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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. Luminosity Distribution for Broad Absorption Line QSOs

    NASA Astrophysics Data System (ADS)

    Cales, S. L.; Canalizo, G.; Lacy, M.

    2004-12-01

    The relationship of Broad Absorption Line (BAL) QSOs to the general QSO population remains uncertain. We present a preliminary set of BALQSOs from a large sample of BALQSOs identified from the SDSS Data Release 2 (DR2) Catalog in order to further study the relationship. The use of the SDSS DR2 allows us to access a much larger population of BAL and non-BAL QSOs relative to previous studies. To inspect this relationship we use spectroscopic data from SDSS to compare BALQSO luminosity distributions with those of the non-BALQSO population. Within the BALQSO population, high (Hi) and low (Lo) ionization classifications are studied in relation with their luminosity distribution. Preliminary results show the LoBALQSOs appearing less luminous than the general population and more numerous that previously suggested. Their distribution also shows a secondary peak not observed in the other types of QSOs. From this data we look at three questions; first, are BALQSOs more or less luminous than the non-BALQSO population, second, are there changes in the luminosity of these types of QSOs as a function of redshift, and lastly, how do these results clarify the relationship between BALQSOs and non-BALQSOs. A discussion of possible selection effects is also included.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Distribution of Maximal Luminosity of Galaxies in the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Regős, E.; Szalay, A.; Rácz, Z.; Taghizadeh, M.; Ozogany, K.

    2014-05-01

    Extreme value statistics (EVS) is applied to the pixelized distribution of galaxy luminosities in the Sloan Digital Sky Survey (SDSS). We analyze the DR8 Main Galaxy Sample (MGS) as well as the Luminous Red Galaxy Sample (LRGS). A non-parametric comparison of the EVS of the luminosities with the Fisher-Tippett-Gumbel distribution (limit distribution for independent variables distributed by the Press-Schechter law) indicates a good agreement provided uncertainties arising both from the finite size of the samples and from the sample size distribution are accounted for. This effectively rules out the possibility of having a finite maximum cutoff luminosity.

  10. Distribution of Maximal Luminosity of Galaxies in the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Taghizadeh-Popp, M.; Ozogány, K.; Rácz, Z.; Regoes, E.; Szalay, A. S.

    2012-11-01

    Extreme value statistics is applied to the distribution of galaxy luminosities in the Sloan Digital Sky Survey. We analyze the DR8 Main Galaxy Sample (MGS), as well as the luminous red galaxies (LRGs). Maximal luminosities are sampled from batches consisting of elongated pencil beams in the radial direction of sight. For the MGS, results suggest a small and positive tail index ξ, effectively ruling out the possibility of having a finite maximum cutoff luminosity, and implying that the luminosity distribution function may decay as a power law at the high-luminosity end. Assuming, however, ξ = 0, a non-parametric comparison of the maximal luminosities with the Fisher-Tippett-Gumbel distribution (limit distribution for variables distributed by the Schechter fit) indicates a good agreement provided that uncertainties arising from both the finite batch size and the batch-size distribution are accounted for. For a volume-limited sample of LRGs, results show that they can be described as being the extremes of a luminosity distribution with an exponentially decaying tail, provided that the uncertainties related to batch-size distribution are taken care of.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Luminosity and surface brightness distribution of K-band galaxies from the UKIDSS Large Area Survey

    NASA Astrophysics Data System (ADS)

    Smith, Anthony J.; Loveday, Jon; Cross, Nicholas J. G.

    2009-08-01

    We present luminosity and surface-brightness distributions of 40111 galaxies with K-band photometry from the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS). Various features and limitations of the new UKIDSS data are examined, such as a problem affecting Petrosian magnitudes of extended sources. Selection limits in K- and r-band magnitude, K-band surface brightness and K-band radius are included explicitly in the 1/Vmax estimate of the space density and luminosity function. The bivariate brightness distribution in K-band absolute magnitude and surface brightness is presented and found to display a clear luminosity-surface brightness correlation that flattens at high luminosity and broadens at low luminosity, consistent with similar analyses at optical wavelengths. Best-fitting Schechter function parameters for the K-band luminosity function are found to be M* - 5 logh = -23.19 +/- 0.04,α = -0.81 +/- 0.04 and φ* = (0.0166 +/- 0.0008)h3Mpc-3, although the Schechter function provides a poor fit to the data at high and low luminosity, while the luminosity density in the K band is found to be j = (6.305 +/- 0.067) × 108LsolarhMpc-3. However, we caution that there are various known sources of incompleteness and uncertainty in our results. Using mass-to-light ratios determined from the optical colours, we estimate the stellar mass function, finding good agreement with previous results. Possible improvements are discussed that could be implemented when extending this analysis to the full LAS.

  17. The Bivariate Size-luminosity Distribution Of Z 4-5 LBGs In The Goods Fields

    NASA Astrophysics Data System (ADS)

    Huang, Kuang-Han; Ferguson, H. C.; Ravindranath, S.

