health.

    PubMed

    Mok, Jong Soo; Kwon, Ji Young; Son, Kwang Tae; Choi, Woo Seok; Kim, Poong Ho; Lee, Tae Seek; Kim, Ji Hoe

    2015-09-01

    Molluscan shellfish (gastropods and bivalves) were collected from major fish markets on the Korean coast and analyzed for mercury by direct Hg analyzer and for other metals, such as cadmium, lead, chromium, silver, nickel, copper and zinc, using inductively coupled plasma mass spectrometry. Distribution of heavy metals in muscles, internal organs and whole tissues were determined and a potential risk assessment was conducted to evaluate their hazard for human consumption. Heavy metals were accumulated significantly higher (P < 0.05) in internal organs than in muscles for all species. The mean Cd level, which had the highest level of three hazardous metals (Cd, Pb, and Hg) in all internal-organ samples were above the regulatory limit of Korea and the mean level in whole tissue samples of the selected gastropod species, bay scallop and comb pen shell, exceeded the limit (except in a few cases). The sum of the estimated dietary intake of Cd, Pb and Hg for each part of all tested species accounted for 1.59-16.94, 0.02-0.36, and 0.07-0.16% respectively, of the provisional tolerable daily intake adopted by the Joint FAO/WHO Expert Committee on Food Additives. The hazard index for each part of gastropods and bivalves was below 1.0, however, the maximum HI for internal organs of all analysed species was quite high (0.71). These results suggest that consumption of flesh after removing the internal organs of some molluscan shellfish (all gastropod species, bay scallop and comb pen shell) is a suitable way for reducing Cd exposure.

  3. Implications of Lag-Luminosity Relationship for Unified GRB Paradigms

    NASA Technical Reports Server (NTRS)

    Norris, J. P.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    Spectral lags (tau(sub lag)) are deduced for 1437 long (T(sub 90) greater than 2 s) BATSE gamma-ray bursts (GRBs) with peak flux F(sub p) greater than 0.25 photons cm(sup -2)/s, near to the BATSE trigger threshold. The lags are modeled to approximate the observed distribution in the F(sub p)-T(sub lag) plane, realizing a noise-free representation. Assuming a two-branch lag-luminosity relationship, the lags are self-consistently corrected for cosmological effects to yield distributions in luminosity, distance, and redshift. The results have several consequences for GRB populations and for unified gamma-ray/afterglow scenarios which would account for afterglow break times and gamma-ray spectral evolution in terms of jet opening angle, viewing angle, or a profiled jet with variable Lorentz factor: A component of the burst sample is identified - those with few, wide pulses, lags of a few tenths to several seconds, and soft spectra - whose Log[N]-Log[F(sub p)] distribution approximates a -3/2 power-law, suggesting homogeneity and thus relatively nearby sources. The proportion of these long-lag bursts increases from negligible among bright BATSE bursts to approx. 50% at trigger threshold. Bursts with very long lags, approx. 1-2 less than tau(sub lag) (S) less than 10, show a tendency to concentrate near the Supergalactic Plane with a quadrupole moment of approx. -0.10 +/- 0.04. GRB 980425 (SN 1998bw) is a member of this subsample of approx. 90 bursts with estimated distances less than 100 Mpc. The frequency of the observed ultra-low luminosity bursts is approx. 1/4 that of SNe Ib/c within the same volume. If truly nearby, the core-collapse events associated with these GRBs might produce gravitational radiation detectable by LIGO-II. Such nearby bursts might also help explain flattening of the cosmic ray spectrum at ultra-high energies, as observed by AGASA.

  4. Thermionic nuclear reactor with internal heat distribution and multiple duct cooling

    DOEpatents

    Fisher, C.R.; Perry, L.W. Jr.

    1975-11-01

    A Thermionic Nuclear Reactor is described having multiple ribbon-like coolant ducts passing through the core, intertwined among the thermionic fuel elements to provide independent cooling paths. Heat pipes are disposed in the core between and adjacent to the thermionic fuel elements and the ribbon ducting, for the purpose of more uniformly distributing the heat of fission among the thermionic fuel elements and the ducts.

  5. Vector magnetometry sensor for internal inspection of gas distribution mains. Final report, February 1995-August 1996

    SciTech Connect

    Farra, R.; Fowler, T.

    1997-06-01

    There is a recognized need for an advanced distribution pipe inspection system which can operate in 4` and 6` diameter pipes. This program developed a prototype sensor car based on vector magnetometry. The prototype sensor system was tested in the laboratory. Test data is presented showing defect detection capability for defects as small as 25% of the pipe wall. Field tests were also conducted with mixed results. Varying corrosion levels were observed. However, specific defects were difficult to identify.

  6. Pin-Hole Luminosity Monitor with Feedback

    NASA Astrophysics Data System (ADS)

    Norem, James H.; Spencer, James E.

    Previously, the generalized luminosity { L} was defined and calculated for all incident channels based on an NLC e+e- design. Alternatives were then considered to improve the differing beam-beam effects in the e-e-, eγ and γγ channels. Regardless of the channel, there was a large flux of outgoing, high energy photons that were produced from the beam-beam interaction e.g. beamstrahlung that needs to be disposed of and whose flux depended on { L}. One approach to this problem is to consider it a resource and attempt to take advantage of it by disposing of these straight-ahead photons in more useful ways than simply dumping them. While there are many options for monitoring the luminosity, any method that allows feedback and optimization in real time and in a non-intercepting and non-interfering way during normal data taking is extremely important - especially if it provides other capabilities such as high resolution tuning of spot sizes and can be used for all incident channels without essential modifications to their setup. Our "pin-hole" camera appears to be such a device if it can be made to work with high energy photons in ways that are compatible with the many other constraints and demands on space around the interaction region. The basis for using this method is that it has, in principle, the inherent resolution and bandwidth to monitor the very small spot sizes and their stabilities that are required for very high, integrated luminosity. While there are many possible, simultaneous uses of these outgoing photon beams, we limit our discussion to a single, blind, proof-of-principle experiment that was done on the FFTB line at SLAC to certify the concept of a camera obscura for high energy photons.

  7. Untangling the White Dwarf Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Lam, M. C.

    2017-03-01

    The inversion of the white dwarf luminosity function provides an independent way to prove the past star formation history of the Milky Way independent of any cosmological models. In Rowell & Hambly (2011), the effective volume method uses the average properties of all the objects in a given bin, so a significant amount of information is lost in the early stage of the analysis. In this work, I explore the possibility of assigning objects individually in a probabilistic way using the generalised Schmidt density estimator (1/Vmax).

  8. Oxygen-rich Mira variables: Near-infrared luminosity calibrations. Populations and period-luminosity relations

    NASA Technical Reports Server (NTRS)

    Alvarez, R.; Mennessier, M.-O.; Barthes, D.; Luri, X.; Mattei, J. A.

    1997-01-01

    Hipparcos astrometric and kinematical data of oxygen-rich Mira variables are used to calibrate absolute near-infrared magnitudes and kinematic parameters. Three distinct classes of stars with different kinematics and scale heights were identified. The two most significant groups present characteristics close to those usually assigned to extended/thick disk-halo populations and old disk populations, respectively, and thus they may differ by their metallicity abundance. Two parallel period-luminosity relations are found, one for each population. The shift between these relations is interpreted as the consequence of the effects of metallicity abundance on the luminosity.

  9. Evolution of the luminosity function of quasar accretion disks

    NASA Technical Reports Server (NTRS)

    Caditz, David M.; Petrosian, Vahe; Wandel, Amri

    1991-01-01

    Using an accretion-disk model, accretion disk luminosities are calculated for a grid of black hole masses and accretion rates. It is shown that, as the black-hole mass increases with time, the monochromatic luminosity at a given frequency first increases and then decreases rapidly as this frequency is crossed by the Wien cutoff. The upper limit on the monochromatic luminosity, which is characteristic for a given epoch, constrains the evolution of quasar luminosities and determines the evolultion of the quasar luminosity function.

  10. Status of a broadly distributed endangered species: results and implications of the second International Piping Plover Census

    USGS Publications Warehouse

    Plissner, Jonathan H.; Haig, Susan M.

    2000-01-01

    Methods for monitoring progress toward recovery goals are highly variable and may be problematic for endangered species that are mobile and widely distributed. Recovery objectives for Piping Plovers (Charadrius melodus) include attainment of minimum population sizes within specified recovery units, as determined by two U.S. and two Canadian recovery teams. To assess progress toward these goals, complete surveys of the species' winter and breeding ranges in Canada, the United States, Mexico, the Bahamas, and the Greater Antilles are conducted every 5 years. In 1996, 1200 biologists and volunteers participated in the second International Piping Plover Census, tallying 2515 wintering birds and 5913 adults (2668 breeding pairs) during the breeding census. Winter numbers were 27% lower than those of the first international census conducted in 1991, with substantially fewer wintering birds along the Gulf of Mexico and an overall increase in numbers along the Atlantic Coast. Large numbers of wintering plovers remain undetected. In 1996, the total number of breeding adults was 7.7% higher than in 1991. Regionally, breeding numbers were 31% higher along the Atlantic Coast and 20% higher in the small Great Lakes population, but declined by 5% in the U.S. Great Plains and the Canadian Prairie. Target recovery numbers were met only for Saskatchewan but were approached in Alberta and New England. The results suggest that Piping Plover distribution and habitat use in the U.S. Great Plains/Canadian Prairie region may shift dramatically with water conditions.

  11. Ligand modified nanoparticles increases cell uptake, alters endocytosis and elevates glioma distribution and internalization.

    PubMed

    Gao, Huile; Yang, Zhi; Zhang, Shuang; Cao, Shijie; Shen, Shun; Pang, Zhiqing; Jiang, Xinguo

    2013-01-01

    Nanoparticles (NPs) were widely used in drugs/probes delivery for improved disease diagnosis and/or treatment. Targeted delivery to cancer cells is a highly attractive application of NPs. However, few studies have been performed on the targeting mechanisms of these ligand-modified delivery systems. Additional studies are needed to understand the transport of nanoparticles in the cancer site, the interactions between nanoparticles and cancer cells, the intracellular trafficking of nanoparticles within the cancer cells and the subcellular destiny and potential toxicity. Interleukin 13 (IL-13) peptide can specifically bind IL-13Rα2, a receptor that is highly expressed on glioma cells but is expressed at low levels on other normal cells. It was shown that the nanoparticels modification with the IL-13 peptide could improve glioma treatment by selectively increasing cellular uptake, facilitating cell internalization, altering the uptake pathway and increasing glioma localization.

  12. Determination of the effective inelastic p anti-p cross-section for the D0 Run II luminosity measurement

    SciTech Connect

    Edwards, T.; Yacoob, S.; Andeen, T.; Begel, M.; Casey, B.C.K.; Partridge, R.; Schellman, H.; Sznajder, A.; /Rio de Janeiro State U.

    2004-11-01

    The authors determine the effective inelastic p{bar p} cross-section into the D0 Luminosity Monitor for all run periods prior to September 2004. This number is used to relate the measured inelastic collision rate to the delivered luminosity. The key ingredients are the inelastic p{bar p} cross-section, the Luminosity Monitor efficiency, and the modeling of kinematic distributions for various inelastic processes used to determine the detector acceptance. The resulting value is {sigma}{sub p{bar p},eff} = 46 {+-} 3 mb.

  13. Balanced Expertise Distribution in Remote Ultrasound Imaging Aboard The International Space Station (ISS)

    NASA Technical Reports Server (NTRS)

    Sargsyan, Ashot; Dulchavsky, Scott; Hamilton, Douglas; Melton, Shannon; Martin, David

    2004-01-01

    Astronaut training for ISS operations usually ensures independent performance. With small crew size same crews also conduct all science work onboard. With diverse backgrounds, a good "match" between the existing and required skills can only be anecdotal. Furthermore, full proficiency in most of the complex tasks can be attained only through long training and practice, which may not be justified and may be impossible given the scarcity of training time. To enable a number of operational and science advancements, authors have developed a new approach to expertise distribution in time and among the space and ground personnel. Methods: As part of NASA Operational Ultrasound Project (1998-2003) and the NASA-solicited experiment "Advanced Diagnostic Ultrasound in Microgravity-ADUM" (P.I. -S.D., ongoing), the authors have created a "Balanced Expertise Distribution" approach to perform complex ultrasound imaging tasks on ISS for both operational and science use. The four components of expertise are a) any pre-existing pertinent expertise; b) limited preflight training c) adaptive onboard proficiency enhancement tools; d) real-time ' guidance from the ground. Throughout the pre-flight training and flight time preceding the experiments, the four components are shaped in a dynamic fashion to meet in an optimum combination during the experiment sessions. Results: Procedure validation sessions and feasibility studies have given encouraging results. While several successful real-time remote guidance sessions have been conducted on ISS, Expedition 8 is the first to use an "on-orbit proficiency enhancement" tool. Conclusions: In spite of severely limited training time, daring peer-reviewed research and operational enhancements are feasible through a balanced distribution of expertise in time, as well as among the crewmembers and ground personnel. This approach shows great promise for biomedical research, but may be applicable for other areas of micro gravity-based science

  14. Proceedings of the fourth international conference on parallel and distributed information systems

    SciTech Connect

    1996-12-31

    Parallel and distributed database technology is at the heart of many mission-critical applications such as online transaction processing, data warehousing, business workflow management, interoperable information systems, and information brokering in global networks. The program of PDIS`96 conference reflects both the breadth of the relevant subjects and the rapid progress of this area. The 22 selected papers cover the full spectrum ranging from Web-related issues and data mining to core technologies such as indexing and transactions. In addition to these research papers, the conference also includes 8 industrial contributions on the latest commercial developments and future trends.

  15. Thermodynamics and luminosities of rainbow black holes

    SciTech Connect

    Mu, Benrong; Wang, Peng; Yang, Haitang E-mail: pengw@scu.edu.cn

    2015-11-01

    Doubly special relativity (DSR) is an effective model for encoding quantum gravity in flat spacetime. As result of the nonlinearity of the Lorentz transformation, the energy-momentum dispersion relation is modified. One simple way to import DSR to curved spacetime is ''Gravity's rainbow'', where the spacetime background felt by a test particle would depend on its energy. Focusing on the ''Amelino-Camelia dispersion relation'' which is E{sup 2} = m{sup 2}+p{sup 2}[1−η(E/m{sub p}){sup n}] with n > 0, we investigate the thermodynamical properties of a Schwarzschild black hole and a static uncharged black string for all possible values of η and n in the framework of rainbow gravity. It shows that there are non-vanishing minimum masses for these two black holes in the cases with η < 0 and n ≥ 2. Considering effects of rainbow gravity on both the Hawking temperature and radius of the event horizon, we use the geometric optics approximation to compute luminosities of a 2D black hole, a Schwarzschild one and a static uncharged black string. It is found that the luminosities can be significantly suppressed or boosted depending on the values of η and n.

  16. Thermodynamics and luminosities of rainbow black holes

    NASA Astrophysics Data System (ADS)

    Mu, Benrong; Wang, Peng; Yang, Haitang

    2015-11-01

    Doubly special relativity (DSR) is an effective model for encoding quantum gravity in flat spacetime. As result of the nonlinearity of the Lorentz transformation, the energy-momentum dispersion relation is modified. One simple way to import DSR to curved spacetime is ``Gravity's rainbow'', where the spacetime background felt by a test particle would depend on its energy. Focusing on the ``Amelino-Camelia dispersion relation'' which is E2 = m2+p2[1-η(E/mp)n] with n > 0, we investigate the thermodynamical properties of a Schwarzschild black hole and a static uncharged black string for all possible values of η and n in the framework of rainbow gravity. It shows that there are non-vanishing minimum masses for these two black holes in the cases with η < 0 and n >= 2. Considering effects of rainbow gravity on both the Hawking temperature and radius of the event horizon, we use the geometric optics approximation to compute luminosities of a 2D black hole, a Schwarzschild one and a static uncharged black string. It is found that the luminosities can be significantly suppressed or boosted depending on the values of η and n.

  17. High Luminosity LHC: Challenges and plans

    DOE PAGES

    Arduini, G.; Barranco, J.; Bertarelli, A.; ...

    2016-12-28

    The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will undergo a major upgrade in the 2020s. This will increase its rate of collisions by a factor of five beyond the original design value and the integrated luminosity by a factor ten. The new configuration, known as High Luminosity LHC (HL-LHC), willmore » rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11–12 T superconducting magnets, including Nb3Sn-based magnets never used in accelerators before, compact superconducting cavities for longitudinal beam rotation, new technology and physical processes for beam collimation. As a result, the dynamics of the HL-LHC beams will be also particularly challenging and this aspect is the main focus of this paper.« less

  18. High Luminosity LHC: Challenges and plans

    SciTech Connect

    Arduini, G.; Barranco, J.; Bertarelli, A.; Biancacci, N.; Bruce, R.; Bruning, O.; Buffat, X.; Cai, Y.; Carver, L. R.; Fartoukh, S.; Giovannozzi, Massimo; Iadarola, G.; Li, K.; Lechner, A.; Medrano, L. Medina; Metral, E.; Nosochkov, Y.; Papaphilippou, Y.; Pellegrini, D.; Pieloni, T.; Qiang, J.; Redaelli, S.; Romano, A.; Rossi, L.; Rumolo, G.; Salvant, B.; Schenk, M.; Tambasco, C.; Tomas, R.; Valishev, S.; Van der Veken, F. F.

    2016-12-28

    The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will undergo a major upgrade in the 2020s. This will increase its rate of collisions by a factor of five beyond the original design value and the integrated luminosity by a factor ten. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11–12 T superconducting magnets, including Nb3Sn-based magnets never used in accelerators before, compact superconducting cavities for longitudinal beam rotation, new technology and physical processes for beam collimation. As a result, the dynamics of the HL-LHC beams will be also particularly challenging and this aspect is the main focus of this paper.

  19. High Luminosity LHC: challenges and plans

    NASA Astrophysics Data System (ADS)

    Arduini, G.; Barranco, J.; Bertarelli, A.; Biancacci, N.; Bruce, R.; Brüning, O.; Buffat, X.; Cai, Y.; Carver, L. R.; Fartoukh, S.; Giovannozzi, M.; Iadarola, G.; Li, K.; Lechner, A.; Medina Medrano, L.; Métral, E.; Nosochkov, Y.; Papaphilippou, Y.; Pellegrini, D.; Pieloni, T.; Qiang, J.; Redaelli, S.; Romano, A.; Rossi, L.; Rumolo, G.; Salvant, B.; Schenk, M.; Tambasco, C.; Tomás, R.; Valishev, S.; Van der Veken, F. F.

    2016-12-01

    The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will undergo a major upgrade in the 2020s. This will increase its rate of collisions by a factor of five beyond the original design value and the integrated luminosity by a factor ten. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11-12 T superconducting magnets, including Nb3Sn-based magnets never used in accelerators before, compact superconducting cavities for longitudinal beam rotation, new technology and physical processes for beam collimation. The dynamics of the HL-LHC beams will be also particularly challenging and this aspect is the main focus of this paper.

  20. Effect of initial salt concentrations on cell performance and distribution of internal resistance in microbial desalination cells.

    PubMed

    Yang, Euntae; Choi, Mi-Jin; Kim, Kyoung-Yeol; Chae, Kyu-Jung; Kim, In S

    2015-01-01

    Microbial desalination cells (MDCs) are modified microbial fuel cells (MFCs) that concurrently produce electricity and desalinate seawater, but adding a desalination compartment and an ion-exchange membrane may increase the internal resistance (Ri), which can limit the cell performance. However, the effects of a desalination chamber and initial NaCl concentrations on the internal resistances and the cell performances (i.e. Coulombic efficiency (CE), current and power density) of MDCs have yet to be thoroughly explored; thus, the cell performance and Ri distributions of MDCs having different initial concentrations and an MFC having no desalination chamber were compared. In the MDCs, the current and power density generation increased from 2.82 mA and 158.2 mW/m2 to 3.17 mA and 204.5 mW/m2 when the initial NaCl concentrations were increased from 5 to 30 g/L, as a consequence of the internal resistances decreasing from 2432.0 to 2328.4 Ω. And even though the MFC has a lower Ri than the MDCs, lower cell performances (current: 2.59 mA; power density: 141.6 mW/m2 and CE: 62.1%) were observed; there was no effect of improved junction potential in the MFC. Thus, in the MDCs, the higher internal resistances due to the addition of a desalination compartment can be offset by reducing the electrolyte resistance and improving the junction potential at higher NaCl concentrations.

  1. Aerosol generation and distribution system for the Third International Cloud Condensation Nuclei Workshop

    NASA Technical Reports Server (NTRS)

    Katz, U.; Dea, J. Y.

    1981-01-01

    In order to obtain identical samples participating CCN instruments and aerosol characterizing equipment were located along and connected to a 8.2 cm diameter aluminum tube through which the test aerosols were pumped directly from the source at very slight overpressure. Of the total of 29 experiments, 18 were carried out with artificial NaCl or (NH4)2SO4 aerosols. These were generated from salt solutions by pneumatic atomizers of special design to ensure high constancy of the aerosol output concentration. In three experiments with insoluble CCN (AgI, paraffin wax) the aerosols were generated thermally. In some of the tests, an electrostatic classifier was used for narrowing the particle size distributions.

  2. Luminosity Dependence and Redshift Evolution of Strong Emission-Line Diagnostics in Star-Forming Galaxies

    NASA Astrophysics Data System (ADS)

    Cowie, L. L.; Barger, A. J.; Songaila, A.

    2016-01-01

    We examine the redshift evolution of standard strong emission-line diagnostics for Hβ-selected star-forming galaxies using the local SDSS sample and a new z=0.2{--}2.3 sample obtained from Hubble Space Telescope WFC3 grism and Keck DEIMOS and MOSFIRE data. We use the SDSS galaxies to show that there is a systematic dependence of the strong emission-line properties on Balmer-line luminosity, which we interpret as showing that both the N/O abundance and the ionization parameter increase with increasing line luminosity. Allowing for the luminosity dependence tightens the diagnostic diagrams and the metallicity calibrations. The combined SDSS and high-redshift samples show that there is no redshift evolution in the line properties once the luminosity correction is applied, i.e., all galaxies with a given L({{H}}β ) have similar strong emission-line distributions at all the observed redshifts. We argue that the best metal diagnostic for the high-redshift galaxies may be a luminosity-adjusted version of the [N ii]6584/Hα metallicity relation. Based in part on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA and was made possible by the generous financial support of the W. M. Keck Foundation.

  3. The Radio and Optical Luminosity Evolution of Quasars II - The SDSS Sample

    SciTech Connect

    Singal, J.; Petrosian, V.; Stawarz, L.; Lawrence, A.

    2012-12-28

    We determine the radio and optical luminosity evolutions and the true distribution of the radio loudness parameter R, defined as the ratio of the radio to optical luminosity, for a set of more than 5000 quasars combining SDSS optical and FIRST radio data. We apply the method of Efron and Petrosian to access the intrinsic distribution parameters, taking into account the truncations and correlations inherent in the data. We find that the population exhibits strong positive evolution with redshift in both wavebands, with somewhat greater radio evolution than optical. With the luminosity evolutions accounted for, we determine the density evolutions and local radio and optical luminosity functions. The intrinsic distribution of the radio loudness parameter R is found to be quite different than the observed one, and is smooth with no evidence of a bi-modality in radio loudness. The results we find are in general agreement with the previous analysis of Singal et al., 2011 which used POSS-I optical and FIRST radio data.

  4. Internal calibration of a distributed hydrological model using satellite data of land surface temperature similarly to ground discharge measurements

    NASA Astrophysics Data System (ADS)

    Corbari, C.; Ravazzani, G.; Mancini, M.; Li, J.; Su, B.

    2012-04-01

    This study proposes a new methodology for the calibration of distributed hydrological models at basin scale through the constraints on an internal model variable using remote sensing data of land surface temperature. The model algorithm solves the system of energy and mass balances in term of the equilibrium pixel temperature or representative equilibrium temperature that governs the fluxes of energy and mass over the basin domain. This equilibrium surface temperature, which is a critical model state variable, is compared to land surface temperature from MODIS. So soil hydraulic parameters and vegetation variables will be calibrated according to the comparison between observed and simulated land surface temperature minimizing the errors. A similar procedure will also be applied performing the traditional calibration using only discharge measurements. The distributed energy water balance model, Flash-flood Event-based Spatially-distributed rainfall-runoff Transformation - Energy Water Balance model (FEST-EWB), will be used to test this approach for the Upper Yangtze River basin (China). This work was supported in the framework of the Dragon 2 Programme between the European Space Agency (ESA) together with the National Remote Sensing Centre of China (NRSCC).

  5. Operation of the Run IIB D0 Luminosity System and Determination of the Run IIB Luminosity Constant

    SciTech Connect

    Prewitt, Michelle Victoria; /Rice U.

    2010-04-01

    The luminosity system is an integral part of the D0 detector that must be properly maintained to provide accurate luminosity measurements for physics analysis. After the addition of a readout layer to the silicon vertex detector in 2006, it was necessary to re-calculate the effective inelastic cross section to which the luminosity monitor is sensitive. The preliminary analysis showed that the luminosity constant did not change with the addition of the extra layer of silicon. A full study of the revised luminosity constant including a complete analysis of systematic uncertainties has been completed. The luminosity constant was determined to be {sigma}{sub eff} = 48.3 {+-} 1.9 {+-} 0.6 mb, which reduces the D0 contribution to the luminosity measurement uncertainty by almost 3%.

  6. International Union of Basic and Clinical Pharmacology. LXXVII. Kisspeptin receptor nomenclature, distribution, and function.

    PubMed

    Kirby, Helen R; Maguire, Janet J; Colledge, William H; Davenport, Anthony P

    2010-12-01

    Kisspeptins are members of the Arg-Phe amide family of peptides, which have been identified as endogenous ligands for a G-protein-coupled receptor encoded by a gene originally called GPR54 (also known as AXOR12 or hOT7T175). After this pairing, the gene has been renamed KISS1R. The International Union of Basic and Clinical Pharmacology Committee on Receptor Nomenclature and Drug Classification recommends that the official name for the receptor is the kisspeptin receptor to follow the convention of naming the receptor protein after the endogenous ligand. The endogenous ligand was initially called metastin, after its role as a metastasis suppressor, and is now referred to as kisspeptin-54 (KP-54), a C-terminally amidated 54-amino acid peptide cleaved from the 145-amino acid gene product. Shorter C-terminal cleavage fragments [KP-14, KP-13 and KP-10 (the smallest active fragment)] are also biologically active. Both receptor and peptide are widely expressed in human, rat, and mouse; the receptor sequence shares more than 80% homology in these species. Activation of the kisspeptin receptor by kisspeptin is via coupling to G(q/11) and the phospholipase C pathway, causing Ca(2+) mobilization. Mutations in the KISS1R gene result in hypogonadotropic hypogonadotropism, and targeted disruption of Kiss1r in mice reproduces this phenotype, which led to the discovery of the remarkable ability of the kisspeptin receptor to act as a molecular switch for puberty. In addition to regulating the reproductive axis, the kisspeptin receptor is also implicated in cancer, placentation, diabetes, and the cardiovascular system.

  7. Epizootiology, distribution and the impact on international trade of two penaeid shrimp viruses in the Americas.

    PubMed

    Lightner, D V

    1996-06-01

    Marine penaeid shrimp are effected by approximately twenty viruses, the majority of which were discovered as a result of their negative effects on aquaculture. In the Americas, infectious hypodermal and haematopoietic necrosis (IHHN) virus and Taura syndrome (TS) virus have had a significant negative impact on aquaculture industries and, in one instance, on a commercial fishery. Both viruses have become widely distributed as a consequence of the movement of host stocks for aquaculture. IHHN virus (IHHNV) causes catastrophic losses in cultured and wild Penaeus stylirostris. In marked contrast, P. vannamei is relatively resistant to IHHN but infection results, nonetheless, in poor culture performance. TS virus (TSV) is the 'mirror image' of IHHNV in its effect on P. stylirostris and P. vannamei. TSV causes catastrophic losses in P. vannamei, whereas P. stylirostris is highly resistant to TS. In the less than three years since the discovery of TSV in Ecuador in 1992, the virus has spread rapidly and caused massive production losses in most shrimp-growing countries in the Americas.

  8. A Comparative Study of "The International Educational Technology Conference" (IETC) and "The International Conference on Computers in Education" (ICCE): The Program, Essay Distribution, the Themes, and Research Methods

    ERIC Educational Resources Information Center

    Chen, Gwo-Dong; Chen, Chun-Hsiang; Wang, Chin-Yeh; Li, Liang-Yi

    2012-01-01

    The article aims to compare international conferences, "The International Educational Technology Conference" (IETC, 2011) and "The International Conference on Computers in Education" (ICCE, 2010), from various dimensions. The comparison is expected to conclude a better approach for every IETC and ICCE to be held. (Contains 4…

  9. Driving Cells to the Desired State in a Bimodal Distribution through Manipulation of Internal Noise with Biologically Practicable Approaches.

    PubMed

    Shu, Che-Chi; Yeh, Chen-Chao; Jhang, Wun-Sin; Lo, Shih-Chiang

    2016-01-01

    The stochastic nature of gene regulatory networks described by Chemical Master Equation (CME) leads to the distribution of proteins. A deterministic bistability is usually reflected as a bimodal distribution in stochastic simulations. Within a certain range of the parameter space, a bistable system exhibits two stable steady states, one at the low end and the other at the high end. Consequently, it appears to have a bimodal distribution with one sub-population (mode) around the low end and the other around the high end. In most cases, only one mode is favorable, and guiding cells to the desired state is valuable. Traditionally, the population was redistributed simply by adjusting the concentration of the inducer or the stimulator. However, this method has limitations; for example, the addition of stimulator cannot drive cells to the desired state in a common bistable system studied in this work. In fact, it pushes cells only to the undesired state. In addition, it causes a position shift of the modes, and this shift could be as large as the value of the mode itself. Such a side effect might damage coordination, and this problem can be avoided by applying a new method presented in this work. We illustrated how to manipulate the intensity of internal noise by using biologically practicable methods and utilized it to prompt the population to the desired mode. As we kept the deterministic behavior untouched, the aforementioned drawback was overcome. Remarkably, more than 96% of cells has been driven to the desired state. This method is genetically applicable to biological systems exhibiting a bimodal distribution resulting from bistability. Moreover, the reaction network studied in this work can easily be extended and applied to many other systems.

  10. Driving Cells to the Desired State in a Bimodal Distribution through Manipulation of Internal Noise with Biologically Practicable Approaches

    PubMed Central

    Shu, Che-Chi; Yeh, Chen-Chao; Jhang, Wun-Sin; Lo, Shih-Chiang

    2016-01-01

    The stochastic nature of gene regulatory networks described by Chemical Master Equation (CME) leads to the distribution of proteins. A deterministic bistability is usually reflected as a bimodal distribution in stochastic simulations. Within a certain range of the parameter space, a bistable system exhibits two stable steady states, one at the low end and the other at the high end. Consequently, it appears to have a bimodal distribution with one sub-population (mode) around the low end and the other around the high end. In most cases, only one mode is favorable, and guiding cells to the desired state is valuable. Traditionally, the population was redistributed simply by adjusting the concentration of the inducer or the stimulator. However, this method has limitations; for example, the addition of stimulator cannot drive cells to the desired state in a common bistable system studied in this work. In fact, it pushes cells only to the undesired state. In addition, it causes a position shift of the modes, and this shift could be as large as the value of the mode itself. Such a side effect might damage coordination, and this problem can be avoided by applying a new method presented in this work. We illustrated how to manipulate the intensity of internal noise by using biologically practicable methods and utilized it to prompt the population to the desired mode. As we kept the deterministic behavior untouched, the aforementioned drawback was overcome. Remarkably, more than 96% of cells has been driven to the desired state. This method is genetically applicable to biological systems exhibiting a bimodal distribution resulting from bistability. Moreover, the reaction network studied in this work can easily be extended and applied to many other systems. PMID:27911933

  11. On Coupled Stellar Luminosity and Gravitation

    NASA Astrophysics Data System (ADS)

    Neuenschwander, Dwight E.; McCully, C. V.

    2008-09-01

    We derive a analytic nonperturbative solution to the coupled field equations of general relativity and electrodynamics, for a star of initial mass Mo and lifetime-averaged luminosity L. We carry out our solution in familiar spherical coordinates, including an off-diagonal term in the metric tensor to allow for "frame dragging” caused by the radial flux of light. We then show how our metric can be transformed into a diagonal one; and how the "photon dust” electomagnetic stress tensor assumed by early investigators of this problem forms an approximation to our solution. We also estimate the magnitude of some of the small effects inferred by this model of radial frame dragging. We thank The Catalysts, an SNU science alumni organization, for its support.

  12. libprofit: Image creation from luminosity profiles

    NASA Astrophysics Data System (ADS)

    Robotham, A. S. G.; Taranu, D.; Tobar, R.

    2016-12-01

    libprofit is a C++ library for image creation based on different luminosity profiles. It offers fast and accurate two-dimensional integration for a useful number of profiles, including Sersic, Core-Sersic, broken-exponential, Ferrer, Moffat, empirical King, point-source and sky, with a simple mechanism for adding new profiles. libprofit provides a utility to read the model and profile parameters from the command-line and generate the corresponding image. It can output the resulting image as text values, a binary stream, or as a simple FITS file. It also provides a shared library exposing an API that can be used by any third-party application. R and Python interfaces are available: ProFit (ascl:1612.004) and PyProfit (ascl:1612.005).

  13. Copper distribution and speciation across the International GEOTRACES Section GA03

    NASA Astrophysics Data System (ADS)

    Jacquot, Jeremy E.; Moffett, James W.

    2015-06-01

    Copper (Cu) distribution and speciation were characterized along a zonal section in the North Atlantic Ocean from Lisbon, Portugal, to Woods Hole, Massachusetts as part of the U.S. GEOTRACES program. Dissolved Cu profiles displayed many of the same features identified by other researchers, including sub-surface scavenging and a linear increase with depth, but many also exhibited unique properties and geographic trends. Concentrations ranged from 0.43 nM at the surface to 3.07 nM near the seafloor. The highest concentrations were measured in deep waters to the west of Cape Verde and northwest of the Canary Islands while the lowest concentrations were measured in upper waters, mostly between Mauritania and Cape Verde. The westernmost sampling sites overlying or adjacent to the U.S. east coast continental shelf featured surface maxima that decreased in magnitude moving east toward Bermuda, reflecting declining inputs from Cu-enriched coastal waters and North American aerosols. Free Cu (Cu2+) concentrations were tightly controlled by organic complexation and scavenging across the section with values varying between 1.54 fM and 1.07 pM. These results provide the first evidence that Cu2+ concentrations are strongly complexed throughout the water column, even in boundary zones where dissolved Cu concentrations are elevated because of local sources. Strong organic ligands (L) acted as a buffer for Cu2+, restricting concentrations to a narrow range (10-100 fM) throughout most of the water column. Cu2+ and dissolved Cu were strongly scavenged by suspended particulate matter within several benthic nepheloid layers and a hydrothermal plume above the Trans-Atlantic Geotraverse (TAG) vent field on the Mid-Atlantic Ridge (MAR).

  14. Fluorescence characteristics of the fuel tracers triethylamine and trimethylamine for the investigation of fuel distribution in internal combustion engines.

    PubMed

    Lind, Susanne; Aßmann, Simon; Zigan, Lars; Will, Stefan

    2016-03-01

    Laser-induced fluorescence based on fuel tracers like amines is a suitable measurement technique for mixing studies in internal combustion (IC) engines. Triethylamine has often been used in gasoline IC engines; however, no detailed fluorescence characterization for excitation at 263 or 266 nm is available. Trimethylamine (TMA) exhibits high potential as a gaseous fuel tracer but little information about TMA fluorescence is currently available. A picosecond laser source combined with a streak camera equipped with a spectrograph was used to determine the spectral fluorescence emission and fluorescence decay time of both tracers. The tracers were investigated at various temperatures and pressures in a calibration cell with nitrogen as bath gas. The results provide an in-depth understanding of the fluorescence characteristics of both tracers and allow assessment of their application to the investigation of fuel distribution in IC engines.

  15. The luminosity function of quasars and its evolution: A comparison of optically selected quasars and quasars found in radio catalogs

    NASA Technical Reports Server (NTRS)

    Petrosian, V.

    1973-01-01

    The luminosity function of quasars and its evolution are discussed, based on comparison of available data on optically selected quasars and quasars found in radio catalogs. It is assumed that the red shift of quasars is cosmological and the results are expressed in the framework of the Lambda = 0, Q sub Q = 1 cosmological model. The predictions of various density evolution laws are compared with observations of an optically selected sample of quasars and quasar samples from radio catalogs. The differences between the optical luminosity functions, the red shift distributions and the radio to optical luminosity ratios of optically selected quasars and radio quasars rule out luminosity functions where there is complete absence of correlation between radio and optical luminosities. These differences also imply that Schmidt's (1970) luminosity function, where there exists a statistical correlation between radio and optical luminosities, although may be correct for high red shift objects, disagrees with observation at low red shifts. These differences can be accounted for by postulating existence of two classes (1 and 2) of objects.

  16. Effects of internal loading on phosphorus distribution in the Taihu Lake driven by wind waves and lake currents.

    PubMed

    Huang, Lei; Fang, Hongwei; He, Guojian; Jiang, Helong; Wang, Changhui

    2016-12-01

    Wind-driven sediment resuspension exerts significant effects on the P behavior in shallow lake ecosystems. In this study, a comprehensive dynamic phosphorus (P) model that integrates hydrodynamic, wind wave and sediment transport is proposed to assess the importance of internal P cycling due to sediment resuspension on water column P levels. The primary contribution of the model is detailed modeling and rigorous coupling of sediment and P dynamics. The proposed model is applied to predict the P behavior in the shallow Taihu Lake, which is the third largest lake in China, and quantitatively estimate the effects of wind waves and lake currents on P release and distribution. Both the prevailing southeast winds in summer and northwest winds in winter are applied for the simulation, and different wind speeds of 5 m/s and 10 m/s are also considered. Results show that sediment resuspension and the resulting P release have a dominant effect on P levels in Taihu Lake, and likely similar shallow lakes. Wind-driven waves at higher wind speeds significantly enhance sediment resuspension and suspended sediment concentration (SSC). Total P concentration in the water column is also increased but not in proportion to the SSC. The different lake circulations resulting from the different prevailing wind directions also affect the distribution of suspended sediment and P around the lake ultimately influencing where eutrophication is likely to occur. The proposed model demonstrates that internal cycling in the lake is a dominant factor in the lake P and must be considered when trying to manage water quality in this and similar lakes. The model is used to demonstrate the potential effectiveness of remediation of an area where historical releases have led to P accumulation on overall lake quality.

  17. Comparison of the activation time effects and the internal energy distributions for the CID, PQD and HCD excitation modes.

    PubMed

    Ichou, Farid; Schwarzenberg, Adrian; Lesage, Denis; Alves, Sandra; Junot, Christophe; Machuron-Mandard, Xavier; Tabet, Jean-Claude

    2014-06-01

    Reproducibility among different types of excitation modes is a major bottleneck in the field of tandem mass spectrometry library development in metabolomics. In this study, we specifically evaluated the influence of collision voltage and activation time parameters on tandem mass spectrometry spectra for various excitation modes [collision-induced dissociation (CID), pulsed Q dissociation (PQD) and higher-energy collision dissociation (HCD)] of Orbitrap-based instruments. For this purpose, internal energy deposition was probed using an approach based on Rice-Rampserger-Kassel-Marcus modeling with three thermometer compounds of different degree of freedom (69, 228 and 420) and a thermal model. This model treats consecutively the activation and decomposition steps, and the survival precursor ion populations are characterized by truncated Maxwell-Boltzmann internal energy distributions. This study demonstrates that the activation time has a significant impact on MS/MS spectra using the CID and PQD modes. The proposed model seems suitable to describe the multiple collision regime in the PQD and HCD modes. Linear relationships between mean internal energy and collision voltage are shown for the latter modes and the three thermometer molecules. These results suggest that a calibration based on the collision voltage should provide reproducible for PQD, HCD to be compared with CID in tandem in space instruments. However, an important signal loss is observed in PQD excitation mode whatever the mass of the studied compounds, which may affect not only parent ions but also fragment ions depending on the fragmentation parameters. A calibration approach for the CID mode based on the variation of activation time parameter is more appropriate than one based on collision voltage. In fact, the activation time parameter in CID induces a modification of the collisional regime and thus helps control the orientation of the fragmentation pathways (competitive or consecutive dissociations).

  18. A review of trends in the distribution of vector-borne diseases: is international trade contributing to their spread?

    PubMed

    de La Rocque, S; Balenghien, T; Halos, L; Dietze, K; Claes, F; Ferrari, G; Guberti, V; Slingenbergh, J

    2011-04-01

    It is difficult to determine the part that international trade has played in the expansion of vector-borne diseases, because of the multitude of factors that affect the transformation of habitats and the interfaces between vectors and hosts. The introduction of pathogens through trade in live animals or products of animal origin, as well as the arrival of arthropod vectors, is probably quite frequent but the establishment of an efficient transmission system that develops into a disease outbreak remains the exception. In this paper, based on well-documented examples, the authors review the ecological and epidemiological characteristics of vector-borne diseases that may have been affected in their spread and change of distribution by international trade. In addition, they provide a detailed analysis of the risks associated with specific trade routes and recent expansions of vector populations. Finally, the authors highlight the importance, as well as the challenges, of preventive surveillance and regulation. The need for improved monitoring of vector populations and a readiness to face unpredictable epidemiological events are also emphasised, since this will require rapid reaction, not least in the regulatory context.

  19. Internal nutrient sources and nutrient distributions in Alviso Pond A3W, California

    USGS Publications Warehouse

    Topping, Brent R.; Kuwabara, James S.; Garrett, Krista K.; Takekawa, John Y.; Parcheso, Francis; Piotter, Sara; Clearwater, Iris; Shellenbarger, Gregory

    2013-01-01

    about 80,000 kilograms per year (kg/yr), well above the adjective flux range of -50 to 1,500 kg/yr. By contrast, the average benthic flux of orthophosphate was about 12,000 kg/yr, well below the advective flux range of 21,500 to 30,000 kg/yr. Initial benthic flux estimates were also made for trace metals, including copper, nickel, iron, and manganese. These analyses indicated that the two sites, Inlet and Deep, have different pore-water profiles, with Inlet exhibiting much higher benthic flux estimates for nickel, iron, and manganese. These initial benthic-flux values reported for macronutrients are particularly impressive in magnitude when one considers that diffusive flux of dissolved solutes based on pore-water profiles provides a conservative determination that may be enhanced by other biogeochemical processes. These enhancement processes (Boudreau and Jorgensen, 2001) include bioturbation, bioirrigation, wind resuspension, and potential groundwater inflows, some of which are captured in core-incubation experiments (Kuwabara and others, 2009). Hence, the values reported herein represent lower bounds to indicate the potential importance of such internal solute sources. The elevated diffusive fluxes for nutrients in the pond relative to the adjacent estuary indicate that vertical nutrient transport between the pond bed and water column is consistently an important (and at times the most important) source of nutrients that stimulate phytoplankton growth in the water column. One might therefore reasonably hypothesize that this benthic transport of biologically reactive solutes (both nutrients and toxicants) represents the most important step at the base of the food web for trophic transfer.

  20. Fossil group origins. V. The dependence of the luminosity function on the magnitude gap

    NASA Astrophysics Data System (ADS)

    Zarattini, S.; Aguerri, J. A. L.; Sánchez-Janssen, R.; Barrena, R.; Boschin, W.; del Burgo, C.; Castro-Rodriguez, N.; Corsini, E. M.; D'Onghia, E.; Girardi, M.; Iglesias-Páramo, J.; Kundert, A.; Méndez-Abreu, J.; Vilchez, J. M.

    2015-09-01

    Context. In nature we observe galaxy aggregations that span a wide range of magnitude gaps between the two first-ranked galaxies of a system (Δm12). Thus, there are systems with gaps close to zero (e.g., the Coma cluster), and at the other extreme of the distribution, the largest gaps are found among the so-called fossil systems. The observed distribution of magnitude gaps is thought to be a consequence of the orbital decay of M∗ galaxies in massive halos and the associated growth of the central object. As a result, to first order the amplitude of this gap is a good statistical proxy for the dynamical age of a system of galaxies. Fossil and non-fossil systems could therefore have different galaxy populations that should be reflected in their luminosity functions. Aims: In this work we study, for the first time, the dependence of the luminosity function parameters on Δm12 using data obtained by the fossil group origins (FOGO) project. Methods: We constructed a hybrid luminosity function for 102 groups and clusters at z ≤ 0.25 using both photometric data from the SDSS-DR7 and redshifts from the DR7 and the FOGO surveys. The latter consists of ~1200 new redshifts in 34 fossil system candidates. We stacked all the individual luminosity functions, dividing them into bins of Δm12, and studied their best-fit Schechter parameters. We additionally computed a "relative" luminosity function, expressed as a function of the central galaxy luminosity, which boosts our capacity to detect differences - especially at the bright end. Results: We find trends as a function of Δm12 at both the bright and faint ends of the luminosity function. In particular, at the bright end, the larger the magnitude gap, the fainter the characteristic magnitude M∗. The characteristic luminosity in systems with negligible gaps is more than a factor three brighter than in fossil-like ones. Remarkably, we also find differences at the faint end. In this region, the larger the gap, the flatter

  1. Masses and Luminosities of X-Ray Binaries

    NASA Technical Reports Server (NTRS)

    Quirrenbach, Andreas; Frink, Sabine; Tomsick, John

    2004-01-01

    Using SIM, we will perform narrow-angle observations of several X-ray binaries to determine their orbits, and we will observe about 50 X-ray binary systems in wide-angle mode to measure their distances and proper motions. Sources with mass estimates for the compact component of greater than 3 solar masses are generally called black hole candidates since this mass is above the theoretical neutron star limit. Narrow-angle observations of these sources provide a direct test of the dynamical mass estimates on which the black hole evidence is based. Better measurements of the black hole masses will provide constraints on possible evolutionary paths that lead to black hole formation. When combined with X-ray data, mass measurements may provide additional constraints on the black hole spin. Precise mass determinations of neutron star systems can address the question of whether neutron stars can be significantly more massive than 1.4 solar masses, which would eliminate soft models of the neutron star equations of state. The wide-angle observations will probe the Galactic distribution of X-ray binaries through parallaxes and proper motions. They will also eliminate the uncertainties in the luminosities of individual sources, which is currently up to a full order of magnitude. This will enable more detailed comparisons of X-ray observations to physical models such as advection-dominated accretion flows (ADAFs). We intend to carry out the following measurements: 1) Determine the orbits of two black hole candidates to measure the black hole masses; 2) Obtain precise mass measurements for two neutron star systems to constrain neutron star equations of state; 3) Determine the distances and thus luminosities of selected representatives of various classes of X-ray binaries (black hole candidates, neutron stars, jet sources); 4) In the process of distance determination, proper motions will also be measured, from which the age of the population can be estimated.

  2. Constraining the rate and luminosity function of Swift gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Howell, E. J.; Coward, D. M.; Stratta, G.; Gendre, B.; Zhou, H.

    2014-10-01

    We compute the intrinsic isotropic peak luminosity function (LF) and formation rate of long gamma-ray bursts (LGRBs) using a novel approach. We complement a standard log N-log P brightness distribution and Vmax estimations with two observation-time relations: a redshift-observation-time relation (log z-log T) and a new luminosity-observation-time relation (log L-log T). We show that this approach reduces degeneracies that exist between the rate and LF of a brightness distribution. To account for the complex triggering algorithm employed by Swift, we use recent results of Lien et al. (2014) to produce a suite of efficiency functions. Using these functions with the above methods, we show that a log L-log T method can provide good constraints on the form of the LF, particularly the high end. Using a sample of 175 peak luminosities determined from redshifts with well-defined selection criteria, our results suggest that LGRBs occur at a local rate (without beaming corrections) of [0.7 < ρ0 < 0.8] Gpc-3 yr-1. Within this range, assuming a broken power-law LF, we find best estimates for the low- and high-energy indices of -0.95 ± 0.09 and -2.59 ± 0.93, respectively, separated by a break luminosity 0.80 ± 0.43 × 1052 erg s-1.

  3. DETERMINING THE LUMINOSITY FUNCTION OF SWIFT LONG GAMMA-RAY BURSTS WITH PSEUDO-REDSHIFTS

    SciTech Connect

    Tan Weiwei; Yu Yunwei; Cao Xiaofeng

    2013-07-20

    The determination of the luminosity function (LF) of gamma-ray bursts (GRBs) is an important role for the cosmological applications of the GRBs, which, however, is seriously hindered by some selection effects due to redshift measurements. In order to avoid these selection effects, we suggest calculating pseudo-redshifts for Swift GRBs according to the empirical L-E{sub p} relationship. Here, such a L-E{sub p} relationship is determined by reconciling the distributions of pseudo- and real redshifts of redshift-known GRBs. The values of E{sub p} taken from Butler's GRB catalog are estimated with Bayesian statistics rather than observed. Using the GRB sample with pseudo-redshifts of a relatively large number, we fit the redshift-resolved luminosity distributions of the GRBs with a broken-power-law LF. The fitting results suggest that the LF could evolve with redshift by a redshift-dependent break luminosity, e.g., L{sub b} = 1.2 Multiplication-Sign 10{sup 51}(1 + z){sup 2} erg s{sup -1}. The low- and high-luminosity indices are constrained to 0.8 and 2.0, respectively. It is found that the proportional coefficient between the GRB event rate and the star formation rate should correspondingly decrease with increasing redshifts.