    2011-05-01

    We study the bivariate size-luminosity distribution of z 4 and z 5 Lyman Break Galaxies (LBG) in the GOODS fields. Our sample was selected using the Lyman Break color selection criteria in order to select rest-frame UV-bright star forming galaxies. We selected around 1250 B-dropouts (z 4) and 370 V-dropouts (z 5) in both GOODS fields and the HUDF field, down to ACS F850LP magnitude z_{850} = 26.5 (GOODS ACS dataset) and z_{850}=28.0 (HUDF dataset). We model the size distribution as a lognormal distribution and the luminosity function in the Schechter function form, and connect them with a power law relation between the peak size r_0 and the absolute magnitude M, r_0 = r*(M/M*)^{β}. Galaxy magnitude and size are measured first with SExtractor, then we use GALFIT to fit a single Sersic component to derive the effective radius. We also performed a Monte Carlo simulation in order to account for the measurement bias and scatter of SExtractor and GALFIT. The result of the simulation is convolved with the size-luminosity distribution models to compare with the observed distributions. We will compare our best-fit distribution with the luminosity functions published in the literature at similar redshifts.

  18. 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.

  19. 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.

  20. Differential Density Statistics of the Galaxy Distribution and the Luminosity Function

    NASA Astrophysics Data System (ADS)

    Albani, V. V. L.; Iribarrem, A. S.; Ribeiro, M. B.; Stoeger, W. R.

    2007-03-01

    This paper uses data obtained from the galaxy luminosity function (LF) to calculate two types of radial number density statistics of the galaxy distribution as discussed in Ribeiro, namely, the differential density γ and the integral differential density γ*. By applying the theory advanced by Ribeiro & Stoeger, which connects the relativistic cosmology number counts with the astronomically derived LF, the differential number counts dN/dz are extracted from the LF and used to calculate both γ and γ* with various cosmological distance definitions, namely, area distance, luminosity distance, galaxy area distance, and redshift distance. LF data are taken from the CNOC2 galaxy redshift survey, and γ and γ* are calculated for two cosmological models: Einstein-de Sitter and an Ωm0=0.3, ΩΛ0=0.7 standard cosmology. The results confirm the strong dependency of both statistics on the distance definition, as predicted in Ribeiro, as well as showing that plots of γ and γ* against the luminosity and redshift distances indicate that the CNOC2 galaxy distribution follows a power-law pattern for redshifts higher than 0.1. These findings support Ribeiro's theoretical proposition that using different cosmological distance measures in statistical analyses of galaxy surveys can lead to significant ambiguity in drawing conclusions about the behavior of the observed large-scale distribution of galaxies.

  1. 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

  2. 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.

  3. Can cluster merger shocks reproduce the luminosity and shape distribution of radio relics?

    NASA Astrophysics Data System (ADS)

    Nuza, Sebastián E.; Gelszinnis, Jakob; Hoeft, Matthias; Yepes, Gustavo

    2017-09-01

    Radio relics in galaxy clusters are believed to trace merger shock fronts. If cosmological structure formation determines the luminosity, size and shape distributions of radio relics, then merger shocks need to be lighted up in a homogeneous way. We investigate if a mock relic sample, obtained from zoomed galaxy cluster simulations, is able to match the properties of relics measured in the NRAO VLA Sky Survey (NVSS). We compile a list of all radio relics known to date and homogeneously measure their parameters in all NVSS images and apply the same procedure to relics in our simulations. Number counts in the mock relic sample increase more steeply towards lower relic flux densities, suggesting an incompleteness of NVSS in this regime. Overall, we find that NVSS and mock samples show similar properties. However, large simulated relics tend to be somewhat smaller and closer to the cluster centre than observed ones. Besides this, the mock sample reproduces very well-known correlations for radio relics, in particular those relating the radio luminosity with the largest linear size and the X-ray luminosity. We show that these correlations are largely governed by the sensitivity of the NVSS observations. Mock relics show a similar orientation with respect to the direction to the cluster centre as the NVSS sample. Moreover, we find that their maximum radio luminosity roughly correlates with cluster mass, although displaying a large scatter. The overall good agreement between NVSS and the mock sample suggests that properties of radio relics are indeed governed by merger shock fronts, emitting in a homogeneous fashion. Our study demonstrates that the combination of mock observations and data from upcoming radio surveys will allow us to shed light on both the origin of radio relics and the nature of the intracluster medium.

  4. 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

  5. Planetary distribution of the intensity of Auroral luminosity obtained using a model of Aurora precipitation

    NASA Astrophysics Data System (ADS)

    Vorobjev, V. G.; Kirillov, A. S.; Katkalov, Ju. V.; Yagodkina, O. I.

    2013-11-01

    A model of auroral precipitation (AP) developed on the basis of statistical processing of DMSP F6 and F7 satellite data (Vorobjev and Yagodkina, 2005, 2007) was used for the calculation of the global distribution of the auroral luminosity in different spectral ranges. The algorithm for the calculation of the integral intensity in bands N2 LBH (170.0 nm), ING N{2/+} (391.4 nm), 1PG N2 (669.0 nm), and (OI) 557.7-nm emission is shown in detail. The processes of formation of electronically excited atoms O(1S) as a result of the transport of excitation energy from metastable state N2(A3Σ{u/+}), excitation of O(3P) by primary and secondary electrons, and dissociative recombination were taken into account to calculate the intensity of emission at 557.7 nm. A high correlation between the model distribution of the auroral luminosity in the UV spectral range and the observations of the Polar satellite is demonstrated.

  6. Power supply distribution system for calorimeters at the LHC beyond the nominal luminosity

    NASA Astrophysics Data System (ADS)

    Tenti, P.; Spiazzi, G.; Buso, S.; Riva, M.; Maranesi, P.; Belloni, F.; Cova, P.; Menozzi, R.; Delmonte, N.; Bernardoni, M.; Iannuzzo, F.; Busatto, G.; Porzio, A.; Velardi, F.; Lanza, A.; Citterio, M.; Meroni, C.

    2011-06-01

    This paper investigates the use of switching converters for the power supply distribution to calorimeters in the ATLAS experiment when the Large Hadron Collider (LHC) will be upgraded beyond the nominal luminosity. Due to the highly hostile environment the converters must operate in, all the main aspects are considered in the investigation, from the selection of the switching converter topologies to the thermal analysis of components and PCBs, with attention to reliability issues of power devices subject to ionizing radiations. The analysis focuses on the particular, but crucial, case of the power supplies for calorimeters, though several outcomes of the research can profitably be applied to other detectors like muon chambers. Research co-funded by the Italian Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR) and the Istituto Nazionale di Fisica Nucleare (INFN), under the PRIN 2007 program.

  7. The nature of the bimodal luminosity distribution of ultraluminous X-ray pulsars

    NASA Astrophysics Data System (ADS)

    Grebenev, S. A.

    2017-07-01

    The mechanism that can be responsible for the bimodal luminosity distribution of super-Eddington X-ray pulsars in binary systems is pointed out. The transition from the high to low state of these objects is explained by accretion flow spherization due to the radiation pressure at certain (high) accretion rates. The transition between the states can be caused by a gradual change in the accretion rate. The complex behavior of the recently discovered ultraluminous X-ray pulsars M 82 X-2, NGC 5907 ULX-1, and NGC 7793 P13 is explained by the proposed mechanism. The proposed model also naturally explains the measured spinup of the neutron star in these pulsars, which is slower than the expected one by several times.

  8. Cumulative luminosity distributions of supergiant fast X-ray transients in hard X-rays

    NASA Astrophysics Data System (ADS)

    Paizis, A.; Sidoli, L.

    2014-04-01

    We have analysed in a systematic way about nine years of INTEGRAL data (17-100 keV) focusing on supergiant fast X-ray transients (SFXTs) and three classical high-mass X-ray binaries (HMXBs). Our approach has been twofold: image-based analysis, sampled over a ˜ks time frame to investigate the long-term properties of the sources and light-curve-based analysis, sampled over a 100 s time frame to seize the fast variability of each source during its ˜ ks activity. We find that while the prototypical SFXTs (IGR J17544-2619, XTE J1739-302 and SAX J1818.6-1703) are among the sources with the lowest ˜ ks-based duty cycle (<1 per cent activity over nine years of data), when studied at the 100 s level, they are the ones with the highest detection percentage, meaning that, when active, they tend to have many bright short-term flares with respect to the other SFXTs. To investigate in a coherent and self-consistent way all the available results within a physical scenario, we have extracted cumulative luminosity distributions for all the sources of the sample. The characterization of such distributions in hard X-rays, presented for the first time in this work for the SFXTs, shows that a power-law model is a plausible representation for SFXTs, while it can only reproduce the very high luminosity tail of the classical HMXBs, and even then, with a significantly steeper power-law slope with respect to SFXTs. The physical implications of these results within the frame of accretion in wind-fed systems are discussed.

  9. Internal rotation of 13 low-mass low-luminosity red giants in the Kepler field

    NASA Astrophysics Data System (ADS)

    Triana, S. A.; Corsaro, E.; De Ridder, J.; Bonanno, A.; Pérez Hernández, F.; García, R. A.