  4. Fast Spatially Resolved Exhaust Gas Recirculation (EGR) Distribution Measurements in an Internal Combustion Engine Using Absorption Spectroscopy

    SciTech Connect

    Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E.; Perfetto, Anthony; Geckler, Sam; Partridge, William P.

    2015-09-01

    One effective method of reducing NOx emissions while improving efficiency is exhaust gas recirculation (EGR) in internal combustion engines. But, insufficient mixing between fresh air and exhaust gas can lead to cycle-to-cycle and cylinder-to-cylinder nonuniform charge gas mixtures of a multi-cylinder engine, which can in turn reduce engine performance and efficiency. Furthermore, a sensor packaged into a compact probe was designed, built and applied to measure spatiotemporal EGR distributions in the intake manifold of an operating engine. The probe promotes the development of more efficient and higher-performance engines by resolving high-speed in situ CO2 concentration at various locations in the intake manifold. Our study employed mid-infrared light sources tuned to an absorption band of CO2 near 4.3 μm, an industry standard species for determining EGR fraction. The calibrated probe was used to map spatial EGR distributions in an intake manifold with high accuracy and monitor cycle-resolved cylinder-specific EGR fluctuations at a rate of up to 1 kHz.

  5. Fast spatially resolved exhaust gas recirculation (EGR) distribution measurements in an internal combustion engine using absorption spectroscopy.

    PubMed

    Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E; Perfetto, Anthony; Geckler, Sam; Partridge, William P

    2015-09-01

    Exhaust gas recirculation (EGR) in internal combustion engines is an effective method of reducing NOx emissions while improving efficiency. However, insufficient mixing between fresh air and exhaust gas can lead to cycle-to-cycle and cylinder-to-cylinder non-uniform charge gas mixtures of a multi-cylinder engine, which can in turn reduce engine performance and efficiency. A sensor packaged into a compact probe was designed, built and applied to measure spatiotemporal EGR distributions in the intake manifold of an operating engine. The probe promotes the development of more efficient and higher-performance engines by resolving high-speed in situ CO2 concentration at various locations in the intake manifold. The study employed mid-infrared light sources tuned to an absorption band of CO2 near 4.3 μm, an industry standard species for determining EGR fraction. The calibrated probe was used to map spatial EGR distributions in an intake manifold with high accuracy and monitor cycle-resolved cylinder-specific EGR fluctuations at a rate of up to 1 kHz.

  6. Fast Spatially Resolved Exhaust Gas Recirculation (EGR) Distribution Measurements in an Internal Combustion Engine Using Absorption Spectroscopy

    DOE PAGES

    Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E.; ...

    2015-09-01

    One effective method of reducing NOx emissions while improving efficiency is exhaust gas recirculation (EGR) in internal combustion engines. But, insufficient mixing between fresh air and exhaust gas can lead to cycle-to-cycle and cylinder-to-cylinder nonuniform charge gas mixtures of a multi-cylinder engine, which can in turn reduce engine performance and efficiency. Furthermore, a sensor packaged into a compact probe was designed, built and applied to measure spatiotemporal EGR distributions in the intake manifold of an operating engine. The probe promotes the development of more efficient and higher-performance engines by resolving high-speed in situ CO2 concentration at various locations in themore » intake manifold. Our study employed mid-infrared light sources tuned to an absorption band of CO2 near 4.3 μm, an industry standard species for determining EGR fraction. The calibrated probe was used to map spatial EGR distributions in an intake manifold with high accuracy and monitor cycle-resolved cylinder-specific EGR fluctuations at a rate of up to 1 kHz.« less

  7. THE LOW-LUMINOSITY END OF THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Bentz, Misty C.; Denney, Kelly D.; Vestergaard, Marianne; Grier, Catherine J.; Peterson, Bradley M.; De Rosa, Gisella; Pogge, Richard W.; Barth, Aaron J.; Bennert, Vardha N.; Canalizo, Gabriela; Filippenko, Alexei V.; Li Weidong; Gates, Elinor L.; Malkan, Matthew A.; Stern, Daniel; Treu, Tommaso; Woo, Jong-Hak

    2013-04-20

    We present an updated and revised analysis of the relationship between the H{beta} broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create ''AGN-free'' images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the H{beta} time lag, which is assumed to yield the average H{beta} BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R{sub BLR}-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of {alpha}= 0.533{sup +0.035}{sub -0.033}, consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 {+-} 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the R{sub BLR}-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.

  8. RE-ANALYSIS OF THE RADIO LUMINOSITY FUNCTION OF GALACTIC H II REGIONS

    SciTech Connect

    Paladini, R.; Noriega-Crespo, A.; Carey, S. J.; DeZotti, G.

    2009-09-10

    We have re-analyzed continuum and recombination lines radio data available in the literature in order to derive the luminosity function (LF) of Galactic H II regions. The study is performed by considering the first and fourth Galactic quadrants independently. We estimate the completeness level of the sample in the fourth quadrant at 5 Jy, and the one in the first quadrant at 2 Jy. We show that the two samples (fourth or first quadrant) include, as well as giant and supergiant H II regions, a significant number of subgiant sources. The LF is obtained, in each Galactic quadrant, with a generalized Schmidt's estimator using an effective volume derived from the observed spatial distribution of the considered H II regions. The re-analysis also takes advantage of recently published ancillary absorption data allowing to solve the distance ambiguity for several objects. A single power-law fit to the LFs retrieves a slope equal to -2.23 {+-} 0.07 (fourth quadrant) and to -1.85 {+-} 0.11 (first quadrant). We also find marginal evidence of a luminosity break at L{sub knee} = 10{sup 23.45} erg s{sup -1} Hz{sup -1} for the LF in the fourth quadrant. We convert radio luminosities into equivalent H{alpha} and Lyman continuum luminosities to facilitate comparisons with extragalactic studies. We obtain an average total H II regions Lyman continuum luminosity of 0.89 {+-} 0.23 x 10{sup 53} s{sup -1}, corresponding to 30% of the total ionizing luminosity of the Galaxy.

  9. The Luminosity-size Relation of Galaxies to z=1?

    NASA Astrophysics Data System (ADS)

    Cameron, E.; Driver, S. P.

    2007-12-01

    We use the Hubble Ultra Deep Field (UDF) to study the galaxy luminosity-size (M-R_e) distribution. With a careful analysis of selection effects due to both detection completeness and measurement reliability we identify bias-free regions in the M-R_e plane for a series of volume-limited samples. We also investigate the colour-log(n) distribution of these galaxies and further subdivide our data by structural type to separately study compact and diffuse objects. By comparison to the nearby Millennium Galaxy Catalogue, we present tentative evidence for evolution of diffuse, disk-like galaxies with redshift---both in mean surface brightness and the slope of the M-R_e relation. In contrast we find no evidence of structural evolution in the compact galaxy M-R_e relation over this redshift range, although there is a suggestion of colour evolution. We also highlight the importance of considering surface brightness dependent measurement biases in addition to incompleteness biases. In particular, the increasing, systematic under-estimation of Kron fluxes towards low surface brightnesses may cause diffuse, yet luminous, systems to be mistaken for faint, compact objects.

  10. Broadband Electromagnetic Pulses Coinciding with Sprite Luminosity

    NASA Astrophysics Data System (ADS)

    Fullekrug, M.; Roussel-Dupre, R. A.; Symbalisty, E.; Chanrion, O.; van der Velde, O. A.; Odzimek, A.; Whitley, T.; Neubert, T.

    2009-12-01

    This study reports novel optical sprite observations in southern France during the summer months 2009 and the associated electromagnetic radiation emitted in the frequency range >50 kHz. About 10% of the observed sprites are associated with consecutive pulses of >50 kHz electromagnetic radiation. Some of these broadband pulses occur simultaneously with the sprite luminosity. In particular, the electromagnetic radiation of the sprite itself can coincide with a broadband pulse. This behaviour is predicted by the relativistic runaway breakdown theory, in which the lightning electromagnetic field accelerates free electrons to form a narrow particle beam shooting upward into near-Earth space. This vertical relativistic runaway breakdown describes a novel physical process within the Earth's atmosphere, even though it may occur only on extremely rare occasions, i.e., ~100 upward particle beams per day around the globe. The wealth of currently planned future space missions in this research area will greatly enhance the detection likelihood of the predicted particle beams.

  11. IMPROVED PHOTOMETRIC REDSHIFTS WITH SURFACE LUMINOSITY PRIORS

    SciTech Connect

    Xia Lifang; Cohen, Seth; Malhotra, Sangeeta; Rhoads, James; Grogin, Norman; Windhorst, Rogier A.; Hathi, Nimish P.; Pirzkal, Nor; Xu Chun

    2009-07-15

    We apply Bayesian statistics with prior probabilities of galaxy surface luminosity (SL) to improve photometric redshifts. We apply the method to a sample of 1266 galaxies with spectroscopic redshifts in the GOODS North and South fields at 0.1 {approx}< z {approx}< 2.0. We start with spectrophotometric redshifts (SPZs) based on Probing Evolution and Reionization Spectroscopically grism spectra, which cover a wavelength range of 6000-9000 A, combined with (U)BViz(JHK) broadband photometry in the GOODS fields. The accuracy of SPZ redshifts is estimated to be {sigma}({delta}(z)) = 0.035 with an systematic offset of -0.026, where {delta}(z) = {delta}z/(1 + z), for galaxies in redshift range of 0.5 {approx}< z {approx}< 1.25. The addition of the SL prior probability helps break the degeneracy of SPZ redshifts between low redshift 4000 A break galaxies and high-redshift Lyman break galaxies which are mostly catastrophic outliers. For the 1138 galaxies at z {approx}< 1.6, the fraction of galaxies with redshift deviation {delta}(z)>0.2 is reduced from 15.0% to 10.4%, while the rms scatter of the fractional redshift error does not change much.

  12. Distributions.

    ERIC Educational Resources Information Center

    Bowers, Wayne A.

    This monograph was written for the Conference of the New Instructional Materials in Physics, held at the University of Washington in summer, 1965. It is intended for students who have had an introductory college physics course. It seeks to provide an introduction to the idea of distributions in general, and to some aspects of the subject in…

  13. Galaxy Clustering in the Completed SDSS Redshift Survey: The Dependence on Color and Luminosity

    NASA Astrophysics Data System (ADS)

    Zehavi, Idit; Zheng, Zheng; Weinberg, David H.; Blanton, Michael R.; Bahcall, Neta A.; Berlind, Andreas A.; Brinkmann, Jon; Frieman, Joshua A.; Gunn, James E.; Lupton, Robert H.; Nichol, Robert C.; Percival, Will J.; Schneider, Donald P.; Skibba, Ramin A.; Strauss, Michael A.; Tegmark, Max; York, Donald G.

    2011-07-01

    We measure the luminosity and color dependence of galaxy clustering in the largest-ever galaxy redshift survey, the main galaxy sample of the Sloan Digital Sky Survey Seventh Data Release. We focus on the projected correlation function wp (rp ) of volume-limited samples, extracted from the parent sample of ~700,000 galaxies over 8000 deg2, extending up to redshift of 0.25. We interpret our measurements using halo occupation distribution (HOD) modeling assuming a ΛCDM cosmology (inflationary cold dark matter with a cosmological constant). The amplitude of wp (rp ) grows slowly with luminosity for L < L * and increases sharply at higher luminosities, with a large-scale bias factor b(> L) × (σ8/0.8) = 1.06 + 0.21(L/L *)1.12, where L is the sample luminosity threshold. At fixed luminosity, redder galaxies exhibit a higher amplitude and steeper correlation function, a steady trend that runs through the "blue cloud" and "green valley" and continues across the "red sequence." The cross-correlation of red and blue galaxies is close to the geometric mean of their autocorrelations, dropping slightly below at rp < 1 h -1 Mpc. The luminosity trends for the red and blue galaxy populations separately are strikingly different. Blue galaxies show a slow but steady increase of clustering strength with luminosity, with nearly constant shape of wp (rp ). The large-scale clustering of red galaxies shows little luminosity dependence until a sharp increase at L > 4 L *, but the lowest luminosity red galaxies (0.04-0.25 L *) show very strong clustering on small scales (rp < 2 h -1 Mpc). Most of the observed trends can be naturally understood within the ΛCDM+HOD framework. The growth of wp (rp ) for higher luminosity galaxies reflects an overall shift in the mass scale of their host dark matter halos, in particular an increase in the minimum host halo mass M min. The mass at which a halo has, on average, one satellite galaxy brighter than L is M 1 ≈ 17 M min(L) over most of the

  14. Uptake of injected 125I-ricin by rat liver in vivo. Subcellular distribution and characterization of the internalized ligand.

    PubMed Central

    Frénoy, J P; Turpin, E; Janicot, M; Gehin-Fouque, F; Desbuquois, B

    1992-01-01

    Subcellular-fractionation techniques were used to characterize the endocytic pathway followed by ricin in rat liver in vivo and tentatively identify the site(s) at which the ricin interchain disulphide bridge is split. After injection of 125I-ricin, hepatic uptake of radioactivity was maximum at 30 min (40% of injected dose). At 5 min, about 80% of the radioactivity in the homogenate was recovered in the microsomal (P) fraction, but later on the recovery of the radioactivity in the mitochondrial-lysosomal (ML) fractions progressively increased (50% at 30 min) at the expense of that in the P fraction. Subfractionation of the P and ML fractions on analytical sucrose-density gradients revealed a time-dependent translocation of the radioactivity from low- to high-density endocytic structures, with median relative densities at 5 and 60 min of about 1.15 and 1.16 (P fraction) and 1.19 and 1.22 (ML fraction) respectively. The late distribution of the radioactivity in the ML fraction was similar to that of the lysosomal marker acid phosphatase. Studies with co-injected lactose and mannan showed that ricin was internalized mainly via the mannose receptor. In the presence of mannan, the late recovery of radioactivity in the ML fraction was decreased, and the distribution of the radioactivity associated with the P fraction was shifted toward lower densities (median relative density 1.13), indicating a different pathway of endocytosis. Analysis of the radioactivity associated with the ML and S fractions by SDS/PAGE revealed a time-dependent increase in the amount of intact A- and B-chains and low-molecular-mass products. When ML fractions containing partially processed ricin were incubated at 37 degrees C at pH 5 or at pH 7.2 in the presence of ATP, only low-molecular-mass products were generated. We conclude that internalized ricin associates with endocytic structures whose size and density of equilibration increase with time, and that, although detectable in these structures

  15. Geophysical experiments to image the shallow internal structure and the moisture distribution of a mine waste rock pile

    NASA Astrophysics Data System (ADS)

    Poisson, Jérôme; Chouteau, Michel; Aubertin, Michel; Campos, Daniel

    2009-02-01

    Several field surveys of a waste rock pile were carried out during the summers of 2002 and 2003 using ground-penetrating radar, electromagnetic conductivity and DC resistivity imaging. The waste rock deposit is prone to generate acid mine drainage (AMD) due to the oxidation of sulphidic minerals. One of the most critical factors that lead to the production of AMD is unsaturated water flow and the ensuing moisture distribution in the waste rock. This geophysical characterization study, performed over a 30 m × 30 m test zone, was designed to image the internal structure controlling the water flux at shallow depth. The subsurface was found to consist of three zones for the first 6 m of the pile, mainly based on electrical resistivities: a thin superficial conductive material, an intermediate 2 to 3 m thick highly resistive zone, and a lower, more conductive medium. With the help of hydrogeological tests, chemical analyses and two 2.5 m-deep trenches, it is shown that the two conductive zones are correlated with fine-grained waste rock and the resistive zone correlates with a coarser material. In the two deeper zones, the contact between the two types of waste rock is typically highlighted by a sharp resistive/conductive boundary. An increase of conductance in the relatively thin upper layer towards the edge of the pile appears to be caused by an increase in thickness of the fine-grained material. Additional geophysical surveys carried out on a profile along the flank of the upper bench of the pile show that the main features of the internal structure are sub-parallel to the slope, at least for the first 3 m in depth. The data also show an increase in resistivity from the top to bottom of the slope, in accordance with expected particle segregation, from fine-grained material at the top to coarser material at the bottom. Wide-angle reflection GPR monitoring during large scale infiltration tests seems to indicate preferential flow paths towards the direction of coarser

  16. Upgrade of the D0 luminosity monitor readout system

    SciTech Connect

    Anderson, John; Bridges, Lloyd; Casey, Brendan; Enari, Yuji; Green, Johnny; Johnson, Marvin; Kwarciany, Rick; Miao, Chyi-Chiang; Partridge, Richard; Yoo, Hwi Dong; Wang, Jigang; /Brown U. /Fermilab

    2006-12-01

    We describe upgrades to the readout system for the D0 Luminosity Monitor. The D0 Luminosity Monitor consists of plastic scintillation detectors with fine-mesh photomultiplier readout that cover the pseudorapidity range 2.7 < |{eta}| < 4.4. The detector is designed to provide a precise measurement of the rate for non-diffractive inelastic collisions that is used to calculate the TeVatron luminosity at D0. The new readout system is based on custom VME electronics that make precise time-of-flight and charge measurements for each luminosity counter. These measurements are used to identify beam crossings with non-diffractive interactions by requiring in-time hits in both the forward and backward luminosity counters. We have also significantly increased signal/noise for the photomultiplier signals by developing a new front-end preamplifier and improving the grounding scheme.

  17. The Luminosity Function at z ~ 8 from 97 Y-band Dropouts: Inferences about Reionization

    NASA Astrophysics Data System (ADS)

    Schmidt, Kasper B.; Treu, Tommaso; Trenti, Michele; Bradley, Larry D.; Kelly, Brandon C.; Oesch, Pascal A.; Holwerda, Benne W.; Shull, J. Michael; Stiavelli, Massimo

    2014-05-01

    We present the largest search to date for Y-band dropout galaxies (z ~ 8 Lyman break galaxies, LBGs) based on 350 arcmin2 of Hubble Space Telescope observations in the V, Y, J, and H bands from the Brightest of Reionizing Galaxies (BoRG) survey. In addition to previously published data, the BoRG13 data set presented here includes approximately 50 arcmin2 of new data and deeper observations of two previous BoRG pointings, from which we present 9 new z ~ 8 LBG candidates, bringing the total number of BoRG Y-band dropouts to 38 with 25.5 <= mJ <= 27.6 (AB system). We introduce a new Bayesian formalism for estimating the galaxy luminosity function, which does not require binning (and thus smearing) of the data and includes a likelihood based on the formally correct binomial distribution as opposed to the often-used approximate Poisson distribution. We demonstrate the utility of the new method on a sample of 97 Y-band dropouts that combines the bright BoRG galaxies with the fainter sources published in Bouwens et al. from the Hubble Ultra Deep Field and Early Release Science programs. We show that the z ~ 8 luminosity function is well described by a Schechter function over its full dynamic range with a characteristic magnitude M^\\star = -20.15^{+0.29}_{-0.38}, a faint-end slope of \\alpha = -1.87^{+0.26}_{-0.26}, and a number density of log _{10} \\phi ^\\star [{Mpc}^{-3}] = -3.24^{+0.25}_{-0.24}. Integrated down to M = -17.7, this luminosity function yields a luminosity density log _{10} \\epsilon [erg\\, s^{-1\\, Hz^{-1}\\, Mpc^{-3}}] = 25.52^{+0.05}_{-0.05}. Our luminosity function analysis is consistent with previously published determinations within 1σ. The error analysis suggests that uncertainties on the faint-end slope are still too large to draw a firm conclusion about its evolution with redshift. We use our statistical framework to discuss the implication of our study for the physics of reionization. By assuming theoretically motivated priors on the clumping

  18. The H alpha Luminosity Function and Star Formation Rate at Z approximately 0.2

    NASA Astrophysics Data System (ADS)

    Tresse, Laurence; Maddox, Steve J.

    1998-03-01

    We have measured the Hα + [N II] fluxes of the I-selected Canada-France Redshift Survey (CFRS) galaxies lying at a redshift z below 0.3 and hence derived the Hα luminosity function. The magnitude limits of the CFRS mean that only the galaxies with MB >~ -21 mag were observed at these redshifts. We obtained a total Hα luminosity density of at least 1039.44+/-0.04 ergs s-1 Mpc-3 at a mean z = 0.2 for galaxies with rest-frame EW(Hα + [N II]) >~ 10 Å. This is twice the value found in the local universe by Gallego et al. Our Hα star formation rate, derived from Madau, is higher than the UV observations at the same z, implying a UV dust extinction of ~1 mag. We found a strong correlation between the Hα luminosity and the absolute magnitude in the B band: M(BAB) = 46.7 - 1.6 log L(Hα). This work will serve as a basis of future studies of Hα luminosity distributions measured from optically selected spectroscopic surveys of the distant universe, and it will provide a better understanding of the physical processes responsible for the observed galaxy evolution.

  19. The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars

    SciTech Connect

    Ajello, M.; Shaw, M.S.; Romani, R.W.; Dermer, C.D.; Costamante, L.; King, O.G.; Max-Moerbeck, W.; Readhead, A.; Reimer, A.; Richards, J.L.; Stevenson, M.

    2012-04-16

    Fermi has provided the largest sample of {gamma}-ray selected blazars to date. In this work we use a complete sample of FSRQs detected during the first year of operation to determine the luminosity function (LF) and its evolution with cosmic time. The number density of FSRQs grows dramatically up to redshift {approx}0.5-2.0 and declines thereafter. The redshift of the peak in the density is luminosity dependent, with more luminous sources peaking at earlier times; thus the LF of {gamma}-ray FSRQs follows a luminosity-dependent density evolution similarly to that of radio-quiet AGN. Also using data from the Swift Burst Alert Telescope we derive the average spectral energy distribution of FSRQs in the 10 keV-100GeV band and show that there is no correlation of the peak {gamma}-ray luminosity with {gamma}-ray peak frequency. The coupling of the SED and LF allows us to predict that the contribution of FSRQs to the Fermi isotropic {gamma}-ray background is 9.3{sub -1.0}{sup +1.6}% ({+-}3% systematic uncertainty) in the 0.1-100GeV band. Finally we determine the LF of unbeamed FSRQs, finding that FSRQs have an average Lorentz factor of {gamma} = 11.7{sub -2.2}{sup +3.3}, that most are seen within 5{sup o} of the jet axis, and that they represent only {approx}0.1% of the parent population.

  20. The luminosities of the coldest brown dwarfs

    SciTech Connect

    Tinney, C. G.; Faherty, Jacqueline K.; Kirkpatrick, J. Davy; Cushing, Mike; Morley, Caroline V.; Wright, Edward L.

    2014-11-20

    In recent years, brown dwarfs have been extended to a new Y-dwarf class with effective temperatures colder than 500 K and masses in the range of 5-30 Jupiter masses. They fill a crucial gap in observable atmospheric properties between the much colder gas-giant planets of our own solar system (at around 130 K) and both hotter T-type brown dwarfs and the hotter planets that can be imaged orbiting young nearby stars (both with effective temperatures in the range of 1500-1000 K). Distance measurements for these objects deliver absolute magnitudes that make critical tests of our understanding of very cool atmospheres. Here we report new distances for nine Y dwarfs and seven very late T dwarfs. These reveal that Y dwarfs do indeed represent a continuation of the T-dwarf sequence to both fainter luminosities and cooler temperatures. They also show that the coolest objects display a large range in absolute magnitude for a given photometric color. The latest atmospheric models show good agreement with the majority of these Y-dwarf absolute magnitudes. This is also the case for WISE0855-0714, the coldest and closest brown dwarf to the Sun, which shows evidence for water ice clouds. However, there are also some outstanding exceptions, which suggest either binarity or the presence of condensate clouds. The former is readily testable with current adaptive optics facilities. The latter would mean that the range of cloudiness in Y dwarfs is substantial with most hosting almost no clouds—while others have dense clouds, making them prime targets for future variability observations to study cloud dynamics.

  1. Correlation analysis of radio properties and accretion-disk luminosity for low luminosity AGNs

    NASA Astrophysics Data System (ADS)

    Su, Renzhi; Liu, Xiang; Zhang, Zhen

    2017-01-01

    The correlation between the jet power and accretion disk luminosity is investigated and analyzed with our model for 7 samples of low luminosity active galactic nuclei (LLAGNs). The main results are: (1) the power-law correlation index (P_{jet} ∝ L_{disk} ^{μ}) typically ranges μ=0.4-0.7 for the LLAGN samples, and there is a hint of steep index for the LLAGN sample which hosted by a high fraction of elliptical galaxies, and there are no significant correlation between the μ and the LLAGN types (Seyfert, LINER); (2) for μ≈1, as noted in Liu et al., the accretion disk dominates the jet power and the black hole (BH) spin is not important, for the LLAGN samples studied in this paper we find that the μ is significantly less than unity, implying that BH spin may play a significant role in the jet power of LLAGNs; (3) the BH spin-jet power is negatively correlated with the BH mass in our model, which means a high spin-jet efficiency in the `low' BH-mass LLAGNs; (4) an anti-correlation between radio loudness and disk luminosity is found, which is apparently due to the flatter power-law index in the jet-disk correlation of the LLAGNs, and the radio loudness can be higher in the LLAGNs than in luminous AGNs/quasars when the BH spin-jet power is comparable to or dominate over the accretion-jet power in the LLAGNs. The high radio-core dominance of the LLAGNs is also discussed.

  2. THE LUMINOSITIES OF PROTOSTARS IN THE SPITZER c2d AND GOULD BELT LEGACY CLOUDS

    SciTech Connect

    Dunham, Michael M.; Arce, Hector G.; Allen, Lori E.; Evans II, Neal J.; Harvey, Paul M.; Broekhoven-Fiene, Hannah; Matthews, Brenda C.; Chapman, Nicholas L.; Cieza, Lucas A.; Gutermuth, Robert A.; Hatchell, Jennifer; Huard, Tracy L.; Miller, Jennifer F.; Kirk, Jason M.; Merin, Bruno; Peterson, Dawn E.; Spezzi, Loredana

    2013-04-15

    Motivated by the long-standing 'luminosity problem' in low-mass star formation whereby protostars are underluminous compared to theoretical expectations, we identify 230 protostars in 18 molecular clouds observed by two Spitzer Space Telescope Legacy surveys of nearby star-forming regions. We compile complete spectral energy distributions, calculate L{sub bol} for each source, and study the protostellar luminosity distribution. This distribution extends over three orders of magnitude, from 0.01 L{sub Sun} to 69 L{sub Sun }, and has a mean and median of 4.3 L{sub Sun} and 1.3 L{sub Sun }, respectively. The distributions are very similar for Class 0 and Class I sources except for an excess of low luminosity (L{sub bol} {approx}< 0.5 L{sub Sun }) Class I sources compared to Class 0. 100 out of the 230 protostars (43%) lack any available data in the far-infrared and submillimeter (70 {mu}m <{lambda} < 850 {mu}m) and have L{sub bol} underestimated by factors of 2.5 on average, and up to factors of 8-10 in extreme cases. Correcting these underestimates for each source individually once additional data becomes available will likely increase both the mean and median of the sample by 35%-40%. We discuss and compare our results to several recent theoretical studies of protostellar luminosities and show that our new results do not invalidate the conclusions of any of these studies. As these studies demonstrate that there is more than one plausible accretion scenario that can match observations, future attention is clearly needed. The better statistics provided by our increased data set should aid such future work.

  3. Simulation of the LHC BRAN luminosity monitor for high luminosity interaction regions

    SciTech Connect

    Miyamoto, R.; Matis, H.; Ratti, A.; Stiller, J.; White, S.M.

    2010-05-23

    The BRAN (Beam RAte of Neutrals) detector monitors the collision rates in the high luminosity interaction regions of LHC (ATLAS and CMS). This Argon gas ionization detector measures the forward neutral particles from collisions at the interaction point. To predict and improve the understanding of the detector's performance, we produced a detailed model of the detector and its surroundings in Fluka. In this paper, we present the model and results of our simulations including the detectors estimated response to interactions for beam energies of 3.5, 5, and 7 TeV.

  4. Distances to dense cores that contain very low luminosity objects

    NASA Astrophysics Data System (ADS)

    Maheswar, G.; Lee, C. W.; Dib, S.

    2011-12-01

    Aims: We estimate the distances to dense molecular cores that harbour very low luminosity objects (VeLLOs) detected by the Spitzer Space Telescope and attempt to confirm their VeLLO nature. Methods: The cloud distances are estimated using a near-IR photometric method. We use a technique that performs a spectral classification of stars lying towards the fields containing the clouds as either main-sequence stars or giants. In this technique, the observed (J - H) and (H - Ks) colours are dereddened simultaneously using trial values of AV and a normal interstellar extinction law. The best fit of the dereddened colours to the intrinsic colours giving a minimum value of χ2 then yields the corresponding spectral type and AV for the star. The main-sequence stars, thus classified, are then utilized in an AV versus distance plot to bracket the cloud distances. The typical error in the estimation of distances to the clouds are found to be ~18%. Results: We estimate distances to seven cloud cores, IRAM 04191, L1521F, BHR 111, L328, L673-7, L1014, and L1148 using the above method. These clouds contain VeLLO candidates. The estimated distances to the cores are found to be 127 ± 25 pc (IRAM 04191), 136 ± 36 pc (L1521F), 355 ± 65 pc (BHR 111), 217 ± 30 pc (L328), 240 ± 45 pc (L673-7), 258 ± 50 pc (L1014), and 301 ± 55 pc (L1148). We re-evaluated the internal luminosities of the VeLLOs discovered in these seven clouds using the distances estimated from this work. Except for L1014 - IRS (Lint = 0.15 L⊙), all other VeLLO candidates are found to be consistent with the definition of a VeLLO (Lint ≤ 0.1 L⊙). In addition to the cores that harbour VeLLO candidates, we also obtained distances to the clouds L323, L675, L676, CB 188, L1122, L1152, L1155, L1157, and L1158, which are located in the directions of the above seven cores. Towards L1521F and L1148, we found evidence of multiple dust layers.

  5. A Global Study of the Practice and Impact of Distributed Instructional Leadership in International Baccalaureate (IB) Schools

    ERIC Educational Resources Information Center

    Hallinger, Philip; Lee, Moosung

    2012-01-01

    Over the last half century, international schools have come to represent an increasingly important sector in the changing global education context. International Baccalaureate (IB) schools in particular, and international schools more generally, can be viewed as specific types of educational contexts for leadership practice. In this article we…

  6. Meta-Analysis of Survival Curve Data Using Distributed Health Data Networks: Application to Hip Arthroplasty Studies of the International Consortium of Orthopaedic Registries

    ERIC Educational Resources Information Center

    Cafri, Guy; Banerjee, Samprit; Sedrakyan, Art; Paxton, Liz; Furnes, Ove; Graves, Stephen; Marinac-Dabic, Danica

    2015-01-01

    The motivating example for this paper comes from a distributed health data network, the International Consortium of Orthopaedic Registries (ICOR), which aims to examine risk factors for orthopedic device failure for registries around the world. Unfortunately, regulatory, privacy, and propriety concerns made sharing of raw data impossible, even if…

  7. Multi-Bunch Simulations of the ILC for Luminosity Performance Studies

    SciTech Connect

    White, G.; Walker, N.; Schulte, D.; /CERN

    2005-07-11

    To study the luminosity performance of the International Linear Collider (ILC) with different design parameters, a simulation was constructed that tracks a multi-bunch representation of the beam from the Damping Ring extraction through to the Interaction Point. The simulation code PLACET is used to simulate the LINAC, MatMerlin is used to track through the Beam Delivery System and GUINEA-PIG for the beam-beam interaction. Included in the simulation are ground motion and wakefield effects, intra-train fast feedback and luminosity-based feedback systems. To efficiently study multiple parameters/multiple seeds, the simulation is deployed on the Queen Mary High-Throughput computing cluster at Queen Mary, University of London, where 100 simultaneous simulation seeds can be run.

  8. Initial velocity distribution of MALDI/LDI ions measured by internal MALDI source Fourier-transform ion cyclotron resonance mass spectrometry.

    PubMed

    Chagovets, Vitaliy; Frankevich, Vladimir; Zenobi, Renato

    2014-11-01

    A new method for measuring the ion velocity distribution using an internal matrix-assisted laser desorption/ionization (MALDI) source Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer is described. The method provides the possibility of studying ion velocities without any influence of electric fields in the direction of the instrument axis until the ions reach the ICR cell. It also allows to simultaneously account for and to estimate not only the velocity distribution but the angular distribution as well. The method was demonstrated using several types of compounds in laser desorption/ionization (LDI) mode.

  9. Gamma-ray luminosity and photon index evolution of FSRQ blazars and contribution to the gamma-ray background

    SciTech Connect

    Singal, J.; Ko, A.; Petrosian, V.

    2014-05-10

    We present the redshift evolutions and distributions of the gamma-ray luminosity and photon spectral index of flat spectrum radio quasar (FSRQ) type blazars, using non-parametric methods to obtain the evolutions and distributions directly from the data. The sample we use for analysis consists of almost all FSRQs observed with a greater than approximately 7σ detection threshold in the first-year catalog of the Fermi Gamma-ray Space Telescope's Large Area Telescope, with redshifts as determined from optical spectroscopy by Shaw et al. We find that FSQRs undergo rapid gamma-ray luminosity evolution, but negligible photon index evolution, with redshift. With these evolutions accounted for we determine the density evolution and luminosity function of FSRQs and calculate their total contribution to the extragalactic gamma-ray background radiation, resolved and unresolved, which is found to be 16(+10/–4)%, in agreement with previous studies.

  10. How Accurate Are Infrared Luminosities from Monochromatic Photometric Extrapolation?

    NASA Astrophysics Data System (ADS)

    Lin, Zesen; Fang, Guanwen; Kong, Xu

    2016-12-01

    Template-based extrapolations from only one photometric band can be a cost-effective method to estimate the total infrared (IR) luminosities ({L}{IR}) of galaxies. By utilizing multi-wavelength data that covers across 0.35-500 μm in GOODS-North and GOODS-South fields, we investigate the accuracy of this monochromatic extrapolated {L}{IR} based on three IR spectral energy distribution (SED) templates out to z˜ 3.5. We find that the Chary & Elbaz template provides the best estimate of {L}{IR} in Herschel/Photodetector Array Camera and Spectrometer (PACS) bands, while the Dale & Helou template performs best in Herschel/Spectral and Photometric Imaging Receiver (SPIRE) bands. To estimate {L}{IR}, we suggest that extrapolations from the available longest wavelength PACS band based on the Chary & Elbaz template can be a good estimator. Moreover, if the PACS measurement is unavailable, extrapolations from SPIRE observations but based on the Dale & Helou template can also provide a statistically unbiased estimate for galaxies at z≲ 2. The emission with a rest-frame 10-100 μm range of IR SED can be well described by all three templates, but only the Dale & Helou template shows a nearly unbiased estimate of the emission of the rest-frame submillimeter part.

  11. Seeking the epoch of maximum luminosity for dusty quasars

    SciTech Connect

    Vardanyan, Valeri; Weedman, Daniel; Sargsyan, Lusine E-mail: dweedman@isc.astro.cornell.edu

    2014-08-01

    Infrared luminosities νL{sub ν}(7.8 μm) arising from dust reradiation are determined for Sloan Digital Sky Survey (SDSS) quasars with 1.4 luminosity does not show a maximum at any redshift z < 5, reaching a plateau for z ≳ 3 with maximum luminosity νL{sub ν}(7.8 μm) ≳ 10{sup 47} erg s{sup –1}; luminosity functions show one quasar Gpc{sup –3} having νL{sub ν}(7.8 μm) > 10{sup 46.6} erg s{sup –1} for all 2 luminosity has not yet been identified at any redshift below 5. The most ultraviolet luminous quasars, defined by rest frame νL{sub ν}(0.25 μm), have the largest values of the ratio νL{sub ν}(0.25 μm)/νL{sub ν}(7.8 μm) with a maximum ratio at z = 2.9. From these results, we conclude that the quasars most luminous in the ultraviolet have the smallest dust content and appear luminous primarily because of lessened extinction. Observed ultraviolet/infrared luminosity ratios are used to define 'obscured' quasars as those having >5 mag of ultraviolet extinction. We present a new summary of obscured quasars discovered with the Spitzer Infrared Spectrograph and determine the infrared luminosity function of these obscured quasars at z ∼ 2.1. This is compared with infrared luminosity functions of optically discovered, unobscured quasars in the SDSS and in the AGN and Galaxy Evolution Survey. The comparison indicates comparable numbers of obscured and unobscured quasars at z ∼ 2.1 with a possible excess of obscured quasars at fainter luminosities.

  12. Does the obscured AGN fraction really depend on luminosity?

    NASA Astrophysics Data System (ADS)

    Sazonov, S.; Churazov, E.; Krivonos, R.

    2015-12-01

    We use a sample of 151 local non-blazar active galactic nuclei (AGN) selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstrate that in addition to negative bias, due to absorption in the torus, in finding obscured AGN in hard X-ray flux-limited surveys, there is also positive bias in finding unobscured AGN, due to Compton reflection in the torus. These biases can be even stronger taking into account plausible intrinsic collimation of hard X-ray emission along the axis of the obscuring torus. Given the AGN luminosity function, which steepens at high luminosities, these observational biases lead to a decreasing observed fraction of obscured AGN with increasing luminosity even if this fraction has no intrinsic luminosity dependence. We find that if the central hard X-ray source in AGN is isotropic, the intrinsic (i.e. corrected for biases) obscured AGN fraction still shows a declining trend with luminosity, although the intrinsic obscured fraction is significantly larger than the observed one: the actual fraction is larger than ˜85 per cent at L ≲ 1042.5 erg s-1 (17-60 keV), and decreases to ≲60 per cent at L ≳ 1044 erg s-1. In terms of the half-opening angle θ of an obscuring torus, this implies that θ ≲ 30° in lower luminosity AGN, and θ ≳ 45° in higher luminosity ones. If, however, the emission from the central supermassive black hole is collimated as dL/dΩ ∝ cos α, the intrinsic dependence of the obscured AGN fraction is consistent with a luminosity-independent torus half-opening angle θ ˜ 30°.

  13. The star formation rate distribution function of the local Universe

    NASA Astrophysics Data System (ADS)

    Bothwell, M. S.; Kennicutt, R. C.; Johnson, B. D.; Wu, Y.; Lee, J. C.; Dale, D.; Engelbracht, C.; Calzetti, D.; Skillman, E.

    2011-08-01

    We present total infrared (IR) and ultraviolet (UV) luminosity functions derived from large representative samples of galaxies at z˜ 0, selected at IR and UV wavelengths from the Imperial IRAS Faint Source Catalogue redshift data base (IIFSCz) catalogue, and the GALEX All-Sky Imaging Survey (AIS), respectively. We augment these with deep Spitzer and GALEX imaging of galaxies in the 11 Mpc Local Volume Legacy (LVL) Survey, allowing us to extend these luminosity functions to lower luminosities (˜106 L⊙), and providing good constraints on the slope of the luminosity function at the extreme faint end for the first time. Using conventional star formation prescriptions, we generate from our data the star formation rate (SFR) distribution function for the local Universe. We find that it has a Schechter form, the faint-end slope has a constant value (to the limits of our data) of α=-1.51 ± 0.08 and the ‘characteristic’ SFR ψ* is 9.2 M⊙ yr-1. We also show the distribution function of the SFR volume density; we then use this to calculate a value for the total SFR volume density at z˜ 0 of 0.025 ± 0.0016 M⊙ yr-1 Mpc-3, of which ˜20 per cent is occurring in starbursts. Decomposing the total star formation by infrared luminosity, it can be seen that 9 ± 1 per cent is due to LIRGs, and 0.7 ± 0.2 per cent is occurring in ULIRGs. By comparing UV and IR emission for galaxies in our sample, we also calculate the fraction of star formation occurring in dust-obscured environments, and examine the distribution of dusty star formation: we find a very shallow slope at the highly extincted end, which may be attributable to line-of-sight orientation effects as well as conventional internal extinction.

  14. COMPARING SYMBIOTIC NEBULAE AND PLANETARY NEBULAE LUMINOSITY FUNCTIONS

    SciTech Connect

    Frankowski, Adam; Soker, Noam E-mail: soker@physics.technion.ac.i

    2009-10-01

    We compare the observed symbiotic nebulae (SyN) luminosity function (SyNLF) in the [O III] lambda5007 A line to the planetary nebulae (PN) luminosity function (PNLF) and find that the intrinsic SyNLF (ISyNLF) of galactic SyNs has-within its uncertainty of 0.5-0.8 mag-very similar cutoff luminosity and general shape to those of the PNLF. The [O III]/(Halpha+[N II]) line ratios of SyNs and PNs are shown to be also related. Possible implications of these results for the universality of the PNLF are briefly outlined.

  15. The Similarity of Luminosity in Quasar Doppelganger Pairs

    NASA Astrophysics Data System (ADS)

    Brotherton, Michael S.; Rochais, Thomas Bernard; Singh, Vikram; Chick, William T.; Maithil, Jaya; Sutter, Jessica; Shang, Zhaohui

    2017-01-01

    Quasars, the accreting supermassive black holes at the centers of galaxies, are among the most luminous objects in the universe and in principle ideal for use as so-called "standard candles" with applications in cosmology. Despite possessing a number of spectral features long known to correlate with luminosity, quasars have failed to realize their potential. We have employed spectral principal component analysis to identify more than 1000 quasar pairs from the Sloan Digital Sky Survey with virtually identical ultraviolet spectra, which we call doppelgangers, in order to understand the limits of determining luminosity from spectral features alone. While the majority of doppelgangers have very similar luminosity, there exists a surprisingly large scatter and objects with identical spectra can differ in luminosity by factors of four or larger. We offer some possible physical explanations for this large variance and how it quantifies the problem of ever using quasars as standard candles based on spectral features.

  16. the D0 Luminosity Monitor operations and performance

    SciTech Connect

    Prewitt, Michelle; /Rice U.

    2011-09-01

    The D0 Luminosity Monitor (LM) plays a crucial role in D0 physics analyses by providing the normalization for many cross section measurements. The detector consists of two sets of 24 scintillator wedges read out with photomultiplier tubes. The detector is located in the forward regions surrounding the beam pipe, covering a pseudo-rapidity range of 2.7 < |{eta}| < 4.4. The LM is sensitive to a large fraction of the total inelastic cross section and measures the luminosity by counting the number of empty proton-antiproton bunch crossings, using Poisson statistics to extract the instantaneous luminosity. The techniques used to convert the measurements made by the LM into the assessed luminosity will be discussed, as well as the performance and operational details of the detector.

  17. Unified treatment of the luminosity distance in cosmology

    NASA Astrophysics Data System (ADS)

    Yoo, Jaiyul; Scaccabarozzi, Fulvio

    2016-09-01

    Comparing the luminosity distance measurements to its theoretical predictions is one of the cornerstones in establishing the modern cosmology. However, as shown in Biern & Yoo, its theoretical predictions in literature are often plagued with infrared divergences and gauge-dependences. This trend calls into question the sanity of the methods used to derive the luminosity distance. Here we critically investigate four different methods—the geometric approach, the Sachs approach, the Jacobi mapping approach, and the geodesic light cone (GLC) approach to modeling the luminosity distance, and we present a unified treatment of such methods, facilitating the comparison among the methods and checking their sanity. All of these four methods, if exercised properly, can be used to reproduce the correct description of the luminosity distance.

  18. The Kinematics of the Lag-Luminosity Relationship

    SciTech Connect

    Salmonson, J D

    2004-03-17

    Herein I review the argument that kinematics, i.e. relativistic motions of the emitting source in gamma-ray bursts (GRBs), are the cause of the lag-luminosity relationship observed in bursts with known redshifts.

  19. Luminosity for NLC Design Variations(LCC-0014)

    SciTech Connect

    Thompson, K

    2004-04-20

    In this note we give Guineapig [l] simulation results for the luminosity and luminosity spectrum of three baseline NLC designs at 0.5 TeV (NLC-A-500, NLCB-500, and NLC-C-500) and 1.0 TeV (NLC-A-1000, NLC-B-1000, and NLC-C-1000) [2]. We examine the effects of variations of several design parameters away from the NLC-B-500 and NLC-B-1000 designs. One of our purposes is to study possible trade-offs of parameters to ease tolerances or increase luminosity. Another (future) application will be to examine how the basic designs might be modified in special cases where one wants to optimize the luminosity for particular physics channels.

  20. The luminosity functions of embedded stellar clusters. 1: Method of solution and analytic results

    NASA Technical Reports Server (NTRS)

    Fletcher, Andre B.; Stahler, Steven W.

    1994-01-01

    We describe a method for computing the history of the luminosity function in a young cluster still forming within a molecular cloud complex. Our method, which utilizes detailed results from stellar evolution theory, assumes that clusters arise from the continuous collapse of dense cloud cores over a protracted period of time. It is also assumed that stars reaching the main sequence are distributed in mass according to a prescribed initial mass function (IMF). We keep track separately of the contributions to the luminosity function from the populations of protostars, pre-main-sequence stars, and main-sequence stars. We derive expressions for the fractional contribution of these populations to both the total number of stars produced and the total cluster luminosity. In our model, the number of protostars rises quickly at first, but then levels off to a nearly constant value, which it maintains until the dispersal of the cloud complex. The number fraction of protostars always decreases with time. Averaged over the life of the parent cloud, this fraction is typically a few percent. The protostar mass distribution can be expressed as an integral over the IMF.

  1. LHC luminosity upgrade with large Piwinski angle scheme: a recent look

    SciTech Connect

    Bhat, C.M.; Zimmermann, f.; /CERN

    2011-09-01

    Luminosity upgrade at the LHC collider using longitudinally flat bunches in combination with the large crossing angle (large Piwinski angle scheme) is being studied with renewed interest in recent years. By design, the total beam-beam tune shift at the LHC is less than 0.015 for two interaction points together. But the 2010-11 3.5 TeV collider operation and dedicated studies indicated that the beam-beam tune shift is >0.015 per interaction point. In view of this development we have revisited the requirements for the Large Piwinski Angle scheme at the LHC. In this paper we present a new set of parameters and luminosity calculations for the desired upgrade by investigating: (1) current performance of the LHC injectors, (2) e-cloud issues on nearly flat bunches and (3) realistic beam particle distributions from longitudinal beam dynamics simulations. We also make some remarks on the needed upgrades on the LHC injector accelerators.

  2. Flat bunch creation and acceleration: a possible path for the LHC luminosity upgrade

    SciTech Connect

    Bhat, C.M.; /Fermilab

    2009-05-01

    Increasing the collider luminosity by replacing bunches having Gaussian line-charge distribution with flat bunches, but with same beam-beam tune shift at collision, has been studied widely in recent years. But, creation of 'stable' flat bunches (and their acceleration) using a multiple harmonic RF system has not been fully explored. Here, we review our experience with long flat bunches in the barrier RF buckets at Fermilab.We presentsome preliminary results from beam dynamics simulations and recent beam studies in the LHC injectors to create stable flat bunches using double harmonic RF systems. The results deduced from these studies will be used to model the necessary scheme for luminosity upgrade in the LHC. We have also described a viable (and economical) way for creation and acceleration of flat bunches in the LHC. The flat bunch scheme may have many advantages over the LHC baseline scenario, particularly because of the reduced momentum spread of the bunch for increased intensities.

  3. BL Lacs from the EMSS: Number-counts and implications for the luminosity function

    NASA Technical Reports Server (NTRS)

    Wolter, Anna; Gioia, Isabella M.; Maccacaro, Tommaso; Schild, Rudy E.; Morris, Simon L.; Stocke, John T.

    1989-01-01

    BL Lac objects, extracted from the Einstein Extended Medium Sensitivity Survey (EMSS), are examined. X-ray selection proved to be a powerful tool to find new BL Lacs, and allows the creation of complete, well defined and sizable samples. X-ray selected BL Lac objects (XBL) have in general more starlight in the optical spectra than radio selected BL Lacs. Redshifts for a significant fraction of objects in samples of XBL can be determined. It is thus possible to study the cosmological properties of BL Lac objects. Different models of luminosity functions of BL Lacs, including relativistic beaming, are considered and integrated over luminosity and redshift. The results are compared with the observed number-counts. The observed redshift distribution and the models' predictions are analyzed.

  4. The Size-Luminosity Relation of Disk Galaxies in EDisCS Clusters

    NASA Astrophysics Data System (ADS)

    Gogarten, Stephanie M.; Dalcanton, Julianne J.; Simard, Luc; Rudnick, Gregory; Desai, Vandana

    2007-05-01

    We present the size-luminosity relation (SLR) for disk galaxies observed in eight clusters from the ESO Distant Cluster Survey (EDisCS). These clusters, at redshifts 0.4 < z < 0.8, were observed with the Hubble Space Telescope's Advanced Camera for Surveys. We describe the evolution of the size-luminosity relation with redshift. Previous studies have yielded conflicting opinions over whether or not there has been evolution in the SLR since z˜1, mostly hinging on the proper characterization of selection effects. Additionally, we compare the SLR for cluster and field galaxies to see if the cluster environment has an effect on the evolution of the average size and/or surface brightness. We also derive a theoretical SLR from a simple model of galaxy formation and empirical distribution functions for mass and angular momentum. Comparing this model to our observations provides constraints for galaxy evolution models, particularly models of star formation.

  5. Galactic structure from the Spacelab infrared telescope. II - Luminosity models of the Milky Way

    NASA Technical Reports Server (NTRS)

    Kent, S. M.; Dame, T. M.; Fazio, G.

    1991-01-01

    A 2.4-micron map of the northern Galactic plan is used to determine the 3D luminosity distribution of the Milky Way. The radial surface brightness profile of the disk is found to have an exponential scale length of 3.0 kpc. In the solar neighborhood, the scale height is about 247 pc, which is in agreement with star counts perpendicular to the Galactic plane. The scale height is not constant with the radius but decreases to about 165 pc. To the first order, the bulge can be represented by an oblate spheroid with an axis ratio of 0.61. The 2.2-micron/12-micron flux ratio for the bulge is typical of other dust-free spheroidal systems. Luminosity fluctuations along the Galactic plane are found to be caused chiefly by variations in the line-of-sight extinction.