    2017-06-01

    Context. The Kepler space telescope has provided time series of red giants of such unprecedented quality that a detailed asteroseismic analysis becomes possible. For a limited set of about a dozen red giants, the observed oscillation frequencies obtained by peak-bagging together with the most recent pulsation codes allowed us to reliably determine the core/envelope rotation ratio. The results so far show that the current models are unable to reproduce the rotation ratios, predicting higher values than what is observed and thus indicating that an efficient angular momentum transport mechanism should be at work. Here we provide an asteroseismic analysis of a sample of 13 low-luminosity low-mass red giant stars observed by Kepler during its first nominal mission. These targets form a subsample of the 19 red giants studied previously, which not only have a large number of extracted oscillation frequencies, but also unambiguous mode identifications. Aims: We aim to extend the sample of red giants for which internal rotation ratios obtained by theoretical modeling of peak-bagged frequencies are available. We also derive the rotation ratios using different methods, and compare the results of these methods with each other. Methods: We built seismic models using a grid search combined with a Nelder-Mead simplex algorithm and obtained rotation averages employing Bayesian inference and inversion methods. We compared these averages with those obtained using a previously developed model-independent method. Results: We find that the cores of the red giants in this sample are rotating 5 to 10 times faster than their envelopes, which is consistent with earlier results. The rotation rates computed from the different methods show good agreement for some targets, while some discrepancies exist for others.

  10. Monitoring of Interaction-Point Parameters Using the 3-Dimensional Luminosity Distribution Measured at PEP-II

    SciTech Connect

    Viaud, B.F.; Kozanecki, W.; O'Grady, C.; Thompson, J.; Weaver, M.; /SLAC

    2006-07-28

    The 3-D luminosity distribution at the IP of the SLAC B-Factory is monitored using e{sup +}e{sup -} {yields} e{sup +}e{sup -}, {mu}{sup +}{mu}{sup -} events reconstructed online in the BABAR detector. The transverse centroid and spatial orientation of the luminosity ellipsoid reliably monitor IP orbit drifts. The longitudinal centroid is sensitive to small variations in the average relative RF phase of the beams and provides a detailed measurement of the phase transient along the bunch train. The longitudinal luminosity distribution depends on the e{sup +,-} overlap bunch length and the vertical IP {beta}-functions. Relative variations in horizontal luminous size are detectable at the micron level. In addition to continuous on-line monitoring of all the parameters above, we performed detailed studies of their variation along the bunch train to investigate a temporary luminosity degradation. We also compare {beta}*{sub y} measurements, collected over a year of high-luminosity operation, with HER and LER lattice functions measured by resonant transverse excitation. Our bunch-length measurements are consistent with those obtained by other methods and provide direct evidence for bunch-length modulation.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Globular Cluster Systems in Brightest Cluster Galaxies: Bimodal Metallicity Distributions and the Nature of the High-Luminosity Clusters

    NASA Astrophysics Data System (ADS)

    Harris, William E.; Whitmore, Bradley C.; Karakla, Diane; Okoń, Waldemar; Baum, William A.; Hanes, David A.; Kavelaars, J. J.

    2006-01-01

    We present new (B, I) photometry for the globular cluster systems in eight brightest cluster galaxies (BCGs), obtained with the ACS/WFC camera on the Hubble Space Telescope. In the very rich cluster systems that reside within these giant galaxies, we find that all have strongly bimodal color distributions that are clearly resolved by the metallicity-sensitive (B-I) index. Furthermore, the mean colors and internal color range of the blue subpopulation are remarkably similar from one galaxy to the next, to well within the +/-0.02-0.03 mag uncertainties in the foreground reddenings and photometric zero points. By contrast, the mean color and internal color range for the red subpopulation differ from one galaxy to the next by twice as much as the blue population. All the BCGs show population gradients, with much higher relative numbers of red clusters within 5 kpc of their centers, consistent with their having formed at later times than the blue, metal-poor population. A striking new feature of the color distributions emerging from our data is that for the brightest clusters (MI<-10.5) the color distribution becomes broad and less obviously bimodal. This effect was first noticed by Ostrov et al. and Dirsch et al. for the Fornax giant NGC 1399; our data suggest that it may be a characteristic of many BCGs and perhaps other large galaxies. Our data indicate that the blue (metal-poor) clusters brighter than MI~=-10 become progressively redder with increasing luminosity, following a mass/metallicity scaling relation Z~M0.55. A basically similar relation has been found for M87 by Strader et al. (2005). We argue that these GCS characteristics are consistent with a hierarchical-merging galaxy formation picture in which the metal-poor clusters formed in protogalactic clouds or dense starburst complexes with gas masses in the range 107-1010 Msolar, but where the more massive clusters on average formed in bigger clouds with deeper potential wells where more preenrichment could

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. The ugrizYJHK luminosity distributions and densities from the combined MGC, SDSS and UKIDSS LAS data sets

    NASA Astrophysics Data System (ADS)

    Hill, David T.; Driver, Simon P.; Cameron, Ewan; Cross, Nicholas; Liske, Jochen; Robotham, Aaron

    2010-05-01

    We combine data from the Millennium Galaxy Catalogue, Sloan Digital Sky Survey and UKIRT Infrared Deep Sky Survey Large Area Survey to produce ugrizYJHK luminosity functions and densities from within a common, low-redshift volume (z < 0.1, ~ 71000h-31 Mpc3 for L* systems) with 100 per cent spectroscopic completeness. In the optical the fitted Schechter functions are comparable in shape to those previously reported values but with higher normalizations (typically 0, 30, 20, 15, 5 per cent higher φ* values in u, g, r, i, z, respectively, over those reported by the SDSS team). We attribute these to differences in the redshift ranges probed, incompleteness and adopted normalization methods. In the near-IR (NIR) we find significantly different Schechter function parameters (mainly in the M* values) to those previously reported and attribute this to the improvement in the quality of the imaging data over previous studies. This is the first homogeneous measurement of the extragalactic luminosity density which fully samples both the optical and NIR regimes. Unlike previous compilations that have noted a discontinuity between the optical and NIR regimes our homogeneous data set shows a smooth cosmic spectral energy distribution (CSED). After correcting for dust attenuation we compare our CSED to the expected values based on recent constraints on the cosmic star formation history and the initial mass function.

  3. 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…

  4. Analysis of luminosity distributions of strong lensing galaxies: subtraction of diffuse lensed signal

    NASA Astrophysics Data System (ADS)

    Biernaux, J.; Magain, P.; Hauret, C.

    2017-08-01

    Context. Strong gravitational lensing gives access to the total mass distribution of galaxies. It can unveil a great deal of information about the lenses' dark matter content when combined with the study of the lenses' light profile. However, gravitational lensing galaxies, by definition, appear surrounded by lensed signal, both point-like and diffuse, that is irrelevant to the lens flux. Therefore, the observer is most often restricted to studying the innermost portions of the galaxy, where classical fitting methods show some instabilities. Aims: We aim at subtracting that lensed signal and at characterising some lenses' light profile by computing their shape parameters (half-light radius, ellipticity, and position angle). Our objective is to evaluate the total integrated flux in an aperture the size of the Einstein ring in order to obtain a robust estimate of the quantity of ordinary (luminous) matter in each system. Methods: We are expanding the work we started in a previous paper that consisted in subtracting point-like lensed images and in independently measuring each shape parameter. We improve it by designing a subtraction of the diffuse lensed signal, based only on one simple hypothesis of symmetry. We apply it to the cases where it proves to be necessary. This extra step improves our study of the shape parameters and we refine it even more by upgrading our half-light radius measurement method. We also calculate the impact of our specific image processing on the error bars. Results: The diffuse lensed signal subtraction makes it possible to study a larger portion of relevant galactic flux, as the radius of the fitting region increases by on average 17%. We retrieve new half-light radii values that are on average 11% smaller than in our previous work, although the uncertainties overlap in most cases. This shows that not taking the diffuse lensed signal into account may lead to a significant overestimate of the half-light radius. We are also able to measure

  5. 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.

  6. COLLECTIVE PROPERTIES OF X-RAY BINARY POPULATIONS OF GALAXIES. I. LUMINOSITY AND ORBITAL PERIOD DISTRIBUTIONS OF HIGH-MASS X-RAY BINARIES

    SciTech Connect

    Bhadkamkar, Harshal; Ghosh, Pranab

    2012-02-10

    We introduce a method for obtaining the X-ray luminosity function (XLF) and the binary-period distribution of populations of high-mass X-ray binaries (HMXBs) in the stellar fields (i.e.,outside globular clusters) of normal galaxies. We start from standard distributions of the parameters of those primordial binaries which are the progenitors of HMXBs and follow the transformation of these distributions with the aid of a Jacobian formalism as the former evolve into the latter through the processes of the first mass transfer and the supernova (SN) that follows. We discuss the distributions of the post-SN binaries and the HMXBs. We show that our calculated model XLF has a differential slope Almost-Equal-To - 1.6 with a flattening at low luminosities, in excellent agreement with observations. The calculated binary-period distribution, which basically has a slightly sloping plateau-like character at intermediate periods, with a rise to this plateau at shorter periods and fall-off from it at longer periods, is in agreement with the observed distribution within observational uncertainties. We discuss the physical origin of these distributions. We demonstrate that, while the effects of both (1) the distribution of the properties of the massive companion in the HMXBs and (2) the primordial orbital distribution and the SN dynamics are important, the former appear to be dominant in determining the XLF, and the latter in determining the HMXB binary-period distribution. We discuss the possible roles of stellar-mass black holes and ultraluminous X-ray sources in the observed 'universal' XLF of HMXBs.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Distribution of Luminosity, Gas, and Stellar Populations in Local Luminous Infrared Galaxies as a Function of Merger Stage

    NASA Astrophysics Data System (ADS)

    Larson, Kirsten L.