  6. Frequency domain analysis of triggered lightning return stroke luminosity velocity

    NASA Astrophysics Data System (ADS)

    Carvalho, F. L.; Uman, M. A.; Jordan, D. M.; Moore, R. C.

    2017-02-01

    Fourier analysis is applied to time domain return stroke luminosity signals to calculate the phase and group velocities and the amplitude of the luminosity signals as a function of frequency measured between 4 m and 115 m during 12 triggered lightning strokes. We show that pairs of time domain luminosity signals measured at different heights can be interpreted as the input and the output of a system whose frequency domain transfer function can be determined from the measured time domain signals. From the frequency domain transfer function phase we find the phase and group velocities, and luminosity amplitude as a function of triggered lightning channel height and signal frequency ranging from 50 kHz to 300 kHz. We show that higher-frequency luminosity components propagate faster than the lower frequency components and that higher-frequency luminosity components attenuate more rapidly than lower frequency components. Finally, we calculate time domain return stroke velocities as a function of channel height using two time delay techniques: (1) measurement at the 20% amplitude level and (2) cross correlation.

  7. Luminosity function and jet structure of Gamma-Ray Burst

    NASA Astrophysics Data System (ADS)

    Pescalli, A.; Ghirlanda, G.; Salafia, O. S.; Ghisellini, G.; Nappo, F.; Salvaterra, R.

    2015-02-01

    The structure of gamma-ray burst (GRB) jets impacts on their prompt and afterglow emission properties. The jet of GRBs could be uniform, with constant energy per unit solid angle within the jet aperture, or it could be structured, namely with energy and velocity that depend on the angular distance from the axis of the jet. We try to get some insight about the still unknown structure of GRBs by studying their luminosity function. We show that low (1046-48 erg s-1) and high (i.e. with L ≥ 1050 erg s-1) luminosity GRBs can be described by a unique luminosity function, which is also consistent with current lower limits in the intermediate luminosity range (1048-50 erg s-1). We derive analytical expressions for the luminosity function of GRBs in uniform and structured jet models and compare them with the data. Uniform jets can reproduce the entire luminosity function with reasonable values of the free parameters. A structured jet can also fit adequately the current data, provided that the energy within the jet is relatively strongly structured, i.e. E ∝ θ-k with k ≥ 4. The classical E ∝ θ-2 structured jet model is excluded by the current data.

  8. Streamlined subglacial bedforms on the Närke plain, south-central Sweden - Areal distribution, morphometrics, internal architecture and formation

    NASA Astrophysics Data System (ADS)

    Möller, Per; Dowling, Thomas P. F.

    2016-08-01

    A flow set of close to 1000 drumlins has been mapped by means of LiDAR-derived digital elevation models and investigated by trenching. The area is situated on the SW part of the Närke plain and its surrounding uplands in south-central Sweden, which was deglaciated in the early Preboreal in a glacioaquatic setting. We find that there is considerable morphological difference in drumlin distribution patterns over crystalline basement areas compared to streamlined terrain over Palaeozoic sedimentary rock basement. The former area is characterized by thin Quaternary drift and the drumlins are all of the rock-cored type, built due to active deposition of sediment around obstacles to glacier flow. The latter area is characterized by deep Quaternary drift and the drumlins are more elongate and also larger in all dimensions, as compared to rock-cored drumlins. Irrespective of these geomorphological differences on local landscape scale we find that drumlin morphometric values remain part of a morphological continuum at the regional scale. Based on the internal sediment architecture as revealed in two cross-drumlin sections we find that the soft-cored drumlins were formed by compressional constructive deformation, along with excavational deformation along the flanks of the emerging drumlins, which shaped the separating troughs. Intermediate-type drumlins are those that demonstrate a coupling between underlying Palaeozoic sediment strata in areas of shallow drift sheet. These are the result of differing rheological response between incorporated sedimentary rock and a deforming bed below the ice-bed interface. An overall conclusion is that we find geomorphic and architectural compositional differences between the drumlins and the flowset they form. We can closely relate these differences to contextual geological variations with respect to basement type and drift depth. We argue that drumlin formation is better explained not by one single 'unifying' process but rather a set of

  9. Influence of forced internal air circulation on airflow distribution and heat transfer in a gas double-dynamic solid-state fermentation bioreactor.

    PubMed

    Chen, Hongzhang; Qin, Lanzhi; Li, Hongqiang

    2014-02-01

    Internal air circulation affects the temperature field distribution in a gas double-dynamic solid-state fermentation bioreactor (GDSFB). To enhance heat transfer through strengthening internal air circulation in a GDSFB, we put an air distribution plate (ADP) into the bioreactor and studied the effects of forced internal air circulation on airflow, heat transfer, and cellulase activity of Trichoderma viride L3. Results showed that ADP could help form a steady and uniform airflow distribution, and with gas-guide tubes, air reversal was formed inside the bioreactor, thus resulting in a smaller temperature difference between medium and air by enhancing convective heat transfer inside the bioreactor. Using an ADP of 5.35 % aperture ratio caused a 1 °C decrease in the average temperature difference during the solid-state fermentation process of T. viride L3. Meanwhile, the cellulase activity of T. viride L3 increased by 13.5 %. The best heat-transfer effect was attained when using an ADP of 5.35 % aperture ratio and setting the fan power to 125 V (4.81 W) in the gas double-dynamic solid-state fermentation (GDSF) process. An option of suitable aperture ratio and fan power may be conducive to ADPs' industrial amplification.

  10. Mass Accretion Rate of Very Low Luminosity Objects

    NASA Astrophysics Data System (ADS)

    Sung, Ren-Shiang; Lai, Shih-Ping; Hsieh, Tien-Hao

    2013-08-01

    We propose to measure the mass accretion rate of six Very Low Luminosity Objects (VeLLOs) using Near-infrared Integral Spectrometer (NIFS). The extremely low luminosity of VeLLOs, L_int ≤ 0.1 L_⊙, was previously thought not existing in the nature because the typical accretion rate gives much larger accretion luminosity even for the lowest mass star (``Luminosity Problem''). The commonly accepted solution is that the accretion rate is not constant but episodic. Thus, VeLLOs could be interpreted as protostars being in the quiescent phase of accretion activities. However, there is no observational data directly measuring the mass accretion rate of VeLLOs. The main goal of this proposal is to examine such theory and directly measure the mass accretion rate of VeLLOs for the first time. We propose to measure the blue continuum excess (veiling) of the stellar spectrum, which is the most reliable method for measuring the accretion rate. The measurements have to be made in infrared due to the very high extinction for highly embedded protostars. Our proposal provide a first opportunity to explain the long time ``Luminosity Problem'' through the observational aspects, and Gemini is the only instrument that can provide accurate and high sensitivity infrared spectroscopy measurements within reasonably short time scale.

  11. Luminosity functions for very low mass stars and brown dwarfs

    NASA Technical Reports Server (NTRS)

    Laughlin, Gregory; Bodenheimer, Peter

    1993-01-01

    A theoretical investigation of the luminosity function for low-mass objects to constrain the stellar initial mass function at the low-mass end is reported. The ways in which luminosity functions for low-mass stars are affected by star formation histories, brown dwarf and premain-sequence cooling rates and main-sequence mass luminosity relations, and the IMF are examined. Cooling rates and the mass-luminosity relation are determined through a new series of evolutionary calculations for very low mass stars and brown dwarfs in the range 0.05-0.50 solar mass. Model luminosity functions are constructed for specific comparison with the results of four recent observational surveys. The likelihood that the stellar mass function in the solar neighborhood is increasing at masses near the bottom of the main sequence and perhaps at lower masses is confirmed. In the most optimistic case, brown dwarfs contribute half of the local missing disk mass. The actual contribution is likely to be considerably less.

  12. The rate and luminosity function of long gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Pescalli, A.; Ghirlanda, G.; Salvaterra, R.; Ghisellini, G.; Vergani, S. D.; Nappo, F.; Salafia, O. S.; Melandri, A.; Covino, S.; Götz, D.

    2016-03-01

    We derive, adopting a direct method, the luminosity function and the formation rate of long Gamma Ray Bursts through a complete, flux-limited, sample of Swift bursts which has a high level of completeness in redshift z (~82%). We parametrise the redshift evolution of the GRB luminosity as L = L0(1 + z)k and we derive k = 2.5, consistently with recent estimates. The de-evolved luminosity function φ(L0) of GRBs can be represented by a broken power law with slopes a = -1.32 ± 0.21 and b = -1.84 ± 0.24 below and above, respectively, a break luminosity L0,b = 1051.45±0.15 erg/s. Under the hypothesis of luminosity evolution we find that the GRB formation rate increases with redshift up to z ~ 2, where it peaks, and then decreases in agreement with the shape of the cosmic star formation rate. We test the direct method through numerical simulations and we show that if it is applied to incomplete (both in redshift and/or flux) GRB samples it can misleadingly result in an excess of the GRB formation rate at low redshifts.

  13. 1. 4 gigahertz luminosity function and its evolution

    SciTech Connect

    Condon, J. J.

    1989-03-01

    The local luminosity function was determined at v = 1.4 GHz from radio observations of two low-redshift galaxy samples: (1) spiral and irregular galaxies with apparent blue magnitudes and declinations and (2) galaxies of all morphologies with blue angular diameters of 1.0 arcmin or greater in the declination range between -2.5 deg and +82 deg. Separate luminosity functions for the radio source populations powered by 'starbursts' and 'monsters' were obtained from the latter sample. The amount of evolution required for the local luminosity function to account for the faint sources is discussed. The cosmological evolution of extragalactic radio sources appears to be so strong at all observed luminosities that the local luminosity function and counts of all sources between S of roughly 10 micro-Jy and S of roughly 10 Jy at v = 1.4 GHz can be matched with a model in which most sources are confined to a hollow shell with z of roughly 0.8. 36 refs.

  14. The intrinsic quasar luminosity function: Accounting for accretion disk anisotropy

    SciTech Connect

    DiPompeo, M. A.; Myers, A. D.; Brotherton, M. S.; Runnoe, J. C.; Green, R. F.

    2014-05-20

    Quasar luminosity functions are a fundamental probe of the growth and evolution of supermassive black holes. Measuring the intrinsic luminosity function is difficult in practice, due to a multitude of observational and systematic effects. As sample sizes increase and measurement errors drop, characterizing the systematic effects is becoming more important. It is well known that the continuum emission from the accretion disk of quasars is anisotropic—in part due to its disk-like structure—but current luminosity function calculations effectively assume isotropy over the range of unobscured lines of sight. Here, we provide the first steps in characterizing the effect of random quasar orientations and simple models of anisotropy on observed luminosity functions. We find that the effect of orientation is not insignificant and exceeds other potential corrections such as those from gravitational lensing of foreground structures. We argue that current observational constraints may overestimate the intrinsic luminosity function by as much as a factor of ∼2 on the bright end. This has implications for models of quasars and their role in the universe, such as quasars' contribution to cosmological backgrounds.

  15. Blinn College Final Grade Distribution Report for Spring 1994 Semester. Student Performance Report. International Research Document No. 012E.

    ERIC Educational Resources Information Center

    Blinn Coll., Brenham, TX.

    Blinn College final course grade distributions are summarized for spring 1990 to 1994 in this four-part report. Section I presents tables of final grade distributions by campus and course in accounting; agriculture; anthropology; biology; business; chemistry; child development; communications; computer science; criminal justice; drama; emergency…

  16. Colours and luminosities of z = 0.1 galaxies in the EAGLE simulation

    NASA Astrophysics Data System (ADS)

    Trayford, James W.; Theuns, Tom; Bower, Richard G.; Schaye, Joop; Furlong, Michelle; Schaller, Matthieu; Frenk, Carlos S.; Crain, Robert A.; Dalla Vecchia, Claudio; McCarthy, Ian G.

    2015-09-01

    We calculate the colours and luminosities of redshift z = 0.1 galaxies from the EAGLE simulation suite using the GALAXEV population synthesis models. We take into account obscuration by dust in birth clouds and diffuse interstellar medium using a two-component screen model, following the prescription of Charlot and Fall. We compare models in which the dust optical depth is constant to models where it depends on gas metallicity, gas fraction and orientation. The colours of EAGLE galaxies for the more sophisticated models are in broad agreement with those of observed galaxies. In particular, EAGLE produces a red sequence of passive galaxies and a blue cloud of star-forming galaxies, with approximately the correct fraction of galaxies in each population and with g - r colours within 0.1 mag of those observed. Luminosity functions from ultraviolet to near-infrared wavelengths differ from observations at a level comparable to systematic shifts resulting from a choice between Petrosian and Kron photometric apertures. Despite the generally good agreement there are clear discrepancies with observations. The blue cloud of EAGLE galaxies extends to somewhat higher luminosities than in the data, consistent with the modest underestimate of the passive fraction in massive EAGLE galaxies. There is also a moderate excess of bright blue galaxies compared to observations. The overall level of agreement with the observed colour distribution suggests that EAGLE galaxies at z = 0.1 have ages, metallicities and levels of obscuration that are comparable to those of observed galaxies.

  17. Short-Lived Circumstellar Interaction in a Low-Luminosity Type IIP Supernova

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, Griffin; Valenti, Stefano; Arcavi, Iair; McCully, Curtis; Howell, Dale Andrew

    2017-01-01

    While interaction with circumstellar material is known to play an important role in Type IIn supernovae, analyses of the more common Type IIP and IIL supernovae have not traditionally included interaction as a significant power source. However, recent campaigns to observe supernovae within days of explosion have revealed narrow emission lines of high-ionization species in the earliest spectra of luminous Type II supernovae of all subclasses. These "flash spectroscopy" features indicate the presence of a confined shell of material around the progenitor star. Here we present the first low-luminosity supernova to show flash spectroscopy features, SN 2016bkv. This supernova peaked at MV = -16 mag and has expansion velocities around maximum light of < 2000 km s-1, placing it at the faint/slow end of the distribution of Type IIP supernovae (similar to SN 2005cs). The detection of flash spectroscopy features in this event demonstrates that circumstellar interaction plays a role even in a low-luminosity Type IIP supernovae. Conversely, it implies that the range of luminosities of Type II supernovae is not solely driven by the presence of circumstellar material.

  18. SurveySim: a new MCMC code to explore the evolution of the IR luminosity function

    NASA Astrophysics Data System (ADS)

    Bonato, Matteo; Kurinsky, Noah; Sajina, Anna; Kirkpatrick, Allison; Pope, Alexandra; Silva, Andrea; Yan, Lin

    2016-01-01

    The Herschel and Spitzer space telescopes have been crucial in furthering our understanding of the formation and evolution of galaxies. However key questions, such as the role of SF and AGN in powering the IR output of galaxies remain unanswered. The large numbers of high redshift galaxies detected by recent IR surveys make individual spectroscopic follow-up impractical. However statistical trends in SED and luminosity function evolution in an entire population can be realized. We present a new open source Markov-Chain Monte Carlo code, SurveySim. It is built to constrain the spectral energy distribution and luminosity function evolution required to produce a given multi-wavelength survey. Its very general design allow us to use a wide range of different dusty galaxy populations (including SFGs, AGNs and Composites), luminosity function forms and SED templates. The code employs a multidimensional color-color diagnostic to determine goodness of fit. It simulates observational errors and takes into account incompleteness. Here, dusty high-z galaxies at different parts of the IR SED have been considered to analyze the relative selection biases.

  19. THE ARECIBO METHANOL MASER GALACTIC PLANE SURVEY. III. DISTANCES AND LUMINOSITIES

    SciTech Connect

    Pandian, J. D.; Menten, K. M.; Goldsmith, P. F. E-mail: kmenten@mpifr-bonn.mpg.d

    2009-12-01

    We derive kinematic distances to the 86 6.7 GHz methanol masers discovered in the Arecibo Methanol Maser Galactic Plane Survey. The systemic velocities of the sources were derived from {sup 13}CO (J = 2-1), CS (J = 5-4), and NH{sub 3} observations made with the ARO Submillimeter Telescope, the APEX telescope, and the Effelsberg 100 m telescope, respectively. Kinematic distance ambiguities were resolved using H I self-absorption with H I data from the VLA Galactic Plane Survey. We observe roughly three times as many sources at the far distance compared to the near distance. The vertical distribution of the sources has a scale height of approx 30 pc, and is much lower than that of the Galactic thin disk. We use the distances derived in this work to determine the luminosity function of 6.7 GHz maser emission. The luminosity function has a peak at approximately 10{sup -6} L{sub sun}. Assuming that this luminosity function applies, the methanol maser population in the Large Magellanic Cloud and M33 is at least 4 and 14 times smaller, respectively, than in our Galaxy.

  20. Galaxy And Mass Assembly (GAMA): the wavelength dependence of galaxy structure versus redshift and luminosity

    NASA Astrophysics Data System (ADS)

    Kennedy, Rebecca; Bamford, Steven P.; Baldry, Ivan; Häußler, Boris; Holwerda, Benne W.; Hopkins, Andrew M.; Kelvin, Lee S.; Lange, Rebecca; Moffett, Amanda J.; Popescu, Cristina C.; Taylor, Edward N.; Tuffs, Richard J.; Vika, Marina; Vulcani, Benedetta

    2015-11-01

    We study how the sizes and radial profiles of galaxies vary with wavelength, by fitting Sérsic functions simultaneously to imaging in nine optical and near-infrared bands. To quantify the wavelength dependence of effective radius we use the ratio, R, of measurements in two rest-frame bands. The dependence of Sérsic index on wavelength, N, is computed correspondingly. Vulcani et al. have demonstrated that different galaxy populations present sharply contrasting behaviour in terms of R and N. Here we study the luminosity dependence of this result. We find that at higher luminosities, early-type galaxies display a more substantial decrease in effective radius with wavelength, whereas late types present a more pronounced increase in Sérsic index. The structural contrast between types thus increases with luminosity. By considering samples at different redshifts, we demonstrate that lower data quality reduces the apparent difference between the main galaxy populations. However, our conclusions remain robust to this effect. We show that accounting for different redshift and luminosity selections partly reconciles the size variation measured by Vulcani et al. with the weaker trends found by other recent studies. Dividing galaxies by visual morphology confirms the behaviour inferred using morphological proxies, although the sample size is greatly reduced. Finally, we demonstrate that varying dust opacity and disc inclination can account for features of the joint distribution of R and N for late-type galaxies. However, dust does not appear to explain the highest values of R and N. The bulge-disc nature of galaxies must also contribute to the wavelength dependence of their structure.

  1. Evolution of the Bolometric Temperature and Luminosity of Young Stellar Objects

    NASA Astrophysics Data System (ADS)

    Myers, P. C.; Adams, F. C.; Chen, H.; Schaff, E.

    1998-01-01

    We model the broadband emission from a star-disk-envelope system to obtain expressions for the bolometric temperature Tbol and luminosity Lbol as functions of time, from the youngest class 0 protostars to stars on the zero-age main sequence. The model predicts evolution, driven by infall and contraction luminosity, in terms of position on the log Tbol-log Lbol diagram, a close analog of the H-R diagram. The evolutionary tracks depend on the envelope initial conditions, the main-sequence mass of the star, and the envelope dissipation timescale. The model Lbol rises due to infall and then falls due to contraction, while Tbol increases steadily toward the main sequence due to central heating and envelope dissipation. In order to smoothly join the protostellar and pre-main-sequence phases it is necessary to model the termination of infall as gradual rather than sudden. This change reduces the peak infall luminosity for the collapse of a singular isothermal sphere by a factor 4, bringing predicted infall luminosities into better agreement with observations. For stars of main-sequence mass 0.5 M⊙, the model decrease in Lbol from its peak value of ~3 L⊙ at Tbol ~ 250 K (class I) to ~0.4 L⊙ at Tbol ~ 3000 K (class II/III) closely matches the observed decrease in median Lbol for young stellar objects in Chamaeleon, Corona Australis, Lupus, Ophiuchus, and Taurus. The model should be useful for estimating the distributions of mass and age, and for describing the birth history, of stars younger than 1 Myr in well-studied complexes.

  2. WITNESSING THE DIFFERENTIAL EVOLUTION OF DISK GALAXIES IN LUMINOSITY AND SIZE VIA GRAVITATIONAL LENSING

    SciTech Connect

    Bandara, Kaushala; Crampton, David; Peng, Chien; Simard, Luc

    2013-11-01

    We take advantage of the magnification in size and flux of a galaxy provided by gravitational lensing to analyze the properties of 62 strongly lensed galaxies from the Sloan Lens ACS (SLACS) Survey. The sample of lensed galaxies spans a redshift range of 0.20 ≤ z ≤ 1.20 with a median redshift of z = 0.61. We use the lens modeling code LENSFIT to derive the luminosities, sizes, and Sérsic indices of the lensed galaxies. The measured properties of the lensed galaxies show a primarily compact, {sup d}isk{sup -}like population with the peaks of the size and Sérsic index distributions corresponding to ∼1.50 kpc and n ∼ 1, respectively. Comparison of the SLACS galaxies to a non-lensing, broadband imaging survey shows that a lensing survey allows us to probe a galaxy population that reaches ∼2 mag fainter. Our analysis allows us to compare the (z) = 0.61 disk galaxy sample (n ≤ 2.5) to an unprecedented local galaxy sample of ∼670, 000 SDSS galaxies at z ∼ 0.1; this analysis indicates that the evolution of the luminosity-size relation since z ∼ 1 may not be fully explained by a pure-size or pure-luminosity evolution but may instead require a combination of both. Our observations are also in agreement with recent numerical simulations of disk galaxies that show evidence of a mass-dependent evolution since z ∼ 1, where high-mass disk galaxies (M{sub *} > 10{sup 9} M{sub ☉}) evolve more in size and low-mass disk galaxies (M{sub *} ≤ 10{sup 9} M{sub ☉}) evolve more in luminosity.

  3. Modeling the Redshift Evolution of the Normal Galaxy X-Ray Luminosity Function

    NASA Technical Reports Server (NTRS)

    Tremmel, M.; Fragos, T.; Lehmer, B. D.; Tzanavaris, P.; Belczynski, K.; Kalogera, V.; Basu-Zych, A. R.; Farr, W. M.; Hornschemeier, A.; Jenkins, L.; Ptak, A.; Zezas, A.

    2013-01-01

    Emission from X-ray binaries (XRBs) is a major component of the total X-ray luminosity of normal galaxies, so X-ray studies of high-redshift galaxies allow us to probe the formation and evolution of XRBs on very long timescales (approximately 10 Gyr). In this paper, we present results from large-scale population synthesis models of binary populations in galaxies from z = 0 to approximately 20. We use as input into our modeling the Millennium II Cosmological Simulation and the updated semi-analytic galaxy catalog by Guo et al. to self-consistently account for the star formation history (SFH) and metallicity evolution of each galaxy. We run a grid of 192 models, varying all the parameters known from previous studies to affect the evolution of XRBs. We use our models and observationally derived prescriptions for hot gas emission to create theoretical galaxy X-ray luminosity functions (XLFs) for several redshift bins. Models with low common envelope efficiencies, a 50% twins mass ratio distribution, a steeper initial mass function exponent, and high stellar wind mass-loss rates best match observational results from Tzanavaris & Georgantopoulos, though they significantly underproduce bright early-type and very bright (L(sub x) greater than 10(exp 41)) late-type galaxies. These discrepancies are likely caused by uncertainties in hot gas emission and SFHs, active galactic nucleus contamination, and a lack of dynamically formed low-mass XRBs. In our highest likelihood models, we find that hot gas emission dominates the emission for most bright galaxies. We also find that the evolution of the normal galaxy X-ray luminosity density out to z = 4 is driven largely by XRBs in galaxies with X-ray luminosities between 10(exp 40) and 10(exp 41) erg s(exp -1).

  4. MODELING THE REDSHIFT EVOLUTION OF THE NORMAL GALAXY X-RAY LUMINOSITY FUNCTION

    SciTech Connect

    Tremmel, M.; Fragos, T.; Zezas, A.; Lehmer, B. D.; Tzanavaris, P.; Belczynski, K.; Kalogera, V.; Farr, W. M.; Basu-Zych, A. R.; Hornschemeier, A.; Jenkins, L.; Ptak, A.

    2013-03-20

    Emission from X-ray binaries (XRBs) is a major component of the total X-ray luminosity of normal galaxies, so X-ray studies of high-redshift galaxies allow us to probe the formation and evolution of XRBs on very long timescales ({approx}10 Gyr). In this paper, we present results from large-scale population synthesis models of binary populations in galaxies from z = 0 to {approx}20. We use as input into our modeling the Millennium II Cosmological Simulation and the updated semi-analytic galaxy catalog by Guo et al. to self-consistently account for the star formation history (SFH) and metallicity evolution of each galaxy. We run a grid of 192 models, varying all the parameters known from previous studies to affect the evolution of XRBs. We use our models and observationally derived prescriptions for hot gas emission to create theoretical galaxy X-ray luminosity functions (XLFs) for several redshift bins. Models with low common envelope efficiencies, a 50% twins mass ratio distribution, a steeper initial mass function exponent, and high stellar wind mass-loss rates best match observational results from Tzanavaris and Georgantopoulos, though they significantly underproduce bright early-type and very bright (L{sub x} > 10{sup 41}) late-type galaxies. These discrepancies are likely caused by uncertainties in hot gas emission and SFHs, active galactic nucleus contamination, and a lack of dynamically formed low-mass XRBs. In our highest likelihood models, we find that hot gas emission dominates the emission for most bright galaxies. We also find that the evolution of the normal galaxy X-ray luminosity density out to z = 4 is driven largely by XRBs in galaxies with X-ray luminosities between 10{sup 40} and 10{sup 41} erg s{sup -1}.

  5. COMBO-17 measurements of the effect of environment on the type-dependent galaxy luminosity function

    NASA Astrophysics Data System (ADS)

    Phleps, S.; Wolf, C.; Peacock, J. A.; Meisenheimer, K.; van Kampen, E.

    2007-06-01

    We have developed a method to calculate overdensities in multicolour surveys, facilitating a direct comparison of the local density contrast measured using galaxy samples that have different redshift error distributions, i.e. for red and blue, or bright and faint galaxies, respectively. We calculate overdensities in small redshift slices (Δ z =0.02, which at z=0.3 corresponds roughly to Δ r_comoving=53~h-1 Mpc) for 9176 galaxies with R≤23.65, MB(Vega)-5log h≤-18, and z≤ 0.7, in three COMBO-17 fields (measuring 31'×31' each). The mean redshift errors of this sample are approximately σ_z/(1+z)≃ 0.015. In the Chandra Deep Field South we identify a region that is underdense by almost a factor 2 compared to the other two fields in the same redshift range (0.25⪉ z ⪉ 0.4). This can be used for an investigation of the variation of the colour-dependent luminosity function with environment: We calculate the luminosity function in this redshift range for red sequence and blue cloud galaxies (as defined by Bell et al. 2004) in each of the fields separately. While the luminosity function of the blue galaxies remains unaffected by different density contrasts, the luminosity function of the red galaxies clearly has a more positive faint-end slope in the Chandra Deep Field South as compared to the other two COMBO-17 fields. The underdensity there is thus mainly due to a deficiency of faint red galaxies. This result is in qualitative agreement with the trends seen at z=0.1, e.g. in the 2dFGRS (Croton et al. 2005), or in the SDSS (Zandivarez et al. 2006).

  6. RHIC 100 GeV Polarized Proton Luminosity

    SciTech Connect

    Zhang, S. Y.

    2014-01-17

    A big problem in RHIC 100 GeV proton run 2009 was the significantly lower luminosity lifetime than all previous runs. It is shown in this note that the beam intensity decay in run 2009 is caused by the RF voltage ramping in store. It is also shown that the beam decay is not clearly related to the beam momentum spread, therefore, not directly due to the 0.7m. β* Furthermore, the most important factor regarding the low luminosity lifetime is the faster transverse emittance growth in store, which is also much worse than the previous runs, and is also related to the RF ramping. In 100 GeV proton run 2012a, the RF ramping was abandoned, but the β* was increased to 0.85m, with more than 20% loss of luminosity, which is not necessary. It is strongly suggested to use smaller β* in 100 GeV polarized proton run 2015/2016

  7. LUMINOSITY OPTIMIZATION USING AUTOMATED IR STEERING AT RHIC.

    SciTech Connect

    DREES,A.D'OTTAVIO,T.

    2004-07-05

    The goal of the RHIC 2004 Au-Au run was to maximize the achieved integrated luminosity. One way is to increase beam currents and minimize beam transverse emittances. Another important ingredient is the minimization of time spent on activities postponing the declaration of ''physics conditions'', i.e. stable beam conditions allowing the experimental detectors to take data. Since collision rates are particularly high in the beginning of the store the integrated luminosity benefits considerably from any minute saved early in the store. In the RHIC run 2004 a new IR steering application uses luminosity monitor signals as a feedback for a fully automated steering procedure. This report gives an overview of the used procedure and summarizes the achieved results.

  8. CLIC Crab Cavity Design Optimisation for Maximum Luminosity

    SciTech Connect

    Dexter, A.C.; Burt, G.; Ambattu, P.K.; Dolgashev, V.; Jones, R.; /Manchester U.

    2012-04-25

    The bunch size and crossing angle planned for CERN's compact linear collider CLIC dictate that crab cavities on opposing linacs will be needed to rotate bunches of particles into alignment at the interaction point if the desired luminosity is to be achieved. Wakefield effects, RF phase errors between crab cavities on opposing linacs and unpredictable beam loading can each act to reduce luminosity below that anticipated for bunches colliding in perfect alignment. Unlike acceleration cavities, which are normally optimised for gradient, crab cavities must be optimised primarily for luminosity. Accepting the crab cavity technology choice of a 12 GHz, normal conducting, travelling wave structure as explained in the text, this paper develops an analytical approach to optimise cell number and iris diameter.

  9. The luminosity of the double-mode Cepheid Y Carinae

    NASA Technical Reports Server (NTRS)

    Evans, Nancy R.

    1992-01-01

    IUE spectra of the double-mode Cepheid Y Carinae have been used to determine the spectral type of the binary companion. From the companion spectral type (B9.O V), the absolute magnitude of the Cepheid is found to be -2.94 mag, with an estimated uncertainty of +/-0.3. This luminosity is in good agreement with that from the period-luminosity-color relation of Feast and Walker for the fundamental mode. This agreement, together with the large magnitude difference between the B9.0 V star and the Cepheid, confirm that the Cepheid is a normal classical Cepheid with a mass much larger than that inferred from the ratio of the two periods (beat mass). The two double-mode Cepheids with independently determined luminosities (Y Car and V 367 Sct) both fall on the blue edge of the instability strip.

  10. The LUCID detector ATLAS luminosity monitor and its electronic system

    NASA Astrophysics Data System (ADS)

    Manghi, F. Lasagni

    2016-07-01

    In 2015 LHC is starting a new run, at higher center of mass energy (13 TeV) and with 25 ns bunch-spacing. The ATLAS luminosity monitor LUCID has been completely rebuilt, both the detector and the electronics, in order to cope with the new running conditions. The new detector electronics features a new read-out board (LUCROD) for signal acquisition and digitization, PMT-charge integration and single-side luminosity measurements, and a revisited LUMAT board for combination of signals from the two detectors. This note describes the new board design, the firmware and software developments, the implementation of luminosity algorithms, the optical communication between boards and the integration into the ATLAS TDAQ system.

  11. Reduction of beta* and increase of luminosity at RHIC

    SciTech Connect

    Pilat,F.; Bai, M.; Bruno, D.; Cameron, P.; Della Penna, A.; Drees, A.; Litvinenko, V.; Luo, Y.; Malitsky, N.; Marr, G.; Ptitsyn, V.; Satogata, T.; Tepikian, S.; Trbojevic, D.

    2009-05-04

    The reduction of {beta}* beyond the 1m design value at RHIC has been consistently achieved over the last 6 years of RHIC operations, resulting in an increase of luminosity for different running modes and species. During the recent 2007-08 deuteron-gold run the reduction to 0.70 from the design 1m achieved a 30% increase in delivered luminosity. The key ingredients allowing the reduction have been the capability of efficiently developing ramps with tune and coupling feedback, orbit corrections on the ramp, and collimation, to minimize beam losses in the final focus triplets, the main aperture limitations for the collision optics. We will describe the operational strategy used to reduce the {beta}*, at first squeezing the beam at store, to test feasibility, followed by the operationally preferred option of squeezing the beam during acceleration, and the resulting luminosity increase. We will conclude with future plans for the beta squeeze.

  12. The K-band luminosity functions of cluster galaxies

    NASA Astrophysics Data System (ADS)

    De Propris, Roberto

    2017-03-01

    We derive the galaxy luminosity function in the Ks band for galaxies in 24 clusters to provide a local reference for higher redshift studies and to analyse how and if the luminosity function varies according to environment and cluster properties. We use new, deep K-band imaging and match the photometry to available redshift information and to optical photometry from the SDSS or the UKST/POSS: More than 80 per cent of the galaxies to K ∼ 14.5 have measured redshifts. We derive composite luminosity functions, for the entire sample and for cluster subsamples. We consider the luminosity functions for red-sequence and blue cloud galaxies. The full composite luminosity function has K* = 12.79 ± 0.14 (MK = -24.81) and α = -1.41 ± 0.10. We find that K* is largely unaffected by the environment, but that the slope α increases towards lower mass clusters and clusters with Bautz-Morgan type < II. The red-sequence luminosity function seems to be approximately universal (within errors) in all environments: It has parameters K* = 13.16 ± 0.15 (MK = -24.44) and α = -1.00 ± 0.12 (for all galaxies). Blue galaxies do not show a good fit to a Schechter function, but the best values for its parameters are K* = 13.51 ± 0.41 (MK = -24.09) and α = -1.60 ± 0.29: We do not have enough statistics to consider environmental variations for these galaxies. We find some evidence that K* in clusters is brighter than in the field and α is steeper, but note that this comparison is based (for the field) on 2MASS photometry, while our data are considerably deeper.

  13. MODELING THE RED SEQUENCE: HIERARCHICAL GROWTH YET SLOW LUMINOSITY EVOLUTION

    SciTech Connect

    Skelton, Rosalind E.; Bell, Eric F.; Somerville, Rachel S.

    2012-07-01

    We explore the effects of mergers on the evolution of massive early-type galaxies by modeling the evolution of their stellar populations in a hierarchical context. We investigate how a realistic red sequence population set up by z {approx} 1 evolves under different assumptions for the merger and star formation histories, comparing changes in color, luminosity, and mass. The purely passive fading of existing red sequence galaxies, with no further mergers or star formation, results in dramatic changes at the bright end of the luminosity function and color-magnitude relation. Without mergers there is too much evolution in luminosity at a fixed space density compared to observations. The change in color and magnitude at a fixed mass resembles that of a passively evolving population that formed relatively recently, at z {approx} 2. Mergers among the red sequence population ('dry mergers') occurring after z = 1 build up mass, counteracting the fading of the existing stellar populations to give smaller changes in both color and luminosity for massive galaxies. By allowing some galaxies to migrate from the blue cloud onto the red sequence after z = 1 through gas-rich mergers, younger stellar populations are added to the red sequence. This manifestation of the progenitor bias increases the scatter in age and results in even smaller changes in color and luminosity between z = 1 and z = 0 at a fixed mass. The resultant evolution appears much slower, resembling the passive evolution of a population that formed at high redshift (z {approx} 3-5), and is in closer agreement with observations. We conclude that measurements of the luminosity and color evolution alone are not sufficient to distinguish between the purely passive evolution of an old population and cosmologically motivated hierarchical growth, although these scenarios have very different implications for the mass growth of early-type galaxies over the last half of cosmic history.

  14. Effect of Gold Nanoparticles on Prostate Dose Distribution under Ir-192 Internal and 18 MV External Radiotherapy Procedures Using Gel Dosimetry and Monte Carlo Method

    PubMed Central

    Khosravi, H.; Hashemi, B.; Mahdavi, S. R.; Hejazi, P.

    2015-01-01

    Background Gel polymers are considered as new dosimeters for determining radiotherapy dose distribution in three dimensions. Objective The ability of a new formulation of MAGIC-f polymer gel was assessed by experimental measurement and Monte Carlo (MC) method for studying the effect of gold nanoparticles (GNPs) in prostate dose distributions under the internal Ir-192 and external 18MV radiotherapy practices. Method A Plexiglas phantom was made representing human pelvis. The GNP shaving 15 nm in diameter and 0.1 mM concentration were synthesized using chemical reduction method. Then, a new formulation of MAGIC-f gel was synthesized. The fabricated gel was poured in the tubes located at the prostate (with and without the GNPs) and bladder locations of the phantom. The phantom was irradiated to an Ir-192 source and 18 MV beam of a Varian linac separately based on common radiotherapy procedures used for prostate cancer. After 24 hours, the irradiated gels were read using a Siemens 1.5 Tesla MRI scanner. The absolute doses at the reference points and isodose curves resulted from the experimental measurement of the gels and MC simulations following the internal and external radiotherapy practices were compared. Results The mean absorbed doses measured with the gel in the presence of the GNPs in prostate were 15% and 8 % higher than the corresponding values without the GNPs under the internal and external radiation therapies, respectively. MC simulations also indicated a dose increase of 14 % and 7 % due to presence of the GNPs, for the same experimental internal and external radiotherapy practices, respectively. Conclusion There was a good agreement between the dose enhancement factors (DEFs) estimated with MC simulations and experiment gel measurements due to the GNPs. The results indicated that the polymer gel dosimetry method as developed and used in this study, can be recommended as a reliable method for investigating the DEF of GNPs in internal and external

  15. On the period-luminosity-colour relation for galactic Cepheids

    NASA Astrophysics Data System (ADS)

    Cester, B.; Marsi, C.

    1984-12-01

    A period-luminosity-colour relation is derived from the data of 29 galactic Cepheids with known distances collected from the literature, and is then compared with the simpler period-luminosity relation. The insignificant reduction in the dispersion seems to argue against the introduction of the colour term. It is, however, demonstrated that this evidence may be fictitious and due to the use of Cepheids, whose membership in a star aggregate is still doubtful. The exclusion of these stars leads to a PLC relation which shows a significantly smaller dispersion than that given by the corresponding PL relation.

  16. Luminosity limit for alpha-viscosity accretion disks

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.; Wandel, Amri

    1991-01-01

    The existence of a luminosity limit for alpha-viscosity physically thin accretion disks around black holes is established, using a new formulation of the radiation equation bridging optically thick and thin regimes. For alpha close to unity, this limit can be lower than the Eddington limit. Physically, this limit is due to the combined effects of gas and radiation pressure which become too large to satisfy vertical hydrostatic balance at intermediate optical depths for sufficiently high luminosities. This effect was overlooked in previous treatments using only the optically thin or thick limits of the radiative equation.

  17. Adaptive Agent Modeling of Distributed Language: Investigations on the Effects of Cultural Variation and Internal Action Representations

    ERIC Educational Resources Information Center

    Cangelosi, Angelo

    2007-01-01

    In this paper we present the "grounded adaptive agent" computational framework for studying the emergence of communication and language. This modeling framework is based on simulations of population of cognitive agents that evolve linguistic capabilities by interacting with their social and physical environment (internal and external symbol…

  18. Comparing the spectral lag of short and long gamma-ray bursts and its relation with the luminosity

    NASA Astrophysics Data System (ADS)

    Bernardini, M. G.; Ghirlanda, G.; Campana, S.; Covino, S.; Salvaterra, R.; Atteia, J.-L.; Burlon, D.; Calderone, G.; D'Avanzo, P.; D'Elia, V.; Ghisellini, G.; Heussaff, V.; Lazzati, D.; Melandri, A.; Nava, L.; Vergani, S. D.; Tagliaferri, G.

    2015-01-01

    We investigated the rest-frame spectral lags of two complete samples of bright long (50) and short (6) gamma-ray bursts (GRB) detected by Swift. We analysed the Swift/Burst Alert Telescope data through a discrete cross-correlation function fitted with an asymmetric Gaussian function to estimate the lag and the associated uncertainty. We find that half of the long GRBs have a positive lag and half a lag consistent with zero. All short GRBs have lags consistent with zero. The distributions of the spectral lags for short and long GRBs have different average values. Limited by the small number of short GRBs, we cannot exclude at more than 2σ significance level that the two distributions of lags are drawn from the same parent population. If we consider the entire sample of long GRBs, we do not find evidence for a lag-luminosity correlation, rather the lag-luminosity plane appears filled on the left-hand side, thus suggesting that the lag-luminosity correlation could be a boundary. Short GRBs are consistent with the long ones in the lag-luminosity plane.

  19. Bias Properties of Extragalactic Distance Indicators. VII. Correlation of Absolute Luminosity and Rotational Velocity for SC Galaxies over the Range of Luminosity Class from I to III-IV

    NASA Astrophysics Data System (ADS)

    Sandage, Allan

    1999-01-01

    A distance-limited subset of the complete flux-limited sample of Sc galaxies in the Revised Shapley-Ames Catalog of Bright Galaxies is isolated by means of separate Spaenhauer diagrams for six individual van den Bergh luminosity class intervals from Sc I+I.2,.3 to Sc III-IV. The distribution functions of kinematic absolute B^0,i_T(220,50) magnitudes and 21 cm line widths, W_20, corrected to edge-on orientation, have been determined for the same six bins of luminosity class. The individual luminosity functions for each luminosity class are bounded on both the bright and faint ends, showing that the present sample includes no dwarf Sc spirals fainter than M(B_T)(220,50)=-18 belonging to luminosity classes I to III-IV, as defined by the regularity of the spiral pattern. Star-forming galaxies with spiral structures as regular as the ones found in these luminosity classes have absolute magnitudes brighter than M_B(H=50)=-18 and 21 cm line widths larger than W_20/sini=2v_rot(max)=165 km s^-1. Furthermore, the 21 cm line-width distributions move toward smaller rotational velocities as the luminosity classes change from I to III, showing that rotation is a principal parameter determining the regularity of the spiral pattern. Whether it is the only parameter awaits a similar investigation for spirals of all luminosity classes along the complete Hubble sequence. In particular, it has not yet been proved that all Im and Sm galaxies, where, by definition, the spiral arms are either lacking or are semichaotic, have absolute magnitudes that are fainter than M_B=-18 and whose 21 cm LWs are smaller than ~165 km s^-1, presumably because of smaller mass than the high-luminosity, regular spirals. The Teerikorpi ``cluster population incompleteness bias'' is demonstrated again. Here, however, as in Papers II-IV of this series, we use field galaxies to show that the slope and zero point of the Tully-Fisher (T-F) relation are systematically incorrect for flux-limited samples, the error

  20. The use of airborne radar reflectometry to establish snow/firn density distribution on Devon Ice Cap, Canadian Arctic: A path to understanding complex heterogeneous internal layering patterns

    NASA Astrophysics Data System (ADS)

    Rutishauser, A.; Grima, C.; Sharp, M. J.; Blankenship, D. D.; Young, D. A.; Dowdeswell, J. A.

    2014-12-01

    The internal layer stratigraphy of polar ice sheets revealed by airborne radio-echo sounding (RES) contains valuable information about past ice sheet mass balance and dynamics. Internal layers in the Antarctic and Greenland ice sheets are considered to be isochrones and are continuous over several hundreds of kilometres. In contrast, internal layers in Canadian Arctic ice caps appear to be very heterogeneous and fragmentary, consisting of highly discontinuous layers that can be traced over only a few to several tens of kilometres. Internal layers most likely relate to former ice surfaces (the upper few meters of snow/firn), the properties which are directly influenced by atmospheric conditions including the air temperature, precipitation rate, and prevailing wind pattern. We hypothesize that the heterogeneous and complex nature of layers in the Canadian Arctic results from highly variable snow and firn conditions at the surface. Characterizing surface properties such as variations in the snow/firn density from dry to wet snow/firn, as well as high-density shallow ice layers and lenses of refrozen water can help to elucidate the complex internal layer pattern in the Canadian Arctic ice caps. Estimates of the snow/firn surface density and roughness can be derived from reflectance and scattering information using the surface radar returns from RES measurements. Here we present estimates of the surface snow/firn density distribution over Devon Ice Cap in the Canadian Arctic derived by the Radar Statistical Reconnaissance (RSR) methodology (Grima et al., 2014, Planetary & Space Sciences) using data collected by recent airborne radar sounding programs. The RSR generates estimates of the statistical distribution of surface echo amplitudes over defined areas along a survey transect. The derived distributions are best-fitted with a theoretical stochastic envelope, parameterized with the signal reflectance and scattering, in order to separate those two components. Finally

  1. The relation between pre-eruptive bubble size distribution, ash particle morphology, and their internal density: Implications to volcanic ash transport and dispersion models

    NASA Astrophysics Data System (ADS)

    Proussevitch, Alexander

    2014-05-01

    Parameterization of volcanic ash transport and dispersion (VATD) models strongly depends on particle morphology and their internal properties. Shape of ash particles affects terminal fall velocities (TFV) and, mostly, dispersion. Internal density combined with particle size has a very strong impact on TFV and ultimately on the rate of ash cloud thinning and particle sedimentation on the ground. Unlike other parameters, internal particle density cannot be measured directly because of the micron scale sizes of fine ash particles, but we demonstrate that it varies greatly depending on the particle size. Small simple type ash particles (fragments of bubble walls, 5-20 micron size) do not contain whole large magmatic bubbles inside and their internal density is almost the same as that of volcanic glass matrix. On the other side, the larger compound type ash particles (>40 microns for silicic fine ashes) always contain some bubbles or the whole spectra of bubble size distribution (BSD), i.e. bubbles of all sizes, bringing their internal density down as compared to simple ash. So, density of the larger ash particles is a function of the void fraction inside them (magmatic bubbles) which, in turn, is controlled by BSD. Volcanic ash is a product of the fragmentation of magmatic foam formed by pre-eruptive bubble population and characterized by BSD. The latter can now be measured from bubble imprints on ash particle surfaces using stereo-scanning electron microscopy (SSEM) and BubbleMaker software developed at UNH, or using traditional high-resolution X-Ray tomography. In this work we present the mathematical and statistical formulation for this problem connecting internal ash density with particle size and BSD, and demonstrate how the TFV of the ash population is affected by variation of particle density.

  2. GALAXY CLUSTERING AND PROJECTED DENSITY PROFILES AS TRACED BY SATELLITES IN PHOTOMETRIC SURVEYS: METHODOLOGY AND LUMINOSITY DEPENDENCE

    SciTech Connect

    Wang Wenting; Jing, Y. P.; Li Cheng; Okumura, Teppei; Han Jiaxin

    2011-06-20

    We develop a new method which measures the projected density distribution w{sub p} (r{sub p} )n of photometric galaxies surrounding a set of spectroscopically identified galaxies and simultaneously the projected cross-correlation function w{sub p} (r{sub p} ) between the two populations. In this method, we are able to divide the photometric galaxies into subsamples in luminosity intervals even when redshift information is unavailable, enabling us to measure w{sub p} (r{sub p} )n and w{sub p} (r{sub p} ) as a function of not only the luminosity of the spectroscopic galaxy, but also that of the photometric galaxy. Extensive tests show that our method can measure w{sub p} (r{sub p} ) in a statistically unbiased way. The accuracy of the measurement depends on the validity of the assumption inherent to the method that the foreground/background galaxies are randomly distributed and are thus uncorrelated with those galaxies of interest. Therefore, our method can be applied to the cases where foreground/background galaxies are distributed in large volumes, which is usually valid in real observations. We have applied our method to data from the Sloan Digital Sky Survey (SDSS) including a sample of 10{sup 5} luminous red galaxies at z {approx} 0.4 and a sample of about half a million galaxies at z {approx} 0.1, both of which are cross-correlated with a deep photometric sample drawn from the SDSS. On large scales, the relative bias factor of galaxies measured from w{sub p} (r{sub p} ) at z {approx} 0.4 depends on luminosity in a manner similar to what is found for those at z {approx} 0.1, which are usually probed by autocorrelations of spectroscopic samples in previous studies. On scales smaller than a few Mpc and at both z {approx} 0.4 and z {approx} 0.1, the photometric galaxies of different luminosities exhibit similar density profiles around spectroscopic galaxies at fixed luminosity and redshift. This provides clear observational support for the assumption commonly

  3. Galaxy Clustering and Projected Density Profiles as Traced by Satellites in Photometric Surveys: Methodology and Luminosity Dependence

    NASA Astrophysics Data System (ADS)

    Wang, Wenting; Jing, Y. P.; Li, Cheng; Okumura, Teppei; Han, Jiaxin

    2011-06-01

    We develop a new method which measures the projected density distribution wp (rp )n of photometric galaxies surrounding a set of spectroscopically identified galaxies and simultaneously the projected cross-correlation function wp (rp ) between the two populations. In this method, we are able to divide the photometric galaxies into subsamples in luminosity intervals even when redshift information is unavailable, enabling us to measure wp (rp )n and wp (rp ) as a function of not only the luminosity of the spectroscopic galaxy, but also that of the photometric galaxy. Extensive tests show that our method can measure wp (rp ) in a statistically unbiased way. The accuracy of the measurement depends on the validity of the assumption inherent to the method that the foreground/background galaxies are randomly distributed and are thus uncorrelated with those galaxies of interest. Therefore, our method can be applied to the cases where foreground/background galaxies are distributed in large volumes, which is usually valid in real observations. We have applied our method to data from the Sloan Digital Sky Survey (SDSS) including a sample of 105 luminous red galaxies at z ~ 0.4 and a sample of about half a million galaxies at z ~ 0.1, both of which are cross-correlated with a deep photometric sample drawn from the SDSS. On large scales, the relative bias factor of galaxies measured from wp (rp ) at z ~ 0.4 depends on luminosity in a manner similar to what is found for those at z ~ 0.1, which are usually probed by autocorrelations of spectroscopic samples in previous studies. On scales smaller than a few Mpc and at both z ~ 0.4 and z ~ 0.1, the photometric galaxies of different luminosities exhibit similar density profiles around spectroscopic galaxies at fixed luminosity and redshift. This provides clear observational support for the assumption commonly adopted in halo occupation distribution models that satellite galaxies of different luminosities are distributed in a similar

  4. How do Super Star Clusters Form?: The Anomalous Luminosity Function of Natal Clusters in Henize 2-10

    NASA Astrophysics Data System (ADS)

    Biswas, I.; Johnson, K. E.

    2005-12-01

    Super Star Clusters (SSCs) are the most extreme star forming environments in the local universe. Results from optical observations have suggested that SSCs are simply the statistical tail of a power law luminosity (mass) distribution of index ˜ -2. However, optical luminosity functions are complicated by evolution effects and extinction. Free of these constraints, centimeter wave radio observations pin down the cluster luminosity function to the first few Myrs when natal SSCs are still embedded in ultradense H II regions. We investigate the earliest stages of SSCs in the starburst galaxy Henize 2-10 using high resolution Very Large Array observations at 5, 8.3, 15, and 23 GHz. We use the Pie Town link at lower frequencies to obtain relatively well matched beams to obtain a linear resolution of ˜ 10 pc. Such a high resolution should allow us to detect natal clusters with masses ˜ 104 M⊙ as 10σ detections. The 23 GHz flux (high frequency emission is dominated by optically thin, thermal emission) indicates that all of the detected SSCs in Henize 2-10 have a mass greater than ˜ 105 M⊙. We rule out the possibility of the clusters being self gravitating from the H92α line width of ˜ 200 km s-1. The absence of the formation of lower mass clusters is inconsistent with a power law luminosity function, which we verify with a KS test. Thus, the luminosity function of natal clusters, which we dub the Initial Cluster Luminosity Function (ICLF), suggests that SSCs require a special mode of star formation. We plan follow-up radio observations to investigate the behavior of the ICLF in a variety of starburst and merger environments.

  5. Intracellular distribution of TM4SF1 and internalization of TM4SF1-antibody complex in vascular endothelial cells

    SciTech Connect

    Sciuto, Tracey E.; Merley, Anne; Lin, Chi-Iou; Richardson, Douglas; Liu, Yu; Li, Dan; Dvorak, Ann M.; Dvorak, Harold F.; Jaminet, Shou-Ching S.

    2015-09-25

    Transmembrane-4 L-six family member-1 (TM4SF1) is a small plasma membrane-associated glycoprotein that is highly and selectively expressed on the plasma membranes of tumor cells, cultured endothelial cells, and, in vivo, on tumor-associated endothelium. Immunofluorescence microscopy also demonstrated TM4SF1 in cytoplasm and, tentatively, within nuclei. With monoclonal antibody 8G4, and the finer resolution afforded by immuno-nanogold transmission electron microscopy, we now demonstrate TM4SF1 in uncoated cytoplasmic vesicles, nuclear pores and nucleoplasm. Because of its prominent surface location on tumor cells and tumor-associated endothelium, TM4SF1 has potential as a dual therapeutic target using an antibody drug conjugate (ADC) approach. For ADC to be successful, antibodies reacting with cell surface antigens must be internalized for delivery of associated toxins to intracellular targets. We now report that 8G4 is efficiently taken up into cultured endothelial cells by uncoated vesicles in a dynamin-dependent, clathrin-independent manner. It is then transported along microtubules through the cytoplasm and passes through nuclear pores into the nucleus. These findings validate TM4SF1 as an attractive candidate for cancer therapy with antibody-bound toxins that have the capacity to react with either cytoplasmic or nuclear targets in tumor cells or tumor-associated vascular endothelium. - Highlights: • Anti-TM4SF1 antibody 8G4 was efficiently taken up by cultured endothelial cells. • TM4SF1–8G4 internalization is dynamin-dependent but clathrin-independent. • TM4SF1–8G4 complexes internalize along microtubules to reach the perinuclear region. • Internalized TM4SF1–8G4 complexes pass through nuclear pores into the nucleus. • TM4SF1 is an attractive candidate for ADC cancer therapy.

  6. Luminosity Variations Along Bunch Trains in PEP-II

    SciTech Connect

    Decker, F.J.; Boyes, M.; Colocho, W.S.; Novokhatski, A.; Sullivan, M.K.; Turner, J.L.; Weathersby, S.P.; Wienands, U.; Yocky, G.; /SLAC

    2007-05-18

    In the spring of 2005 after a long shut-down, the luminosity of the B-Factory PEP-II decreased along the bunch trains by about 25-30%. There were many reasons studied which could have caused this performance degradation, like a bigger phase transient due to an additional RF station in the Low-Energy-Ring (LER), bad initial vacuum, electron cloud, chromaticity, steering, dispersion in cavities, beam optics, etc. The initial specific luminosity of 4.2 sloped down to 3.2 and even 2.8 for a long train (typical: 130 of 144), later in the run with higher currents and shorter trains (65 of 72) the numbers were more like 3.2 down to 2.6. Finally after steering the interaction region for an unrelated reason (overheated BPM buttons) and the consequential lower luminosity for two weeks, the luminosity slope problem was mysteriously gone. Several parameters got changed and there is still some discussion about which one finally fixed the problem. Among others, likely candidates are: the LER betatron function in x at the interaction point got reduced, making the LER x stronger, dispersion reduction in the cavities, and finding and fixing a partially shorted magnet.

  7. Total Infrared Luminosity Estimation of Resolved and Unresolved Galaxies

    NASA Astrophysics Data System (ADS)

    Boquien, M.; Bendo, G.; Calzetti, D.; Dale, D.; Engelbracht, C.; Kennicutt, R.; Lee, J. C.; van Zee, L.; Moustakas, J.

    2010-04-01

    The total infrared (TIR) luminosity from galaxies can be used to examine both star formation and dust physics. We provide here new relations to estimate the TIR luminosity from various Spitzer bands, in particular from the 8 μm and 24 μm bands. To do so, we use data for 45'' subregions within a subsample of nearby face-on spiral galaxies from the Spitzer Infrared Nearby Galaxies Survey (SINGS) that have known oxygen abundances as well as integrated galaxy data from the SINGS, the Local Volume Legacy survey (LVL), and Engelbracht et al. samples. Taking into account the oxygen abundances of the subregions, the star formation rate intensity, and the relative emission of the polycyclic aromatic hydrocarbons at 8 μm, the warm dust at 24 μm, and the cold dust at 70 μm and 160 μm, we derive new relations to estimate the TIR luminosity from just one or two of the Spitzer bands. We also show that the metallicity and the star formation intensity must be taken into account when estimating the TIR luminosity from two wave bands, especially when data longward of 24 μm are not available.

  8. The Luminosity Functions of Low Redshift Field and Cluster Galaxies

    NASA Astrophysics Data System (ADS)

    Jorgensen, I.; Hill, G. J.; Bergmann, M. P.; Elston, R.; Vanden Berk, D.; Jurcevic, J. S.

    1999-12-01

    We present a comparison of the luminosity functions for low redshift field and cluster galaxies. The luminosity functions are established for field galaxies in UBVRI, and for galaxies in the Coma cluster in UBRI. The field galaxy sample is drawn from The Texas Deep Sky Survey (TDSS) of a 2.1 by 2.1 sq. deg. area around the North Galactic Pole. More than 40000 objects have been detected in our survey of this area. We have obtained spectra of approximately 700 galaxies, making the redshift information complete to a total R magnitude of 18.5 mag. We have surveyed the central square degree of the Coma cluster in UBRI. Approximately 16000 objects have been detected in our survey. We have obtained spectra for 220 galaxies in the area with no previous measurements. Together with published data these observations make the redshift information complete for galaxies brighter than a total R magnitude of 17.5. A total of 480 members of the cluster have measured redshifts, while 180 background and foreground galaxies in the field have measured redshifts. The accurate determination of the luminosity functions for low redshift galaxies is important for the interpretation of luminosity functions established for higher redshift galaxies, both in clusters and in the field. This research was supported in part by NASA through grant number HF-01073.01.94A to IJ from the Space Telescope Science Institute.

  9. Solar luminosity variations and the climate of Mars

    NASA Technical Reports Server (NTRS)

    Toon, O. B.; Gierasch, P. J.; Sagan, C.

    1974-01-01

    Attempts to resolve the solar neutrino flux problem have led to suggestions of large scale oscillations in the solar luminosity on a geological time scale. A simple climatological model of Mars indicates that its climate may be much more sensitive to luminosity changes than the earth's because of strong positive feedback mechanisms at work on Mars. Mariner-9 photographs of Mars show an abundance of large sinuous channels that point to an epoch of higher atmospheric pressures and abundant liquid water. Such an epoch could have been the result of large-scale, solar luminosity variations. However, our climatological model suggests that other less controversial mechanisms, such as obliquity or polar albedo changes, also could have led to such an epoch. As more becomes known about Mars, it may prove possible to formulate a history of Martian climate. By discovering effects that cannot be due to other mechanisms one may be able to form a chronology of solar luminosity variations to compare with data from the earth.

  10. Potential for luminosity improvement for low-energy RHIC operation

    SciTech Connect

    Fedotov A. V.

    2012-05-20

    At the Brookhaven National Laboratory, a physics program, motivated by the search of the QCD phase transition critical point, requires operation of the Relativistic Heavy Ion Collider (RHIC) with heavy ions at very low beam energies corresponding to 2.5-20 GeV/n. Several physics runs were already successfully performed at these low energies. However, the luminosity is very low at lowest energies of interest (< 10 GeV/n) limited by the intra-beam scattering and space-charge, as well as by machine nonlinearities. At these low energies, electron cooling could be very effective in counteracting luminosity degradation due to the IBS, while it is less effective against other limitations. Overall potential luminosity improvement for low-energy RHIC operation from cooling is summarized for various energies, taking into account all these limitations as well as beam lifetime measured during the low-energy RHIC runs. We also explore a possibility of further luminosity improvement under the space-charge limitation.

  11. Luminosity Function of Faint Globular Clusters in M87

    SciTech Connect

    Waters, Christopher Z.; Zepf, Stephen E.; Lauer, Tod R.; Baltz, Edward A.; Silk, Joseph; /Oxford U.

    2006-07-14

    We present the luminosity function to very faint magnitudes for the globular clusters in M87, based on a 30 orbit Hubble Space Telescope (HST) WFPC2 imaging program. The very deep images and corresponding improved false source rejection allow us to probe the mass function further beyond the turnover than has been done before. We compare our luminosity function to those that have been observed in the past, and confirm the similarity of the turnover luminosity between M87 and the Milky Way. We also find with high statistical significance that the M87 luminosity function is broader than that of the Milky Way. We discuss how determining the mass function of the cluster system to low masses can constrain theoretical models of the dynamical evolution of globular cluster systems. Our mass function is consistent with the dependence of mass loss on the initial cluster mass given by classical evaporation, and somewhat inconsistent with newer proposals that have a shallower mass dependence. In addition, the rate of mass loss is consistent with standard evaporation models, and not with the much higher rates proposed by some recent studies of very young cluster systems. We also find that the mass-size relation has very little slope, indicating that there is almost no increase in the size of a cluster with increasing mass.

  12. Accretion disk coronae in high-luminosity systems

    NASA Technical Reports Server (NTRS)

    Murray, Stephen D.; Castor, John I.; Klein, Richard I.; Mckee, Christopher F.

    1994-01-01

    We present the results of self-consistent models of Compton-heated accretion disk coronae. The models are calculated using a new method for computing monochromatic radiative transfer n two dimensions. The method splits the radiation into direct and scattered components. The direct radiation is computed by calculating the optical depth along rays, while transfer of the scattered radiation is approximated by flux-limited diffusion. The resulting code agrees with more accurate treatments to within 50%, and is highly efficient, making it practical for use in large hydrodynamic simulations. The coronal models are used to confirm the results of earlier work, and to extend it to higher luminosities. In contrast to earlier work, which found the outer disks to be shadowed by the inner corona at high luminosities, we find our results to form an almost continuous extension of the models at lower luminosities. This is due to the presence of multiply scattered radiation, which acts to partially offset the loss of direct radiation from the central source. Although the analytic methods derived at lower luminosities cannot be used to derive the coronal structure for L/L(sub Edd) approx. greater than 0.1, the results of the models are amenable to semiempirical fits. We also discuss possible observational consequences of the results for coronal veiling and line fluorescence from the disk.

  13. Status and Outlook for the RHIC Luminosity Upgrade

    NASA Astrophysics Data System (ADS)

    Bai, Mei

    2010-02-01

    As the world highest energy heavy ion collider, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been the center for exploring the universe at its infant stage. The operations of RHIC over the past decade has produced many results. A new state of matter, the quark-gluon plasma which is believed to only have existed right after the birth of the universe, was first observed at RHIC during the collisions of Au ions. The experimental data also revealed that this new state of matter behaves like a perfect fluid. In addition to the heavy ion program, RHIC is also capable to accelerate polarized proton beams to high energy, which allows one to explore the spin structure of polarized protons. Both the heavy ion program and spin physics program require high luminosities at RHIC. Various efforts aimed at increasing the RHIC luminosity of heavy ion and polarized proton collisions, such as NEG coating beam pipes to reduce electron clouds, using intrabeam scattering lattice for heavy ion operations as well as longitudinal stochastic cooling. The average store luminosity of Au collisions at a beam energy of 100 GeV/u has reached 1027cm-2s-1. The average store luminosity of RHIC polarized proton collisions at a beam energy of 100 GeV reached 28x1030cm-2s-1 and 55x1030 cm-2s-1 for the polarized proton collisions at a beam energy 250 GeV. Currently, the luminosity is limited by beam-beam effects for polarized proton collisions and intrabeam scattering for heavy ion collisions. Novel techniques are explored and under development to address these issues. The addition of transverse stochastic cooling will minimize the beam size growth due to intrabeam scattering and increase the heavy ion luminosity lifetime. The technique of using 9MHz cavity to accelerate polarized protons minimizes the electron cloud effect, which can cause emittance blowup. It also helps to preserve the longitudinal emittance and yields shorter bunches. The technique of employing an

  14. DIRECT OXYGEN ABUNDANCES FOR LOW-LUMINOSITY LVL GALAXIES

    SciTech Connect

    Berg, Danielle A.; Skillman, Evan D.; Marble, Andrew R.; Engelbracht, Charles W.; Van Zee, Liese; Lee, Janice C.; Kennicutt, Robert C. Jr.; Calzetti, Daniela; Dale, Daniel A.; Johnson, Benjamin D. E-mail: skillman@astro.umn.edu E-mail: amarble@nso.edu E-mail: jlee@stsci.edu E-mail: ddale@uwyo.edu

    2012-08-01

    We present MMT spectroscopic observations of H II regions in 42 low luminosity galaxies in the Spitzer Local Volume Legacy survey. For 31 of the 42 galaxies in our sample, we were able to measure the temperature sensitive [O III] {lambda}4363 line at a strength of 4{sigma} or greater, and thus determine oxygen abundances using the 'direct' method. Our results provide the first 'direct' estimates of oxygen abundance for 19 of these galaxies. 'Direct' oxygen abundances were compared to B-band luminosities, 4.5 {mu}m luminosities, and stellar masses in order to characterize the luminosity-metallicity and mass-metallicity relationships at low luminosity. We present and analyze a 'Combined Select' sample composed of 38 objects (drawn from a sub-set of our parent sample and the literature) with 'direct' oxygen abundances and reliable distance determinations (based on the tip of the red giant branch or Cepheid variables). Consistent with previous studies, the B band and 4.5 {mu}m luminosity-metallicity relationships for the 38 objects were found to be 12 + log(O/H) = (6.27 {+-} 0.21) + (- 0.11 {+-} 0.01)M{sub B} and 12 + log(O/H) = (6.10 {+-} 0.21) + (- 0.10 {+-} 0.01)M{sub [4.5]} with dispersions of {sigma} = 0.15 and 0.14, respectively. The slopes of the optical and near-IR L-Z relationships have been reported to be different for galaxies with luminosities greater than that of the LMC. However, the similarity of the slopes of the optical and near-IR L-Z relationships for our sample probably reflects little influence by dust extinction in the low luminosity galaxies. For this sample, we derive a mass-metallicity relationship of 12 + log(O/H) = (5.61 {+-} 0.24) + (0.29 {+-} 0.03)log (M{sub *}), which agrees with previous studies; however, the dispersion ({sigma} = 0.15) is not significantly lower than that of the L-Z relationships. Because of the low dispersions in these relationships, if an accurate distance is available, the luminosity of a low luminosity galaxy is

  15. Direct Oxygen Abundances for Low-luminosity LVL Galaxies

    NASA Astrophysics Data System (ADS)

    Berg, Danielle A.; Skillman, Evan D.; Marble, Andrew R.; van Zee, Liese; Engelbracht, Charles W.; Lee, Janice C.; Kennicutt, Robert C., Jr.; Calzetti, Daniela; Dale, Daniel A.; Johnson, Benjamin D.

    2012-08-01

    We present MMT spectroscopic observations of H II regions in 42 low luminosity galaxies in the Spitzer Local Volume Legacy survey. For 31 of the 42 galaxies in our sample, we were able to measure the temperature sensitive [O III] λ4363 line at a strength of 4σ or greater, and thus determine oxygen abundances using the "direct" method. Our results provide the first "direct" estimates of oxygen abundance for 19 of these galaxies. "Direct" oxygen abundances were compared to B-band luminosities, 4.5 μm luminosities, and stellar masses in order to characterize the luminosity-metallicity and mass-metallicity relationships at low luminosity. We present and analyze a "Combined Select" sample composed of 38 objects (drawn from a sub-set of our parent sample and the literature) with "direct" oxygen abundances and reliable distance determinations (based on the tip of the red giant branch or Cepheid variables). Consistent with previous studies, the B band and 4.5 μm luminosity-metallicity relationships for the 38 objects were found to be 12 + log(O/H) = (6.27 ± 0.21) + (- 0.11 ± 0.01)MB and 12 + log(O/H) = (6.10 ± 0.21) + (- 0.10 ± 0.01)M [4.5] with dispersions of σ = 0.15 and 0.14, respectively. The slopes of the optical and near-IR L-Z relationships have been reported to be different for galaxies with luminosities greater than that of the LMC. However, the similarity of the slopes of the optical and near-IR L-Z relationships for our sample probably reflects little influence by dust extinction in the low luminosity galaxies. For this sample, we derive a mass-metallicity relationship of 12 + log(O/H) = (5.61 ± 0.24) + (0.29 ± 0.03)log (M sstarf), which agrees with previous studies; however, the dispersion (σ = 0.15) is not significantly lower than that of the L-Z relationships. Because of the low dispersions in these relationships, if an accurate distance is available, the luminosity of a low luminosity galaxy is often a better indicator of metallicity than that

  16. 77 FR 17525 - Cinram Distribution, LLC, a Subsidiary of Cinram International Income Fund, Including On-Site...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-26

    ... (UI) Wages Are Reported Through Real Time Staffing, Aurora, IL; Amended Certification Regarding... People, Aurora, Illinois. The workers are engaged in the supply of optical media distribution services... shows that workers leased from Good People employed on-site at the Aurora, Illinois location of...

  17. THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82

    SciTech Connect

    McGreer, Ian D.; Fan Xiaohui; Jiang Linhua; Richards, Gordon T.; Strauss, Michael A.; Ross, Nicholas P.; White, Martin; Shen Yue; Schneider, Donald P.; Brandt, W. Niel; Myers, Adam D.; DeGraf, Colin; Glikman, Eilat; Ge Jian; Streblyanska, Alina

    2013-05-10

    We present a measurement of the Type I quasar luminosity function at z = 5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M{sub 1450} < -26) with Sloan Digital Sky Survey (SDSS) data covering {approx}6000 deg{sup 2}, then extend to lower luminosities (M{sub 1450} < -24) with newly discovered, faint z {approx} 5 quasars selected from 235 deg{sup 2} of deep, coadded imaging in the SDSS Stripe 82 region (the celestial equator in the Southern Galactic Cap). The faint sample includes 14 quasars with spectra obtained as ancillary science targets in the SDSS-III Baryon Oscillation Spectroscopic Survey, and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7 < z < 5.1 quasars that is highly complete, with 73 spectroscopic identifications out of 92 candidates. Our color selection method is also highly efficient: of the 73 spectra obtained, 71 are high-redshift quasars. These observations reach below the break in the luminosity function (M{sub 1450}{sup *}{approx}-27). The bright-end slope is steep ({beta} {approx}< -4), with a constraint of {beta} < -3.1 at 95% confidence. The break luminosity appears to evolve strongly at high redshift, providing an explanation for the flattening of the bright-end slope reported previously. We find a factor of {approx}2 greater decrease in the number density of luminous quasars (M{sub 1450} < -26) from z = 5 to z = 6 than from z = 4 to z = 5, suggesting a more rapid decline in quasar activity at high redshift than found in previous surveys. Our model for the quasar luminosity function predicts that quasars generate {approx}30% of the ionizing photons required to keep hydrogen in the universe ionized at z = 5.

  18. Galaxy and Mass Assembly (GAMA): ugriz galaxy luminosity functions

    NASA Astrophysics Data System (ADS)

    Loveday, J.; Norberg, P.; Baldry, I. K.; Driver, S. P.; Hopkins, A. M.; Peacock, J. A.; Bamford, S. P.; Liske, J.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Cameron, E.; Conselice, C. J.; Croom, S. M.; Frenk, C. S.; Gunawardhana, M.; Hill, D. T.; Jones, D. H.; Kelvin, L. S.; Kuijken, K.; Nichol, R. C.; Parkinson, H. R.; Phillipps, S.; Pimbblet, K. A.; Popescu, C. C.; Prescott, M.; Robotham, A. S. G.; Sharp, R. G.; Sutherland, W. J.; Taylor, E. N.; Thomas, D.; Tuffs, R. J.; van Kampen, E.; Wijesinghe, D.

    2012-02-01

    Galaxy and Mass Assembly (GAMA) is a project to study galaxy formation and evolution, combining imaging data from ultraviolet to radio with spectroscopic data from the AAOmega spectrograph on the Anglo-Australian Telescope. Using data from Phase 1 of GAMA, taken over three observing seasons, and correcting for various minor sources of incompleteness, we calculate galaxy luminosity functions (LFs) and their evolution in the ugriz passbands. At low redshift, z < 0.1, we find that blue galaxies, defined according to a magnitude-dependent but non-evolving colour cut, are reasonably well fitted over a range of more than 10 magnitudes by simple Schechter functions in all bands. Red galaxies, and the combined blue plus red sample, require double power-law Schechter functions to fit a dip in their LF faintwards of the characteristic magnitude M* before a steepening faint end. This upturn is at least partly due to dust-reddened disc galaxies. We measure the evolution of the galaxy LF over the redshift range 0.002 < z < 0.5 both by using a parametric fit and by measuring binned LFs in redshift slices. The characteristic luminosity L* is found to increase with redshift in all bands, with red galaxies showing stronger luminosity evolution than blue galaxies. The comoving number density of blue galaxies increases with redshift, while that of red galaxies decreases, consistent with prevailing movement from blue cloud to red sequence. As well as being more numerous at higher redshift, blue galaxies also dominate the overall luminosity density beyond redshifts z≃ 0.2. At lower redshifts, the luminosity density is dominated by red galaxies in the riz bands, and by blue galaxies in u and g.

  19. X-Ray and Rotational Luminosity Correlation and Magnetic Heating of Radio Pulsars

    NASA Astrophysics Data System (ADS)

    Shibata, S.; Watanabe, E.; Yatsu, Y.; Enoto, T.; Bamba, A.

    2016-12-01

    Previous works have suggested a correlation between the X-ray luminosity {L}{{x}} and the rotational luminosity {L}{rot} of radio pulsars. However, none of the obtained regression lines is statistically acceptable due to large scatter. We construct a statistical model that has an intrinsic {L}{{x}}-{L}{rot} relation and reproduces the observed {L}{{x}} distribution about it by using a Monte Carlo simulator, which takes into account the effects obscuring the intrinsic relation, i.e., the anisotropy of radiation, additional heating, uncertainty in distance, and the detection limit of the instruments. From the ATNF pulsar catalog we collect 57 “ordinary radio pulsars” with significant detection and 42 with upper limits. The sample does not include high-magnetic-field pulsars (>1013 G), which are analyzed separately. We obtain a statistically acceptable relation {L}{{x}}{(0.5{--}10{keV})={10}31.69({L}{rot}/{L}0)}{c1} with c 1 = 1.03 ± 0.27 and L 0 = 1035.38. The distribution about the obtained {L}{{x}}-{L}{rot} relation is reproduced well by the simulator. Pulsars with abnormally high {L}{{x}} fall into two types: one is the soft gamma-ray pulsars, and the other is pulsars that are thermally bright in comparison with the standard cooling curve. On the other hand, pulsars showing low {L}{{x}} are found to have dim pulsar wind nebulae (PWNs). We argue that there is an unknown mechanism that governs both the magnetospheric emission and the PWNs, and it might involve the production rate of electron-positron pairs. High-field pulsars form a population that is distinct from ordinary pulsars due to their excess luminosities.

  20. Galaxy And Mass Assembly (GAMA): colour- and luminosity-dependent clustering from calibrated photometric redshifts

    NASA Astrophysics Data System (ADS)

    Christodoulou, L.; Eminian, C.; Loveday, J.; Norberg, P.; Baldry, I. K.; Hurley, P. D.; Driver, S. P.; Bamford, S. P.; Hopkins, A. M.; Liske, J.; Peacock, J. A.; Bland-Hawthorn, J.; Brough, S.; Cameron, E.; Conselice, C. J.; Croom, S. M.; Frenk, C. S.; Gunawardhana, M.; Jones, D. H.; Kelvin, L. S.; Kuijken, K.; Nichol, R. C.; Parkinson, H.; Pimbblet, K. A.; Popescu, C. C.; Prescott, M.; Robotham, A. S. G.; Sharp, R. G.; Sutherland, W. J.; Taylor, E. N.; Thomas, D.; Tuffs, R. J.; van Kampen, E.; Wijesinghe, D.

    2012-09-01

    We measure the two-point angular correlation function of a sample of 4289 223 galaxies with r < 19.4 mag from the Sloan Digital Sky Survey (SDSS) as a function of photometric redshift, absolute magnitude and colour down to Mr - 5 log h = -14 mag. Photometric redshifts are estimated from ugriz model magnitudes and two Petrosian radii using the artificial neural network package ANNz, taking advantage of the Galaxy And Mass Assembly (GAMA) spectroscopic sample as our training set. These photometric redshifts are then used to determine absolute magnitudes and colours. For all our samples, we estimate the underlying redshift and absolute magnitude distributions using Monte Carlo resampling. These redshift distributions are used in Limber's equation to obtain spatial correlation function parameters from power-law fits to the angular correlation function. We confirm an increase in clustering strength for sub-L* red galaxies compared with ˜L* red galaxies at small scales in all redshift bins, whereas for the blue population the correlation length is almost independent of luminosity for ˜L* galaxies and fainter. A linear relation between relative bias and log luminosity is found to hold down to luminosities L ˜ 0.03L*. We find that the redshift dependence of the bias of the L* population can be described by the passive evolution model of Tegmark & Peebles. A visual inspection of a random sample from our r < 19.4 sample of SDSS galaxies reveals that about 10 per cent are spurious, with a higher contamination rate towards very faint absolute magnitudes due to over-deblended nearby galaxies. We correct for this contamination in our clustering analysis.

  1. Ultra-high-energy cosmic rays from low-luminosity active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Duţan, Ioana; Caramete, Laurenţiu I.

    2015-03-01

    We investigate the production of ultra-high-energy cosmic ray (UHECR) in relativistic jets from low-luminosity active galactic nuclei (LLAGN). We start by proposing a model for the UHECR contribution from the black holes (BHs) in LLAGN, which present a jet power Pj ⩽1046 erg s-1. This is in contrast to the opinion that only high-luminosity AGN can accelerate particles to energies ⩾ 50 EeV. We rewrite the equations which describe the synchrotron self-absorbed emission of a non-thermal particle distribution to obtain the observed radio flux density from sources with a flat-spectrum core and its relationship to the jet power. We found that the UHECR flux is dependent on the observed radio flux density, the distance to the AGN, and the BH mass, where the particle acceleration regions can be sustained by the magnetic energy extraction from the BH at the center of the AGN. We use a complete sample of 29 radio sources with a total flux density at 5 GHz greater than 0.5 Jy to make predictions for the maximum particle energy, luminosity, and flux of the UHECRs from nearby AGN. These predictions are then used in a semi-analytical code developed in Mathematica (SAM code) as inputs for the Monte-Carlo simulations to obtain the distribution of the arrival direction at the Earth and the energy spectrum of the UHECRs, taking into account their deflection in the intergalactic magnetic fields. For comparison, we also use the CRPropa code with the same initial conditions as for the SAM code. Importantly, to calculate the energy spectrum we also include the weighting of the UHECR flux per each UHECR source. Next, we compare the energy spectrum of the UHECRs with that obtained by the Pierre Auger Observatory.

  2. OT1_dweedman_1: Comparing [CII] 158 micron Luminosities to Spectral Properties of Luminous Starburst Galaxies and AGN

    NASA Astrophysics Data System (ADS)

    Weedman, D.

    2010-07-01

    Herschel PACS spectroscopy of the [CII] emission line at 158 microns is proposed for a carefully selected sample of 123 sources that already have complete low and high resolution mid-infrared spectra between 5 microns and 35 microns from the Spitzer Infrared Spectrograph, and which also have spectral energy distributions (SEDs) from IRAS and Akari photometry. [CII] 158 um is the strongest far-infrared emission line and therefore crucial to compare with other features in luminous, dusty galaxies. Sources have 0.004 < z < 0.34 and 43.0 < log L(IR) < 46.8 (erg per sec) and cover the full range of starburst galaxy and AGN classifications. Obtaining these [CII] line fluxes with PACS will allow: 1. determining how precisely [CII] luminosity measures star formation rate by comparing to PAH features and emission lines that arise in starburst galaxies; 2. determining how [CII] luminosity and equivalent width changes with starburst/AGN fraction, by comparing with strength and equivalent width of PAH and [NeII] emission arising from starbursts, and with strength of high ionization lines [NeV] and [OIV] and silicate absorption or emission arising from AGN; 3. determining how [CII] luminosity and equivalent width changes with dust temperature and bolometric luminosity, as derived from spectral energy distributions, and whether this depends on the starburst/AGN fraction. These determinations will allow interpretation of high redshift sources for which the only available diagnostics are the luminosity and equivalent width of the [CII] line and the far-infrared rest-frame SED. The total observing program requires 20.2 hours of Herschel observing time.

  3. Preparation of Biodegradable Gelatin Nanospheres with a Narrow Size Distribution for Carrier of Cellular Internalization of Plasmid DNA.

    PubMed

    Doi, Norio; Jo, Jun-Ichiro; Tabata, Yasuhiko

    2012-01-01

    The objective of this study is to design biodegradable nanospheres of cationized gelatin as a carrier of cellular internalization of plasmid DNA. Ethylenediamine was chemically introduced into the carboxyl groups of gelatin to obtain cationized gelatin. The gelatin solution was filtered through a glass membrane under high pressure and dropped into 2-butanol, acetone or a mixture of the two to form nanospheres of cationized gelatin. The microspheres of cationized gelatin were prepared by the conventional water-in-oil emulsion method. The resulting nano- and microspheres of cationized gelatin were dehydrothermally treated at 160°C for different time periods to allow them to cross-link chemically. The size of nanospheres, prepared by the filtration method and changed by the type of solvents, was 1.86, 0.83 or 0.24 μm. The in vitro degradation of spheres became faster as the time period of dehydrothermal treatment was shorter. The degradation time of spheres in HCl solution linearly increased with an increase in the cross-linking time, irrespective of the sphere size. However, in the collagenase solution, when compared at the similar cross-linking density, the smaller spheres were degraded more slowly than the larger ones. The plasmid DNA incorporated in the nanospheres was released from the nanospheres with their degradation. The nanospheres incorporating plasmid DNA were internalized into cells, and intracellularly degraded with time to release plasmid DNA. The time period of plasmid DNA release was prolonged by increasing the nanosphere degradation time.

  4. Imaging spectroscopy diagnosis of internal electron temperature and density distributions of plasma cloud surrounding hydrogen pellet in the Large Helical Device

    SciTech Connect

    Motojima, G.; Sakamoto, R.; Goto, M.; Matsuyama, A.; Yamada, H.; Mishra, J. S.

    2012-09-15

    To investigate the behavior of hydrogen pellet ablation, a novel method of high-speed imaging spectroscopy has been used in the Large Helical Device (LHD) for identifying the internal distribution of the electron density and temperature of the plasma cloud surrounding the pellet. This spectroscopic system consists of a five-branch fiberscope and a fast camera, with each objective lens having a different narrow-band optical filter for the hydrogen Balmer lines and the background continuum radiation. The electron density and temperature in the plasma cloud are obtained, with a spatial resolution of about 6 mm and a temporal resolution of 5 Multiplication-Sign 10{sup -5} s, from the intensity ratio measured through these filters. To verify the imaging, the average electron density and temperature also have been measured from the total emission by using a photodiode, showing that both density and temperature increase with time during the pellet ablation. The electron density distribution ranging from 10{sup 22} to 10{sup 24} m{sup -3} and the temperature distribution around 1 eV have been observed via imaging. The electron density and temperature of a 0.1 m plasma cloud are distributed along the magnetic field lines and a significant electron pressure forms in the plasma cloud for typical experimental conditions of the LHD.

  5. Imaging spectroscopy diagnosis of internal electron temperature and density distributions of plasma cloud surrounding hydrogen pellet in the Large Helical Device.

    PubMed

    Motojima, G; Sakamoto, R; Goto, M; Matsuyama, A; Mishra, J S; Yamada, H

    2012-09-01

    To investigate the behavior of hydrogen pellet ablation, a novel method of high-speed imaging spectroscopy has been used in the Large Helical Device (LHD) for identifying the internal distribution of the electron density and temperature of the plasma cloud surrounding the pellet. This spectroscopic system consists of a five-branch fiberscope and a fast camera, with each objective lens having a different narrow-band optical filter for the hydrogen Balmer lines and the background continuum radiation. The electron density and temperature in the plasma cloud are obtained, with a spatial resolution of about 6 mm and a temporal resolution of 5 × 10(-5) s, from the intensity ratio measured through these filters. To verify the imaging, the average electron density and temperature also have been measured from the total emission by using a photodiode, showing that both density and temperature increase with time during the pellet ablation. The electron density distribution ranging from 10(22) to 10(24) m(-3) and the temperature distribution around 1 eV have been observed via imaging. The electron density and temperature of a 0.1 m plasma cloud are distributed along the magnetic field lines and a significant electron pressure forms in the plasma cloud for typical experimental conditions of the LHD.

  6. The Dependence of galaxy colors on luminosity and environment at z~0.4

    SciTech Connect

    Yee, H.K.C.; Hsieh, B.C.; Lin, Huan; Gladders, M.D.; /Carnegie Inst. Observ.

    2005-08-01

    The authors analyze the B-R{sub c} colors of galaxies as functions of luminosity and local galaxy density using a large photometric redshift catalog based on the Red-Sequence Cluster Survey. They select two samples of galaxies with a magnitude limit of M{sub R{sub e}} < -18.5 and redshift ranges of 0.2 {le} z < 0.4 and 0.4 {le} x < 0.6 containing 10{sup 5} galaxies each. they model the color distributions of subsamples of galaxies and derive the red galaxy fraction and peak colors of red and blue galaxies as functions of galaxy luminosity and environment. The evolution of these relationships over the redshift range of x {approx} 0.5 to z {approx} 0.05 is analyzed in combination with published results from the Sloan Digital Sky Survey. They find that there is a strong evolution in the restframe peak color of bright blue galaxies in that they become redder with decreasing redshift, while the colors of faint blue galaxies remain approximately constant. This effect supports the ''downsizing'' scenario of star formation in galaxies. While the general dependence of the galaxy color distributions on the environment is small, they find that the change of red galaxy fraction with epoch is a function of the local galaxy density, suggesting that the downsizing effect may operate with different timescales in regions of different galaxy densities.

  7. Nuclear-to-disk rotation curves and mass-to-luminosity ratio in galaxies

    NASA Astrophysics Data System (ADS)

    Sofue, Yoshiaki

    High-resolution nuclear-to-outer rotation curves for Sb, SBb, Sc, and SBc galaxies generally show a steep nuclear rise and flat rotation from the disk to the halo. The high-velocity central rotation indicates massive cores within bulges. Since this characteristic is common to most galaxies, the high-velocity central rotation cannot be due to a particular orientation of non-circular motion. Using these rotation curves, we derive the distributions of surface-mass density, and compare them directly with observed surface-luminosity distributions. The mass-to-luminosity ratio (ML) increases from the outer bulge to the disk, indicating that the outer disk is already dominated by dark-mass. It, then, increases more rapidly toward the outer optical edge, indicating the massive halo. In the central regions of some galaxies, the ML increases steeply toward the nucleus, reaching a value an order of magnitude greater in the central 100 pc region than that in the disk, which may indicate a massive core of radius ~ 100 parsecs and mass of ~ 109 Msolar. The core may be an object linking a bulge and a black hole at the nucleus.

  8. Widening of Protostellar Outflows: An Infrared Outflow Survey in Low-luminosity Objects

    NASA Astrophysics Data System (ADS)

    Hsieh, Tien-Hao; Lai, Shih-Ping; Belloche, Arnaud

    2017-04-01

    We present an outflow survey toward 20 low-luminosity objects (LLOs), namely, protostars with an internal luminosity lower than 0.2 {L}ȯ . Although a number of studies have reported the properties of individual LLOs, the reasons for their low luminosity remain uncertain. To answer this question, we need to know the evolutionary status of LLOs. Protostellar outflows are found to widen as their parent cores evolve, and therefore the outflow opening angle could be used as an evolutionary indicator. The infrared scattered light escapes out through the outflow cavity and highlights the cavity wall, giving us the opportunity to measure the outflow opening angle. Using the Canada–France–Hawaii Telescope, we detected outflows toward eight LLOs out of 20 at Ks band, and based on archival Spitzer IRAC1 images, we added four outflow-driving sources from the remaining 12 sources. By fitting these images with radiative transfer models, we derive the outflow opening angles and inclination angles. To study the widening of outflow cavities, we compare our sample with the young stellar objects from Arce & Sargent and Velusamy et al. in a plot of opening angle versus bolometric temperature taken as an evolutionary indicator. Our LLO targets match well the trend of increasing opening angle with bolometric temperature reported by Arce & Sargent and are broadly consistent with that reported by Velusamy et al., suggesting that the opening angle could be a good evolutionary indicator for LLOs. Accordingly, we conclude that at least 40% of the outflow-driving LLOs in our sample are young Class 0 objects.

  9. Direct Oxygen Abundances for the Lowest Luminosity LVL Galaxies

    NASA Astrophysics Data System (ADS)

    Berg, Danielle; Skillman, E. D.; Marble, A. R.; van Zee, L.; Engelbracht, C. W.

    2012-01-01

    We present new MMT spectroscopic observations of HII regions in 42 of the lowest luminosity galaxies in the Spitzer Local Volume Legacy (LVL) survey. For 31 of the galaxies in our sample we were able to measure the [OIII] ? auroral line at a strength of 4σ or greater, and thus determine oxygen abundances using the direct method. Direct oxygen abundances were compared to B-band luminosity, 4.5 μm luminosity, and stellar mass to characterize the luminosity-metallicity (L-Z) and mass-metallicity (M-Z) relationships at low-luminosity. We examined a "Combined Select” sample composed of 38 objects, from the present sample and the literature, with direct oxygen abundances and reliable distance determinations (based on the tip of the red giant branch or Cepheid variables). The B-band and 4.5 μm L-Z relationships were found to be 12+log(O/H) = (6.19±0.07) + (-0.12±0.01)MB and 12+log(O/H) = (5.93±0.11) + (-0.11±0.01)M[4.5] with dispersions of σ = 0.17 and σ = 0.14 respectively. Since the slope of the L-Z relationship doesn't seem to vary from the optical to the near-IR, as has been observed in studies of more luminous galaxies, we propose that less extinction due to dust is created in the lowest luminosity galaxies. We subsequently derived a M-Z relationship of 12+log(O/H) = (5.49±0.23) + (0.31±0.03)log M*, with a dispersion of σ = 0.16. None of the relationships seem to hold an advantage with respect to dispersion, supporting the idea of minimized dust. Additionally, the trend of N/O abundance with respect to B-V color and oxygen abundance was examined. Similar to the conclusions of van Zee & Haynes (2006), we find a positive correlation between N/O ratio and B-V color: log(N/O) = 0.92 (B-V) - 1.83. Furthermore, there are no objects with high N/O ratio below 12+log(O/H)=7.9.

  10. Revisiting the Correlations of Peak Luminosity with Spectral Lag and Peak Energy of the Observed Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Jo, Yun-A.; Chang, Heon-Young

    2016-12-01

    An analysis of light curves and spectra of observed gamma-ray bursts in gamma-ray ranges is frequently demanded because the prompt emission contains immediate details regarding the central engine of gamma-ray bursts (GRBs). We have revisited the relationship between the collimation-corrected peak luminosity and the spectral lag, investigating the lag-luminosity relationships in great detail by focusing on spectral lags resulting from all possible combinations of channels. Firstly, we compiled the opening angle data and demonstrated that the distribution of opening angles of 205 long GRBs is represented by a double Gaussian function having maxima at 0.1 and 0.3 radians. We confirmed that the peak luminosity and the spectral lag are anti-correlated, both in the observer frame and in the source frame. We found that, in agreement with our previous conclusion, the correlation coefficient improves significantly in the source frame. It should be noted that spectral lags involving channel 2 (25-50 keV) yield high correlation coefficients, where Swift/Burst Alert Telescope (BAT) has four energy channels (channel 1: 15-25 keV, channel 2: 25-50 keV, channel 3: 50-100 keV, channel 4: 100-200 keV). We also found that peak luminosity is positively correlated with peak energy.

  11. Comparison of Internal Energy Distributions of Ions Created by Electrospray Ionization and Laser Ablation-Liquid Vortex Capture-Electrospray Ionization

    SciTech Connect

    Cahill, John F.; Kertesz, Vilmos; Ovchinnikova, Olga S.; Van Berkel, Gary J.

    2015-06-27

    Recently a number of techniques have combined laser ablation with liquid capture for mass spectrometry spot sampling and imaging applications. The newly developed non-contact liquid-vortex capture probe has been used to efficiently collect 355 nm UV laser ablated material in a continuous flow solvent stream in which the captured material dissolves and then undergoes electrospray ionization. This sampling and ionization approach has produced what appear to be classic electrospray ionization spectra; however, the softness of this sampling/ionization process versus simple electrospray ionization has not been definitely determined. A series of benzlypyridinium salts, known as thermometer ions, were used to compare internal energy distributions between electrospray ionization and the UV laser ablation liquid-vortex capture probe electrospray combination. Measured internal energy distributions were identical between the two techniques, even with differences in laser fluence (0.7-3.1 J cm-2) and when using UV-absorbing or non-UV-absorbing sample substrates. This data indicates ions formed directly by UV laser ablation, if any, are likely an extremely small constituent of the total ion signal observed. Instead, neutral molecules, clusters or particulates ejected from the surface during laser ablation, subsequently captured and dissolved in the flowing solvent stream then electrosprayed are the predominant source of ion signal observed. The electrospray ionization process used controls the softness of the technique.

  12. Comparison of Internal Energy Distributions of Ions Created by Electrospray Ionization and Laser Ablation-Liquid Vortex Capture-Electrospray Ionization

    DOE PAGES

    Cahill, John F.; Kertesz, Vilmos; Ovchinnikova, Olga S.; ...

    2015-06-27

    Recently a number of techniques have combined laser ablation with liquid capture for mass spectrometry spot sampling and imaging applications. The newly developed non-contact liquid-vortex capture probe has been used to efficiently collect 355 nm UV laser ablated material in a continuous flow solvent stream in which the captured material dissolves and then undergoes electrospray ionization. This sampling and ionization approach has produced what appear to be classic electrospray ionization spectra; however, the softness of this sampling/ionization process versus simple electrospray ionization has not been definitely determined. A series of benzlypyridinium salts, known as thermometer ions, were used to comparemore » internal energy distributions between electrospray ionization and the UV laser ablation liquid-vortex capture probe electrospray combination. Measured internal energy distributions were identical between the two techniques, even with differences in laser fluence (0.7-3.1 J cm-2) and when using UV-absorbing or non-UV-absorbing sample substrates. This data indicates ions formed directly by UV laser ablation, if any, are likely an extremely small constituent of the total ion signal observed. Instead, neutral molecules, clusters or particulates ejected from the surface during laser ablation, subsequently captured and dissolved in the flowing solvent stream then electrosprayed are the predominant source of ion signal observed. The electrospray ionization process used controls the softness of the technique.« less

  13. Structural-acoustic model of a rectangular plate-cavity system with an attached distributed mass and internal sound source: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Pirnat, Miha; Čepon, Gregor; Boltežar, Miha

    2014-03-01

    In this paper three approaches are combined to develop a structural-acoustic model of a rectangular plate-cavity system with an attached distributed mass and internal sound source. The first approach results from a recently presented analysis based on the Rayleigh-Ritz method and is used to circumvent the difficulties in obtaining the natural frequencies and mode shapes of a plate with an attached, distributed mass. Furthermore, different plate boundary conditions can be accommodated. The resulting mode shapes are defined as continuous functions; this is advantageous as they can be directly used in the second approach, i.e., the classic modal-interaction approach in order to obtain the coupled equations of the system. Finally, in the third approach a group of point sources emitting a pressure pulse in the time domain is used to model an internal sound source. For the validation of the developed model an experiment was conducted in two configurations using a simply supported aluminium plate and a clamped plate coupled with a plexiglas box containing a loudspeaker. Good agreement was found between the analytical and experimental data.

  14. Evaluation of internal potential distribution and carrier extraction properties of organic solar cells through Kelvin probe and time-of-flight measurements

    NASA Astrophysics Data System (ADS)

    Tanaka, Yuya; Noguchi, Yutaka; Oda, Keisuke; Nakayama, Yasuo; Takahashi, Jun-ichi; Tokairin, Hiroshi; Ishii, Hisao

    2014-09-01

    The carrier extraction property of a prototypical small molecule organic solar cell (OSC) composed of copper phthalocyanine (CuPc), C60, and bathocuproine (BCP) was studied on the basis of the internal potential distribution and carrier dynamics in the device. The internal potential distribution in the OSC structure at the interfaces and in the bulk region was determined by the Kelvin probe method. Significant potential gradients were found in the CuPc film on indium tin oxide and in the C60 film on CuPc, consistent with charge transfer through the contacts. Moreover, surface potential of the BCP layer grew linearly with increasing film thickness with a slope of ca. 35 mV/nm (giant surface potential: GSP), which indicated spontaneous orientation polarization in the film. The potential gradient and GSP significantly changed the built-in potential of the device. Current-voltage and modified time-of-flight measurements revealed that the BCP layer worked as an electron injection and extraction layer despite the wide energy gap. These results were discussed based on the contributions of GSP and the gap states in the BCP layer.

  15. Evaluation of internal potential distribution and carrier extraction properties of organic solar cells through Kelvin probe and time-of-flight measurements

    SciTech Connect

    Tanaka, Yuya; Oda, Keisuke; Nakayama, Yasuo; Noguchi, Yutaka Ishii, Hisao; Takahashi, Jun-ichi; Tokairin, Hiroshi

    2014-09-21

    The carrier extraction property of a prototypical small molecule organic solar cell (OSC) composed of copper phthalocyanine (CuPc), C⁶⁰, and bathocuproine (BCP) was studied on the basis of the internal potential distribution and carrier dynamics in the device. The internal potential distribution in the OSC structure at the interfaces and in the bulk region was determined by the Kelvin probe method. Significant potential gradients were found in the CuPc film on indium tin oxide and in the C⁶⁰ film on CuPc, consistent with charge transfer through the contacts. Moreover, surface potential of the BCP layer grew linearly with increasing film thickness with a slope of ca. 35 mV/nm (giant surface potential: GSP), which indicated spontaneous orientation polarization in the film. The potential gradient and GSP significantly changed the built-in potential of the device. Current–voltage and modified time-of-flight measurements revealed that the BCP layer worked as an electron injection and extraction layer despite the wide energy gap. These results were discussed based on the contributions of GSP and the gap states in the BCP layer.

  16. Distribution of 24 elements in the internal organs of normal males and the metallic workers in Japan

    SciTech Connect

    Teraoka, H.

    1981-07-01

    Concentrations of 24 elements in the internal organs from 12 health males and from 7 metallic workers in Japan were recorded. Markedly high concentrations of chromium were found in the respiratory organs (e.g., hilar lymph node and lung) of chromium plating and chromate refining workers, as well as in spleen, liver, kidney, and heart. High chromium concentrations were also found in one male who had terminated his employment 30 years prior to his death. In addition, high concentrations of nickel and tin were also found in the above-mentioned workers. Marked accumulations of titanium, the main element of paints, were found in the respiratory organs, spleen, liver, kidney, and heart of an airplane painter. The painter also had high concentrations of chromium, nickel, and cobalt in some of his organs. It was also noted that high concentrations of silicon, aluminum, and titanium--elements of rock--occurred in a stone mason.