    Luminous infrared galaxies (LIRGs) are galaxies where intense infrared emission is driven by star formation and active galactic nuclei. In the local universe it is clear that many LIRGs are major mergers of gas rich spiral galaxies. I have performed a careful visual classification of local (z < 0.08) LIRGs as either single non-interacting systems, minor mergers, or one of 5 major merger stages. I then used these classifications to compare galaxy merger stage with molecular gas mass, automated morphology parameters, annular optical B -- I colors, and infrared surface brightness profiles. I have found that all sources above an infrared luminosity of LIR > 1011:5Lsun are merging galaxies, while below this luminosity threshold, minor mergers and secular processes dominate. The mean molecular gas fraction ( MGF = MH2=(M* + MH2)) has an average value of 18+/-2% for non-interacting and early stage major merger LIRGs, which increases to 33±3% for intermediate stage major merger LIRGs. This is consistent with the hypotheses that during the early-mid stages of major mergers, atomic gas (H I) at large galactocentric radii is swept inward where it is converted into molecular gas (H2). The interactions also drive star formation throughout the galaxy as is evident by the blue B -- I color for LIRGs at every merger stage. Late stage mergers show a reddening in their nuclear 2 kpc region, presumably also from increase in nuclear gas and dust as the galaxy nuclei coalesce. Using deep Spitzer 3.6 and 4.5 mum imaging, I find that these interactions form tidal tails and debris that extend out to 80 kpc from the galaxy nuclei. This large scale tidal debris builds up over the course of a major merger and forms up-bending infrared surface brightness profiles. I further investigate the utility of automated morphology parameters and present a refined surface brightness method for gini, M20, and concentration indices. With this new method the M20 parameter correlates with merger stage and

  15. A MULTIWAVELENGTH STUDY OF A SAMPLE OF 70 mum SELECTED GALAXIES IN THE COSMOS FIELD. I. SPECTRAL ENERGY DISTRIBUTIONS AND LUMINOSITIES

    SciTech Connect

    Kartaltepe, Jeyhan S.; Sanders, D. B.; Le Floc'h, E.; Ilbert, O.; Frayer, D. T.; Aussel, H.; Arnouts, S.; Salvato, M.; Scoville, N. Z.; Capak, P.; Surace, J.; Yan, L.; Brusa, M.; Hasinger, G.; Caputi, K.; Carollo, C. M.; Civano, F.; Elvis, M.; Faure, C.; Koekemoer, A. M. E-mail: jeyhan@noao.ed

    2010-02-01

    We present a large robust sample of 1503 reliable and unconfused 70 mum selected sources from the multiwavelength data set of the Cosmic Evolution Survey. Using the Spitzer IRAC and MIPS photometry, we estimate the total infrared (IR) luminosity, L{sub IR} (8-1000 mum), by finding the best-fit template from several different template libraries. The long-wavelength 70 and 160 mum data allow us to obtain a reliable estimate of L{sub IR}, accurate to within 0.2 and 0.05 dex, respectively. The 70 mum data point enables a significant improvement over the luminosity estimates possible with only a 24 mum detection. The full sample spans a wide range in IR luminosity, L{sub IR} approx 10{sup 8}-10{sup 14} L{sub sun}, with a median luminosity of 10{sup 11.4} L{sub sun}. We identify a total of 687 luminous, 303 ultraluminous, and 31 hyperluminous infrared galaxies (LIRGs, ULIRGs, and HyLIRGs) over the redshift range 0.01 < z < 3.5 with a median redshift of 0.5. Presented here are the full spectral energy distributions (SEDs) for each of the sources compiled from the extensive multiwavelength data set from the ultraviolet (UV) to the far-infrared. A catalog of the general properties of the sample (including the photometry, redshifts, and L{sub IR}) is included with this paper. We find that the overall shape of the SED and trends with L{sub IR} (e.g., IR color temperatures and optical-IR ratios) are similar to what has been seen in studies of local objects; however, our large sample allows us to see the extreme spread in UV to near-infrared colors spanning nearly 3 orders of magnitude. In addition, using SED fits we find possible evidence for a subset of cooler ultraluminous objects than observed locally. However, until direct observations at longer wavelengths are obtained, the peak of emission and the dust temperature cannot be well constrained. We use these SEDs, along with the deep radio and X-ray coverage of the field, to identify a large sample of candidate active

  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 Multiwavelength Study of a Sample of 70 μm Selected Galaxies in the COSMOS Field. I. Spectral Energy Distributions and Luminosities

    NASA Astrophysics Data System (ADS)

    Kartaltepe, Jeyhan S.; Sanders, D. B.; Le Floc'h, E.; Frayer, D. T.; Aussel, H.; Arnouts, S.; Ilbert, O.; Salvato, M.; Scoville, N. Z.; Surace, J.; Yan, L.; Brusa, M.; Capak, P.; Caputi, K.; Carollo, C. M.; Civano, F.; Elvis, M.; Faure, C.; Hasinger, G.; Koekemoer, A. M.; Lee, N.; Lilly, S.; Liu, C. T.; McCracken, H. J.; Schinnerer, E.; Smolčić, V.; Taniguchi, Y.; Thompson, D. J.; Trump, J.

    2010-02-01

    We present a large robust sample of 1503 reliable and unconfused 70 μm selected sources from the multiwavelength data set of the Cosmic Evolution Survey. Using the Spitzer IRAC and MIPS photometry, we estimate the total infrared (IR) luminosity, L IR (8-1000 μm), by finding the best-fit template from several different template libraries. The long-wavelength 70 and 160 μm data allow us to obtain a reliable estimate of L IR, accurate to within 0.2 and 0.05 dex, respectively. The 70 μm data point enables a significant improvement over the luminosity estimates possible with only a 24 μm detection. The full sample spans a wide range in IR luminosity, L IR ≈ 108-1014 L sun, with a median luminosity of 1011.4 L sun. We identify a total of 687 luminous, 303 ultraluminous, and 31 hyperluminous infrared galaxies (LIRGs, ULIRGs, and HyLIRGs) over the redshift range 0.01 < z < 3.5 with a median redshift of 0.5. Presented here are the full spectral energy distributions (SEDs) for each of the sources compiled from the extensive multiwavelength data set from the ultraviolet (UV) to the far-infrared. A catalog of the general properties of the sample (including the photometry, redshifts, and L IR) is included with this paper. We find that the overall shape of the SED and trends with L IR (e.g., IR color temperatures and optical-IR ratios) are similar to what has been seen in studies of local objects; however, our large sample allows us to see the extreme spread in UV to near-infrared colors spanning nearly 3 orders of magnitude. In addition, using SED fits we find possible evidence for a subset of cooler ultraluminous objects than observed locally. However, until direct observations at longer wavelengths are obtained, the peak of emission and the dust temperature cannot be well constrained. We use these SEDs, along with the deep radio and X-ray coverage of the field, to identify a large sample of candidate active galactic nuclei (AGNs). We find that the fraction of AGNs

  18. 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.

  19. Identifying the Low-Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores

    NASA Astrophysics Data System (ADS)

    Dunham, Michael M.; Crapsi, Antonio; Evans, Neal J., II; Bourke, Tyler L.; Huard, Tracy L.; Myers, Philip C.; Kauffmann, Jens

    2008-11-01

    We present the results of a search for all embedded protostars with internal luminosities <=1.0 L⊙ in the full sample of nearby, low-mass star-forming regions surveyed by the Spitzer Space Telescope Legacy Project "From Molecular Cores to Planet Forming Disks" (c2d). The internal luminosity of a source, Lint, is the luminosity of the central source and excludes luminosity arising from external heating. On average, the Spitzer c2d data are sensitive to embedded protostars with Lint >= 4 × 10-3(d/140 pc)2 L⊙, a factor of 25 better than the sensitivity of the Infrared Astronomical Satellite (IRAS) to such objects. We present a set of selection criteria used to identify candidates from the Spitzer data and examine complementary data to decide whether each candidate is truly an embedded protostar. We find a tight correlation between the 70 μm flux and internal luminosity of a protostar, an empirical result based on both observations and detailed two-dimensional radiative transfer models of protostars. We identify 50 embedded protostars with Lint <= 1.0 L⊙ 15 have Lint <= 0.1 L⊙. The intrinsic distribution of source luminosities increases to lower luminosities. While we find sources down to the above sensitivity limit, indicating that the distribution may extend to luminosities lower than probed by these observations, we are able to rule out a continued rise in the distribution below Lint = 0.1 L⊙. Between 75% and 85% of cores classified as starless prior to being observed by Spitzer remain starless to our luminosity sensitivity; the remaining 15%-25% harbor low-luminosity, embedded protostars. We compile complete spectral energy distributions for all 50 objects and calculate standard evolutionary signatures (Lbol, Tbol, and Lbol/Lsmm) and argue that these objects are inconsistent with the simplest picture of star formation, wherein mass accretes from the core onto the protostar at a constant rate.

  20. 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.

  1. 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…

  2. 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.

  3. 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.

  4. 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.

  5. Spatial distribution of external and internal intercostal activity in dogs

    PubMed Central

    Legrand, Alexandre; De Troyer, André

    1999-01-01

    The observation that the external and internal interosseous intercostal muscles in the dog show marked regional differences in mechanical advantage has prompted us to re-examine the topographic distribution of electrical activity among these muscles during spontaneous breathing. Inspiratory activity was recorded only from the areas of the external intercostals with an inspiratory mechanical advantage, and expiratory activity was recorded only from the areas of the internal intercostals with an expiratory mechanical advantage. The expiratory discharges previously recorded from the caudal external intercostals and the inspiratory discharges recorded from the rostral internal intercostals were probably due to cross-contamination. Activity in each muscle area was also quantified relative to the activity measured during tetanic, supramaximal nerve stimulation (maximal activity). External intercostal inspiratory activity was consistently greater in the areas with a greater inspiratory advantage (i.e. the dorsal aspect of the rostral segments) than in the areas with a smaller inspiratory advantage, and internal intercostal expiratory activity was invariably greatest in the areas with the greatest expiratory advantage (i.e. the dorsal aspect of the caudal segments). This topographic distribution of neural drive confers to the external intercostal muscles an inspiratory action on the lung during breathing and to the internal interosseous intercostals an expiratory action. PMID:10373710

  6. 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.