  17. A review of a method for dynamic load distribution, dynamical modeling, and explicit internal force control when two manipulators mutually lift and transport a rigid body object

    SciTech Connect

    Unseren, M.A.

    1997-04-20

    The paper reviews a method for modeling and controlling two serial link manipulators which mutually lift and transport a rigid body object in a three dimensional workspace. A new vector variable is introduced which parameterizes the internal contact force controlled degrees of freedom. A technique for dynamically distributing the payload between the manipulators is suggested which yields a family of solutions for the contact forces and torques the manipulators impart to the object. A set of rigid body kinematic constraints which restrict the values of the joint velocities of both manipulators is derived. A rigid body dynamical model for the closed chain system is first developed in the joint space. The model is obtained by generalizing the previous methods for deriving the model. The joint velocity and acceleration variables in the model are expressed in terms of independent pseudovariables. The pseudospace model is transformed to obtain reduced order equations of motion and a separate set of equations governing the internal components of the contact forces and torques. A theoretic control architecture is suggested which explicitly decouples the two sets of equations comprising the model. The controller enables the designer to develop independent, non-interacting control laws for the position control and internal force control of the system.

  18. Relative controls of external and internal variability on time-variable transit time distributions, and the importance of StorAge Selection function approaches

    NASA Astrophysics Data System (ADS)

    Kim, M.; Pangle, L. A.; Cardoso, C.; Lora, M.; Meira, A.; Volkmann, T. H. M.; Wang, Y.; Harman, C. J.; Troch, P. A. A.

    2015-12-01

    Transit time distributions (TTDs) are an efficient way of characterizing complex transport dynamics of a hydrologic system. Time-invariant TTD has been studied extensively, but TTDs are time-varying under unsteady hydrologic systems due to both external variability (e.g., time-variability in fluxes), and internal variability (e.g., time-varying flow pathways). The use of "flow-weighted time" has been suggested to account for the effect of external variability on TTDs, but neglects the role of internal variability. Recently, to account both types of variability, StorAge Selection (SAS) function approaches were developed. One of these approaches enables the transport characteristics of a system - how the different aged water in the storage is sampled by the outflow - to be parameterized by time-variable probability distribution called the rank SAS (rSAS) function, and uses it directly to determine the time-variable TTDs resulting from a given timeseries of fluxes in and out of a system. Unlike TTDs, the form of the rSAS function varies only due to changes in flow pathways, but is not affected by the timing of fluxes alone. However, the relation between physical mechanisms and the time-varying rSAS functions are not well understood. In this study, relative effects of internal and external variability on the TTDs are examined using observations from a homogeneously packed 1 m3 sloping soil lysimeter. The observations suggest the importance of internal variability on TTDs, and reinforce the need to account for this variability using time-variable rSAS functions. Furthermore, the relative usefulness of two other formulations of SAS functions and the mortality rate (which plays a similar role to SAS functions in the McKendrick-von Foerster model of age-structured population dynamics) are also discussed. Finally, numerical modeling is used to explore the role of internal and external variability for hydrologic systems with diverse geomorphic and climate characteristics

  19. OH megamasers in high-luminosity IRAS galaxies

    NASA Technical Reports Server (NTRS)

    Mirabel, I. F.; Sanders, D. B.

    1987-01-01

    OH megamaser emission and H I and CO profiles from the distant infrared galaxies IRAS 10173 + 0828, III Zw 035, and Zw 475.056 are reported. The OH isotropic luminosities at 1667 MHz are 463, 534, and 6.6 solar luminosities, respectively. Far-infrared pumping efficiencies of the OH greater than 1 percent are found in IRAS 10173 + 0828 and III Zw 035. These two galaxies show anomalously large 1667/1665 MHz emission line ratios. OH megamasers reside in the nuclei of superluminous far-infrared galaxies that have a high content of molecular gas, high efficiency of star formation, and in some instances, a striking deficiency of atomic hydrogen.

  20. Intermediate-Band Photometric Luminosity Descrimination for M Stars

    NASA Astrophysics Data System (ADS)

    Robertson, T. H.; Furiak, N. M.

    1995-12-01

    Synthetic photometry has been used to design an intermediate-band filter to be used with CCD cameras to facilitate the luminosity classification of M stars. Spectrophotometric data published by Gunn & Stryker (1983) were used to test various bandwidths and centers. Based on these calculations an intermediate-band filter has been purchased. This filter is being used in conjunction with standard BVRI filters to test its effectiveness in luminosity classification of M stars having a wide range of temperatures and different chemical compositions. The results of the theoretical calculations, filter design specifications and preliminary results of the testing program are presented. This research is supported in part by funds provided by Ball State University, The Fund for Astrophysical Research and the Indiana Academy of Science.

  1. An Independent Derivation of the Oxford Jet Kinetic Luminosity Formula

    NASA Astrophysics Data System (ADS)

    Punsly, Brian

    2005-04-01

    This Letter presents a theoretical derivation of an estimate for a radio source jet kinetic luminosity. The expression yields jet powers that are quantitatively similar to a more sophisticated empirical relation published by C. Willott, K. Blundell, and S. Rawlings at Oxford. The formula allows one to estimate the jet kinetic luminosity from the measurement of the optically thin radio lobe emission in quasars and radio galaxies. Motivated by recent X-ray observations, the derivation assumes that most of the energy in the lobes is in plasma thermal energy with a negligible contribution from magnetic energy (not equipartition). The close agreement of the two independent expressions makes the veracity of these estimates seem very plausible.

  2. The Luminosity Measurement for the DZERO Experiment at Fermilab

    SciTech Connect

    Snow, Gregory R.

    2016-08-01

    Primary project objective: The addition of University of Nebraska-Lincoln (UNL) human resources supported by this grant helped ensure that Fermilab’s DZERO experiment had a reliable luminosity measurement through the end of Run II data taking and an easily-accessible repository of luminosity information for all collaborators performing physics analyses through the publication of its final physics results. Secondary project objective: The collaboration between the UNL Instrument Shop and Fermilab’s Scintillation Detector Development Center enhanced the University of Nebraska’s future role as a particle detector R&D and production facility for future high energy physics experiments. Overall project objective: This targeted project enhanced the University of Nebraska’s presence in both frontier high energy physics research in DZERO and particle detector development, and it thereby served the goals of the DOE Office of Science and the Experimental Program to Stimulate Competitive Research (EPSCoR) for the state of Nebraska.

  3. High Speed Measurements of the LHC Luminosity Monitor

    NASA Astrophysics Data System (ADS)

    Beche, J. F.; Byrd, J. M.; Monroy, M.; Ratti, A.; Turner, W.; Bravin, E.

    2006-11-01

    The LHC luminosity monitor is a gas ionization chamber designed to operate in the high radiation environment present in the TAN neutral absorbers at the LHC. One of the challenges is to measure the luminosity of individual bunch crossings with a minimum separation of 25 nsec. To test the time response and other aspects of a prototype chamber, we have performed a test using an x-ray beam of 40-60 keV with pulse spacing of 26 nsec as an ionizing beam. The tests were made at BL 8.3.2 at the Advanced Light Source (ALS). This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  4. Luminosity variations in several parallel auroral arcs before auroral breakup

    NASA Astrophysics Data System (ADS)

    Safargaleev, V.; Lyatsky, W.; Tagirov, V.

    1997-08-01

    Variation of the luminosity in two parallel auroral arcs before auroral breakup has been studied by using digitised TV-data with high temporal and spatial resolution. The intervals when a new arc appears near already existing one were chosen for analysis. It is shown, for all cases, that the appearance of a new arc is accompanied by fading or disappearance of another arc. We have named these events out-of-phase events, OP. Another type of luminosity variation is characterised by almost simultaneous enhancement of intensity in the both arcs (in-phase event, IP). The characteristic time of IP events is 10-20 s, whereas OP events last about one minute. Sometimes out-of-phase events begin as IP events. The possible mechanisms for OP and IP events are discussed.

  5. 4D fast tracking for experiments at high luminosity LHC

    NASA Astrophysics Data System (ADS)

    Neri, N.; Cardini, A.; Calabrese, R.; Fiorini, M.; Luppi, E.; Marconi, U.; Petruzzo, M.

    2016-11-01

    The full exploitation of the physics potential of the high luminosity LHC is a big challenge that requires new instrumentation and innovative solutions. We present here a conceptual design and simulation studies of a fast timing pixel detector with embedded real-time tracking capabilities. The system is conceived to operate at 40 MHz event rate and to reconstruct tracks in real-time, using precise space and time 4D information of the hit, for fast trigger decisions. This work is part of an R&D project aimed at building an innovative tracking detector with superior time (10 ps) and position (10 μm) resolutions to be used in very harsh radiation environments, for the ultimate flavour physics experiment at the high luminosity phase of the LHC.

  6. SLHC, the High-Luminosity Upgrade (public event)

    ScienceCinema

    None

    2016-07-12

    In the morning of June 23rd a public event is organised in CERN's Council Chamber with the aim of providing the particle physics community with up-to-date information about the strategy for the LHC luminosity upgrade and to describe the current status of preparation work. The presentations will provide an overview of the various accelerator sub-projects, the LHC physics prospects and the upgrade plans of ATLAS and CMS. This event is organised in the framework of the SLHC-PP project, which receives funding from the European Commission for the preparatory phase of the LHC High Luminosity Upgrade project. Informing the public is among the objectives of this EU-funded project. A simultaneous transmission of this meeting will be broadcast, available at the following address: http://webcast.cern.ch/

  7. Luminosity Limitations of Linear Colliders Based on Plasma Acceleration

    SciTech Connect

    Lebedev, Valeri; Burov, Alexey; Nagaitsev, Sergei

    2016-01-01

    Particle acceleration in plasma creates a possibility of exceptionally high accelerating gradients and appears as a very attractive option for future linear electron-positron and/or photon-photon colliders. These high accelerating gradients were already demonstrated in a number of experiments. Furthermore, a linear collider requires exceptionally high beam brightness which still needs to be demonstrated. In this article we discuss major phenomena which limit the beam brightness of accelerated beam and, consequently, the collider luminosity.

  8. Physics of a high-luminosity Tau-Charm Factory

    SciTech Connect

    King, M.E.

    1992-10-01

    This paper highlights the physics capabilities of a Tau-Charm Factory; i.e., high luminosity ({approximately}10{sup 33}cm{sup {minus}2}s{sup {minus}1}) e{sup +}e{sup {minus}} collider operating in the center-of-mass energy range of 3-5 GeV, with a high-precision, general-purpose detector. Recent developments in {tau} and charm physics are emphasized.

  9. The two period-luminosity relations for population I Cepheids

    NASA Technical Reports Server (NTRS)

    Bohm-Vitense, Erika

    1994-01-01

    We summarize the evidence that most Population I Cepheids with periods less than approximately 8 days pulsate in the first overtone mode. Fundamental model and first overtone pulsators must follow different period-luminosity (P - L) relations. We demonstrate these different relations for different stellar systems, especially for the calibrating Cepheids in clusters and for Cepheids in the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC), M31, and IC 4182.

  10. Dynamic aperture studies for the LHC high luminosity lattice

    SciTech Connect

    Maria, R. de; Giovannozzi, M.; McIntosh, E.; Nosochkov, Y. M.; Cai, Y.; Wang, M. -H.

    2015-07-14

    Since quite some time, dynamic aperture studies have been undertaken with the aim of specifying the required field quality of the new magnets that will be installed in the LHC ring in the framework of the high-luminosity upgrade. In this paper the latest results concerning the specification work will be presented, taking into account both injection and collision energies and the field quality contribution from all the magnets in the newly designed interaction regions.

  11. High-field Magnet Development toward the High Luminosity LHC

    SciTech Connect

    Apollinari, Giorgio

    2014-07-01

    The upcoming Luminosity upgrade of the LHC (HL-LHC) will rely on the use of Accelerator Quality Nb3Sn Magnets which have been the focus of an intense R&D effort in the last decade. This contribution will describe the R&D and results of Nb3Sn Accelerator Quality High Field Magnets development efforts, with emphasis on the activities considered for the HL-LHC upgrades.

  12. Parallax and Luminosity Measurements of an L SubDwarf

    DTIC Science & Technology

    2008-01-10

    determination of both parameters would provide a powerful test of interior and evolutionary models for low-mass stars and brown dwarfs. Subject headinggs...stars: chemically peculiar — stars: fundamental parameters — stars: individual (2MASS J05325346+8246465) — stars: low-mass, brown dwarfs — subdwarfs...Online material: color figures 1. INTRODUCTION The lowest luminosity stars and brown dwarfs are among the most useful probes of planetary , stellar

  13. LHC Abort Gap Cleaning Studies During Luminosity Operation

    SciTech Connect

    Gianfelice-Wendt, E.; Bartmann, W.; Boccardi, A.; Bracco, C.; Bravin, E.; Goddard, B.; Hofle, W.; Jacquet, D.; Jeff, A.; Kain, V.; Meddahi, M.; /CERN

    2012-05-11

    The presence of significant intensities of un-bunched beam is a potentially serious issue in the LHC. Procedures using damper kickers for cleaning both the Abort Gap (AG) and the buckets targeted for injection, are currently in operation at flat bottom. Recent observations of relatively high population of the AG during physics runs brought up the need for AG cleaning during luminosity operation. In this paper the results of experimental studies performed in October 2011 are presented.

  14. The CLASS BL Lac sample: the radio luminosity function

    NASA Astrophysics Data System (ADS)

    Marchã, M. J. M.; Caccianiga, A.

    2013-04-01

    This paper presents a new sample of BL Lac objects selected from a deep (30 mJy) radio survey of flat spectrum radio sources (the CLASS blazar survey). The sample is one of the largest well-defined samples in the low-power regime with a total of 130 sources of which 55 satisfy the `classical' optical BL Lac selection criteria, and the rest have indistinguishable radio properties. The primary goal of this study is to establish the radio luminosity function (RLF) on firm statistical ground at low radio luminosities where previous samples have not been able to investigate. The gain of taking a peek at lower powers is the possibility to search for the flattening of the luminosity function which is a feature predicted by the beaming model but which has remained elusive to observational confirmation. In this study, we extend for the first time the BL Lac RLF down to very low radio powers ˜1022 W Hz-1, i.e. two orders of magnitude below the RLF currently available in the literature. In the process, we confirm the importance of adopting a broader, and more physically meaningful set of classification criteria to avoid the systematic missing of low-luminosity BL Lacs. Thanks to the good statistics we confirm the existence of weak but significant positive cosmological evolution for the BL Lac population, and we detect, for the first time the flattening of the RLF at L ˜ 1025 W Hz-1 in agreement with the predictions of the beaming model.

  15. Optimization of the Luminosity Spectrum in the NLC

    SciTech Connect

    Thompson, Kathleen A

    1999-05-11

    The energy spectrum of electrons at the interaction point of a linear collider is determined largely by the beamstrahlung spectrum. The beamstrahlung spectrum in turn is sensitive to the design parameters at the interaction point. In this paper we examine the optimization of the luminosity spectrum for discovery and detailed exploration of various physics processes of interest in the NLC, in particular, top and stop pair production, and a class of processes occurring via W-W scattering.

  16. The VIMOS VLT deep survey. The ultraviolet galaxy luminosity function and luminosity density at 3 ≤ z ≤ 4

    NASA Astrophysics Data System (ADS)

    Paltani, S.; Le Fèvre, O.; Ilbert, O.; Arnouts, S.; Bardelli, S.; Tresse, L.; Zamorani, G.; Zucca, E.; Bottini, D.; Garilli, B.; Le Brun, V.; Maccagni, D.; Picat, J.-P.; Scaramella, R.; Scodeggio, M.; Vettolani, G.; Zanichelli, A.; Adami, C.; Bolzonella, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Franzetti, P.; Gavignaud, I.; Guzzo, L.; Iovino, A.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Bondi, M.; Bongiorno, A.; Brinchmann, J.; Cucciati, O.; de la Torre, S.; Lamareille, F.; Mellier, Y.; Merluzzi, P.; Temporin, S.; Vergani, D.; Walcher, C. J.

    2007-03-01

    Aims:We study the luminosity function of the high-redshift galaxy population with redshifts 3≤ z ≤ 4 using a purely I-band magnitude-selected spectroscopic sample obtained in the framework of the VIMOS VLT Deep Survey (VVDS). Methods: We determine the luminosity function from the VVDS, taking care to add as few assumptions and as simple corrections as possible, and compare our results with those obtained from photometric studies, based on Lyman-break selections or photometric-redshift measurements. Results: We find that in the redshift range 3≤ z ≤ 4, the VVDS luminosity function is parameterized by φ^*=1.24+0.48-0.50×10-3 mag-1 Mpc-3 and M^*=-21.49+0.19-0.19, assuming a slope α=-1.4 consistent with most previous studies. While φ* is comparable to previously found values, M* is significantly brighter by about 0.5 mag at least. Using the conservative slope α=-1.4, we find a luminosity density at 1700 Å L1700(M<-18.5)=2.4×1019 W Mpc-3 and L1700Total=3.1×1019 W Mpc-3, comparable to that estimated in other studies. Conclusions: .The unexpectedly large number of very bright galaxies found in the VVDS indicates that the color-selection and photometric-redshift techniques that are generally used to build high-redshift galaxy samples may be affected by a significant fraction of color-measurement failures or by incomplete modelling of the mix of stellar emission, AGN contribution, dust absorption and intergalactic extinction assumed to identify high-redshift galaxies, making pure magnitude selection better able to trace the full population. Because of the difficulty to identify all low-luminosity galaxies in a spectroscopic survey, the luminosity density could still be significantly underestimated. We also find that the relative contribution of the most luminous galaxies compared to the fainter ones is at least twice as large in the VVDS compared to former estimates. Therefore, the VVDS paints a quite different picture of the role of the most actively star

  17. 3D Tomography of Accretionary Lapilli From The Island of Stromboli (Aeolian Archipelago, Italy): Spatial Arrangement, Internal Structure, Grain Size Distribution and Chemical Characterization

    NASA Astrophysics Data System (ADS)

    Morgavi, D.; Ielpo, M.; Valentini, L.; Laeger, K.; Paredes, J.; Petrelli, M.; Costa, A.; Perugini, D.

    2015-12-01

    The Secche di Lazzaro formation (7 Ka) is a phreatomagmatic deposit in the south-western part of the island of Stromboli (Aeolian Archipelago, Italy). The volcanic sequence is constituted by three main sub-units. In two of them abundant accretionary lapilli are present. We performed granulometric analysis to describe the spatial arrangement and the grain-size distribution of the lapilli inside the deposit. Lapilli were characterized by SEM investigations (BSE images). EMPA and LA-ICP-MS analyses of major and trace elements on glasses and minerals were performed. Although BSE images provide accurate morphological information, they do not allow the real 3D microstructure to be accessed. Therefore, non-invasive 3D imaging of the lapilli was performed by X-ray micro-tomography (X-mCT). The results of the X-mCT measurements provided a set of 2D cross-sectional slices stacked along the vertical axis, with a voxel size varying between 2.7 and 4.1 mm, depending on the size of the sample. The X-mCT images represent a mapping of X-ray attenuation, which in turn depends on the density of the phases distributed within the sample. This technique helped us to better constrain the particle and crystal distribution inside the accretionary lapilli. The recognized phases are: glass, clinopyroxene, plagioclase and Ti-Fe minerals. We discover also a high concentration of Na, Cl and SO3 in the ash matrix. This evidence is ubiquitous in all the accretionary lapilli. The work presented here could define a new route for future studies in the field of physical volcanology as X-ray micro-tomography could be a useful, non destructive technique to better characterize the internal structure of accretionary lapilli helping us to describe grain-size distribution of component particles and their spatial distribution within aggregates.

  18. Transit time distributions and StorAge Selection functions in a sloping soil lysimeter with time-varying flow paths: Direct observation of internal and external transport variability

    NASA Astrophysics Data System (ADS)

    Kim, Minseok; Pangle, Luke A.; Cardoso, Charléne; Lora, Marco; Volkmann, Till H. M.; Wang, Yadi; Harman, Ciaran J.; Troch, Peter A.

    2016-09-01

    Transit times through hydrologic systems vary in time, but the nature of that variability is not well understood. Transit times variability was investigated in a 1 m3 sloping lysimeter, representing a simplified model of a hillslope receiving periodic rainfall events for 28 days. Tracer tests were conducted using an experimental protocol that allows time-variable transit time distributions (TTDs) to be calculated from data. Observed TTDs varied with the storage state of the system, and the history of inflows and outflows. We propose that the observed time variability of the TTDs can be decomposed into two parts: "internal" variability associated with changes in the arrangement of, and partitioning between, flow pathways; and "external" variability driven by fluctuations in the flow rate along all flow pathways. These concepts can be defined quantitatively in terms of rank StorAge Selection (rSAS) functions, which is a theory describing lumped transport dynamics. Internal variability is associated with temporal variability in the rSAS function, while external is not. The rSAS function variability was characterized by an "inverse storage effect," whereby younger water is released in greater proportion under wetter conditions than drier. We hypothesize that this effect is caused by the rapid mobilization of water in the unsaturated zone by the rising water table. Common approximations used to model transport dynamics that neglect internal variability were unable to reproduce the observed breakthrough curves accurately. This suggests that internal variability can play an important role in hydrologic transport dynamics, with implications for field data interpretation and modeling.

  19. The graviton luminosity of the sun and other stars

    NASA Technical Reports Server (NTRS)

    Gould, R. J.

    1985-01-01

    Graviton production in electron-electron (e-e) and electron-ion (e-z) scattering is evaluated in the Born approximation. The calculation is compared with that for photon production, that is, Coulomb quadrupole bremsstrahlung, and a number of results are taken over from that problem. Application is made to the sun, and it is found that for the solar plasma the main contribution to the graviton luminosity comes from the central core at r/R approximately 0.1. The total luminosity (Lg) in gravitons is about 7.9 x 10 to the 14th ergs/s, close to an earlier estimate by Weinberg (1965, 1972); about 33 percent of the total results from e-e collisions with the rest from e-z collisions (mainly e-p and e-alpha). Approximate corrections to Born formulas are evaluated, and this Lg includes the associated (approximately + or - 10 percent, respectively) modification. The quantum-mechanical aspects of the solar Lg problem are discussed, and it is shown why a previous classical calculation overestimated Lg by about an order of magnitude. Production of gravitons in binary collisions in other types of stars is discussed briefly. It is found that Lg varies very little along the main sequence. White dwarfs have a typical graviton luminosity LWD approximately 10 to the 19th ergs/s, while neutron stars have LNS approximately 10 to the 25th ergs/s; these estimates are very rough.

  20. Disk Luminosity Function Based on the Lowell Proper Motion Survey

    NASA Astrophysics Data System (ADS)

    Kim, Mee-Jeong; Lee, Sang-Gak

    1991-12-01

    Disk stellar luminosity function has been derived with stars in the Lowell Proper Motion Survey which contains about 9000 stars with mu => 0.27" of arc/yr, 8 < m_pg < 17 and with bright stars in the Smithsonian Astrophysical Observatory (SAO) Star Catalogue. Luminosity function has been obtained with stars within 20 pc by Luyten's mean absolute magnitudes method using Reduced Proper Motion Diagram to select disk stars. Magnitudes and colors, in the SAO Star Catalogue as well as in the Lowell Proper Motion Survey have been transformed to the UBV system from the published UBV data. It has been found that stars which have higher proper motion than the original limit of the proper motion survey are missed, when the relation between the absolute magnitude and reduced proper motion is applied to sample stars without considering the dispersion in magnitude. Correction factors for missing stars have been estimated according to their limits of proper motion which are dependent on the absolute magnitude. Resulting lumi- nosity function shows Wielen's dip at M_B ~ 10, and systematic enhancement of stars on the average of about delta log Phi(M_B) ~ 0.2 compared with Luyten's luminosity function.

  1. Study of the luminosity function for field galaxies

    NASA Technical Reports Server (NTRS)

    Felten, J. E.

    1977-01-01

    Nine determinations of the luminosity function (LF) for field galaxies are adjusted, analyzed, and compared. Adjustments are made for differences in definitions as well as in assumptions regarding magnitude systems, the Hubble constant, and galactic absorption. Eight of the nine adjusted determinations are found to be in fairly good agreement, and the discrepancy in the ninth is attributed to incompleteness effects. A large-scale normalization of the LF is performed using the method and some integral counts of Gott and Turner (1976); the large-scale mean LF of (mostly field) galaxies is found to be about 2.3 times less than a previously derived 'local' LF. The large-scale luminosity density in space arising from sources within the B(0) isophotes of galaxies is evaluated, and a value of 86 million (H/50) suns per cu Mpc is obtained for a galactic absorption coefficient of 0.25 magnitude. It is noted that the true large-scale luminosity density is probably within a factor of 1.6 of the reported value.

  2. The effect of large scale inhomogeneities on the luminosity distance

    NASA Astrophysics Data System (ADS)

    Brouzakis, Nikolaos; Tetradis, Nikolaos; Tzavara, Eleftheria

    2007-02-01

    We study the form of the luminosity distance as a function of redshift in the presence of large scale inhomogeneities, with sizes of order 10 Mpc or larger. We approximate the Universe through the Swiss-cheese model, with each spherical region described by the Lemaitre Tolman Bondi metric. We study the propagation of light beams in this background, assuming that the locations of the source and the observer are random. We derive the optical equations for the evolution of the beam area and shear. Through their integration we determine the configurations that can lead to an increase of the luminosity distance relative to the homogeneous cosmology. We find that this can be achieved if the Universe is composed of spherical void-like regions, with matter concentrated near their surface. For inhomogeneities consistent with the observed large scale structure, the relative increase of the luminosity distance is of the order of a few per cent at redshifts near 1, and falls short of explaining the substantial increase required by the supernova data. On the other hand, the effect we describe is important for the correct determination of the energy content of the Universe from observations.

  3. Tidal dwarf galaxies and the luminosity-metallicity relation .

    NASA Astrophysics Data System (ADS)

    Sweet, S. M.; Drinkwater, M. J.; Meurer, G.; Bekki, K.; Dopita, M. A.; Kilborn, V.; Nicholls, D.

    We present a recalibration of the luminosity-metallicity relation for gas-rich, star-forming dwarfs to magnitudes as faint as M_R˜ -13. We use the \\citet{Dopita2013} metallicity calibrations to calibrate the relation for all of the data in this analysis. Metal-rich dwarfs classified as tidal dwarf galaxy (TDG) candidates in the literature are typically of metallicity 12 + log(O/H) = 8.70 ± 0.05, while SDSS dwarfs fainter than M_R = -16 have a mean metallicity of 12 + log(O/H) = 8.28 ± 0.10, regardless of their luminosity. Our hydrodynamical simuations predict that TDGs should have metallicities elevated above the normal luminosity-metallicity relation. Metallicity can therefore be a useful diagnostic for identifying TDG candidate populations in the absence of tidal tails. At magnitudes brighter than M_R˜ -16 our sample of 53 star-forming galaxies in 9 HI gas-rich groups is consistent with the normal relation defined by the SDSS sample. At fainter magnitudes there is an increase in dispersion in metallicity of our sample. In our sample we identify three (16% of dwarfs) strong TDG candidates (12 + log(O/H) > 8.6), and four (21%) very metal poor dwarfs (12 + log(O/H) < 8.0), which are likely gas-rich dwarfs with recently ignited star formation. Further details of this analysis are available in Sweet et al. (2013, ApJ submitted).

  4. A Search for Low-Luminosity BL Lacertae Objects

    NASA Astrophysics Data System (ADS)

    Rector, Travis A.; Stocke, John T.; Perlman, Eric S.

    1999-05-01

    Many properties of BL Lacs have become explicable in terms of the ``relativistic beaming'' hypothesis, whereby BL Lacs are FR 1 radio galaxies viewed nearly along the jet axis. However, a possible problem with this model is that a transition population between beamed BL Lacs and unbeamed FR 1 galaxies has not been detected. A transition population of ``low-luminosity BL Lacs'' was predicted to exist in abundance in X-ray-selected samples such as the Einstein Extended Medium Sensitivity Survey (EMSS) by Browne & Marcha. However, these BL Lacs may have been misidentified as clusters of galaxies. We have conducted a search for such objects in the EMSS with the ROSAT High-Resolution Imager (HRI) here we present ROSAT HRI images, optical spectra, and VLA radio maps for a small number of BL Lacs that were previously misidentified in the EMSS catalog as clusters of galaxies. While these objects are slightly lower in luminosity than other EMSS BL Lacs, their properties are too similar to the other BL Lacs in the EMSS sample to ``bridge the gap'' between BL Lacs and FR 1 radio galaxies. Also, the number of new BL Lacs found is too low to alter significantly the X-ray luminosity function or value for the X-ray-selected EMSS BL Lac sample. Thus, these observations do not explain fully the discrepancy between the X-ray- and radio-selected BL Lac samples.

  5. The Luminosity Dependence of the Galaxy Merger Rate

    NASA Astrophysics Data System (ADS)

    Patton, D. R.; Atfield, J. E.

    2008-09-01

    We measure the number of companions per galaxy (Nc) as a function of r-band absolute magnitude for both the Sloan Digital Sky Survey and the Croton and coworkers semianalytic catalog applied to the Millennium Run simulation. For close pairs with projected separations of 5-20 h-1 kpc, velocity differences less than 500 km s-1, and luminosity ratios between 1:2 and 2:1, we find good agreement between the observations and simulations, with Nc consistently close to 0.02 over the range -22 < Mr < - 18. For larger pair separations, Nc(Mr) instead becomes increasingly steep toward the faint end, implying that luminosity-dependent clustering plays an important role on small scales. Using the simulations to assess and correct for projection effects, we infer that the real-space Nc(Mr) for close pairs peaks at about M* and declines by at least a factor of 2 as Mr becomes fainter. Conversely, by measuring the number density of close companions, we estimate that at least 90% of all major mergers occur between galaxies which are fainter than L*. Finally, measurements of the luminosity density of close companions indicate that L* galaxies likely dominate in terms of the overall importance of major mergers in the evolution of galaxy populations at low redshift.

  6. High Luminosity Heavy Quark and Electromagnetic Probes at RHIC

    SciTech Connect

    David, G; Frawley, A D; Rapp, R; Ullrich, T; Vogt, R; Xu, Z

    2008-03-30

    The Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory was designed to study the properties of quantum chromodynamics (QCD) in a hot and dense medium. The first years of RHIC operation and accompanying theoretical studies have helped pinpoint certain classes of measurements needed to more fully probe the medium and determine its properties. The medium created in these heavy-ion (AA) collisions appears to thermalize quickly and exhibits collective flow patterns consistent with hydrodynamic predictions. The initial temperature of the medium is not known and it is not yet understood whether deconfinement and chiral symmetry restoration are realized during its evolution. The answers to these questions require higher luminosities and detector upgrades, referred to as RHIC-II. The goal of RHIC II is to achieve the answers to the above questions by increasing the ion luminosity. The measurements thus far at RHIC could not fully address these fundamental questions, either due to incomplete detection capabilities or insufficient statistics to draw meaningful and robust conclusions. Working groups were formed to determine which physics topics could best be addressed by the combination of planned upgrades and increased luminosity. Reports from each working group were used to prepare a white paper for RHIC II, along with additional inputs from the conveners of all working groups.

  7. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Calculation of the temperature distribution in ridged-waveguide laser diodes

    NASA Astrophysics Data System (ADS)

    Piprek, J.; Nürnberg, R.

    1988-11-01

    A numerical solution is obtained of the steady-state heat conduction equation for InGaAsP/InP ridge-waveguide lasers (λ = 1.3 μm) soldered upside down to a heat sink. Two-dimensional temperature distributions perpendicular to the ridge are obtained. It is assumed that the heat sources inside such a laser are the active region and the contact at the top of the ridge. An increase in the temperature of the junction and the corresponding thermal resistance of a laser chip and solder are calculated for several sets of laser parameters. The results indicate that the thermal properties are particularly sensitive to the width of the ridge and the thickness of the solder. The results obtained should be useful in thermal optimization of ridge-waveguide laser diodes.

  8. Magnitude of Residual Internal Anatomy Motion on Heavy Charged Particle Dose Distribution in Respiratory Gated Lung Therapy

    SciTech Connect

    Mori, Shinichiro Asakura, Hiroshi; Kandatsu, Susumu; Kumagai, Motoki; Baba, Masayuki; Endo, Masahiro

    2008-06-01

    Purpose: To assess the variation in carbon beam dose distribution due to residual motion in lung cancer patients undergoing respiratory-gated radiotherapy. Methods and Materials: A total of 11 lung cancer patients underwent four-dimensional computed tomography with a 256-multislice computed tomography scanner under free-breathing conditions. A compensating bolus was designed to cover the treatment beam for all planning target volumes during a 30% duty cycle centered on exhalation (gating window). This bolus was applied to the four-dimensional computed tomography data for one respiratory cycle, and then the carbon beam dose distribution was calculated. Results: A water equivalent pathlength variation of <5 mm was observed in the gating window, but this increased to {<=}20 mm on inhalation. As a result, beam overshoot/undershoot occurred around inhalation, which increased the excessive dosing to normal tissues and the organs at risk. The dose for >95% volume irradiation is dependent on the respiratory phase but not the gating window. However, the dose for >95% volume irradiation correlated well with the tumor displacement distance. More than 90% of the dose for >95% volume irradiation could be delivered in the gating window with <4-mm tumor displacement resulting from exhalation. Conclusion: The results of our study have shown that even when the treatment beam delivery occurs outside the gating window, the prescribed dose to the target is not affected in patients with a tumor displacement of <4 mm. Thus, respiratory gating is not required in radiotherapy for patients with <4-mm tumor displacement in a respiratory cycle.

  9. BIOKINETICS OF SYSTEMICALLY DISTRIBUTED CO-60 IN THE RAT: AN EXPERIMENTAL MODEL USEFUL IN EVALUATING MEDICAL COUNTERMEASURES FOR INTERNAL CONTAMINATION

    PubMed Central

    Weber, Waylon; Doyle-Eisele, Melanie; Seilkop, Steven K.; Guilmette, Raymond

    2012-01-01

    LBERI, a member of the Medical Countermeasures to Radiologic Threats (MCART) consortium funded by NIAID, was tasked to develop biokinetic models for the distribution of radionuclide threats using the most likely routes of incorporation in both small and large animals. In the present paper, the biokinetics of systemically administered soluble cobalt-60 (60Co) have been examined. Male and female jugular-vein-catheterized (JVC) F344 rats received intravenous (IV) doses of 11.2 kBq of 60CoCl2. The distribution of the radiocobalt was followed for 28 d, with tissue sampling done at 1 and 4 h, and at 1, 2, 4, 8, 16, and 28 d. Urine and feces were collected daily. Tissues and excreta were analyzed by gamma pulse height analysis. Within 8d, 93% of the cobalt was eliminated from the body primarily though urine. The highest tissue burdens were found in liver, gastrointestinal (GI) tract, and muscle shortly after administration. These tissues cleared quickly so that by the conclusion of the 28-d study, less than 3% of the recovered dose remained in the body. The results are comparable to published literature values for tissue content of 60Co and for excretion patterns up to 30 d after injection. These results will provide the data needed to construct a biokinetic model for the unperturbed biokinetics of 60Co in rats, which will subsequently be used to evaluate the impact of administered decorporating agents on organ radiation doses. The animal model described in this paper is representative of that used for other routes of radionuclide administration such as inhalation, ingestion and wound contamination that have been studied at LBERI in support of the MCART and NIAID programs. PMID:22929473

  10. Intracellular Distribution of TM4SF1 and Internalization of TM4SF1-antibody Complex in Vascular Endothelial Cells

    PubMed Central

    Sciuto, Tracey E.; Merley, Anne; Lin, Chi-Iou; Richardson, Douglas; Liu, Yu; Li, Dan; Dvorak, Ann M.; Dvorak, Harold F.; Jaminet, Shou-Ching S.

    2015-01-01

    Transmembrane-4 L-six family member-1 (TM4SF1) is a small plasma membrane-associated glycoprotein that is highly and selectively expressed on the plasma membranes of tumor cells, cultured endothelial cells, and, in vivo, on tumor-associated endothelium. Immunofluorescence microscopy also demonstrated TM4SF1 in cytoplasm and, tentatively, within nuclei. With monoclonal antibody 8G4, and the finer resolution afforded by immuno-nanogold transmission electron microscopy, we now demonstrate TM4SF1 in uncoated cytoplasmic vesicles, nuclear pores and nucleoplasm. Because of its prominent surface location on tumor cells and tumor-associated endothelium, TM4SF1 has potential as a dual therapeutic target using an antibody drug conjugate (ADC) approach. For ADC to be successful, antibodies reacting with cell surface antigens must be internalized for delivery of associated toxins to intracellular targets. We now report that 8G4 is efficiently taken up into cultured endothelial cells by uncoated vesicles in a dynamin-dependent, clathrin-independent manner. It is then transported along microtubules through the cytoplasm and passes through nuclear pores into the nucleus. These findings validate TM4SF1 as an attractive candidate for cancer therapy with antibody-bound toxins that have the capacity to react with either cytoplasmic or nuclear targets in tumor cells or tumor-associated vascular endothelium. PMID:26241677

  11. Uses of subcellular metal distribution in prey to predict metal bioaccumulation and internal exposure in a predator.

    PubMed

    Cheung, Ma-Shan; Wang, Wen-Xiong

    2008-05-01

    In the present study, rock oysters (Saccostrea cucullata) were first exposed to cadmium and zinc for two weeks to modify their subcellular metal partitionings. The relationship between subcellular metal (Cd and Zn) partitioning in the oysters and metal bioaccumulation and fractionation in predatory gastropods (Thais clavigera) was then examined by feeding to the predator oysters that were preexposed to metal for two to four weeks. We also investigated the relationship between the PAM in the oysters and the biochemical biomarkers in the gastropods. Thais clavigera accumulated Cd effectively from their prey, but no correlation was found between the Cd body concentrations in T. clavigera and the internal metal partitioning in the prey. A significant positive correlation was found between the Cd in the trophically available metal (TAM) fraction of oysters and the Cd in the metal-sensitive fraction of T. clavigera and between the Cd in the TAM fraction of oysters and the metallothionein induction in whelks. Zinc was highly regulated by both S. cucullata and T. clavigera, and their Zn body concentrations remained constant throughout the exposure period. No relationship between Zn bioaccumulation and any of the subcellular fractions was found. The present study may lead to a better understanding of the dietary metal exposure mechanism.

  12. Internal distribution of Cd in lettuce and resulting effects on Cd trophic transfer to the snail: Achatina fulica.

    PubMed

    Li, Cheng-Cheng; Dang, Fei; Cang, Long; Zhou, Dong-Mei; Peijnenburg, Willie J G M

    2015-09-01

    The mechanisms underlying Cd trophic transfer along the soil-lettuce-snail food chain were investigated. The fate of Cd within cells, revealed by assessment of Cd chemical forms and of subcellular partitioning, differed between the two examined lettuce species that we examined (L. longifolia and L. crispa). The species-specific internal Cd fate not only influenced Cd burdens in lettuce, with higher Cd levels in L. crispa, but also affected Cd transfer efficiency to the consumer snail (Achatina fulica). Especially, the incorporation of Cd chemical forms (Cd in the inorganic, water-soluble and pectates and protein-integrated forms) in lettuce could best explain Cd trophic transfer, when compared to dietary Cd levels alone and/or subcellular Cd partitioning. Trophically available metal on the subcellular partitioning base failed to shed light on Cd transfer in this study. After 28-d of exposure, most Cd was trapped in the viscera of Achatina fulica, and cadmium bio-magnification was noted in the snails, as the transfer factor of lettuce-to-snail soft tissue was larger than one. This study provides a first step to apply a chemical speciation approach to dictate the trophic bioavailability of Cd through the soil-plant-snail system, which might be an important pre-requisite for mechanistic understanding of metal trophic transfer.

  13. A Heuristic Prediction of the Cosmic Evolution of the Co-luminosity Functions

    NASA Astrophysics Data System (ADS)

    Obreschkow, D.; Heywood, I.; Klöckner, H.-R.; Rawlings, S.

    2009-09-01

    We predict the emission line luminosity functions (LFs) of the first 10 rotational transitions of 12C16O in galaxies at redshift z = 0 to z = 10. This prediction relies on a recently presented simulation of the molecular cold gas content in ~3 × 107 evolving galaxies based on the Millennium Simulation. We combine this simulation with a model for the conversion between molecular mass and CO-line intensities, which incorporates the following mechanisms: (1) molecular gas is heated by the cosmic microwave background (CMB), starbursts (SBs), and active galactic nuclei (AGNs); (2) molecular clouds in dense or inclined galaxies can overlap; (3) compact gas can attain a smooth distribution in the densest part of disks; (4) CO luminosities scale with metallicity changes between galaxies; and (5) CO luminosities are always detected against the CMB. We analyze the relative importance of these effects and predict the cosmic evolution of the CO-LFs. The most notable conclusion is that the detection of regular galaxies (i.e., no AGN, no massive SB) at high z gsim 7 in CO emission will be dramatically hindered by the weak contrast against the CMB, in contradiction to earlier claims that CMB heating will ease the detection of high-redshift CO. The full simulation of extragalactic CO lines and the predicted CO-LFs at any redshift can be accessed online (http://s-cubed.physics.ox.ac.uk/, go to "S3-SAX") and they should be useful for the modeling of CO-line surveys with future telescopes, such as the Atacama Large Millimeter/submillimeter Array or the Square Kilometre Array.

  14. Evidence of Parsec-scale Jets in Low-luminosity Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Mezcua, M.; Prieto, M. A.

    2014-05-01

    The nuclear radio emission of low-luminosity active galactic nuclei (LLAGNs) is often associated with unresolved cores. In this paper we show that most LLAGNs present extended jet radio emission when observed with sufficient angular resolution and sensitivity. They are thus able to power, at least, parsec-scale radio jets. To increase the detection rate of jets in LLAGNs, we analyze subarcsecond resolution data of three low-ionization nuclear emission regions. This yields the detection of extended jet-like radio structures in NGC 1097 and NGC 2911 and the first resolved parsec-scale jet of NGC 4594 (Sombrero). The three sources belong to a sample of nearby LLAGNs for which high-spatial-resolution spectral energy distribution of their core emission is available. This allows us to study their accretion rate and jet power (Q jet) without drawing on (most) of the ad hoc assumptions usually considered in large statistical surveys. We find that those LLAGNs with large-scale radio jets (>100 pc) have Q jet > 1042 erg s-1, while the lowest Q jet correspond to those LLAGNs with parsec-scale (<=100 pc) jets. The Q jet is at least as large as the radiated bolometric luminosity for all LLAGN, in agreement with previous statistical studies. Our detection of parsec-scale jets in individual objects further shows that the kinematic jet contribution is equally important in large- or parsec-scale objects. We also find that the Eddington-scaled accretion rate is still highly sub-Eddingtonian (<10-4) when adding the Q jet to the total emitted luminosity (radiated plus kinetic). This indicates that LLAGNs are not only inefficient radiators but that they also accrete inefficiently or are very efficient advectors.

  15. Early black holes in cosmological simulations: luminosity functions and clustering behaviour

    NASA Astrophysics Data System (ADS)

    DeGraf, Colin; Di Matteo, Tiziana; Khandai, Nishikanta; Croft, Rupert; Lopez, Julio; Springel, Volker

    2012-08-01

    We examine predictions for the quasar luminosity functions (QLFs) and quasar clustering at high redshift (z ≥ 4.75) using MassiveBlack, our new hydrodynamic cosmological simulation which includes a self-consistent model for black hole (BH) growth and feedback. We show that the model reproduces the Sloan QLF within observational constraints at z ≥ 5. We find that the high-z QLF is consistent with a redshift-independent occupation distribution of BHs among dark matter haloes (which we provide) such that the evolution of the QLF follows that of the halo mass function. The sole exception is the bright end at z = 6 and 7, where BHs in high-mass haloes tend to be unusually bright due to extended periods of Eddington growth caused by high-density cold flows into the halo centre. We further use these luminosity functions to make predictions for the number density of quasars in upcoming surveys, predicting that there should be ˜119 ± 28 (˜87 ± 28) quasars detectable in the F125W band of the WIDE (DEEP) fields of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) from z = 5 to 6, ˜19 ± 7 (˜18 ± 9) from z = 6 to 7 and ˜1.7 ± 1.5 (˜1.5 ± 1.5) from z = 7 to 8. We also investigate quasar clustering, finding that the correlation length is fully consistent with current constraints for Sloan quasars (r0 ˜ 17 h-1 Mpc at z = 4 for quasars above mi = 20.2) and grows slowly with redshift up to z = 6 (r0 ˜ 22 h-1 Mpc). Finally, we note that the quasar clustering strength depends weakly on luminosity for low LBH, but gets stronger at higher LBH as the BHs are found in higher mass haloes.

  16. Evidence of parsec-scale jets in low-luminosity active galactic nuclei

    SciTech Connect

    Mezcua, M.; Prieto, M. A.

    2014-05-20

    The nuclear radio emission of low-luminosity active galactic nuclei (LLAGNs) is often associated with unresolved cores. In this paper we show that most LLAGNs present extended jet radio emission when observed with sufficient angular resolution and sensitivity. They are thus able to power, at least, parsec-scale radio jets. To increase the detection rate of jets in LLAGNs, we analyze subarcsecond resolution data of three low-ionization nuclear emission regions. This yields the detection of extended jet-like radio structures in NGC 1097 and NGC 2911 and the first resolved parsec-scale jet of NGC 4594 (Sombrero). The three sources belong to a sample of nearby LLAGNs for which high-spatial-resolution spectral energy distribution of their core emission is available. This allows us to study their accretion rate and jet power (Q {sub jet}) without drawing on (most) of the ad hoc assumptions usually considered in large statistical surveys. We find that those LLAGNs with large-scale radio jets (>100 pc) have Q {sub jet} > 10{sup 42} erg s{sup –1}, while the lowest Q {sub jet} correspond to those LLAGNs with parsec-scale (≤100 pc) jets. The Q {sub jet} is at least as large as the radiated bolometric luminosity for all LLAGN, in agreement with previous statistical studies. Our detection of parsec-scale jets in individual objects further shows that the kinematic jet contribution is equally important in large- or parsec-scale objects. We also find that the Eddington-scaled accretion rate is still highly sub-Eddingtonian (<10{sup –4}) when adding the Q {sub jet} to the total emitted luminosity (radiated plus kinetic). This indicates that LLAGNs are not only inefficient radiators but that they also accrete inefficiently or are very efficient advectors.

  17. On the Existence of Low-Luminosity Cataclysmic Variables Beyond the Orbital Period Minimum

    NASA Technical Reports Server (NTRS)

    Howell, Steve B.; Rappaport, Saul; Politano, Michael

    1997-01-01

    Models of the present-day intrinsic population of cataclysmic variables predict that 99 per cent of these systems should be of short orbital period. The Galaxy is old enough that approx. 70 per cent of these stars will have already reached their orbital period minimum (approx. 80 min), and should be evolving back toward longer periods. Mass-transfer rates in these highly evolved binaries are predicted to be less or equal to 10(exp -11), leading to M(sub V) of approx. 10 or fainter, and the secondaries would be degenerate, brown dwarf-like stars. Recent observations of a group of low-luminosity dwarf novae (TOADS) provide observational evidence for systems with very low intrinsic M,. and possibly low-mass secondaries. We carry out population synthesis and evolution calculations for a range of assumed ages of the Galaxy in order to study P(sub orb) and M distributions for comparison with the TOAD observations. We speculate that at least some of the TOADs are the predicted very low- luminosity, post-period-minimum cataclysmic variables containing degenerate (brown dwarf-like) secondaries having masses between 0.02 and 0.06 M, and radii near 0.1 R., We show that these low-luminosity systems are additionally interesting in that they can be used to set a lower limit on the age of the Galaxy. The TOAD with the longest orbital period currently known (123 min), corresponds to a Galaxy age of at least 8.6 x 10(exp 9) yr.

  18. MULTI-WAVELENGTH OBSERVATIONS OF A SAMPLE OF INTERMEDIATE-LUMINOSITY RADIO-LOUD ACTIVE GALAXIES

    SciTech Connect

    Lewis, Karen T.; Sambruna, Rita M.; Cheung, Chi C.; Eracleous, Michael; Kadler, Matthias

    2011-07-15

    We present the results from exploratory (12-23 ks) XMM-Newton observations of six optically selected, radio-loud active galactic nuclei (AGNs), together with new radio data and a reanalysis of their archival SDSS spectra. The sources were selected in an effort to expand the current sample of radio-loud AGNs suitable for detailed X-ray spectroscopy studies. The sample includes three broad-line and three narrow-line sources, with X-ray luminosities of the order of L{sub 2-10keV} {approx} 10{sup 43} erg s{sup -1}. The EPIC spectra of the broad-lined sources can be described by single power laws with photon indices {Gamma} {approx} 1.6 and little to negligible absorption (N{sub H} {approx}<10{sup 21} cm{sup -2}); on the contrary, significant absorption is detected in the narrow-lined objects, N{sub H} {approx} 10{sup 23} cm{sup -2}, one of which displays a prominent (equivalent width {approx}2 keV) Fe K{alpha} emission line. Studying their location in several luminosity-luminosity diagrams for radio-loud AGNs, we find that the sources fall at the lower end of the distribution for bright, classical radio-loud AGNs and close to LINER-like sources. As such, and as indicated by the ratios of their optical emission lines, we conclude that the sources of our sample fall on the border between radiatively efficient and inefficient accretion flows. Future deeper studies of these targets at X-rays and longer wavelengths will expand our understanding of the central engines of radio-loud AGNs at a critical transition region.

  19. THE RELATIONSHIP BETWEEN X-RAY LUMINOSITY AND MAJOR FLARE LAUNCHING IN GRS 1915+105

    SciTech Connect

    Punsly, Brian; Rodriguez, Jerome E-mail: brian.punsly@comdev-usa.com

    2013-02-20

    We perform the most detailed analysis to date of the X-ray state of the Galactic black hole candidate GRS 1915+105 just prior to (0-4 hr) and during the brief (1-7 hr) ejection of major (superluminal) radio flares. A very strong model independent correlation is found between the 1.2 keV-12 keV X-ray flux 0-4 hr before flare ejections with the peak optically thin 2.3 GHz emission of the flares. This suggests a direct physical connection between the energy in the ejection and the luminosity of the accretion flow preceding the ejection. In order to quantify this concept, we develop techniques to estimate the intrinsic (unabsorbed) X-ray luminosity, L {sub intrinsic}, from RXTE All Sky Monitor data and to implement known methods to estimate the time-averaged power required to launch the radio emitting plasmoids, Q (sometimes called jet power). We find that the distribution of intrinsic luminosity from 1.2 keV-50 keV, L {sub intrinsic} (1.2-50), is systematically elevated just before ejections compared to arbitrary times when there are no major ejections. The estimated Q is strongly correlated with L {sub intrinsic} (1.2-50) 0-4 hr before the ejection, the increase in L {sub intrinsic} (1.2-50) in the hours preceding the ejection and the time-averaged L {sub intrinsic} (1.2-50) during the flare rise. Furthermore, the total time-averaged power during the ejection (Q + the time average of L {sub intrinsic} (1.2-50) during ejection) is strongly correlated with L {sub intrinsic} (1.2-50) just before launch with near equality if the distance to the source is Almost-Equal-To 10.5 kpc.

  20. The 2-10 keV unabsorbed luminosity function of AGN from the LSS, CDFS, and COSMOS surveys

    NASA Astrophysics Data System (ADS)

    Ranalli, P.; Koulouridis, E.; Georgantopoulos, I.; Fotopoulou, S.; Hsu, L.-T.; Salvato, M.; Comastri, A.; Pierre, M.; Cappelluti, N.; Carrera, F. J.; Chiappetti, L.; Clerc, N.; Gilli, R.; Iwasawa, K.; Pacaud, F.; Paltani, S.; Plionis, E.; Vignali, C.

    2016-05-01

    The XMM-Large scale structure (XMM-LSS), XMM-Cosmological evolution survey (XMM-COSMOS), and XMM-Chandra deep field south (XMM-CDFS) surveys are complementary in terms of sky coverage and depth. Together, they form a clean sample with the least possible variance in instrument effective areas and point spread function. Therefore this is one of the best samples available to determine the 2-10 keV luminosity function of active galactic nuclei (AGN) and their evolution. The samples and the relevant corrections for incompleteness are described. A total of 2887 AGN is used to build the LF in the luminosity interval 1042-1046 erg s-1 and in the redshift interval 0.001-4. A new method to correct for absorption by considering the probability distribution for the column density conditioned on the hardness ratio is presented. The binned luminosity function and its evolution is determined with a variant of the Page-Carrera method, which is improved to include corrections for absorption and to account for the full probability distribution of photometric redshifts. Parametric models, namely a double power law with luminosity and density evolution (LADE) or luminosity-dependent density evolution (LDDE), are explored using Bayesian inference. We introduce the Watanabe-Akaike information criterion (WAIC) to compare the models and estimate their predictive power. Our data are best described by the LADE model, as hinted by the WAIC indicator. We also explore the recently proposed 15-parameter extended LDDE model and find that this extension is not supported by our data. The strength of our method is that it provides unabsorbed, non-parametric estimates, credible intervals for luminosity function parameters, and a model choice based on predictive power for future data. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and NASA.Tables with the samples of the posterior probability distributions

  1. Internal combustion engine control for series hybrid electric vehicles by parallel and distributed genetic programming/multiobjective genetic algorithms

    NASA Astrophysics Data System (ADS)

    Gladwin, D.; Stewart, P.; Stewart, J.

    2011-02-01

    This article addresses the problem of maintaining a stable rectified DC output from the three-phase AC generator in a series-hybrid vehicle powertrain. The series-hybrid prime power source generally comprises an internal combustion (IC) engine driving a three-phase permanent magnet generator whose output is rectified to DC. A recent development has been to control the engine/generator combination by an electronically actuated throttle. This system can be represented as a nonlinear system with significant time delay. Previously, voltage control of the generator output has been achieved by model predictive methods such as the Smith Predictor. These methods rely on the incorporation of an accurate system model and time delay into the control algorithm, with a consequent increase in computational complexity in the real-time controller, and as a necessity relies to some extent on the accuracy of the models. Two complementary performance objectives exist for the control system. Firstly, to maintain the IC engine at its optimal operating point, and secondly, to supply a stable DC supply to the traction drive inverters. Achievement of these goals minimises the transient energy storage requirements at the DC link, with a consequent reduction in both weight and cost. These objectives imply constant velocity operation of the IC engine under external load disturbances and changes in both operating conditions and vehicle speed set-points. In order to achieve these objectives, and reduce the complexity of implementation, in this article a controller is designed by the use of Genetic Programming methods in the Simulink modelling environment, with the aim of obtaining a relatively simple controller for the time-delay system which does not rely on the implementation of real time system models or time delay approximations in the controller. A methodology is presented to utilise the miriad of existing control blocks in the Simulink libraries to automatically evolve optimal control

  2. Fossil group origins. III. The relation between optical and X-ray luminosities

    NASA Astrophysics Data System (ADS)

    Girardi, M.; Aguerri, J. A. L.; De Grandi, S.; D'Onghia, E.; Barrena, R.; Boschin, W.; Méndez-Abreu, J.; Sánchez-Janssen, R.; Zarattini, S.; Biviano, A.; Castro-Rodriguez, N.; Corsini, E. M.; del Burgo, C.; Iglesias-Páramo, J.; Vilchez, J. M.

    2014-05-01

    Aims: This study is part of the Fossil group origins (FOGO) project which aims to carry out a systematic and multiwavelength study of a large sample of fossil systems. Here we focus on the relation between the optical luminosity (Lopt) and X-ray luminosity (LX). Methods: Out of a total sample of 28 candidate fossil systems, we consider a sample of 12 systems whose fossil classification has been confirmed by a companion study. They are compared with the complementary sample of 16 systems whose fossil nature has not been confirmed and with a subsample of 102 galaxy systems from the RASS-SDSS galaxy cluster survey. Fossil and normal systems span the same redshift range 0 distribution. For each fossil system, the LX in the 0.1-2.4 keV band is computed using data from the ROSAT All Sky Survey to be comparable to the estimates of the comparison sample. For each fossil and normal system we homogeneously compute Lopt in the r-band within the characteristic cluster radius, using data from the Sloan Digital Sky Survey Data Release 7. Results: We sample the LX-Lopt relation over two orders of magnitude in LX. Our analysis shows that fossil systems are not statistically distinguishable from the normal systems through the 2D Kolmogorov-Smirnov test nor the fit of the LX-Lopt relation. Thus, the optical luminosity of the galaxy system does strongly correlate with the X-ray luminosity of the hot gas component, independently of whether the system is fossil or not. We discuss our results in comparison with previous literature. Conclusions: We conclude that our results are consistent with the classical merging scenario of the brightest galaxy formed via merger/cannibalism of other group galaxies with conservation of the optical light. We find no evidence for a peculiar state of the hot intracluster medium. Tables 1 and 2 are available in electronic form at http://www.aanda.org

  3. Evaluation of dual energy quantitative CT for determining the spatial distributions of red marrow and bone for dosimetry in internal emitter radiation therapy

    SciTech Connect

    Goodsitt, Mitchell M. Shenoy, Apeksha; Howard, David; Christodoulou, Emmanuel; Dewaraja, Yuni K.; Shen, Jincheng; Schipper, Matthew J.; Wilderman, Scott; Chun, Se Young

    2014-05-15

    for external calibrations exhibited much larger RMS errors than size matched internal calibration. Use of an average body size external-to-internal calibration correction factor reduced the errors to closer to those for internal calibration. RMS errors of less than 30% or about 0.01 for the bone and 0.1 for the red marrow volume fractions would likely be satisfactory for human studies. Such accuracies were achieved for 3 × 3 segmentation of 5 mm slice images for: (a) internal calibration with 4 times dose for all size body phantoms, (b) internal calibration with 2 times dose for the small and medium size body phantoms, and (c) corrected external calibration with 4 times dose and all size body phantoms. Conclusions: Phantom studies are promising and demonstrate the potential to use dual energy quantitative CT to estimate the spatial distributions of red marrow and bone within the vertebral spongiosa.

  4. Spitzer Local Volume Legacy (LVL) Star-Forming Regions: Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, Daniel A.; Lee, Janice C.; LVL Team

    2015-01-01

    The conversion of gas into stars is one of the most fundamental processes in the universe, yet the effects of environmental conditions are poorly constrained. Observations of star-forming regions (young star clusters and HII regions) have shown evidence of a fractal pattern in their mass and luminosity distributions. The Mass Function (MF), and similarly the Luminosity Function (LF), of star-forming regions can be approximated as a power-law and is characterized by the power-law slope. A consistent slope of -2 has been observed across numerous galaxies, however, systematic deviations from this canonical slope have been measured across different environments. We present the LF slopes for 258 nearby galaxies in the Local Volume Legacy (LVL) sample utilizing tens of thousands of Hα- and FUV-selected sources. We test any relationships between LF slope and global galaxy properties to quantify the effect of environment on the star formation process. In addition, we combine the entire star-forming region sample in an attempt to characterize a previously proposed break in the HII region LF power-law at L˜38.6 erg/s.

  5. The galaxy luminosity-size relation and selection biases in the Hubble Ultra Deep Field

    NASA Astrophysics Data System (ADS)

    Cameron, E.; Driver, S. P.

    2007-05-01

    We use the Hubble Ultra Deep Field to study the galaxy luminosity-size (M-Re) distribution. With a careful analysis of selection effects due to both detection completeness and measurement reliability, we identify bias-free regions in the M-Re plane for a series of volume-limited samples. By comparison to a nearby survey also having well-defined selection limits, namely the Millennium Galaxy Catalogue, we present clear evidence for evolution in surface brightness since z ~ 0.7. Specifically, we demonstrate that the mean, rest-frame B-band <μ>e for galaxies in a sample spanning 8 mag in luminosity between MB = -22 and -14 mag increases by ~1.0 mag arcsec-2 from z ~ 0.1 to 0.7. We also highlight the importance of considering surface brightness-dependent measurement biases in addition to incompleteness biases. In particular, the increasing, systematic underestimation of Kron fluxes towards low surface brightnesses may cause diffuse, yet luminous, systems to be mistaken for faint, compact objects.

  6. COSMOLOGICAL DEPENDENCE OF THE MEASUREMENTS OF LUMINOSITY FUNCTION, PROJECTED CLUSTERING AND GALAXY-GALAXY LENSING SIGNAL

    SciTech Connect

    More, Surhud

    2013-11-10

    Observables such as the galaxy luminosity function, Φ(M), projected galaxy clustering, w {sub p}(r {sub p}), and the galaxy-galaxy lensing signal, ΔΣ(r {sub p}), are often measured from galaxy redshift surveys assuming a fiducial cosmological model for calculating distances to, and between galaxies. There are a growing number of studies that perform joint analyses of these measurements and constrain cosmological parameters. We quantify the amount by which such measurements systematically vary as the fiducial cosmology used for the measurements is changed, and show that these effects can be significant at high redshifts (z ∼ 0.5). Cosmological analyses (or halo occupation distribution analyses) that use the luminosity function, clustering and the galaxy-galaxy lensing signal but ignore such systematic effects may bias the inference of the parameters. We present a simple way to account for the differences in the cosmological model used for the measurements and those used for the prediction of observables, thus allowing a fair comparison between models and data.

  7. Angular Diameters, Temperatures, And Luminosities Of Massive Stars: Prospects For Sim-lite

    NASA Astrophysics Data System (ADS)

    Richardson, Noel; Gies, D.; Ridgway, S.; Boyajian, T.; Aufdenberg, J. P.; Ireland, M.; Schaefer, G.; CHARA

    2009-05-01

    O and B stars are among the brightest stars observable in galaxies, and are often considered signs of recent star formation or used for distance estimates. However, the fundamental properties of these stars (temperature and luminosity) are poorly understood because we do not have accurate distances and diameters of nearby O and B stars. SIM Lite will be able to provide parallaxes for these bright stars accurate to 1% at a distance of 2.6 kpc. Long Baseline Optical Interferometry, from instruments such as CHARA/PAVO, can yield temperatures and luminosities accurate to 5% for these stars once the distance is known from SIM. Here we present an initial observing list for the CHARA array and the PAVO (R band) beam combiner, as well as spectral energy distributions for the sample. These SEDs will provide a direct comparison for angular diameter measurements of hot stars that will be measured with the CHARA array in the next year. This project is supported by NASA-JPL#1349293

  8. Population declines lead to replicate patterns of internal range structure at the tips of the distribution of the California red-legged frog (Rana draytonii)

    USGS Publications Warehouse

    Richmond, Jonathan Q.; Backlin, Adam R.; Tatarian, Patricia J.; Solvesky, Ben G.; Fisher, Robert N.

    2014-01-01

    Demographic declines and increased isolation of peripheral populations of the threatened California red-legged frog (Rana draytonii) have led to the formation of internal range boundaries at opposite ends of the species’ distribution. While the population genetics of the southern internal boundary has been studied in some detail, similar information is lacking for the northern part of the range. In this study, we used microsatellite and mtDNA data to examine the genetic structuring and diversity of some of the last remaining R. draytonii populations in the northern Sierra Nevada, which collectively form the northern external range boundary. We compared these data to coastal populations in the San Francisco Bay Area, where the species is notably more abundant and still exists throughout much of its historic range. We show that ‘external’ Sierra Nevada populations have lower genetic diversity and are more differentiated from one another than their ‘internal’ Bay Area counterparts. This same pattern was mirrored across the distribution in California, where Sierra Nevada and Bay Area populations had lower allelic variability compared to those previously studied in coastal southern California. This genetic signature of northward range expansion was mirrored in the phylogeography of mtDNA haplotypes; northern Sierra Nevada haplotypes showed greater similarity to haplotypes from the south Coast Ranges than to the more geographically proximate populations in the Bay Area. These data cast new light on the geographic origins of Sierra Nevada R. draytonii populations and highlight the importance of distinguishing the genetic effects of contemporary demographic declines from underlying signatures of historic range expansion when addressing the most immediate threats to population persistence. Because there is no evidence of contemporary gene flow between any of the Sierra Nevada R. draytonii populations, we suggest that management activities should focus on

  9. A MULTIVARIATE FIT LUMINOSITY FUNCTION AND WORLD MODEL FOR LONG GAMMA-RAY BURSTS

    SciTech Connect

    Shahmoradi, Amir

    2013-04-01

    It is proposed that the luminosity function, the rest-frame spectral correlations, and distributions of cosmological long-duration (Type-II) gamma-ray bursts (LGRBs) may be very well described as a multivariate log-normal distribution. This result is based on careful selection, analysis, and modeling of LGRBs' temporal and spectral variables in the largest catalog of GRBs available to date: 2130 BATSE GRBs, while taking into account the detection threshold and possible selection effects. Constraints on the joint rest-frame distribution of the isotropic peak luminosity (L{sub iso}), total isotropic emission (E{sub iso}), the time-integrated spectral peak energy (E{sub p,z}), and duration (T{sub 90,z}) of LGRBs are derived. The presented analysis provides evidence for a relatively large fraction of LGRBs that have been missed by the BATSE detector with E{sub iso} extending down to {approx}10{sup 49} erg and observed spectral peak energies (E{sub p} ) as low as {approx}5 keV. LGRBs with rest-frame duration T{sub 90,z} {approx}< 1 s or observer-frame duration T{sub 90} {approx}< 2 s appear to be rare events ({approx}< 0.1% chance of occurrence). The model predicts a fairly strong but highly significant correlation ({rho} = 0.58 {+-} 0.04) between E{sub iso} and E{sub p,z} of LGRBs. Also predicted are strong correlations of L{sub iso} and E{sub iso} with T{sub 90,z} and moderate correlation between L{sub iso} and E{sub p,z}. The strength and significance of the correlations found encourage the search for underlying mechanisms, though undermine their capabilities as probes of dark energy's equation of state at high redshifts. The presented analysis favors-but does not necessitate-a cosmic rate for BATSE LGRBs tracing metallicity evolution consistent with a cutoff Z/Z{sub Sun} {approx} 0.2-0.5, assuming no luminosity-redshift evolution.

  10. Schlieren photographs and internal pressure distributions for three-dimensional sidewall-compression scramjet inlets at a Mach number of 6 in CF4

    NASA Technical Reports Server (NTRS)

    Holland, Scott D.

    1993-01-01

    Three-dimensional sidewall-compression scramjet inlets with leading-edge sweeps of 30 deg and 70 deg were tested in the Langley Hypersonic CF4 Tunnel at a Mach number of 6 and a free-stream ratio of specific heats of 1.2. The parametric effects of leading-edge sweep, cowl position, contraction ratio, and Reynolds number were investigated. The models were instrumented with static pressure orifices distributed on the sidewalls, baseplate, and cowl. Schlieren movies were made of selected tunnel runs for flow visualization of the entrance plane and cowl region. Although these movies could not show the internal flow, the effect of the internal flow on the external flow was evident by way of spillage. The purpose is to provide a preliminary data release for the investigation. The models, facility, and testing methods are described, and the test matrix and a tabulation of tunnel runs are provided. Line plots highlighting the stated parametric effects and a representative set of schlieren photographs are presented without analysis.

  11. Analysis of equilibrium and kinetic models of internal reforming on solid oxide fuel cell anodes: Effect on voltage, current and temperature distribution

    NASA Astrophysics Data System (ADS)

    Ahmed, Khaliq; Fӧger, Karl

    2017-03-01

    The SOFC is well-established as a high-efficiency energy conversion technology with demonstrations of micro-CHP systems delivering 60% net electrical efficiency [1]. However, there are key challenges in the path to commercialization. Foremost among them is stack durability. Operating at high temperatures, the SOFC invariably suffers from thermally induced material degradation. This is compounded by thermal stresses within the SOFC stack which are generated from a number of interacting factors. Modelling is used as a tool for predicting undesirable temperature and current density gradients. For an internal reforming SOFC, fidelity of the model is strongly linked to the representation of the fuel reforming reactions, which dictate species concentrations and net heat release. It is critical for simulation of these profiles that the set of reaction rate expressions applicable for the particular anode catalyst are chosen in the model. A relatively wide spectrum of kinetic correlations has been reported in the literature. This work presents a comparative analysis of the internal distribution of temperature, current, voltage and compositions on a SOFC anode, using various combinations of reaction kinetics and equilibrium expressions for the reactions. The results highlight the significance of the fuel reforming chemistry and kinetics in the prediction of cell performance.

  12. Discovery of a low-luminosity spiral DRAGN

    NASA Astrophysics Data System (ADS)

    Mulcahy, D. D.; Mao, M. Y.; Mitsuishi, I.; Scaife, A. M. M.; Clarke, A. O.; Babazaki, Y.; Kobayashi, H.; Suganuma, R.; Matsumoto, H.; Tawara, Y.

    2016-11-01

    Standard galaxy formation models predict that large-scale double-lobed radio sources, known as DRAGNs, will always be hosted by elliptical galaxies. In spite of this, in recent years a small number of spiral galaxies have also been found to host such sources. These so-called spiral DRAGNs are still extremely rare, with only 5 cases being widely accepted. Here we report on the serendipitous discovery of a new spiral DRAGN in data from the Giant Metrewave Radio Telescope (GMRT) at 322 MHz. The host galaxy, MCG+07-47-10, is a face-on late-type Sbc galaxy with distinctive spiral arms and prominent bulge suggesting a high black hole mass. Using WISE infra-red and GALEX UV data we show that this galaxy has a star formation rate of 0.16-0.75 M⊙ yr-1, and that the radio luminosity is dominated by star-formation. We demonstrate that this spiral DRAGN has similar environmental properties to others of this class, but has a comparatively low radio luminosity of L1.4 GHz = 1.12 × 1022 W Hz-1, two orders of magnitude smaller than other known spiral DRAGNs. We suggest that this may indicate the existence of a previously unknown low-luminosity population of spiral DRAGNS. FITS cutout image of the observed spiral DRAGN MCG+07-47- 10 is 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/595/L8

  13. Pulsar gamma-rays: Spectra luminosities and efficiencies

    NASA Technical Reports Server (NTRS)

    Harding, A. K.

    1980-01-01

    The general characteristics of pulsar gamma ray spectra are presented for a model where the gamma rays are produced by curvature radiation from energetic particles above the polar cap and attenuated by pair production. The shape of the spectrum is found to depend on pulsar period, magnetic field strength, and primary particle energy. By a comparison of numerically calculated spectra with the observed spectra of the Crab and Vela pulsars, it is determined that primary particles must be accelerated to energies of about 3 x 10 to the 7th power mc sq. A genaral formula for pulsar gamma ray luminosity is determined and is found to depend on period and field strength.

  14. IUE observations of blue halo high luminosity stars

    NASA Technical Reports Server (NTRS)

    Hack, M.; Franco, M. L.; Stalio, R.

    1981-01-01

    Two high luminosity population II blue stars of high galactic latitude, BD+33 deg 2642 and HD 137569 were observed at high resolution. The stellar spectra show the effect of mass loss in BD+33 deg 2642 and abnormally weak metallic lines in HD 137569. The interstellar lines in the direction of BD+33 deg 2642, which lies at a height z greater than or equal to 6.2 kpc from the galactic plane, are split into two components. No high ionization stages are found at the low velocity component; nor can they be detected in the higher velocity clouds because of mixing with the corresponding stellar/circumstellar lines.

  15. The bright end of the luminosity function at z ~ 9

    NASA Astrophysics Data System (ADS)

    Laporte, N.; Pelló, R.; Hayes, M.; Schaerer, D.; Boone, F.; Richard, J.; Le Borgne, J. F.; Kneib, J. P.; Combes, F.

    2012-06-01

    Context. We present additional constraints on the galaxy luminosity function at z ~ 9 based on observations carried out with ESO/VLT FORS2, HAWK-I, and X-Shooter around the lensing cluster A2667, as part of our project designed to select z ~ 7-10 candidates accessible to spectroscopy. We find that only one selected J-dropout source in this field fulfills the color and magnitude criteria. This source was recently confirmed as a mid-z interloper based on X-Shooter spectroscopy. Aims: Owing to the considerable depth and area covered by our survey, we are able to set strong constraints on the bright end of the galaxy luminosity function and hence on the star formation history at very high redshift. Methods: We used our non-detection of reliable J-dropout sources over the ~36 arcmin2 field of view towards A2667 to carefully determine the lens-corrected effective volume and the corresponding upper limit to the density of sources. Results: Our strongest limit is obtained for Φ(M1500 = -21.4 ± 0.50) < 6.70 × 10-6 Mpc-3 mag-1 at z ~ 9. A maximum-likelihood fit of the luminosity function to all available data points including the present new result yields M⋆ > -19.7 with fixed α = -1.74 and Φ⋆ = 1.10 × 10-3 Mpc-3. The corresponding star-formation rate density should be ρSFR < 5.97 × 10-3 M⊙ yr-1 Mpc3 at z ~ 9. These results are in good agreement with the most recent estimates already published for this range of redshift and luminosity domain. Conclusions: This new result confirms previously measured decreases in the density of luminous galaxies at very high redshift, hence provides strong constraints on the design of future surveys aiming to explore the very high-redshift Universe. Based on observations collected at The European Southern Observatory, Paranal, Chile, as part of the ESO 082.A-0163 and 087.A-0118.

  16. APD performance in a luminosity monitor at LEP

    NASA Astrophysics Data System (ADS)

    Bartolomé, E.; Boix, G.; Casado, M. P.; Chmeissani, M.; Clemente, S.; Fernández, E.; Garrido, L.; Lorenz, E.; Martínez, M.; Merino, G.; Riu, I.; Sánchez, F.; Wright, A.

    2000-03-01

    Avalanche Photo-Diodes (APDs) are being used as optical readout elements in a sampling electromagnetic calorimeter made of alternate layers of tungsten and plastic scintillators. The calorimeter serves as a small-angle luminosity monitor in the stray magnetic field of the ALEPH detector at LEP (CERN). Its scintillators are coupled both to APDs and conventional PMTs simultaneously via wavelength shifter fibres. In this paper we present results on the overall performance of the APDs, including gain and stability versus time and energy, based on the direct comparison of the two photosensitive devices.

  17. Mira Period-Luminosity Relations at Near-Infrared

    NASA Astrophysics Data System (ADS)

    Yuan, Wenlong; Macri, Lucas M.; He, Shiyuan; Long, James; Huang, Jianhua; Ngeow, Chow-Choong; Kanbur, Shashi

    2017-01-01

    We built JHK template light curves for ~200 Oxygen-rich Miras in LMC by scaling their I-band light curves. The I-(JHK) colors at individual epochs were derived using a Gaussian process method, and then modeled as a function of generic parameters. We obtained their JHK Period-Luminosity relations (PLRs) at maximum light and mean light with dispersions comparable to Cepheid PLRs. We also derived Mira PLRs in M33 and obtained a Mira distance to this system. We present the method for template development and preliminary results.

  18. Luminosities and mass-loss rates of SMC and LMC AGB stars and red supergiants

    NASA Astrophysics Data System (ADS)

    Groenewegen, M. A. T.; Sloan, G. C.; Soszyński, I.; Petersen, E. A.

    2009-11-01

    Context: Mass loss is one of the fundamental properties of Asymptotic Giant Branch (AGB) stars, and through the enrichment of the interstellar medium, AGB stars are key players in the life cycle of dust and gas in the universe. However, a quantitative understanding of the mass-loss process is still largely lacking, particularly its dependence on metallicity. Aims: To investigate the relation between mass loss, luminosity and pulsation period for a large sample of evolved stars in the Small and Large Magellanic Cloud. Methods: Dust radiative transfer models are presented for 101 carbon stars and 86 oxygen-rich evolved stars in the Magellanic Clouds for which 5-35 μm Spitzer IRS spectra are available. The spectra are complemented with available optical and infrared photometry to construct the spectral energy distribution. A minimisation procedure is used to fit luminosity, mass-loss rate and dust temperature at the inner radius. Different effective temperatures and dust content are also considered. Periods from the literature and from new OGLE-III data are compiled and derived. Results: We derive (dust) mass-loss rates and luminosities for the entire sample. Based on luminosities, periods and amplitudes and colours, the O-rich stars are classified as foreground objects, AGB stars and Red Super Giants. For the O-rich stars silicates based on laboratory optical constants are compared to “astronomical silicates”. Overall, the grain type by Volk & Kwok (1988, ApJ, 331, 435) fits the data best. However, the fit based on laboratory optical constants for the grains can be improved by abandoning the small-particle limit. The influence of grain size, core-mantle grains and porosity are explored. A computationally convenient method that seems to describe the observed properties in the 10 μm window are a distribution of hollow spheres with a large vacuum fraction (typically 70%), and grain size of about 1 μm. Relations between mass-loss rates and luminosity and pulsation

  19. Cross-correlation of SDSS DR7 Quasars and DR10 BOSS Galaxies: The Weak Luminosity Dependence of Quasar Clustering at z ~ 0.5

    NASA Astrophysics Data System (ADS)

    Shen, Yue; McBride, Cameron K.; White, Martin; Zheng, Zheng; Myers, Adam D.; Guo, Hong; Kirkpatrick, Jessica A.; Padmanabhan, Nikhil; Parejko, John K.; Ross, Nicholas P.; Schlegel, David J.; Schneider, Donald P.; Streblyanska, Alina; Swanson, Molly E. C.; Zehavi, Idit; Pan, Kaike; Bizyaev, Dmitry; Brewington, Howard; Ebelke, Garrett; Malanushenko, Viktor; Malanushenko, Elena; Oravetz, Daniel; Simmons, Audrey; Snedden, Stephanie

    2013-12-01

    We present the measurement of the two-point cross-correlation function (CCF) of 8198 Sloan Digital Sky Survey Data Release 7 quasars and 349,608 Data Release 10 CMASS galaxies from the Baryonic Oscillation Spectroscopic Survey at 0.3 < z < 0.9. The CCF can be reasonably well fit by a power-law model ξQG(r) = (r/r 0)-γ on projected scales of rp = 2-25 h -1 Mpc with r 0 = 6.61 ± 0.25 h -1 Mpc and γ = 1.69 ± 0.07. We estimate a quasar linear bias of bQ = 1.38 ± 0.10 at langzrang = 0.53 from the CCF measurements, which corresponds to a characteristic host halo mass of ~4 × 1012 h -1 M ⊙, compared with a ~1013 h -1 M ⊙ characteristic host halo mass for CMASS galaxies. Based on the clustering measurements, most quasars at \\bar{z}\\sim 0.5 are not the descendants of their higher luminosity counterparts at higher redshift, which would have evolved into more massive and more biased systems at low redshift. We divide the quasar sample in luminosity and constrain the luminosity dependence of quasar bias to be dbQ /dlog L = 0.20 ± 0.34 or 0.11 ± 0.32 (depending on different luminosity divisions) for quasar luminosities -23.5 > Mi (z = 2) > -25.5, implying a weak luminosity dependence of clustering for luminous quasars at \\bar{z}\\sim 0.5. We compare our measurements with theoretical predictions, halo occupation distribution (HOD) models, and mock catalogs. These comparisons suggest that quasars reside in a broad range of host halos. The host halo mass distributions significantly overlap with each other for quasars at different luminosities, implying a poor correlation between halo mass and instantaneous quasar luminosity. We also find that the quasar HOD parameterization is largely degenerate such that different HODs can reproduce the CCF equally well, but with different satellite fractions and host halo mass distributions. These results highlight the limitations and ambiguities in modeling the distribution of quasars with the standard HOD approach.

  20. Cross-correlation of SDSS DR7 quasars and DR10 BOSS galaxies: The weak luminosity dependence of quasar clustering at z ∼ 0.5

    SciTech Connect

    Shen, Yue; McBride, Cameron K.; Swanson, Molly E. C.; White, Martin; Kirkpatrick, Jessica A.; Ross, Nicholas P.; Schlegel, David J.; Zheng, Zheng; Myers, Adam D.; Guo, Hong; Zehavi, Idit; Padmanabhan, Nikhil; Parejko, John K.; Schneider, Donald P.; Streblyanska, Alina; Pan, Kaike; Bizyaev, Dmitry; Brewington, Howard; Ebelke, Garrett; Malanushenko, Viktor; and others

    2013-12-01

    We present the measurement of the two-point cross-correlation function (CCF) of 8198 Sloan Digital Sky Survey Data Release 7 quasars and 349,608 Data Release 10 CMASS galaxies from the Baryonic Oscillation Spectroscopic Survey at 0.3 < z < 0.9. The CCF can be reasonably well fit by a power-law model ξ{sub QG}(r) = (r/r {sub 0}){sup –γ} on projected scales of r{sub p} = 2-25 h {sup –1} Mpc with r {sub 0} = 6.61 ± 0.25 h {sup –1} Mpc and γ = 1.69 ± 0.07. We estimate a quasar linear bias of b{sub Q} = 1.38 ± 0.10 at (z) = 0.53 from the CCF measurements, which corresponds to a characteristic host halo mass of ∼4 × 10{sup 12} h {sup –1} M {sub ☉}, compared with a ∼10{sup 13} h {sup –1} M {sub ☉} characteristic host halo mass for CMASS galaxies. Based on the clustering measurements, most quasars at z-bar ∼0.5 are not the descendants of their higher luminosity counterparts at higher redshift, which would have evolved into more massive and more biased systems at low redshift. We divide the quasar sample in luminosity and constrain the luminosity dependence of quasar bias to be db{sub Q} /dlog L = 0.20 ± 0.34 or 0.11 ± 0.32 (depending on different luminosity divisions) for quasar luminosities –23.5 > M{sub i} (z = 2) > –25.5, implying a weak luminosity dependence of clustering for luminous quasars at z-bar ∼0.5. We compare our measurements with theoretical predictions, halo occupation distribution (HOD) models, and mock catalogs. These comparisons suggest that quasars reside in a broad range of host halos. The host halo mass distributions significantly overlap with each other for quasars at different luminosities, implying a poor correlation between halo mass and instantaneous quasar luminosity. We also find that the quasar HOD parameterization is largely degenerate such that different HODs can reproduce the CCF equally well, but with different satellite fractions and host halo mass distributions. These results highlight the limitations

  1. The Radio and IR Luminosity Function of compact Galactic HII regions

    NASA Astrophysics Data System (ADS)

    Paladini, R.; De Zotti, G.; Noriega-Crespo, A.; Carey, S. J.

    2009-01-01

    We present the radio luminosity function (LF) of compact Galactic HII regions, derived by using ˜ 200 sources from the recombination line survey by Caswell & Haynes (1987). The data set is complete for Speak > 1.3 Jy at 5 GHz, corresponding to an integrated flux density of ˜ 3 Jy. The LF is reconstructed by means of a generalized Schmidt's estimator which takes into account the actual spatial distribution of the HII regions along the plane of the Galaxy. The resulting LF is described by a two-component power-law, with a cut-off at log L(α) = ˜ 38.3 erg/sec. This work will be complemented with the derivation, by means of the MIPSGAL data set, of the IR counterpart of the radio LF here presented. An extension of this work will consist in deriving the IR counterpart of the radio LF here obtained, by making use of the MIPSGAL data set.

  2. Characterizing the redshifts and luminosities of WISE selected obscured AGN using SALT optical spectra.

    NASA Astrophysics Data System (ADS)

    Hviding, Raphael E.; Hickox, Ryan C.; Hainline, Kevin N.; Carroll, Christopher M.; DiPompeo, Mike A.; Jones, Mackenzie L.

    2016-08-01

    We present the results of several optical spectroscopic surveys covering over 100 candidate luminous obscured active galactic nuclei (AGN) identified by their mid-infrared emission detected with the Wide-Field Infrared Survey Explorer (WISE). These galaxies were selected based on red WISE colors and galaxy-like optical emission, and were studied using long-slit optical spectroscopy with the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT). Our spectra were analyzed to obtain redshifts and emission line flux ratios for each galaxy. These results verify that WISE is an effective section method for luminous obscured AGN, allow for the characterization of redshifts and luminosities of the WISE color selected obscured AGN population, and could potentially contribute to large statistical studies of obscured AGN distributions in the future.

  3. Models of stellar population at high redshift, as constrainedby PN yields and luminosity function

    NASA Astrophysics Data System (ADS)

    Maraston, C.

    The stellar phase of Thermally-Pulsating Asymptotic giant branch is the last major evolutionary stage of intermediate-mass stars which afterwards evolve into planetary nebulae. The TP-AGB phase is affected by mass-loss and instabilities which notoriously make its theoretical modelling uncertain. This review focuses on the effects such modelling has on stellar population models for galaxies, with particular focus on the high-z Universe where galaxies are young and contain a large number of short-living TP-AGB stars. I shall present the models, discuss how different prescriptions for the treatment of the TP-AGB affect the theoretical integrated spectral energy distribution and how these compare to galaxy data, and discuss implications for the PN nebulae luminosity function stemming from the various assumptions. Finally I shall discuss the inclusion of hot evolved stars on stellar population models and how they compare to data for old galaxies at our present time.

  4. A high-redshift IRAS galaxy with huge luminosity - Hidden quasar or protogalaxy?

    NASA Technical Reports Server (NTRS)

    Rowan-Robinson, M.; Broadhurst, T.; Oliver, S. J.; Taylor, A. N.; Lawrence, A.; Mcmahon, R. G.; Lonsdale, C. J.; Hacking, P. B.; Conrow, T.

    1991-01-01

    An emission line galaxy with the enormous far-IR luminosity of 3 x 10 to the 14th solar has been found at z = 2.286. The spectrum is very unusual, showing lines of high excitation but with very weak Lyman-alpha emission. A self-absorbed synchrotron model for the IR energy distribution cannot be ruled out, but a thermal origin seems more plausible. A radio-quiet quasar embedded in a very dusty galaxy could account for the IR emission, as might a starburst embedded in 1-10 billion solar masses of dust. The latter case demands so much dust that the object would probably be a massive galaxy in the process of formation. The presence of a large amount of dust in an object of such high redshift implies the generation of heavy elements at an early cosmological epoch.

  5. A Statistical Method for Estimating Luminosity Functions Using Truncated Data

    NASA Astrophysics Data System (ADS)

    Schafer, Chad M.

    2007-06-01

    The observational limitations of astronomical surveys lead to significant statistical inference challenges. One such challenge is the estimation of luminosity functions given redshift (z) and absolute magnitude (M) measurements from an irregularly truncated sample of objects. This is a bivariate density estimation problem; we develop here a statistically rigorous method which (1) does not assume a strict parametric form for the bivariate density; (2) does not assume independence between redshift and absolute magnitude (and hence allows evolution of the luminosity function with redshift); (3) does not require dividing the data into arbitrary bins; and (4) naturally incorporates a varying selection function. We accomplish this by decomposing the bivariate density φ(z,M) vialogφ(z,M)=f(z)+g(M)+h(z,M,θ), where f and g are estimated nonparametrically and h takes an assumed parametric form. There is a simple way of estimating the integrated mean squared error of the estimator; smoothing parameters are selected to minimize this quantity. Results are presented from the analysis of a sample of quasars.

  6. Spectral-luminosity relation within individual Fermi gamma rays bursts

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Nava, L.; Ghisellini, G.

    2010-02-01

    We study the spectra of all long gamma ray bursts (GRBs) of known redshift detected by the Fermi satellite untill the end of July 2009. Their fluxes and fluences are large enough to allow a time dependent study of their spectral characteristics in the 8 keV-1 MeV energy range. We find that the peak energy Epeak of their EL(E) spectrum correlates with the luminosity in a remarkably tight way within individual bursts. This time-resolved Epeak - Liso correlation is very similar for all the considered bursts and has a slope and normalisation similar to the analogous Epeak - Liso correlation defined by the time-integrated spectra of different bursts detected by several different satellites. For a few of the considered GRBs, we could also study the behaviour of the Epeak - Liso correlation during the rising and decaying phases of individual pulses within each burst, finding no differences. Our results indicate the presence of a similar physical mechanism, operating for the duration of different GRBs, tightly linking the burst luminosity with the peak energy of the spectrum emitted at different times. Such a physical mechanism is the same during the rise and decay phase of individual pulses composing a GRB. While calling for a robust physical interpretation, these results strongly indicate that the Epeak - Liso spectral energy correlation found considering the time-integrated spectra of different bursts is real and not the result of instrumental selection effects.

  7. Metallicity effects on synthetic Cepheid Period-Luminosity relations

    NASA Astrophysics Data System (ADS)

    Musella, I.

    On the basis of new theoretical results (Bono, Marconi & Stellingwerf, 1998, hereafter BMS; Bono, Caputo, Castellani & Marconi, 1998, hereafter BCCM) useful predictions concerning the Period-Luminosity (PLR) and Period-Luminosity-Color (PLCR) relations both for optical and infrared magnitudes are presented. It is shown that, following the dependence of the instability strip on metallicity, there is a non negligible dependence of the PLRs and PLCRs on the metallicity of the pulsating stars, mainly for optical bands. In particular theoretical results predict a dependence of the PLR on metals which is reversed with respect to current empirical evaluations (see for instance Gould 1994, Sasselov et al. 1997, Kennicutt et al. 1998, hereafter K98). To give a possible explanation for this discrepancy the typical observational procedures used to estimate extragalactic distances through Cepheid PLRs are here tested, with the aim of disentangling, if possible, the reddening and metallicity effects. To this purpose, synthetic PLRs for different metallicities were produced and treated as typical observational samples.

  8. Low extreme-ultraviolet luminosities impinging on protoplanetary disks

    SciTech Connect

    Pascucci, I.; Hendler, N. P.; Ricci, L.; Gorti, U.; Hollenbach, D.; Brooks, K. J.; Contreras, Y.

    2014-11-01

    The amount of high-energy stellar radiation reaching the surface of protoplanetary disks is essential to determine their chemistry and physical evolution. Here, we use millimetric and centimetric radio data to constrain the extreme-ultraviolet (EUV) luminosity impinging on 14 disks around young (∼2-10 Myr) sun-like stars. For each object we identify the long-wavelength emission in excess to the dust thermal emission, attribute that to free-free disk emission, and thereby compute an upper limit to the EUV reaching the disk. We find upper limits lower than 10{sup 42} photons s{sup –1} for all sources without jets and lower than 5 × 10{sup 40} photons s{sup –1} for the three older sources in our sample. These latter values are low for EUV-driven photoevaporation alone to clear out protoplanetary material in the timescale inferred by observations. In addition, our EUV upper limits are too low to reproduce the [Ne II] 12.81 μm luminosities from three disks with slow [Ne II]-detected winds. This indicates that the [Ne II] line in these sources primarily traces a mostly neutral wind where Ne is ionized by 1 keV X-ray photons, implying higher photoevaporative mass loss rates than those predicted by EUV-driven models alone. In summary, our results suggest that high-energy stellar photons other than EUV may dominate the dispersal of protoplanetary disks around sun-like stars.

  9. The Discovery of Low-Luminosity BL Lacs

    NASA Astrophysics Data System (ADS)

    Rector, Travis A.; Stocke, John T.

    1995-12-01

    Many of the properties of BL Lacs have become explicable in terms of the ``relativistic beaming'' hypothesis whereby BL Lacs are ``highly beamed'' FR-I radio galaxies (i.e. our line of sight to these objects is nearly along the jet axis). Further, radio-selected BL Lacs (RBLs) are believed to be seen nearly ``on-axis'' (the line-of-sight angle theta ~ 8deg ) while X-ray selected BL Lacs (XBLs) are seen at larger angles (theta ~ 30deg ; the X-ray emitting jet is believed to be less collimated). However, a major problem with this model was that a transition population between beamed BL Lacs and unbeamed FR-Is had not been detected. Low-luminosity BL Lacs may be such a transition population, and were predicted to exist by Browne and Marcha (1993). We present ROSAT HRI images, VLA radio maps and optical spectra which confirm the existence of low-luminosity BL Lacs, objects which were previously mis-identified in the EMSS catalog as clusters of galaxies. Thus our results strengthen the relativistic beaming hypothesis.

  10. High luminosity electron-hadron collider eRHIC

    SciTech Connect

    Ptitsyn, V.; Aschenauer, E.; Bai, M.; Beebe-Wang, J.; Belomestnykh, S.; Ben-Zvi, I.; Blaskiewicz, M..; Calaga, R.; Chang, X.; Fedotov, A.; Gassner, D.; Hammons, L.; Hahn, H.; Hammons, L.; He, P.; Hao, Y.; Jackson, W.; Jain, A.; Johnson, E.C.; Kayran, D.; Kewisch, J.; Litvinenko, V.N.; Luo, Y.; Mahler, G.; McIntyre, G.; Meng, W.; Minty, M.; Parker, B.; Pikin, A.; Rao, T.; Roser, T.; Skaritka, J.; Sheehy, B.; Skaritka, J.; Tepikian, S.; Than, Y.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.; Wang, G.; Webb, S.; Wu, Q.; Xu, W.; Pozdeyev, E.; Tsentalovich, E.

    2011-03-28

    We present the design of a future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan on adding 20 (potentially 30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 10{sup 34} cm{sup -2} s{sup -1} can be achieved in eRHIC using the low-beta interaction region with a 10 mrad crab crossing. We report on the progress of important eRHIC R&D such as the high-current polarized electron source, the coherent electron cooling, ERL test facility and the compact magnets for recirculation passes. A natural staging scenario of step-by-step increases of the electron beam energy by building-up of eRHIC's SRF linacs is presented.

  11. A PAH Deficit in Extremely Low Luminosity Galaxies

    NASA Astrophysics Data System (ADS)

    Wu, Rongying; Hogg, D. W.

    2006-12-01

    We present a study of 29 extremely low luminosity galaxies randomly selected from the footprint of the Sloan Digital Sky Survey (SDSS). The galaxies comprise a statistically complete sample of galaxies with Mr > -15 and recession velocity v < 2000 km s^-1 as measured in SDSS Data Release 2 (DR2). We also observe these sample galaxies in all four channels with the Spitzer Infrared Array Camera (IRAC). The photometry in SDSS shows that these galaxies appear to be visually blue (g-r < 0.6), and the IRAC color analysis shows that they are blue in IRAC infrared color [3.6]-[8]. The IRAC [3.6] magnitude measures the starlight, and the [8] measures PAH emissions. We find that these star-forming galaxies show very low PAH to star ratios. This result agrees with earlier observations on other dwarf galaxies including SBS0335-052 and small samples from ISO and the overlap of the SDSS with the Spitzer First Look Survey, but it is worth emphasizing that this sample has a lower mean luminosity than those samples. The PAH deficiency of these galaxies is discussed in the context of their metallicity and dust properties.

  12. The low-luminosity galaxy population in the NGC5044 Group

    NASA Astrophysics Data System (ADS)

    Cellone, Sergio A.; Buzzoni, Alberto

    2005-01-01

    We present multicolour imaging for a sample of 33 dwarf and intermediate-luminosity galaxies in the field of the NGC5044 Group, complemented with mid-resolution spectroscopy for a subsample of 13 objects. With these data, a revised membership and morphological classification is made for the galaxies in the sample. We were able to confirm all but one of the `definite members' included in the spectroscopic subsample, galaxies which were originally classified based on morphological criteria. An important fraction of background galaxies, however, is probably present among `likely' and `possible' members. The presence of a nucleus could be detected in just five out of the nine galaxies originally classified as dE,N, confirming the intrinsic difficulty of photographic-plate morphological classification for this kind of object. Our deep surface photometry provided clear evidence for disc structure in at least three galaxies previously catalogued as dE or dS0. Their transition-type properties are also evident from the colour-magnitude diagram, where they lie near the late-type galaxy locus, suggesting an evolutionary connection between a parent disc-galaxy population and at least some present-day dEs. Six new dSph candidates were also found, most of them at small projected distances from NGC5044, the central galaxy of the group. The NGC5044 Group appears clearly defined in redshift space, with a mean heliocentric radial velocity of = 2461 +/- 84km s-1 (z= 0.0082), and a moderate dispersion of σvr= 431 km s-1. Our kinematical data show no luminosity segregation for early-type galaxies: both dwarf and bright E/S0 systems show very similar velocity distributions (σvr~ 290 km s-1). This is in contrast to late-type galaxies, which seem to display a broader distribution (σvr~ 680 km s-1).

  13. THE MID-INFRARED LUMINOSITY FUNCTION AT z < 0.3 FROM 5MUSES: UNDERSTANDING THE STAR FORMATION/ACTIVE GALACTIC NUCLEUS BALANCE FROM A SPECTROSCOPIC VIEW

    SciTech Connect

    Wu Yanling; Shi Yong; Helou, George; Armus, Lee; Stierwalt, Sabrina; Dale, Daniel A.; Papovich, Casey; Rahman, Nurur; Dasyra, Kalliopi E-mail: yong@ipac.caltech.edu E-mail: lee@ipac.caltech.edu E-mail: ddale@uwyo.edu E-mail: nurur@astro.umd.edu

    2011-06-10

    We present rest-frame 15 and 24 {mu}m luminosity functions (LFs) and the corresponding star-forming LFs at z < 0.3 derived from the 5MUSES sample. Spectroscopic redshifts have been obtained for {approx}98% of the objects and the median redshift is {approx}0.12. The 5-35 {mu}m Infrared Spectrograph spectra allow us to estimate accurately the luminosities and build the LFs. Using a combination of starburst and quasar templates, we quantify the star formation (SF) and active galactic nucleus (AGN) contributions in the mid-IR spectral energy distribution. We then compute the SF LFs at 15 and 24 {mu}m, and compare with the total 15 and 24 {mu}m LFs. When we remove the contribution of AGNs, the bright end of the LF exhibits a strong decline, consistent with the exponential cutoff of a Schechter function. Integrating the differential LF, we find that the fractional contribution by SF to the energy density is 58% at 15 {mu}m and 78% at 24 {mu}m, while it goes up to {approx}86% when we extrapolate our mid-IR results to the total IR luminosity density. We confirm that the AGNs play more important roles energetically at high luminosities. Finally, we compare our results with work at z {approx} 0.7 and confirm that evolution on both luminosity and density is required to explain the difference in the LFs at different redshifts.

  14. The metallicity dependence of the long-duration gamma-ray burst rate from host galaxy luminosities

    NASA Astrophysics Data System (ADS)

    Wolf, Christian; Podsiadlowski, Philipp

    2007-03-01

    We investigate the difference between the host galaxy properties of core-collapse supernovae (CC SNe) and long-duration gamma-ray bursts (LGRBs), and quantify a possible metallicity dependence of the efficiency of producing LGRBs. We use a sample of 16 CC SNe and 16 LGRBs from Fruchter et al. which have similar redshift distributions to eliminate galaxy evolution biases. We make a forward prediction of their host galaxy luminosity distributions from the overall cosmic metallicity distribution of star formation. The latter is based on luminosity functions, star formation rates (SFRs) and luminosity-metallicity (L-Z) relations of galaxies. This approach is supported by the finding that LGRB hosts follow the L-Z relations of star-forming galaxies. We then compare predictions for metallicity-dependent event efficiencies with the observed host data. We find that ultraviolet-based SFR estimates predict the host distribution of CC SNe perfectly well in a metallicity-independent form. In contrast, LGRB hosts are on average fainter by one magnitude, almost as faint as the Large Magellanic Cloud. Assuming this to be a metallicity effect, the present data are insufficient to discriminate between a sharp cut-off and a soft decrease in efficiency towards higher metallicity. For a sharp cut-off, however, we find a best value for the cut-off metallicity, as reflected in the oxygen abundance, 12 + log(O/H)lim ~= 8.7 +/- 0.3 at 95 per cent confidence including systematic uncertainties, in the calibration of Asplund, Grevesse & Sauval. This value is somewhat lower than the traditionally quoted value for the Sun, but is comparable to the revised solar oxygen abundance. LGRB models that require sharp metallicity cut-offs well below approximately one-half the revised solar metallicity appear to be effectively ruled out, as they would require fainter LGRB hosts than those that are observed. We also discuss the likely implications of the still ongoing metallicity `calibration debate'.

  15. Variations of the core luminosity and solar neutrino fluxes

    NASA Astrophysics Data System (ADS)

    Grandpierre, Attila

    The aim of the present work is to analyze the geological and astrophysical data as well as presenting theoretical considerations indicating the presence of dynamic processes present in the solar core. The dynamic solar model (DSM) is suggested to take into account the presence of cyclic variations in the temperature of the solar core. Comparing the results of calculations of the CO2 content, albedo and solar evolutionary luminosity changes with the empirically determined global earthly temperatures, and taking into account climatic models, I determined the relation between the earthly temperature and solar luminosity. These results indicate to the observed maximum of 10o change on the global terrestrial surface temperature a related solar luminosity change around 4-5 % on a ten million years timescale, which is the timescale of heat diffusion from the solar core to the surface. The related solar core temperature changes are around 1 % only. At the same time, the cyclic luminosity changes of the solar core are shielded effectively by the outer zones since the radiation diffusion takes more than 105 years to reach the solar surface. The measurements of the solar neutrino fluxes with Kamiokande 1987-1995 showed variations higher than 40 % around the average, at the Super-Kamiokande the size of the apparent scatter decreased to 13 %. This latter scatter, if would be related completely to stochastic variations of the central temperature, would indicate a smaller than 1 % change. Fourier and wavelet analysis of the solar neutrino fluxes indicate only a marginally significant period around 200 days (Haubold, 1998). Helioseismic measurements are known to be very constraining. Actually, Castellani et al. (1999) remarked that the different solar models lead to slightly different sound speeds, and the different methods of regularization yield slightly different sound speeds, too. Therefore, they doubled the found parameter variations, and were really conservative assuming

  16. Population distribution and internal migration.

    PubMed

    1994-07-01

    In China, population density is about 3 times higher than the world average. Currently, 94% of the population inhabit the developed eastern and southeastern parts of the country, which account for only 46% of China's territory. In contrast, the western and northwestern parts of China contain only 6% of the total population. From 1949 to 1990, the urban population grew from almost 57.7 million to 301.9 million. The strategy of urbanization is to strictly limit the size of large cities and to develop medium-sized and small cities in line with the level of economic development. From 1980 to 1990 the number of cities increased from 223 to 461 and the number of towns from 2874 to 55,000. The overwhelming majority of China's population still live in the countryside. According to the 1990 national population census, during the period from July 1, 1985, to July 1, 1990, the total number of migrants in China reached 34.13 million, of whom 18.83 million were male and 15.30 million were female. There were 23.02 million intra-provincial migrants and 11.07 million inter-provincial migrants. Among the causes of migration: 1) 14.67 million people migrated for job transfers, business, and recruitment, 2) 11.68 million migrated to live with relatives and for marriage, 3) 4.14 million migrated to study and for training. In addition, 3.64 million migrated because of retirement or for other reasons. The number of migrants nationwide topped 100 million in 1992, which is attributed to the large rural surplus labor force flowing into urban areas. Moreover, imbalanced regional economic development and the booming tourist industry have also added to population mobility. More than 40 million rural migrants are outside their official place of residence. The large size of the migrant population has brought about serious problems in increased city traffic and public security. The government is committed to controlling the surplus rural laborers by enabling this segment to migrate to those places where there are jobs.

  17. Seven rules of international distribution.

    PubMed

    Arnold, D

    2000-01-01

    A multinational entering a new market in a developing country knows that on its own, it cannot master local business practices, meet regulatory requirements, hire and manage local personnel, and gain access to potential customers. So it partners with a local distributor. At first, sales take off, revenues grow, and the entry seems like a smart move. But when sales plateau, the corporation begins blaming the distributor for not investing sufficiently in business growth or expanding markets, and the distributor claims that it hasn't received enough support and that the corporation's expectations are too high. The key to solving such problems lies in recognizing that the phases are predictable and can be planned for. As a new business grows in an emerging market, its marketing strategy needs to evolve, and each sequential phase requires different skills, financial investments, and management resources. The author offers seven strategies to manage the multinational-distributor partnership. He discusses what to consider when choosing a distributor, how to structure the relationship between the two partners, what resources the multinational should commit, and what can be expected in return. He states that a successful distributor must risk investing in training, information services, and advertising and promotion in order to implement the company's marketing strategy and grow the business. Paying attention at the start of a partnership can result in a better working relationship between a multinational and a distributor, along with more consistent sales and growth for the corporation.

  18. The High-Redshift Quasar Luminosity Function from Multi-Epoch Imaging Surveys

    NASA Astrophysics Data System (ADS)

    AlSayyad, Yusra

    Upcoming time-domain imaging surveys such as the LSST will detect over a million high-redshift z > 4 quasars, making complete spectroscopic followup unfeasible. Statistical estimates such as luminosity functions and clustering measurements will require purely photometric methods for classifying quasars, estimating redshifts and estimating selection functions. We validate these methods and constrain the optical, type I quasar luminosity function (QLF) at 3.75 < z < 4.5 for -27.5 < M1450 3.75) and constraint on the characteristic luminosity (M*1450 = -26.7) from a single, uniformly-selected survey at z 4. We used the Sloan Digital Sky Survey (SDSS) repeated imaging of the 275 sq. deg. equatorial region of the sky (-50 < R.A. < +60; -1.26 < Dec. < +1.26), known as Stripe 82, to select a statistical sample of z 4 quasars. We extracted 40 million lightcurves from the imaging using forced photometry on all u, g, r, i, z epochs at the positions of sources detected on a deep i-band co-add. We developed a classification method based on photometric information alone (colors and variability metrics derived from these new multi-band lightcurves), which we validated with a spectroscopically complete 55 sq. deg. sub-region augmented with 102 new spectroscopic observations of quasars at z > 3.4 with i < 22.5. We demonstrate that selection functions for ensemble classifiers can be estimated by building generative models of empirical distributions of quasars previously selected with a diverse set of selection criteria. The z 4 QLF contributes to our understanding of supermassive black hole growth and cosmic reionization of both H I and He II which likely began at z 4 as a result of hard UV emissivity from quasars. The resulting QLF measurement is consistent with the previous lower number densities reported from deep, narrow-field surveys (COSMOS); it is not consistent with higher number densities reported from the NDWFS-DLS and CANDELS GOODS-S fields. In the context of recent 2

  19. The IRIS Data Management Center: An international "network of networks", providing open, automated access to geographically distributed sensors of geophysical and environmental data.

    NASA Astrophysics Data System (ADS)

    Benson, R. B.; Ahern, T. K.; Trabant, C.

    2006-12-01

    The IRIS Data Management System has long supported international collaboration for seismology by both deploying a global network of seismometers and creating and maintaining an open and accessible archive in Seattle, WA, known as the Data Management Center (DMC). With sensors distributed on a global scale spanning more than 30 years of digital data, the DMC provides a rich repository of observations across broad time and space domains. Primary seismological data types include strong motion and broadband seismometers, conventional and superconducting gravimeters, tilt and creep meters, GPS measurements, along with other similar sensors that record accurate and calibrated ground motion. What may not be as well understood is the volume of environmental data that accompanies typical seismological data these days. This poster will review the types of time-series data that are currently being collected, how they are collected, and made freely available for download at the IRIS DMC. Environmental sensor data that is often co-located with geophysical data sensors include temperature, barometric pressure, wind direction and speed, humidity, insolation, rain gauge, and sometimes hydrological data like water current, level, temperature and depth. As the primary archival institution of the International Federation of Digital Seismograph Networks (FDSN), the IRIS DMC collects approximately 13,600 channels of real-time data from 69 different networks, from close to 1600 individual stations, currently averaging 10Tb per year in total. A major contribution to the IRIS archive currently is the EarthScope project data, a ten-year science undertaking that is collecting data from a high-resolution, multi-variate sensor network. Data types include magnetotelluric, high-sample rate seismics from a borehole drilled into the San Andreas fault (SAFOD) and various types of strain data from the Plate Boundary Observatory (PBO). In addition to the DMC, data centers located in other countries

  20. Mini Survey of SDSS [OIII] AGN with Swift: Testing the Hypothesis that L(sub [OIII]) Traces AGN Luminosity

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. Recent work strongly suggests every massive galaxy has a central black hole. However most of these objects either are not radiating or have been very difficult to detect We are now in the era of large surveys, and the luminosity function (LF] of AGN has been estimated in various ways. In the X-ray band. Chandra and XMM surveys have revealed that the LF of hard X-ray selected AGN shows a strong luminosity-dependent evolution with a dramatic break towards low L(sub x) (at all z). This is seen for all types of AGN, but is stronger for the broad-line objects. In sharp contrast, the local LF of optically-selected samples shows no such break and no differences between narrow and broad-line objects. If as been suggested, hard X ray and optical emission line can both can be fair indicators of AGN activity, it is important to first understand how reliable these characteristics are if we hope to understand the apparent discrepancy in the LFs.

  1. Discrete knot ejection from the jet in a nearby low-luminosity active galactic nucleus, M81*

    NASA Astrophysics Data System (ADS)

    King, Ashley L.; Miller, Jon M.; Bietenholz, Michael; Gültekin, Kayhan; Reynolds, Mark T.; Mioduszewski, Amy; Rupen, Michael; Bartel, Norbert

    2016-08-01

    Observational constraints of the relativistic jets from black holes have largely come from the most powerful and extended jets, leaving the nature of the low-luminosity jets a mystery. M81* is one of the nearest low-luminosity jets and it emitted an extremely large radio flare in 2011, allowing us to study compact core emission with unprecedented sensitivity and linear resolution. Using a multiwavelength campaign, we were able to track the flare as it re-brightened and became optically thick. Simultaneous X-ray observations indicated that the radio re-brightening was preceded by a low-energy X-ray flare at least 12 days earlier. Associating the time delay (tdelay) between the two bands with the cooling time in a synchrotron flare, we find that the magnetic field strength was 1.9 < B < 9.2 G, which is consistent with magnetic field estimate from spectral energy distribution modelling, B < 10.2 G. In addition, Very Long Baseline Array observations at 23 GHz clearly illustrate a discrete knot moving at a low relativistic speed of vapp/c = 0.51 +/- 0.17 associated with the initial radio flare. The observations indicate radial jet motions for the first time in M81*. This has profound implications for jet production, as it means radial motion can be observed in even the lowest-luminosity AGN, but at slower velocities and smaller radial extents (≍104 RG).

  2. Is the dependence of spectral index on luminosity real in optically selected AGN samples?

    NASA Astrophysics Data System (ADS)

    Tang, Su Min; Zhang, Shuang Nan; Hopkins, Philip F.

    2007-05-01

    We critically examine the dependence of spectral index on luminosity in optically selected AGN samples. An analysis of optically selected high-z quasars showed an anticorrelation of αOX, the spectral index between the rest-frame 2500 Å and 2 keV, with optical luminosity. We examine this relationship by means of Monte Carlo simulations and conclude that a constant αOX independent of optical luminosity is still consistent with this high-z sample. We further find that contributions of large dispersions and narrow range of optical luminosity are most important for the apparent, yet artificial, αOX-lo correlation reported. We also examine another, but more complete, low-z optical selected AGN sub-sample from Steffen et al., and our analysis shows that a constant αOX independent of optical luminosity is also consistent with the data. By comparing X-ray and optical luminosity functions, we find that a luminosity-independent αOX is in fact more preferred than the luminosity-dependent αOX model. We also discuss the selection effects caused by flux limits, which might systematically bias the lX-lo relation and cause discrepancy in optically selected and X-ray selected AGN samples. To correctly establish a dependence of αOX of AGNs on their luminosity, a larger and more complete sample is needed and consequences of luminosity dispersions and selection effects in flux-limited samples must be taken into account properly.

  3. Modern and subrecent spatial distribution and characteristics of sediment infill controlled by internal depositional dynamics, Laguna Potrok Aike (southern Patagonia, Argentina)

    NASA Astrophysics Data System (ADS)

    Kastner, S.; Ohlendorf, C.; Haberzettl, T.; Lücke, A.; Maidana, N. I.; Mayr, C.; Schäbitz, F.; Zolitschka, B.

    2009-04-01

    Situated in the dry steppe environment of south-eastern Patagonia the 100 m deep and max. 770 ka old maar lake Laguna Potrok Aike (51°58'S, 70°23'W) has a high potential as a palaeolimnological key site for the reconstruction of terrestrial palaeoclimate conditions. As this area is sensitive to variations in southern hemispheric wind and pressure systems the lake holds a unique lacustrine record of palaeoclimatic and palaeoecological variability. Depositional changes inferred from the lacustrine sediment sequence as well as subaerial and subaquatic lake level terraces provide detailed information about the water budget of the lake related to the variability of the Southern Hemispheric Westerlies. For this reason the lake was chosen as an ICDP drilling site in 2008 within the "Potrok Aike maar lake sediment archive drilling project" (PASADO). Based on high resolution multi-proxy investigations of the last 16,000 years carried out on a 18.9 m long sediment record (Haberzettl et al., 2007; Mayr et al., 2009; Wille et al., 2007) this study focuses on the understanding of internal depositional dynamics which control the characteristics and spatial distribution of the sediment infill of this lake. Furthermore, it provides information improving the accuracy of the interpretation of the long sediment record recovered within the PASADO project. A survey of the spatial sediment distribution was carried out in 2005 using 46 gravity cores of up to 49 cm length covering a range of water depths from 9 to 100 m. All 46 cores were scanned with X-ray fluorescence technique and for magnetic susceptibility with up to 1 mm spatial resolution. Using Ca and Ti as well as magnetic susceptibility data the cores were correlated and linked to the established age model (Haberzettl et al., 2005). As these parameters vary considerably and not consistently within the suite of littoral cores, a correlation prior to the 2005 sediment surface is solely based on cores from water depths exceeding

  4. The Herschel Virgo Cluster Survey. I. Luminosity function

    NASA Astrophysics Data System (ADS)

    Davies, J. I.; Baes, M.; Bendo, G. J.; Bianchi, S.; Bomans, D. J.; Boselli, A.; Clemens, M.; Corbelli, E.; Cortese, L.; Dariush, A.; De Looze, I.; di Serego Alighieri, S.; Fadda, D.; Fritz, J.; Garcia-Appadoo, D. A.; Gavazzi, G.; Giovanardi, C.; Grossi, M.; Hughes, T. M.; Hunt, L. K.; Jones, A. P.; Madden, S.; Pierini, D.; Pohlen, M.; Sabatini, S.; Smith, M. W. L.; Verstappen, J.; Vlahakis, C.; Xilouris, E. M.; Zibetti, S.

    2010-07-01

    We describe the Herschel Virgo Cluster Survey (HeViCS) and the first data obtained as part of the science demonstration phase (SDP). The data cover a central 4×4 sq deg region of the cluster. We use SPIRE and PACS photometry data to produce 100, 160, 250, 350 and 500 μm luminosity functions (LFs) for optically bright galaxies that are selected at 500 μm and detected in all bands. We compare these LFs with those previously derived using IRAS, BLAST and Herschel-ATLAS data. The Virgo cluster LFs do not have the large numbers of faint galaxies or examples of very luminous galaxies seen previously in surveys covering less dense environments. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  5. Estimates of the radii, masses, and luminosities of LAMOST stars

    NASA Astrophysics Data System (ADS)

    Sichevskij, S. G.

    2017-01-01

    Based on the spectral observations of the LAMOST (DR2) survey, the radii, masses, and luminosities of 700 481 stars were estimated. These stars belong to spectral types A, F, G, and K, and have metallicities between -0.845 and 0.0. To determine the properties of the stars, we used up-to-date models of the stellar interior structure, computed with account for the stellar evolution rate and the initial mass function. The use of evolutionary estimates for two types of stars—with and without rotation—allowed us to account for the uncertainty associated with the lack of data on the rotation velocity of the stars under consideration. The obtained stellar radii, together with the photometric estimates of interstellar extinction and angular diameters can be used to study the dependence of interstellar extinction on distance as well as to estimate the stellar distances.

  6. CMS HCAL Endcap Simulations for the High Luminosity LHC

    NASA Astrophysics Data System (ADS)

    Pedro, Kevin

    2013-04-01

    The long-term high luminosity upgrade to the LHC will increase the levels of radiation affecting the CMS calorimeters. By the end of Phase 2, parts of the electromagnetic and hadronic endcap calorimeters could receive up to 10 MRad of radiation. A model of the radiation damage to HCAL, which has been implemented in the CMS fast simulation, will be described. The effects of radiation on physics capabilities with jets will be presented, with the most important effect coming from scaling of photodetector noise due to recalibration. In addition, a standalone Geant4 simulation with a simplified geometry can be used to test configurations with new radiation-hard ECALs. Results for pion response and resolution with new configurations will be shown.

  7. On the maximum luminosity in X-ray bursts

    NASA Technical Reports Server (NTRS)

    Van Paradijs, J.

    1981-01-01

    A qualitative model is proposed which relates the burst behavior of 1608-52 observed by Murakami et al (1980) to the composition of the envelope in which the X-ray bursts occur. The model provides an explanation for the large scatter in the peak fluxes when the accretion rate is high. A flux would be transported outward at the top of the convective region which equals 1.5 to 2 times the Eddington limit appropriate to a helium-rich gas. Upon traversing the outer part of the accreted layer, which is not affected by the nuclear processes and is therefore hydrogen-rich, this flux is about a factor of 3 to 4 higher than the local value of the Eddington luminosity.

  8. 60 micron luminosity evolution of rich clusters of galaxies

    SciTech Connect

    Kelly, D.M.; Rieke, G.H. )

    1990-10-01

    The average 60-micron flux has been determined for a collection of optically selected galaxy clusters at redshifts ranging from 0.30 to 0.92. The result, 26 mJy per cluster, represents the faintest flux determination known of using the IRAS data base. The flux from this set of clusters has been compared to the 60-micron flux from a sample of nearby galaxy clusters. It is found that the far-infrared luminosity evolution in cluster galaxies can be no more than a factor of 1.7 from z = 0.4 to the present epoch. This upper limit is close to the evolution predicted for simple aging of the stellar populations. Additional processes such as mergers, cannibalism, or enhanced rates of starbursts appear to occur at a low enough level that they have little influence on the far-infrared emission from clusters over this redshift range. 38 refs.

  9. 60 micron luminosity evolution of rich clusters of galaxies

    NASA Technical Reports Server (NTRS)

    Kelly, Douglas M.; Rieke, George H.

    1990-01-01

    The average 60-micron flux has been determined for a collection of optically selected galaxy clusters at redshifts ranging from 0.30 to 0.92. The result, 26 mJy per cluster, represents the faintest flux determination known of using the IRAS data base. The flux from this set of clusters has been compared to the 60-micron flux from a sample of nearby galaxy clusters. It is found that the far-infrared luminosity evolution in cluster galaxies can be no more than a factor of 1.7 from z = 0.4 to the present epoch. This upper limit is close to the evolution predicted for simple aging of the stellar populations. Additional processes such as mergers, cannibalism, or enhanced rates of starbursts appear to occur at a low enough level that they have little influence on the far-infrared emission from clusters over this redshift range.

  10. TWO MASSIVE, LOW-LUMINOSITY CORES TOWARD INFRARED DARK CLOUDS

    SciTech Connect

    Swift, Jonathan J.

    2009-11-10

    This article presents high-resolution interferometric mosaics in the 850 mum wave band of two massive, quiescent infrared dark clouds. The two clouds were chosen based on their likelihood to represent environments preceding the formation of massive stars. The brightest compact sources detected in each cloud have masses approx110 M{sub sun} and approx60 M{sub sun} with radii <0.1 pc, implying mean densities of (n) approx 10{sup 6} cm{sup -3} and (N) approx 1 g cm{sup -2}. Supplementary data show these cores to be cold and inactive. Low upper limits to their bolometric luminosities and temperatures place them at a very early stage of evolution, while current models of massive star formation suggest they have the potential to form massive stars.

  11. Type Ia Supernova Spectral Line Ratios as LuminosityIndicators

    SciTech Connect

    Bongard, Sebastien; Baron, E.; Smadja, G.; Branch, David; Hauschildt, Peter H.

    2005-12-07

    Type Ia supernovae have played a crucial role in thediscovery of the dark energy, via the measurement of their light curvesand the determination of the peak brightness via fitting templates to theobserved lightcurve shape. Two spectroscopic indicators are also known tobe well correlated with peak luminosity. Since the spectroscopicluminosity indicators are obtained directly from observed spectra, theywill have different systematic errors than do measurements usingphotometry. Additionally, these spectroscopic indicators may be usefulfor studies of effects of evolution or age of the SNe~;Ia progenitorpopulation. We present several new variants of such spectroscopicindicators which are easy to automate and which minimize the effects ofnoise. We show that these spectroscopic indicators can be measured byproposed JDEM missions such as snap and JEDI.

  12. Jet or Shock Breakout? The Low-Luminosity GRB 060218

    NASA Astrophysics Data System (ADS)

    Irwin, Christopher; Chevalier, Roger

    2016-01-01

    We consider a model for the long-duration, low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The components of our model are: (1) a long-lived (tj ~ 3000 s) central engine and accompanying low-luminosity (Lj ~ 1045 erg s-1), mildly relativistic jet; (2) a low-mass (~ 10-2 Msun) envelope surrounding the progenitor star; and (3) a modest amount of dust (AV ~ 0.1) in the circumstellar or interstellar environment. Blackbody emission from the transparency radius in a low-power jet outflow can fit the prompt thermal X-ray emission, and the prompt nonthermal X-rays and γ-rays may be produced via Compton scattering of thermal photons from hot leptons in the jet interior or the external shocks. The later mildly relativistic phase of this outflow can produce the radio emission via synchrotron radiation from the forward shock. Meanwhile, interaction of the associated SN 2006aj with a circumstellar envelope extending to ~ 1013 cm can explain the early optical peak. The X-ray afterglow can be interpreted as a light echo of the prompt emission from dust at ~ 30 pc. Our model is a plausible alternative to that of Nakar, who recently proposed shock breakout of a jet smothered by an extended envelope as the source of prompt emission. Both our results and Nakar's suggest that ultra-long bursts such as GRB 060218 and GRB 100316D may originate from unusual progenitors with extended circumstellar envelopes, and that a jet is necessary to decouple the prompt high-energy emission from the supernova.

  13. Jet or shock breakout? The low-luminosity GRB 060218

    NASA Astrophysics Data System (ADS)

    Irwin, Christopher M.; Chevalier, Roger A.

    2016-08-01

    We consider a model for the low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The model components are: (1) a long-lived (tj ˜ 3000 s) central engine and accompanying low-luminosity (Lj ˜ 1047 erg s-1), mildly relativistic (γ ˜ 10) jet; (2) a low-mass (˜4 × 10-3 M⊙) envelope surrounding the progenitor star; and (3) a modest amount of dust (AV ˜ 0.1 mag) in the circumstellar or interstellar environment. Blackbody emission from the transparency radius in a low-power jet outflow can fit the prompt thermal X-ray emission, and the non-thermal X-rays and gamma-rays may be produced via Compton scattering of thermal photons from hot leptons in the jet interior or the external shocks. The later mildly relativistic phase of this outflow can produce the radio emission via synchrotron radiation from the forward shock. Meanwhile, interaction of the associated SN 2006aj with a circumstellar envelope extending to ˜1013 cm can explain the early optical emission. The X-ray afterglow can be interpreted as a light echo of the prompt emission from dust at ˜30 pc. Our model is a plausible alternative to that of Nakar, who recently proposed shock breakout of a jet smothered by an extended envelope as the source of prompt emission. Both our results and Nakar's suggest that bursts such as GRB 060218 may originate from unusual progenitors with extended circumstellar envelopes, and that a jet is necessary to decouple the prompt emission from the supernova.

  14. The Galaxy UV Luminosity Function before the Epoch of Reionization

    NASA Astrophysics Data System (ADS)

    Mason, Charlotte A.; Trenti, Michele; Treu, Tommaso

    2015-11-01

    We present a model for the evolution of the galaxy ultraviolet (UV) luminosity function (LF) across cosmic time where star formation is linked to the assembly of dark matter halos under the assumption of a mass-dependent, but redshift-independent, efficiency. We introduce a new self-consistent treatment of the halo star formation history, which allows us to make predictions at z > 10 (lookback time ≲500 Myr), when growth is rapid. With a calibration at a single redshift to set the stellar-to-halo mass ratio, and no further degrees of freedom, our model captures the evolution of the UV LF over all available observations (0 ≲ z ≲ 10). The significant drop in luminosity density of currently detectable galaxies beyond z ˜ 8 is explained by a shift of star formation toward less massive, fainter galaxies. Assuming that star formation proceeds down to atomic cooling halos, we derive a reionization optical depth τ ={0.056}-0.010+0.007, fully consistent with the latest Planck measurement, implying that the universe is fully reionized at z={7.84}-0.98+0.65. In addition, our model naturally produces smoothly rising star formation histories for galaxies with L ≲ L* in agreement with observations and hydrodynamical simulations. Before the epoch of reionization at z > 10 we predict the LF to remain well-described by a Schechter function, but with an increasingly steep faint-end slope (α ˜ -3.5 at z ˜ 16). Finally, we construct forecasts for surveys with James Webb Space Telescope (JWST) and Wide-field Infrared Survey Telescope (WFIRST) and predict that galaxies out to z ˜ 14 will be observed. Galaxies at z > 15 will likely be accessible to JWST and WFIRST only through the assistance of strong lensing magnification.

  15. Quantitative evidence of an intrinsic luminosity spread in the Orion nebula cluster

    NASA Astrophysics Data System (ADS)

    Reggiani, M.; Robberto, M.; Da Rio, N.; Meyer, M. R.; Soderblom, D. R.; Ricci, L.

    2011-10-01

    Aims: We study the distribution of stellar ages in the Orion nebula cluster (ONC) using accurate HST photometry taken from HST Treasury Program observations of the ONC utilizing the cluster distance estimated by Menten and collaborators. We investigate whether there is an intrinsic age spread in the region and whether the age depends on the spatial distribution. Methods: We estimate the extinction and accretion luminosity towards each source by performing synthetic photometry on an empirical calibration of atmospheric models using the package Chorizos of Maiz-Apellaniz. The position of the sources in the HR-diagram is compared with different theoretical isochrones to estimate the mean cluster age and age dispersion. On the basis of Monte Carlo simulations, we quantify the amount of intrinsic age spread in the region, taking into account uncertainties in the distance, spectral type, extinction, unresolved binaries, accretion, and photometric variability. Results: According to the evolutionary models of Siess and collaborators, the mean age of the Cluster is 2.2 Myr with a scatter of few Myr. With Monte Carlo simulations, we find that the observed age spread is inconsistent with that of a coeval stellar population, but in agreement with a star formation activity between 1.5 and 3.5 Myr. We also observe some evidence that ages depends on the spatial distribution.

  16. Optimizing granules size distribution for aerobic granular sludge stability: Effect of a novel funnel-shaped internals on hydraulic shear stress.

    PubMed

    Zhou, Jia-Heng; Zhang, Zhi-Ming; Zhao, Hang; Yu, Hai-Tian; Alvarez, Pedro J J; Xu, Xiang-Yang; Zhu, Liang

    2016-09-01

    A novel funnel-shaped internals was proposed to enhance the stability and pollutant removal performance of an aerobic granular process by optimizing granule size distribution. Results showed up to 68.3±1.4% of granules in novel reactor (R1) were situated in optimal size range (700-1900μm) compared to less than 29.7±1.1% in conventional reactor (R2), and overgrowth of large granules was effectively suppressed without requiring additional energy. Consequently, higher total nitrogen (TN) removal (81.6±2.1%) achieved in R1 than in R2 (48.1±2.7%). Hydraulic analysis revealed the existence of selectively assigning hydraulic pressure in R1. The total shear rate (τtotal) on large granules was 3.07±0.14 times higher than that of R2, while τtotal of small granules in R1 was 70.7±4.6% in R2. Furthermore, large granules in R1 with intact extracellular polymeric substances (EPS) outer layer structure entrapped hydroxyapatite at center, which formed a core structure and further enhanced the stability of aerobic granules.

  17. Meta-analysis of survival curve data using distributed health data networks: application to hip arthroplasty studies of the International Consortium of Orthopaedic Registries.

    PubMed

    Cafri, Guy; Banerjee, Samprit; Sedrakyan, Art; Paxton, Liz; Furnes, Ove; Graves, Stephen; Marinac-Dabic, Danica

    2015-12-01

    The motivating example for this paper comes from a distributed health data network, the International Consortium of Orthopaedic Registries (ICOR), which aims to examine risk factors for orthopedic device failure for registries around the world. Unfortunately, regulatory, privacy, and propriety concerns made sharing of raw data impossible, even if de-identified. Therefore, this article describes an approach to extraction and analysis of aggregate time-to-event data from ICOR. Data extraction is based on obtaining a survival probability and variance estimate for each unique combination of the explanatory variables at each distinct event time for each registry. The extraction procedure allows for a great deal of flexibility; models can be specified after the data have been collected, for example, modeling of interaction effects and selection of subgroups of patients based on their values on the explanatory variables. Our analysis models are adapted from models presented elsewhere--but allowing for censoring in the calculation of the correlation between serial survival probabilities and using the square root of the covariance matrix to transform the data to avoid computational problems in model estimation. Simulations and a real-data example are provided with strengths and limitations of the approach discussed.

  18. 2012 best practices for repositories collection, storage, retrieval, and distribution of biological materials for research international society for biological and environmental repositories.

    PubMed

    2012-04-01

    Third Edition [Formula: see text] [Box: see text] Printed with permission from the International Society for Biological and Environmental Repositories (ISBER) © 2011 ISBER All Rights Reserved Editor-in-Chief Lori D. Campbell, PhD Associate Editors Fay Betsou, PhD Debra Leiolani Garcia, MPA Judith G. Giri, PhD Karen E. Pitt, PhD Rebecca S. Pugh, MS Katherine C. Sexton, MBA Amy P.N. Skubitz, PhD Stella B. Somiari, PhD Individual Contributors to the Third Edition Jonas Astrin, Susan Baker, Thomas J. Barr, Erica Benson, Mark Cada, Lori Campbell, Antonio Hugo Jose Froes Marques Campos, David Carpentieri, Omoshile Clement, Domenico Coppola, Yvonne De Souza, Paul Fearn, Kelly Feil, Debra Garcia, Judith Giri, William E. Grizzle, Kathleen Groover, Keith Harding, Edward Kaercher, Joseph Kessler, Sarah Loud, Hannah Maynor, Kevin McCluskey, Kevin Meagher, Cheryl Michels, Lisa Miranda, Judy Muller-Cohn, Rolf Muller, James O'Sullivan, Karen Pitt, Rebecca Pugh, Rivka Ravid, Katherine Sexton, Ricardo Luis A. Silva, Frank Simione, Amy Skubitz, Stella Somiari, Frans van der Horst, Gavin Welch, Andy Zaayenga 2012 Best Practices for Repositories: Collection, Storage, Retrieval and Distribution of Biological Materials for Research INTERNATIONAL SOCIETY FOR BIOLOGICAL AND ENVIRONMENTAL REPOSITORIES (ISBER) INTRODUCTION T he availability of high quality biological and environmental specimens for research purposes requires the development of standardized methods for collection, long-term storage, retrieval and distribution of specimens that will enable their future use. Sharing successful strategies for accomplishing this goal is one of the driving forces for the International Society for Biological and Environmental Repositories (ISBER). For more information about ISBER see www.isber.org . ISBER's Best Practices for Repositories (Best Practices) reflect the collective experience of its members and has received broad input from other repository professionals. Throughout this document

  19. The XXL Survey. II. The bright cluster sample: catalogue and luminosity function

    NASA Astrophysics Data System (ADS)

    Pacaud, F.; Clerc, N.; Giles, P. A.; Adami, C.; Sadibekova, T.; Pierre, M.; Maughan, B. J.; Lieu, M.; Le Fèvre, J. P.; Alis, S.; Altieri, B.; Ardila, F.; Baldry, I.; Benoist, C.; Birkinshaw, M.; Chiappetti, L.; Démoclès, J.; Eckert, D.; Evrard, A. E.; Faccioli, L.; Gastaldello, F.; Guennou, L.; Horellou, C.; Iovino, A.; Koulouridis, E.; Le Brun, V.; Lidman, C.; Liske, J.; Maurogordato, S.; Menanteau, F.; Owers, M.; Poggianti, B.; Pomarède, D.; Pompei, E.; Ponman, T. J.; Rapetti, D.; Reiprich, T. H.; Smith, G. P.; Tuffs, R.; Valageas, P.; Valtchanov, I.; Willis, J. P.; Ziparo, F.

    2016-06-01

    Context. The XXL Survey is the largest survey carried out by the XMM-Newton satellite and covers a total area of 50 square degrees distributed over two fields. It primarily aims at investigating the large-scale structures of the Universe using the distribution of galaxy clusters and active galactic nuclei as tracers of the matter distribution. The survey will ultimately uncover several hundreds of galaxy clusters out to a redshift of ~2 at a sensitivity of ~10-14 erg s-1 cm-2 in the [0.5-2] keV band. Aims: This article presents the XXL bright cluster sample, a subsample of 100 galaxy clusters selected from the full XXL catalogue by setting a lower limit of 3 × 10-14 erg s-1 cm-2 on the source flux within a 1' aperture. Methods: The selection function was estimated using a mixture of Monte Carlo simulations and analytical recipes that closely reproduce the source selection process. An extensive spectroscopic follow-up provided redshifts for 97 of the 100 clusters. We derived accurate X-ray parameters for all the sources. Scaling relations were self-consistently derived from the same sample in other publications of the series. On this basis, we study the number density, luminosity function, and spatial distribution of the sample. Results: The bright cluster sample consists of systems with masses between M500 = 7 × 1013 and 3 × 1014 M⊙, mostly located between z = 0.1 and 0.5. The observed sky density of clusters is slightly below the predictions from the WMAP9 model, and significantly below the prediction from the Planck 2015 cosmology. In general, within the current uncertainties of the cluster mass calibration, models with higher values of σ8 and/or ΩM appear more difficult to accommodate. We provide tight constraints on the cluster differential luminosity function and find no hint of evolution out to z ~ 1. We also find strong evidence for the presence of large-scale structures in the XXL bright cluster sample and identify five new superclusters. Based on

  20. The Radio luminosity Function of Radio-Loud Quasars from the 7C Redshift Survey

    NASA Technical Reports Server (NTRS)

    Willott, Chris J.; Rawlings, Steve; Blundell, Katherine M.; Lacy, Mark

    1998-01-01

    We present a complete sample of 24 radio-loud quasars (RLQs) from the new 7C Redshift Survey. Every quasar with a low-frequency (151 MHz) radio flux-density S(sub 151) > 0.5 Jy in two regions of the sky covering 0.013 sr is included; 23 of these have sufficient extended flux to meet the selection criteria, 18 of these have steep radio spectra (hereafter denoted as SSQs). The key advantage of this sample over most samples of RLQs is the lack of an optical magnitude limit. By combining the 7C and 3CRR samples, we have investigated the properties of RLQs as a function of redshift z and radio luminosity L(sub 151). We derive the radio luminosity function (RLF) of RLQs and find that the data are well fitted by a single power-law with slope alpha(sub 1) = 1.9 +/- 0.1 (for H(sub 0) = 50 km/s.Mpc, OMEGA(sub M) = 1, OMEGA(sub DELTA) = 0). We find that there must be a break in the RLQ RLF at log(sub 10)(L(sub 151)/W Hz.sr) approximately < or = 27, in order for the models to be consistent with the 7C and 6C source counts. The z-dependence of the RLF follows a one-tailed gaussian which peaks at z = 1.7 +/- 0.2. We find no evidence for a decline in the co-moving space density of RLQs at higher redshifts. A positive correlation between the radio and optical luminosities of SSQs is observed, confirming a result of Serjeant. We are able to rule out this correlation being due to selection effects or biases in our combined sample. The radio-optical correlation and best-fit model RLF enable us to estimate the distribution of optical magnitudes of quasars in samples selected at low radio frequencies, We con- clude that for samples with S(sub 151) approximately < or = 1 Jy one must use optical data significantly deeper than the POSS-I limit (R approximately equal 20), in order to avoid severe incompleteness.

  1. THE NUCLEAR INFRARED EMISSION OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Mason, R. E.; Lopez-Rodriguez, E.; Packham, C.; Alonso-Herrero, A.; Elitzur, M.; Aretxaga, I.; Roche, P. F.; Oi, N.

    2012-07-15

    We present high-resolution mid-infrared (MIR) imaging, nuclear spectral energy distributions (SEDs), and archival Spitzer spectra for 22 low-luminosity active galactic nuclei (LLAGNs; L{sub bol} {approx}< 10{sup 42} erg s{sup -1}). Infrared (IR) observations may advance our understanding of the accretion flows in LLAGNs, the fate of the obscuring torus at low accretion rates, and, perhaps, the star formation histories of these objects. However, while comprehensively studied in higher-luminosity Seyferts and quasars, the nuclear IR properties of LLAGNs have not yet been well determined. We separate the present LLAGN sample into three categories depending on their Eddington ratio and radio emission, finding different IR characteristics for each class. (1) At the low-luminosity, low-Eddington-ratio (log L{sub bol}/L{sub Edd} < -4.6) end of the sample, we identify 'host-dominated' galaxies with strong polycyclic aromatic hydrocarbon bands that may indicate active (circum-)nuclear star formation. (2) Some very radio-loud objects are also present at these low Eddington ratios. The IR emission in these nuclei is dominated by synchrotron radiation, and some are likely to be unobscured type 2 AGNs that genuinely lack a broad-line region. (3) At higher Eddington ratios, strong, compact nuclear sources are visible in the MIR images. The nuclear SEDs of these galaxies are diverse; some resemble typical Seyfert nuclei, while others lack a well-defined MIR 'dust bump'. Strong silicate emission is present in many of these objects. We speculate that this, together with high ratios of silicate strength to hydrogen column density, could suggest optically thin dust and low dust-to-gas ratios, in accordance with model predictions that LLAGNs do not host a Seyfert-like obscuring torus. We anticipate that detailed modeling of the new data and SEDs in terms of accretion disk, jet, radiatively inefficient accretion flow, and torus components will provide further insights into the nuclear

  2. The HerMES submillimetre local and low-redshift luminosity functions

    NASA Astrophysics Data System (ADS)

    Marchetti, L.; Vaccari, M.; Franceschini, A.; Arumugam, V.; Aussel, H.; Béthermin, 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.; Page, M. J.; Papageorgiou, A.; Pearson, C. P.; Pérez-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.

    2016-02-01

    We used wide-area surveys over 39 deg2 by the HerMES (Herschel Multi-tiered Extragalactic Survey) collaboration, performed with the Herschel Observatory SPIRE multiwavelength camera, to estimate the low-redshift, 0.02 < z < 0.5, monochromatic luminosity functions (LFs) of galaxies at 250, 350 and 500 μm. Within this redshift interval, we detected 7087 sources in five independent sky areas, ˜40 per cent of which have spectroscopic redshifts, while for the remaining objects photometric redshifts were used. The SPIRE LFs in different fields did not show any field-to-field variations beyond the small differences to be expected from cosmic variance. SPIRE flux densities were also combined with Spitzer photometry and multiwavelength archival data to perform a complete spectral energy distribution fitting analysis of SPIRE detected sources to calculate precise k-corrections, as well as the bolometric infrared (IR; 8-1000 μm) LFs and their low-z evolution from a combination of statistical estimators. Integration of the latter prompted us to also compute the local luminosity density and the comoving star formation rate density (SFRD) for our sources, and to compare them with theoretical predictions of galaxy formation models. The LFs show significant and rapid luminosity evolution already at low redshifts, 0.02 < z < 0.2, with L_{IR}^{*} ∝ (1+z)^{6.0± 0.4} and Φ _{IR}^{*} ∝ (1+z)^{-2.1± 0.4}, L_{250}^{*} ∝ (1+z)^{5.3± 0.2} and Φ _{250}^{*} ∝ (1+z)^{-0.6± 0.4} estimated using the IR bolometric and the 250 μm LFs, respectively. Converting our IR LD estimate into an SFRD assuming a standard Salpeter initial mass function and including the unobscured contribution based on the UV dust-uncorrected emission from local galaxies, we estimate an SFRD scaling of SFRD0 + 0.08z, where SFRD0 ≃ (1.9 ± 0.03) × 10-2 [M⊙ Mpc-3] is our total SFRD estimate at z ˜ 0.02.

  3. The jets-accretion relation, mass-luminosity relation in Fermi blazars

    NASA Astrophysics Data System (ADS)

    Yu, Xiaoling; Zhang, Xiong; Zhang, Haojing; Xiong, Dingrong; Li, Bijun; Cha, Yongjuan; Chen, Yongyun; Huang, Xia; Wang, Yuwei

    2015-05-01

    A sample of 111 Fermi blazars each with a well-established radio core luminosity, broad-line luminosity, bolometric luminosity and black hole mass has been compiled from the literatures. We present a significant correlation between radio core and broad-line emission luminosities that supports a close link between accretion processes and relativistic jets. Analysis reveals a relationship of which is consistant with theoretical predicted coefficient and supports that blazar jets are powered by energy extraction from a rapidly spinning Kerr black hole through the magnetic field provided by the accretion disk. Through studying the correlation between the intrinsic bolometric luminosity and the black hole mass, we find a relationship of which supports mass-luminosity relation for Fermi blazars derived in this work is a powerlaw relation similar to that for main-sequence stars. Finally, EVOLUTIONARY SEQUENCE OF BLAZARS is discussed.

  4. Measurement of the luminosity in the ZEUS experiment at HERA II

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Andruszkow, J.; Bold, T.; Borzemski, P.; Buettner, C.; Caldwell, A.; Chwastowski, J.; Daniluk, W.; Drugakov, V.; Eskreys, A.; Figiel, J.; Galas, A.; Gil, M.; Helbich, M.; Januschek, F.; Jurkiewicz, P.; Kisielewska, D.; Klein, U.; Kotarba, A.; Lohmann, W.; Ning, Y.; Oliwa, K.; Olkiewicz, K.; Paganis, S.; Pieron, J.; Przybycien, M.; Ren, Z.; Ruchlewicz, W.; Schmidke, W.; Schneekloth, U.; Sciulli, F.; Stopa, P.; Sztuk-Dambietz, J.; Suszycki, L.; Sutiak, J.; Wierba, W.; Zawiejski, L.

    2014-04-01

    The luminosity in the ZEUS detector was measured using photons from electron bremsstrahlung off protons. In 2001 the HERA collider was upgraded for operation at higher luminosity. At the same time the luminosity-measuring system of the ZEUS experiment was modified to tackle the expected higher photon rate and synchrotron radiation. The existing lead-scintillator calorimeter was equipped with radiation hard scintillator tiles and shielded against synchrotron radiation. In addition, a magnetic spectrometer was installed to measure the luminosity independently using photons converted in the beam-pipe exit window. The redundancy provided a reliable and robust luminosity determination with a systematic uncertainty of 1.7%. The experimental setup, the techniques used for luminosity determination and the estimate of the systematic uncertainty are reported.

  5. Line-driven disc wind model for ultrafast outflows in active galactic nuclei - scaling with luminosity

    NASA Astrophysics Data System (ADS)

    Nomura, M.; Ohsuga, K.

    2017-03-01

    In order to reveal the origin of the ultrafast outflows (UFOs) that are frequently observed in active galactic nuclei (AGNs), we perform two-dimensional radiation hydrodynamics simulations of the line-driven disc winds, which are accelerated by the radiation force due to the spectral lines. The line-driven winds are successfully launched for the range of MBH = 106-9 M⊙ and ε = 0.1-0.5, and the resulting mass outflow rate (dot{M_w}), momentum flux (dot{p_w}), and kinetic luminosity (dot{E_w}) are in the region containing 90 per cent of the posterior probability distribution in the dot{M}_w-Lbol plane, dot{p}_w-Lbol plane, and dot{E}_w-Lbol plane shown in Gofford et al., where MBH is the black hole mass, ε is the Eddington ratio, and Lbol is the bolometric luminosity. The best-fitting relations in Gofford et al., d log dot{M_w}/d log {L_bol}˜ 0.9, d log dot{p_w}/d log {L_bol}˜ 1.2, and d log dot{E_w}/d log {L_bol}˜ 1.5, are roughly consistent with our results, d log dot{M_w}/d log {L_bol}˜ 9/8, d log dot{p_w}/d log {L_bol}˜ 10/8, and d log dot{E_w}/d log {L_bol}˜ 11/8. In addition, our model predicts that no UFO features are detected for the AGNs with ε ≲ 0.01, since the winds do not appear. Also, only AGNs with MBH ≲ 108 M⊙ exhibit the UFOs when ε ∼ 0.025. These predictions nicely agree with the X-ray observations. These results support that the line-driven disc wind is the origin of the UFOs.

  6. Gas related effects on multi-gap RPC performance in high luminosity experiments

    NASA Astrophysics Data System (ADS)

    Lyu, P.; Wang, Y.; Guo, B.; Han, D.; Xie, B.; Li, Y.; Wang, F.

    2016-11-01

    The Multi-gap Resistive Plate Chamber (MRPC) is a new type of gas detector developed in recent years. It has excellent time resolution (better than 100 ps) and high efficiency (higher than 95%). This detector has been used to construct large-area time-of-flight (TOF) system in many nuclear and particle physics experiments. However, as a type of gaseous detector, the aging of the gas mixture under long-time exposure to ionizing radiation cannot be neglected. With the increase of accelerator luminosity, impurities in the gas mixture can be potentially dangerous for long-term operation of the MRPC. This has been observed in some experiments, for example with the RHIC-STAR muon telescope detector. The CBM-TOF, used for hadron identification, is proposed to be assembled with MRPCs. These counters have to stand particle fluxes as high as 25 kHz/cm2, and thus the gas pollution is a critical aspect to be studied. In order to better understand the gas quality's impact on the MRPC performance, a two-dimensional simulation based on the SIMPLE algorithm is carried out to imitate the distribution of impurities in a MRPC gas box. The preliminary results show that gas pollution grows stronger with the increase of the gas-flowing volume. In addition, we conducted a series of experiments with a 50 × 50 cm2, 8-gap MRPC prototype. The results match the simulation quite well. Gas pollution indeed has a severe impact on the MRPC performance, and further study can be very useful to reduce gas aging effects in high-luminosity experiments.

  7. Luminosity function of [O II] emission-line galaxies in the MassiveBlack-II simulation

    NASA Astrophysics Data System (ADS)

    Park, KwangHo; Di Matteo, Tiziana; Ho, Shirley; Croft, Rupert; Wilkins, Stephen M.; Feng, Yu; Khandai, Nishikanta

    2015-11-01

    We examine the luminosity function (LF) of [O II] emission-line galaxies in the high-resolution cosmological simulation MassiveBlack-II (MBII). From the spectral energy distribution of each galaxy, we select a sub-sample of star-forming galaxies at 0.06 ≤ z ≤ 3.0 using the [O II] emission line luminosity L([O II]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [O II] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([O II]) = 1043.0 erg s-1 while the low redshifts (z ≤ 0.3) show an excess in the prediction of bright [O II] galaxies, but still displaying a good match with observations below L([O II]) = 1041.6 erg s-1. Based on the validity in reproducing the properties of [O II] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [O II] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from -3 to -2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)-1 at z ≤ 2 while the faint end evolves as ˜3(z + 1)-1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [O III] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. Finally, we show that the auto-correlation function of [O II] and [O III] emitting galaxies shows a rapid evolution from z = 2 to 1.

  8. The effects of magnetic field, age and intrinsic luminosity on Crab-like pulsar wind nebulae

    NASA Astrophysics Data System (ADS)

    Torres, D. F.; Martín, J.; de Oña Wilhelmi, E.; Cillis, Analia

    2013-12-01

    We investigate the time-dependent behaviour of Crab-like pulsar wind nebulae (PWNe) generating a set of models using four different initial spin-down luminosities (L0 = {1, 0.1, 0.01, 0.001} × L0,Crab), eight values of magnetic fraction (η = 0.001, 0.01, 0.03, 0.1, 0.5, 0.9, 0.99 and 0.999, i.e. from fully particle dominated to fully magnetically dominated nebulae) and three distinctive ages: 940, 3000 and 9000 years. We find that the self-synchrotron Compton (SSC) contribution is irrelevant for LSD = 0.1, 1 and 10 per cent of the Crab power, disregarding the age and the magnetic fraction. SSC only becomes relevant for highly energetic (˜70 per cent of the Crab), particle dominated nebulae at low ages (of less than a few kyr), located in a far-infrared (FIR) background with relatively low energy density. Since no pulsar other than Crab is known to have these features, these results clarify why the Crab nebula, and only it, is SSC dominated. No young PWN would be detectable at TeV energies if the pulsar's spin-down power is 0.1 per cent Crab or lower. For 1 per cent of the Crab spin-down, only particle-dominated nebulae can be detected by HESS-like telescopes when young enough (with details depending on the precise injection and environmental parameters). Above 10 per cent of the Crab's power, all PWNe are detectable by HESS-like telescopes if they are particle dominated, no matter the age. The impact of the magnetic fraction on the final spectral energy distribution is varied and important, generating order of magnitude variations in the luminosity output for systems that are otherwise the same (equal P, dot{P}, injection and environment).

  9. Very low-luminosity Class I/flat outflow sources in σ Orionis

    NASA Astrophysics Data System (ADS)

    Riaz, B.; Thompson, M.; Whelan, E. T.; Lodieu, N.

    2015-01-01

    We present an optical to submillimetre multiwavelength study of two very low-luminosity Class I/flat systems, Mayrit 1701117 and Mayrit 1082188, in the σ Orionis cluster. We performed moderate-resolution (R ˜ 1000) optical (˜0.4-0.9 μm) spectroscopy with the Cassegrain Twin Spectrograph (TWIN) spectrograph at the Calar Alto 3.5-m telescope. The spectra for both sources show prominent emission in accretion- and outflow-associated lines. The mean accretion rate measured from multiple line diagnostics is 6.4 × 10-10 M⊙ yr-1 for Mayrit 1701117 and 2.5 × 10-10 M⊙ yr-1 for Mayrit 1082188. The outflow mass-loss rates for the two systems are similar and estimated to be ˜1 × 10-9 M⊙ yr-1. The activity rates are within the range observed for low-mass Class I protostars. We obtained submillimetre continuum observations with the Submillimetre Common-User Bolometer Array (SCUBA-2) bolometer at the James Clerk Maxwell Telescope. Both objects are detected at a ≥5σ level in the SCUBA-2 850-μm band. The bolometric luminosity of the targets as measured from the observed spectral energy distribution over ˜0.8-850 μm is 0.18 ± 0.04 L⊙ for Mayrit 1701117 and 0.16 ± 0.03 L⊙ for Mayrit 1082188 and is in the very low mass range. The total dust+gas mass derived from submillimetre fluxes is ˜36 MJup and ˜22 MJup for Mayrit 1701117 and Mayrit 1082188, respectively. There is the possibility that some of the envelope material might be dissipated by the strong outflows driven by these sources, resulting in a final mass of the system close to or below the substellar limit.

  10. A Viewing Angle-Kinetic Luminosity Scheme for BL Lacertae Objects

    NASA Technical Reports Server (NTRS)

    Georganopoulos, Markos; Marscher, Alan P.

    1998-01-01

    We propose a unified classification for BL Lacertae objects (BLs), focusing on the synchrotron peak frequency of the spectral energy distribution. The unification scheme is based on the angle theta that describes the orientation of the relativistic jet and on the electron kinetic luminosity Lamba(sub kin) of the jet. We assume that Lamba(sub kin) scales with the size of the jet (r) in a self-similar fashion (Lamba(sub kin) is proportional to r(exp 2)), as supported by observational data. The jets are self-similar in geometry and have the same pressure and median magnetic field at the inlet, independent of size. The self-similarity is broken for the highest energy electrons, which radiate mainly at high frequencies, since for large sources they suffer more severe radiative energy losses over a given fraction of the jet length. We calculate the optically thin synchrotron spectrum using an accelerating inner jet model based on simple relativistic gas dynamics and show that it can fit the observed infrared-to-X-ray spectrum of PKS 2155-304. We couple the accelerating jet model to the unification scheme and compare the results to complete samples of BLs. The negative apparent evolution of X-ray-selected BLs is explained as a result of positive evolution of the jet electron kinetic luminosity Lamba(sub kin). We review observational arguments in favor of the existence of scaled-down accretion disks and broad emission-line regions in BLs. The proposed unification scheme can explain the lack of observed broad emission lines in X-ray-selected BLs as well as the existence of those lines preferentially in luminous radio-selected BLs. Finally, we review observational arguments that suggest the extension of this unification scheme to all blazars.

  11. Supermassive black holes and their host galaxies. I. Bulge luminosities from dedicated near-infrared data

    SciTech Connect

    Läsker, Ronald; Van de Ven, Glenn; Ferrarese, Laura

    2014-01-01

    In an effort to secure, refine, and supplement the relation between central supermassive black hole masses, M {sub •}, and the bulge luminosities of their host galaxies, L {sub bul}, we obtained deep, high spatial resolution K-band images of 35 nearby galaxies with securely measured M {sub •}, using the wide-field WIRCam imager at the Canada-France-Hawaii-Telescope. A dedicated data reduction and sky subtraction strategy was adopted to estimate the brightness and structure of the sky, a critical step when tracing the light distribution of extended objects in the near-infrared. From the final image product, bulge and total magnitudes were extracted via two-dimensional profile fitting. As a first order approximation, all galaxies were modeled using a simple Sérsic-bulge+exponential-disk decomposition. However, we found that such models did not adequately describe the structure that we observed in a large fraction of our sample galaxies which often include cores, bars, nuclei, inner disks, spiral arms, rings, and envelopes. In such cases, we adopted profile modifications and/or more complex models with additional components. The derived bulge magnitudes are very sensitive to the details and number of components used in the models, although total magnitudes remain almost unaffected. Usually, but not always, the luminosities and sizes of the bulges are overestimated when a simple bulge+disk decomposition is adopted in lieu of a more complex model. Furthermore, we found that some spheroids are not well fit when the ellipticity of the Sérsic model is held fixed. This paper presents the details of the image processing and analysis, while we discuss how model-induced biases and systematics in bulge magnitudes impact the M {sub •}-L {sub bul} relation in a companion paper.

  12. The dust grain size-stellar luminosity trend in debris discs

    NASA Astrophysics Data System (ADS)

    Pawellek, Nicole; Krivov, Alexander V.

    2015-12-01

    The cross-section of material in debris discs is thought to be dominated by the smallest grains that can still stay in bound orbits despite the repelling action of stellar radiation pressure. Thus the minimum (and typical) grain size smin is expected to be close to the radiation pressure blowout size sblow. Yet a recent analysis of a sample of Herschel-resolved debris discs showed the ratio smin/sblow to systematically decrease with the stellar luminosity from about 10 for solar-type stars to nearly unity in the discs around the most luminous A-type stars. Here, we explore this trend in more detail, checking how significant it is and seeking to find possible explanations. We show that the trend is robust to variation of the composition and porosity of dust particles. For any assumed grain properties and stellar parameters, we suggest a recipe of how to estimate the `true' radius of a spatially unresolved debris disc, based solely on its spectral energy distribution. The results of our collisional simulations are qualitatively consistent with the trend, although additional effects may also be at work. In particular, the lack of grains with small smin/sblow for lower luminosity stars might be caused by the grain surface energy constraint that should limit the size of the smallest collisional fragments. Also, a better agreement between the data and the collisional simulations is achieved when assuming debris discs of more luminous stars to have higher dynamical excitation than those of less-luminous primaries. This would imply that protoplanetary discs of more massive young stars are more efficient in forming big planetesimals or planets that act as stirrers in the debris discs at the subsequent evolutionary stage.

  13. Luminosity function of [OII] emission-line galaxies in the MassiveBlack-II simulation

    DOE PAGES

    Park, KwangHo; Khandai, Nishikanta; Matteo, Tiziana Di; ...

    2015-09-18

    We examine the luminosity function (LF) of [OII] emission-line galaxies in the high-resolution cosmological simulation MassiveBlack-II (MBII). From the spectral energy distribution of each galaxy, we select a sub-sample of star-forming galaxies at 0.06 ≤ z ≤ 3.0 using the [OII] emission line luminosity L([OII]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [OII] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([OII]) = 1043.0 erg s–1 while the low redshifts (z ≤ 0.3) show an excessmore » in the prediction of bright [OII] galaxies, but still displaying a good match with observations below L([OII]) = 1041.6 erg s–1. Based on the validity in reproducing the properties of [OII] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [OII] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from –3 to –2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)–1 at z ≤ 2 while the faint end evolves as ~3(z + 1)–1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [OIII] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. As a result, we show that the auto-correlation function of [OII] and [OIII] emitting galaxies shows a rapid evolution from z = 2 to 1.« less

  14. THE FAINT END OF THE CLUSTER-GALAXY LUMINOSITY FUNCTION AT HIGH REDSHIFT

    SciTech Connect

    Mancone, Conor L.; Baker, Troy; Gonzalez, Anthony H.; Ashby, Matthew L. N.; Snyder, Greg; Stanford, Spencer A.; Brodwin, Mark; Eisenhardt, Peter R. M.; Stern, Daniel; Wright, Edward L.

    2012-12-20

    We measure the faint-end slope of the galaxy luminosity function (LF) for cluster galaxies at 1 < z < 1.5 using Spitzer IRAC data. We investigate whether this slope, {alpha}, differs from that of the field LF at these redshifts, and with the cluster LF at low redshifts. The latter is of particular interest as low-luminosity galaxies are expected to undergo significant evolution. We use seven high-redshift spectroscopically confirmed galaxy clusters drawn from the IRAC Shallow Cluster Survey to measure the cluster-galaxy LF down to depths of M* + 3 (3.6 {mu}m) and M* + 2.5 (4.5 {mu}m). The summed LF at our median cluster redshift (z = 1.35) is well fit by a Schechter distribution with {alpha}{sub 3.6{mu}m} = -0.97 {+-} 0.14 and {alpha}{sub 4.5{mu}m} = -0.91 {+-} 0.28, consistent with a flat faint-end slope and is in agreement with measurements of the field LF in similar bands at these redshifts. A comparison to {alpha} in low-redshift clusters finds no statistically significant evidence of evolution. Combined with past studies which show that M* is passively evolving out to z {approx} 1.3, this means that the shape of the cluster LF is largely in place by z {approx} 1.3. This suggests that the processes that govern the buildup of the mass of low-mass cluster galaxies have no net effect on the faint-end slope of the cluster LF at z {approx}< 1.3.

  15. PHASE-AVERAGED SPECTRA AND LUMINOSITIES OF GAMMA-RAY EMISSIONS FROM YOUNG ISOLATED PULSARS

    SciTech Connect

    Li, X.; Jiang, Z. J.; Zhang, L.

    2013-03-10

    We study the phase-averaged spectra and luminosities of {gamma}-ray emissions from young, isolated pulsars within a revised outer gap model. In the revised version of the outer gap, there are two possible cases for the outer gaps: the fractional size of the outer gap is estimated through the photon-photon pair process in the first case (Case I), and is limited by the critical field lines in the second case (Case II). The fractional size is described by Case I if the fractional size at the null charge surface in Case I is smaller than that in Case II, and vice versa. Such an outer gap can extend from the inner boundary, whose radial distance to the neutron star is less than that of the null charge surface to the light cylinder for a {gamma}-ray pulsar with a given magnetic inclination. When the shape of the outer gap is determined, assuming that high-energy emission at an averaged radius of the field line in the center of the outer gap, with a Gaussian distribution of the parallel electric field along the gap height, represents typical emission, the phase-averaged {gamma}-ray spectrum for a given pulsar can be estimated in the revised model with three model parameters. We apply the model to explain the phase-averaged spectra of the Vela (Case I) and Geminga (Case II) pulsars. We also use the model to fit the phase-averaged spectra of 54 young, isolated {gamma}-ray pulsars, and then calculate the {gamma}-ray luminosities and compare them with the observed data from Fermi-LAT.

  16. Testing and Improving the Luminosity Relations for Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Collazzi, Andrew C.

    2012-01-01

    Gamma Ray Bursts (GRBs) have several luminosity relations where a measurable property of a burst light curve or spectrum is correlated with the burst luminosity. These luminosity relations are calibrated for the fraction of bursts with spectroscopic redshifts and hence the known luminosities. GRBs have thus become known as a type of "standard candle” where standard candle is meant in the usual sense that luminosities can be derived from measurable properties of the bursts. GRBs can therefore be used for the same cosmology applications as Type Ia supernovae, including the construction of the Hubble Diagram and measuring massive star formation rate. The greatest disadvantage of using GRBs as standard candles is that their accuracy is lower than desired. With the recent advent of GRBs as a new standard candle, every effort must be made to test and improve the distance measures. Here, methods are employed to do just that. First, generalized forms of two tests are performed on the luminosity relations. All the luminosity relations pass one of these tests, and all but two pass the other. Even with this failure, redundancies in using multiple luminosity relations allows all the luminosity relations to retain value. Next, the "Firmani relation” is shown to have poorer accuracy than first advertised. It is also shown to be derivable from two other luminosity relations. For these reasons, the Firmani relation is useless for cosmology. The Amati relation is then revisited and shown to be an artifact of a combination of selection effects. Therefore, the Amati relation is also not good for cosmology. Fourthly, the systematic errors involved in measuring a luminosity indicator (Epeak) are measured. The result is an irreducible systematic error of 28%. Finally, the work concludes with a discussion about the impact of the work and the future of GRB luminosity relations.

  17. SDSS DR4: Progress on the Hot Wire Dwarf Luminosity Function

    DTIC Science & Technology

    2009-01-01

    SDSS DR4: Progress on the hot white dwarf luminosity function This article has been downloaded from IOPscience. Please scroll down to see the full...TITLE AND SUBTITLE SDSS DR4: progress on the hot white dwarf luminosity function 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...Sloan Digital Sky Survey ( SDSS ) data release 4 (DR4) WD catalog data allowed us to obtain a luminosity function (LF)for the hottest WDs. The LF was

  18. The Connection Between Galaxy Environment and the Luminosity Function Slopes of Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, Daniel A.; Lee, Janice C.; Thilker, David A.; Calzetti, Daniela; Kennicutt, Robert

    2016-06-01

    We present the first study of GALEX far ultra-violet (FUV) luminosity functions of individual star-forming regions within a sample of 258 nearby galaxies spanning a large range in total stellar mass and star formation properties. We identify ~65,000 star-forming regions (i.e., FUV sources), measure each galaxy's luminosity function, and characterize the relationships between the luminosity function slope (α) and several global galaxy properties. A final sample of \

  19. The Local [C ii] 158 μm Emission Line Luminosity Function

    NASA Astrophysics Data System (ADS)

    Hemmati, Shoubaneh; Yan, Lin; Diaz-Santos, Tanio; Armus, Lee; Capak, Peter; Faisst, Andreas; Masters, Daniel

    2017-01-01

    We present, for the first time, the local [C ii] 158 μm emission line luminosity function measured using a sample of more than 500 galaxies from the Revised Bright Galaxy Sample. [C ii] luminosities are measured from the Herschel PACS observations of the Luminous Infrared Galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey and estimated for the rest of the sample based on the far-infrared (far-IR) luminosity and color. The sample covers 91.3% of the sky and is complete at S60 μm > 5.24 Jy. We calculate the completeness as a function of [C ii] line luminosity and distance, based on the far-IR color and flux densities. The [C ii] luminosity function is constrained in the range ∼107–9 L⊙ from both the 1/Vmax and a maximum likelihood methods. The shape of our derived [C ii] emission line luminosity function agrees well with the IR luminosity function. For the CO(1-0) and [C ii] luminosity functions to agree, we propose a varying ratio of [C ii]/CO(1-0) as a function of CO luminosity, with larger ratios for fainter CO luminosities. Limited [C ii] high-redshift observations as well as estimates based on the IR and UV luminosity functions are suggestive of an evolution in the [C ii] luminosity function similar to the evolution trend of the cosmic star formation rate density. Deep surveys using the Atacama Large Millimeter Array with full capability will be able to confirm this prediction.

  20. Time Variability and Luminosity of X-ray Sources of Face-on Spiral Galaxy NGC 1232

    NASA Astrophysics Data System (ADS)

    Cantua, Oscar; Rucas, Tyler; Singh, Pranjal; Schlegel, Eric M.

    2017-01-01

    The ACIS detector (Advanced CCD Imaging Spectrometer) onboard the Chandra X-ray Observatory has imaged the face-on spiral NGC 1232 over six epochs for a total exposure of ~250 ksec. We describe each observation as well as the merged data set. Each exposure contains ~50 individual sources. We focus on the time variability and luminosity distributions of the sources. We also describe our search for diffuse emission as well as our search for evidence for a reported collision with a dwarf galaxy. Finally, we compare the merged data set and the detected sources with other wavebands.

  1. Reprocessing the Hipparcos data of evolved stars. III. Revised Hipparcos period-luminosity relationship for galactic long-period variable stars

    NASA Astrophysics Data System (ADS)

    Knapp, G. R.; Pourbaix, D.; Platais, I.; Jorissen, A.

    2003-06-01

    We analyze the K band luminosities of a sample of galactic long-period variables using parallaxes measured by the Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from measurements by COBE, and are corrected for interstellar and circumstellar extinction. The sample contains stars of several spectral types: M, S and C, and of several variability classes: Mira, semiregular SRa, and SRb. We find that the distribution of stars in the period-luminosity plane is independent of circumstellar chemistry, but that the different variability types have different P-L distributions. Both the Mira variables and the SRb variables have reasonably well-defined period-luminosity relationships, but with very different slopes. The SRa variables are distributed between the two classes, suggesting that they are a mixture of Miras and SRb, rather than a separate class of stars. New period-luminosity relationships are derived based on our revised Hipparcos parallaxes. The Miras show a similar period-luminosity relationship to that found for Large Magellanic Cloud Miras by Feast et al. (\\cite{Feast-1989:a}). The maximum absolute K magnitude of the sample is about -8.2 for both Miras and semi-regular stars, only slightly fainter than the expected AGB limit. We show that the stars with the longest periods (P>400 d) have high mass loss rates and are almost all Mira variables. Based on observations from the Hipparcos astrometric satellite operated by the European Space Agency (ESA \\cite{Hipparcos}). Table \\ref{Tab:data1} is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/403/993

  2. The Herschel ATLAS: Evolution of the 250 Micrometer Luminosity Function Out to z = 0.5

    NASA Technical Reports Server (NTRS)

    Dye, S.; Dunne, L.; Eales, S.; Smith, D. J. B.; Amblard, A.; Auld, R.; Baes, M.; Baldry, I. K.; Bamford, S.; Blain, A. W.; Bonfield, D. G.; Bremer, M.; Burgarella, D.; Buttiglione, S.; Cameron, E.; Cava, A.; Clements, D. L.; Cooray, A.; Croom, S.; Dariush, A.; de Zotti, G.; Driver, S.; Dunlop, J. S.; Frayer, D.; Leeuw, L.

    2010-01-01

    We have determined the luminosity function of 250 micrometer-selected galaxies detected in the approximately equal to 14 deg(sup 2) science demonstration region of the Herschel-ATLAS project out to a redshift of z = 0.5. Our findings very clearly show that the luminosity function evolves steadily out to this redshift. By selecting a sub-group of sources within a fixed luminosity interval where incompleteness effects are minimal, we have measured a smooth increase in the comoving 250 micrometer luminosity density out to z = 0.2 where it is 3.6(sup +1.4) (sub -0.9) times higher than the local value.

  3. Luminosities of H alpha emitting regions in a pair of interacting galaxies in the Bootes void

    NASA Technical Reports Server (NTRS)

    Weistrop, D.; Hintzen, P.; Kennicutt, R.; Liu, C.; Lowenthal, J.; Cheng, K.-P.; Oliversen, R.; Woodgate, B.

    1993-01-01

    Luminosities of H alpha emission from a pair of interacting galaxies in the low density environment of the Bootes void are presented. CG 692 (IRAS 1519+5050) has an H alpha luminosity of 2 x 10(exp 42) ergs s(exp -1), indicating a star formation rate of 18.4 solar mass yr(exp -1). Individual extranuclear H alpha regions have luminosities of approximately 10(exp 40) ergs s(exp -1). These luminosities are similar to those found for H II regions in bright, late-type galaxies in more densely populated parts of the Universe.

  4. Modeling collision energy transfer in APCI/CID mass spectra of PAHs using thermal-like post-collision internal energy distributions.

    PubMed

    Solano, Eduardo A; Mohamed, Sabria; Mayer, Paul M

    2016-10-28

    The internal energy transferred when projectile molecular ions of naphthalene collide with argon gas atoms was extracted from the APCI-CID (atmospheric-pressure chemical ionization collision-induced dissociation) mass spectra acquired as a function of collision energy. Ion abundances were calculated by microcanonical integration of the differential rate equations using the Rice-Ramsperger-Kassel-Marcus rate constants derived from a UB3LYP/6-311G+(3df,2p)//UB3LYP/6-31G(d) fragmentation mechanism and thermal-like vibrational energy distributions pME,Tchar. The mean vibrational energy excess of the ions was characterized by the parameter Tchar ("characteristic temperature"), determined by fitting the theoretical ion abundances to the experimental breakdown graph (a plot of relative abundances of the ions as a function of kinetic energy) of activated naphthalene ions. According to these results, the APCI ion source produces species below Tchar = 1457 K, corresponding to 3.26 eV above the vibrational ground state. Subsequent collisions heat the ions up further, giving rise to a sigmoid curve of Tchar as a function of Ecom (center-of-mass-frame kinetic energy). The differential internal energy absorption per kinetic energy unit (dEvib/dEcom) changes with Ecom according to a symmetric bell-shaped function with a maximum at 6.38 ± 0.32 eV (corresponding to 6.51 ± 0.27 eV of vibrational energy excess), and a half-height full width of 6.30 ± 1.15 eV. This function imposes restrictions on the amount of energy that can be transferred by collisions, such that a maximum is reached as kinetic energy is increased. This behavior suggests that the collisional energy transfer exhibits a pronounced increase around some specific value of energy. Finally, the model is tested against the CID mass spectra of anthracene and pyrene ions and the corresponding results are discussed.

  5. Modeling collision energy transfer in APCI/CID mass spectra of PAHs using thermal-like post-collision internal energy distributions

    NASA Astrophysics Data System (ADS)

    Solano, Eduardo A.; Mohamed, Sabria; Mayer, Paul M.

    2016-10-01

    The internal energy transferred when projectile molecular ions of naphthalene collide with argon gas atoms was extracted from the APCI-CID (atmospheric-pressure chemical ionization collision-induced dissociation) mass spectra acquired as a function of collision energy. Ion abundances were calculated by microcanonical integration of the differential rate equations using the Rice-Ramsperger-Kassel-Marcus rate constants derived from a UB3LYP/6-311G+(3df,2p)//UB3LYP/6-31G(d) fragmentation mechanism and thermal-like vibrational energy distributions p M (" separators=" E , T char ) . The mean vibrational energy excess of the ions was characterized by the parameter Tchar ("characteristic temperature"), determined by fitting the theoretical ion abundances to the experimental breakdown graph (a plot of relative abundances of the ions as a function of kinetic energy) of activated naphthalene ions. According to these results, the APCI ion source produces species below Tchar = 1457 K, corresponding to 3.26 eV above the vibrational ground state. Subsequent collisions heat the ions up further, giving rise to a sigmoid curve of Tchar as a function of Ecom (center-of-mass-frame kinetic energy). The differential internal energy absorption per kinetic energy unit (dEvib/dEcom) changes with Ecom according to a symmetric bell-shaped function with a maximum at 6.38 ± 0.32 eV (corresponding to 6.51 ± 0.27 eV of vibrational energy excess), and a half-height full width of 6.30 ± 1.15 eV. This function imposes restrictions on the amount of energy that can be transferred by collisions, such that a maximum is reached as kinetic energy is increased. This behavior suggests that the collisional energy transfer exhibits a pronounced increase around some specific value of energy. Finally, the model is tested against the CID mass spectra of anthracene and pyrene ions and the corresponding results are discussed.

  6. The Luminosity Profile and Structural Parameters of the Andromeda Galaxy

    NASA Astrophysics Data System (ADS)

    Courteau, Stéphane; Widrow, Lawrence M.; McDonald, Michael; Guhathakurta, Puragra; Gilbert, Karoline M.; Zhu, Yucong; Beaton, Rachael Lynn; Majewski, Steven R.

    2011-09-01

    We have constructed an extended composite luminosity profile for the Andromeda galaxy, M31, and have decomposed it into three basic luminous structural components: a bulge, a disk, and a halo. The dust-free Spitzer/Infrared Array Camera (IRAC) imaging and extended spatial coverage of ground-based optical imaging and deep star counts allow us to map M31's structure from its center to 22 kpc along the major axis. We apply, and address the limitations of, different decomposition methods for the one-dimensional luminosity profiles and two-dimensional images. These methods include nonlinear least-squares and Bayesian Monte Carlo Markov chain analyses. The basic photometric model for M31 has a Sérsic bulge with shape index n ~= 2.2 ± .3 and effective radius Re = 1.0 ± 0.2 kpc, and a dust-free exponential disk of scale length Rd = 5.3 ± .5 kpc the parameter errors reflect the range between different decomposition methods. Despite model covariances, the convergence of solutions based on different methods and current data suggests a stable set of structural parameters. The ellipticities (epsilon = 1 - b/a) of the bulge and the disk from the IRAC image are 0.37 ± 0.03 and 0.73 ± 0.03, respectively. The bulge parameter n is rather insensitive to bandpass effects and its value (2.2) suggests a first rapid formation via mergers followed by secular growth from the disk. The M31 halo has a two-dimensional power-law index ~= - 2.5 ± 0.2 (or -3.5 in three-dimensional), comparable to that of the Milky Way. We find that the M31 bulge light is mostly dominant over the range R min <~ 1.2 kpc. The disk takes over in the range 1.2 kpc <~ R min <~ 9 kpc, whereas the halo dominates at R min >~ 9 kpc. The stellar nucleus, bulge, disk, and halo components each contribute roughly 0.05%, 23%, 73%, and 4% of the total light of M31 out to 200 kpc along the minor axis. Nominal errors for the structural parameters of the M31 bulge, disk, and halo amount to 20%. If M31 and the Milky Way are

  7. Failed Collapsar Jets to Explain Low Luminosity GRB Properties

    NASA Astrophysics Data System (ADS)

    Hamidani, Hamid; Umeda, Hideyuki; Takahashi, Koh

    Using the collapsar scenario for long GRBs [1], we present series of numerical simulations to investigate properties of expanding jets, driven by engines deploying the same total energy (1052 erg), differently. We include a wide range of engine durations (Tinj), from 0.1 to 100 s, as well as different initial opening angles (θ0) for the deployed energy. We employ an AMR 2D special relativistic hydrodynamical code, using a 25 solar mass Wolf-Rayet star as the progenitor [2]. We analyze the effect of the engine duration on the jet's hydrodynamic properties, and discuss the implications on GRB and SN emissions. Our results show that the expanding jet's hydrodynamical properties significantly differ, in particular outflow collimation and relativistic acceleration. The implication of this is that brief engines (with Tinj < Tbreakout, either due to a short Tinj or to a large θ0) represent excellent systems to explain the debated low-luminosity GRBs (llGRBs), displaying two of llGRBs peculiar features: i) the estimated llGRBs rate at least about 100 times higher than that of GRBs [3,4,5], and ii) potentially energetic SN emission [6]. We find that these two features only arise from brief engines. The conclusion is that brief engines dominate collapsars, at least at low redshift.

  8. 'Harder when Brighter' Spectral Variability in Low-Luminosity AGN

    NASA Astrophysics Data System (ADS)

    Connolly, S.; McHardy, I.; Skipper, C.; Dwelly, T.

    2015-07-01

    We present X-ray spectral variability of four low accretion rate AGN - M81, NGC 1097, NGC 1052 and NGC 3998 - as observed by Swift and RXTE. All four objects were selected due to having spectra which hardened with increasing count rate, converse to the `softer when brighter' behaviour normally observed in AGN with higher accretion rates. The spectra were summed in flux bins and fitted with a variety of models. A simple absorbed power law model was found to fit the spectra of M81, NGC 1097 and NGC 3998 well, whilst NGC 1052 required a partially covered power law model. In all four cases, the most likely main source of spectral variability is found to be luminosity-dependent changes in the photon index of the power law component. An anticorrelation between the photon index and the count rate is found in all of the sources. The anticorrelation is likely to be caused by accretion via a radiatively-inefficient accretion flow, expected in low-Eddington ratio systems such as these, and/or due to the presence of a jet. This behaviour is similar to that seen in the `hard state' of X-ray binaries, implying that these LLAGN are in a similar state.

  9. The mass-luminosity relation in an introductory astronomy lab

    NASA Astrophysics Data System (ADS)

    LoPresto, Michael C.

    2016-11-01

    Exposing students in general education science courses of lower mathematical levels to experiments that make use of quantitative skills such as collecting and analyzing data is very important because they provide examples of how science is actually done. Experiments with relatively simple procedures that are also interesting and engaging which serve this purpose can be hard to find. This can especially be true for introductory college astronomy courses; however, courses of this type often do still have a laboratory component because most students, regardless of major, are required to take at least one laboratory science course. When required to work with data in a quantitative fashion, the difficulty students with lower mathematical skills often have is that any actual physical meaning of an experiment can become completely lost in a procedure that, to them, seems to be purely an exercise in complex mathematics and for which they have resorted to simply following by rote, from which, perhaps needless to say, they are likely to learn little or nothing. I have seen this happen numerous times and it has inspired me to focus on attempting to develop meaningful laboratory experiences for students of lower mathematical level courses, such as introductory astronomy and conceptual physics, that involve both the gathering and analysis of numerical data. What follows is a simple experiment of this type on the mass-luminosity relation for stars on the main sequence of the Hertzsprung-Russell diagram that has proven useful for an introductory astronomy laboratory course.

  10. ATLAS ALFA—measuring absolute luminosity with scintillating fibres

    NASA Astrophysics Data System (ADS)

    Franz, S.; Barrillon, P.

    2009-10-01

    ALFA is a high-precision scintillating fibre tracking detector under construction for the absolute determination of the LHC luminosity at the ATLAS interaction point. This detector, mounted in so-called Roman Pots, will track protons elastically scattered under μrad angles at IP1.In total there are four pairs of vertically arranged detector modules which approach the LHC beam axis to mm distance. Each detector module consists of ten layers of two times 64 scintillating fibres each (U and V planes). The fibres are coupled to 64 channels Multi-Anodes PhotoMultipliers Tubes read out by compact front-end electronics. Each detector module is complemented by so-called overlap detectors: Three layers of two times 30 scintillating fibres which will be used to measure the relative positioning of two vertically arranged main detectors. The total number of channels is about 15000. Conventional plastic scintillator tiles are mounted in front of the fibre detectors and will serve as trigger counter. The extremely restricted space inside the pots makes the coupling to the read out devices very challenging. Several technologies have been tested in a beam at DESY and a cosmic-ray setup at CERN. A possible upgrade of the photo detection could consist in the replacement of the PMT by Geiger-mode avalanche photodiodes. Preliminary tests are being performed comparing the performance of these devices with the ones of the PMTs.

  11. Type II intermediate-luminosity optical transients (ILOTs)

    NASA Astrophysics Data System (ADS)

    Kashi, Amit; Soker, Noam

    2017-01-01

    We propose that in a small fraction of intermediate luminosity optical transients (ILOTs) powered by a strongly interacting binary system, the ejected mass in the equatorial plane can block the central source from our line of sight. We can therefore observe only radiation that is reprocessed by polar outflow, much as in type II active galactic nuclei (AGN). An ejection of M_ej,e=10^{-4} M_⊙ (1 M_⊙) at 30 degrees from the equatorial plane and at a velocity of v_e = 100 {km} {s}^{-1} will block the central source in the NIR for about 5 years (500 years). During that period of time the object might disappear in the visible band, and be detected only in the IR band due to polar dust. We raise the possibility that the recently observed disappearance of a red giant in the visible, designated N6946-BH1, is a type II ILOT rather than a failed supernova. For this case we estimate that the ejected mass in the polar direction was M_ej,p≈ 10^{-3} M_⊙. Our scenario predicts that this event should reinstate its visible emission in several decades.

  12. Understanding Intermediate-luminosity X- ray Objects and their Environments

    NASA Astrophysics Data System (ADS)

    Ptak, Andrew

    2002-07-01

    X-ray observations of normal galaxies with ROSAT, ASCA and Chandra have revealed that off-nuclear, compact, Intermediate- luminosity {L_X sim10^39-40 erg/s} X-ray Objects {IXOs} are quite common. On average, we find that 1 in every 5 galaxies contains one of these intriguing objects, based on our ROSAT HRI catalog, which is the most complete IXO catalog yet known. IXOs have received wide attention as putative intermediate- mass black holes with masses 10^2-10^5 M_odot, which would be quite interesting and puzzling. It is also possible that IXOs are ``ordinary'' X-ray binaries with stellar-mass black holes, and their X-ray emission is mildly beamed. Otherwise, little is known about the geometrical and physical properties of this exciting new class of astrophysical objects. X-ray observations of IXOs alone have not been able to provide good diagnostics. Deep, high spatial resolution optical imaging observations can provide important clues to their nature by examining the environment around the accreting black hole. We request funding to analyze 267 HST archival images for 38 IXOs from our catalog in order to search for individual stellar companions and star clusters that may be associated with IXOs, and to generally identify the nature of the regions harboring IXOs. This AR proposal is a companion to a SNAP proposal by PI Colbert, which proposes to image IXOs for which no HST imaging exists yet.

  13. Influence of luminosity bursts on properties of protostellar disks

    NASA Astrophysics Data System (ADS)

    Vorobyov, E. I.; Pavlyuchenkov, Ya. N.; Trinkl, P.

    2014-08-01

    A (2+ 1)-dimensional numerical model for the formation and evolution of young stellar objects with sub-solar masses is presented. The numerical hydrodynamicall code describing the formation and evolution of a protostellar disk in a two-dimensional approximation is supplemented by one-dimensional code for the evolution of the star and an algorithm for establishing the vertical structure of the disk. This code is used to investigate the influence of luminosity bursts with intensities similar to those observed in FU Orionis objects (FUors) on the properties and thermal balance of protostellar disks. A model with gravitational instability and fragmentation of the disk, with subsequent migration of the fragments onto the protostar, is used as a basic model for FUors. Typical FUor bursts ( L ˜ 100 L ⊙) can appreciably influence the thermal balance of their disks and parent envelopes, leading to an increase in the disk temperature by more than a factor of two. On the other hand, massive fragments in the disk are only weakly perturbed by such bursts, partially due to screening by the disk and partially due to their high temperature brought about by adiabatic heating. Apart from massive fragments, the characteristic thermal time scales are appreciably shorter than the dynamical time scales throughout the radial extent of the disk and envelope; this enables the use of a stationary radiative-transfer equation when determining the vertical structure of the disk.

  14. Red and Blue Shifted Broad Lines in High Luminosity QSOs

    NASA Astrophysics Data System (ADS)

    McIntosh, D. H.; Rieke, M. J.; Rix, H.-W.; Foltz, C. B.; Weymann, R. J.; Chaffee, F. H.

    1998-05-01

    We have observed a sample of 25 high luminosity QSOs, in the range 2.0 ≲ z ≲ 2.5, at 1.6micron with the near-infrared spectrograph FSPEC on the Multiple Mirror Telescope. We have measured the systemic redshift z_sys by direct detection of the strong [O 3]lambda5007 line emitted from the narrow-line-region. We have found that the broad Hβ lines, from the same spectra, have a systematic mean red shift of 530+/-80 km s(-1) with respect to systemic. From data in the literature, we have found that the high ionization, rest-frame ultraviolet broad lines C 4lambda1549 and Lyalpha are systematically blue shifted ~ 1500 km s(-1) and ~ 1000 km s(-1) , respectively, from systemic. Therefore, estimating the ionizing flux from the inter-galactic-medium J_ν() IGM via the Proximity Effect, using redshift measurements from these two broad line species, results in an over-estimation of J_ν() IGM by factors of 2.5-4.0. Furthermore, related calculations of the lower limit for the density of baryons Omega_b will be over-estimated by factors of 1.6-2.0. However, the low ionization broad line Mg 2lambda2798 is within 100 km s(-1) of systemic, and thus would be the line of choice for determining the true redshift of distant (z>1) QSOs without near-infrared spectroscopy.

  15. Quasar UV luminosity function evolution up to z = 8

    NASA Astrophysics Data System (ADS)

    Manti, S.; Gallerani, S.; Ferrara, A.; Greig, B.; Feruglio, C.

    2017-04-01

    We study the redshift evolution of the quasar (QSO) UV luminosity function (LF) for 0.5 < z < 6.5, by collecting the most up to date observational data and, in particular, the recently discovered population of faint active galactic nuclei (AGNs). We fit the QSO LF using either a double power-law function or a Schechter function, finding that both forms provide good fits to the data. We derive empirical relations for the LF parameters as a function of redshift and, based on these results, predict the QSO UV LF at z = 8. From the inferred LF evolution, we compute the redshift evolution of the QSO/AGN comoving ionizing emissivity and hydrogen photoionization rate. If faint AGNs are included, the contribution of QSOs to reionization increases substantially. However, their level of contribution critically depends on the detailed shape of the QSO LF, which can be constrained by efficient searches of high-z QSOs. To this aim, we predict the expected (i) number of z > 6 QSOs detectable by ongoing and future near-infrared surveys (as EUCLID and Wide-Field Infrared Survey Telescope), and (ii) number counts for a single radio-recombination line observation with Square Kilometre Array-MID (FoV = 0.49 deg2) as a function of the Hnα flux density, at 0 < z < 8. These surveys (even at z < 6) will be fundamental to better constrain the role of QSOs as reionization sources.

  16. Luminosity distance in Swiss-cheese cosmology with randomized voids and galaxy halos

    NASA Astrophysics Data System (ADS)

    Flanagan, Éanna É.; Kumar, Naresh; Wasserman, Ira

    2013-08-01

    We study the fluctuations in luminosity distance due to gravitational lensing produced both by galaxy halos and large-scale voids. Voids are represented via a “Swiss-cheese” model consisting of a ΛCDM Friedmann-Robertson-Walker background from which a number of randomly distributed, spherical regions of comoving radius 35 Mpc are removed. A fraction of the removed mass is then placed on the shells of the spheres, in the form of randomly located halos. The halos are assumed to be nonevolving and are modeled with Navarro-Frenk-White profiles of a fixed mass. The remaining mass is placed in the interior of the spheres, either smoothly distributed or as randomly located halos. We compute the distribution of magnitude shifts using a variant of the method of Holz and Wald [Phys. Rev. D 58, 063501 (1998)], which includes the effect of lensing shear. In the two models we consider, the standard deviation of this distribution is 0.065 and 0.072 magnitudes and the mean is -0.0010 and -0.0013 magnitudes, for voids of radius 35 Mpc and the sources at redshift 1.5, with the voids chosen so that 90% of the mass is on the shell today. The standard deviation due to voids and halos is a factor ˜3 larger than that due to 35 Mpc voids alone with a 1 Mpc shell thickness, which we studied in our previous work. We also study the effect of the existence of evacuated voids, by comparing to a model where all the halos are randomly distributed in the interior of the sphere with none on its surface. This does not significantly change the variance but does significantly change the demagnification tail. To a good approximation, the variance of the distribution depends only on the mean column density of halos (halo mass divided by its projected area), the concentration parameter of the halos, and the fraction of the mass density that is in the form of halos (as opposed to smoothly distributed); it is independent of how the halos are distributed in space. We derive an approximate analytic

  17. Ultra-faint ultraviolet galaxies at z ∼ 2 behind the lensing cluster A1689: The luminosity function, dust extinction, and star formation rate density

    SciTech Connect

    Alavi, Anahita; Siana, Brian; Freeman, William R.; Dominguez, Alberto; Richard, Johan; Stark, Daniel P.; Robertson, Brant; Scarlata, Claudia; Teplitz, Harry I.; Rafelski, Marc; Kewley, Lisa

    2014-01-10

    We have obtained deep ultraviolet imaging of the lensing cluster A1689 with the WFC3/UVIS camera onboard the Hubble Space Telescope in the F275W (30 orbits) and F336W (4 orbits) filters. These images are used to identify z ∼ 2 star-forming galaxies via their Lyman break, in the same manner that galaxies are typically selected at z ≥ 3. Because of the unprecedented depth of the images and the large magnification provided by the lensing cluster, we detect galaxies 100× fainter than previous surveys at this redshift. After removing all multiple images, we have 58 galaxies in our sample in the range –19.5 < M {sub 1500} < –13 AB mag. Because the mass distribution of A1689 is well constrained, we are able to calculate the intrinsic sensitivity of the observations as a function of source plane position, allowing for accurate determinations of effective volume as a function of luminosity. We fit the faint-end slope of the luminosity function to be α = –1.74 ± 0.08, which is consistent with the values obtained for 2.5 < z < 6. Notably, there is no turnover in the luminosity function down to M {sub 1500} = –13 AB mag. We fit the UV spectral slopes with photometry from existing Hubble optical imaging. The observed trend of increasingly redder slopes with luminosity at higher redshifts is observed in our sample, but with redder slopes at all luminosities and average reddening of (E(B – V)) = 0.15 mag. We assume the stars in these galaxies are metal poor (0.2 Z {sub ☉}) compared to their brighter counterparts (Z {sub ☉}), resulting in bluer assumed intrinsic UV slopes and larger derived values for dust extinction. The total UV luminosity density at z ∼ 2 is 4.31{sub −0.60}{sup +0.68}×10{sup 26} erg s{sup –1} Hz{sup –1} Mpc{sup –3}, more than 70% of which is emitted by galaxies in the luminosity range of our sample. Finally, we determine the global star formation rate density from UV-selected galaxies at z ∼ 2 (assuming a constant dust

  18. The X-ray luminosity functions of Abell clusters from the Einstein Cluster Survey

    NASA Technical Reports Server (NTRS)

    Burg, R.; Giacconi, R.; Forman, W.; Jones, C.

    1994-01-01

    We have derived the present epoch X-ray luminosity function of northern Abell clusters using luminosities from the Einstein Cluster Survey. The sample is sufficiently large that we can determine the luminosity function for each richness class separately with sufficient precision to study and compare the different luminosity functions. We find that, within each richness class, the range of X-ray luminosity is quite large and spans nearly a factor of 25. Characterizing the luminosity function for each richness class with a Schechter function, we find that the characteristic X-ray luminosity, L(sub *), scales with richness class as (L(sub *) varies as N(sub*)(exp gamma), where N(sub *) is the corrected, mean number of galaxies in a richness class, and the best-fitting exponent is gamma = 1.3 +/- 0.4. Finally, our analysis suggests that there is a lower limit to the X-ray luminosity of clusters which is determined by the integrated emission of the cluster member galaxies, and this also scales with richness class. The present sample forms a baseline for testing cosmological evolution of Abell-like clusters when an appropriate high-redshift cluster sample becomes available.

  19. Quark anomalous chromomagnetic moment bounds -- Projection to higher luminosities and energy

    SciTech Connect

    Cheung, K.; Silverman, D.

    1998-12-31

    The statistical limits on detectability of an anomalous chromomagnetic moment of a quark coupling to a gluon are projected to higher luminosities at the Tevatron at Fermilab, and to the LHC. They roughly scale as the energy, and are not strongly improved with increasing luminosity.

  20. A Complete Sample of Bright Swift Long Gamma-Ray Bursts. I. Sample Presentation, Luminosity Function and Evolution

    NASA Astrophysics Data System (ADS)

    Salvaterra, R.; Campana, S.; Vergani, S. D.; Covino, S.; D'Avanzo, P.; Fugazza, D.; Ghirlanda, G.; Ghisellini, G.; Melandri, A.; Nava, L.; Sbarufatti, B.; Flores, H.; Piranomonte, S.; Tagliaferri, G.

    2012-04-01

    We present a carefully selected sub-sample of Swift long gamma-ray bursts (GRBs) that is complete in redshift. The sample is constructed by considering only bursts with favorable observing conditions for ground-based follow-up searches, which are bright in the 15-150 keV Swift/BAT band, i.e., with 1-s peak photon fluxes in excess to 2.6 photons s-1 cm-2. The sample is composed of 58 bursts, 52 of them with redshift for a completeness level of 90%, while another two have a redshift constraint, reaching a completeness level of 95%. For only three bursts we have no constraint on the redshift. The high level of redshift completeness allows us for the first time to constrain the GRB luminosity function and its evolution with cosmic times in an unbiased way. We find that strong evolution in luminosity (δ l = 2.3 ± 0.6) or in density (δ d = 1.7 ± 0.5) is required in order to account for the observations. The derived redshift distributions in the two scenarios are consistent with each other, in spite of their different intrinsic redshift distributions. This calls for other indicators to distinguish among different evolution models. Complete samples are at the base of any population studies. In future works we will use this unique sample of Swift bright GRBs to study the properties of the population of long GRBs.

  1. Very low luminosity active galaxies and the X-ray background

    NASA Technical Reports Server (NTRS)

    Elvis, M.; Soltan, A.; Keel, W. C.

    1984-01-01

    The properties of very low luminosity active galactic nuclei are not well studied, and, in particular, their possible contribution to the diffuse X-ray background is not known. In the present investigation, an X-ray luminosity function for the range from 10 to the 39th to 10 to the 42.5th ergs/s is constructed. The obtained X-ray luminosity function is integrated to estimate the contribution of these very low luminosity active galaxies to the diffuse X-ray background. The construction of the X-ray luminosity function is based on data obtained by Keel (1983) and some simple assumptions about optical and X-ray properties.

  2. Optical Variability of Quasars as a Function of Luminosity and Redshift

    NASA Astrophysics Data System (ADS)

    Gaskell, C. M.; Koratkar, A. P.; Kwon, T.-Y.; Liang, Y.; Scott, J. H.; Wysota, A.

    1987-09-01

    Various models of the "central engine" in quasars make different predictions of how the degree of variability and its timescale vary with luminosity. In the past there have been conflicting claims about the luminosity and redshift dependence of quasar variability. We have examined the photographic light curves obtained at the Rosemary Hill Observatory (U. of Florida) and the Royal Greenwich Observatory (Herstmonceux) for over a hundred quasars (both radio-loud and radio-quiet). We demonstrate how the previously-reported redshift dependence is a consequence of time dilation, and find that, after allowance for this, there is no luminosity dependence in the amplitude of variability. High-luminosity quasars are not less variable than their low-luminosity counterparts. This creates major difficulties for some classes of quasar model with discrete accretion events (e.g., gas cloud or disrupted stars being "swallowed" directly).

  3. Development of the Continuous Acquisition Pixel (CAP) sensor for high luminosity lepton colliders

    NASA Astrophysics Data System (ADS)

    Varner, G.; Aihara, H.; Barbero, M.; Bozek, A.; Browder, T.; Hazumi, M.; Kennedy, J.; Martin, E.; Mueller, J.; Olsen, S.; Palka, H.; Rosen, M.; Ruckman, L.; Stanič, S.; Trabelsi, K.; Tsuboyama, T.; Uchida, K.; Yang, Q.; Yarema, R.

    2006-09-01

    A future higher luminosity B-factory detector and concept study detectors for the proposed International Linear Collider require precision vertex reconstruction while coping with high track densities and radiation exposures. Compared with current silicon strip and hybrid pixels, a significant reduction in the overall detector material thickness is needed to achieve the desired vertex resolution. Considerable progress in the development of thin CMOS-based Monolithic Active Pixel Sensors (MAPS) in recent years makes them a viable technology option and feasibility studies are being actively pursued. The most serious concerns are their radiation hardness and their readout speed. To address these, several prototypes denoted as the Continuous Acquisition Pixel (CAP) sensors have been developed and tested. The latest of the CAP sensor prototypes is CAP3, designed in the TSMC 0.25 μm process with a 5-deep Correlated Double Sample (CDS) pair pipeline in each pixel. A setup with several CAP3 sensors is under evaluation to assess the performance of a full-scale pixel readout system running at realistic readout speed. Given the similarity in the occupancy numbers and hit throughput requirements, per unit area, between a Belle vertex detector upgradation and the requirements for a future ILC pixel detector, this effort can be considered a small-scale functioning prototype for such a future system. The results and plans for the next stages of R&D towards a full Belle Pixel Vertex Detector (PVD) are presented.

  4. Operation of the Cherenkov Detector DIRC of BaBar at High Luminosity

    SciTech Connect

    Spanier, Stefane

    2001-03-07

    The DIRC (acronym for Detection of Internally Reflected Cherenkov (light)) is the ring imaging Cherenkov detector of the BaBar detector at the Pep-II ring of SLAC. It provides the identification of pions, kaons and protons for momenta up to 4 GeV/c with high efficiency. This is needed to reconstruct CP-violating B-decay final states and to provide B-meson flavour tagging for time dependent asymmetry measurements. The DIRC radiators consists of long rectangular bars made of synthetic fused silica and the photon detector is a water tank equipped with an array of 10,752 conventional photomultipliers. At the end of the year 2000 BaBar has recorded about 22 million {bar B}B pairs reaching the design luminosity of L = 3 x 10{sup 33}/cm{sup 2}s. The ability to keep the beam background level low at highest collision rates and the long term reliability of the DIRC components during continuous data taking are requirements of BaBar to accomplish its physics program.

  5. Globular Cluster Luminosity Functions and Specific Frequencies in Dwarf Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Miller, B. W.; Lotz, J. M.

    2005-12-01

    We present the final results on the globular cluster luminosity functions (GCLFs) and specific frequencies (SN) from 69 dwarf elliptical galaxies in the HST Dwarf Elliptical Galaxy Snapshot Survey (Lotz et al. 2004). The GCLFs for the Virgo and Fornax clusters are well fit by a t5 function with a peak at MV0=-7.25 ± 0.2 and an equivalent Gaussian sigma of 1.2 magnitudes. These values are very similar to those of globular clusters systems in giant elliptical galaxies. We also confirm our previous results (Miller et al. 1998) that SN in nucleated dwarfs is about a factor of two higher than in non-nucleated dwarfs. We also discuss the fraction of the stellar mass in dwarf elliptical galaxies that is currently found in globular clusters. Supported by the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., on behalf of the international Gemini partnership of Argentina, Australia, Brazil,