  7. SDC at high luminosity

    SciTech Connect

    Green, D.

    1990-05-01

    Why is it prudent to plan for a luminosity (L) of >10{sup 34}/(cm{sup 2}sec) from the beginning First, the SSC is easily capable of attaining high luminosity. In comparison, for {bar p}p machines such as the Tevatron, increases in L are difficult. Second, after early runs at design luminosity, the only simple upgrade to a general purpose detector is an increase in luminosity. Third, and most important, the only known model independent physics goal of SSC is in the electroweak sector; the ZZ scattering amplitude reaches the unitarity bound for {radical}{cflx s} {approx equal} 3 TeV. In order to reach this mass range, and assure that some new physics is found, high luminosity running is needed. Since high luminosity running is desirable and easily attainable, it is inevitable. Therefore, one should build the hooks'' for upgrades to high L into the SDC from the beginning. The experience of CDF is that if this is not done, upgrades can be painful. Specifically, if possible, SDC should make sure that the chosen technologies allow high L operation. The time to plan for the whole useful lifetime of SDC is from the beginning. 9 refs., 6 figs.

  8. 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,...

  9. Solar Response to Luminosity Variations

    NASA Technical Reports Server (NTRS)

    Arendt, S.

    1990-01-01

    The connection between solar luminosity and magnetic fields is now well-established. Magnetic fields under the guise of sunspots and faculae enhance or suppress heat transfer through the solar surface, leading to changes in the total solar luminosity. This raises the question of the effect that such surface heat transfer perturbations have on the internal structure of the sun. The problem has been considered previously by Foukal and Spruit. Here, researchers generalize the calculation of Spruit, removing the assumption of a constant heat diffusivity coefficient by treating the full mixing length heat transfer expression. Further, they treat the surface conditions in a simpler manner, and show that the previous conclusions of Foukal and Spruit are unaffected by these modifications. The model shows that following the application of a step function emissivity change: a fraction 1 - D(sub 0) of the luminosity change relaxes away after approx. 50 days. This corresponds to the thermal diffusion time across the convection zone, adjusting to a value in correspondence with the surface change. In other words, the whole convection zone feels the perturbation on this timescale. The remaining fraction relaxes away on a timescale of 10 to the 5th power years, corresponding to the convective layer radiating away enough energy so that it can adjust to its new adiabat. These are the same results arrived at by Spruit and Foukal. For variations of sigma on timescales of 10 to 200 years, then, the only important relaxation is the 50 day one. If the amplitude of this relaxation is small, the luminosity follows the sigma variation.

  10. 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.

  11. 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.

  12. 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.

  13. a New Luminosity Function for Galaxies as Given by the Mass-Luminosity Relationship

    NASA Astrophysics Data System (ADS)

    Zaninetti, Lorenzo

    2008-04-01

    The search for a luminosity function for galaxies both alternative or companion to a Schechter function is a key problem in the reduction of data from catalogs of galaxies. Two luminosity functions for galaxies can be built starting from two distributions of mass as given by the fragmentation. A first overall distribution function is the Kiang function, which represents a useful description of the area and volume distribution of the Poisson Voronoi diagrams. The second distribution, which covers the case of low-mass galaxies, is the truncated Pareto distribution: in this model we have a natural bound due to the minimum mass/luminosity observed and an upper bound (function of the considered environment) represented by the boundary with the observed mass/luminosity overall behavior. The mass distribution is then converted into a luminosity distribution through a standard mass-luminosity relationship. The mathematical rules to convert the probability density function are used and the two new functions are normalized to the total number of galaxies per unit volume. The test of the two new luminosity functions for galaxies that cover different ranges in magnitude was made on the Sloan Digital Sky Survey (SDSS) in five different bands; the results are comparable to those of the Schechter function. A new parameter, which indicates the stellar content, is derived. The joint distribution in redshift and flux, the mean redshift and the number density connected with the first luminosity function for galaxies are obtained by analogy with the Schechter function. A new formula, which allows us to express the mass as a function of the absolute magnitude, is derived.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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...

  1. 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.

  2. 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.

  3. Luminosity Function Statistics Applied in GRB Samples

    NASA Astrophysics Data System (ADS)

    Lemos, Luis Juracy Rangel; Bianco, Carlo L.; Ruffini, Remo

    The luminosity function (LF) statistics applied in data of GRBs detected by GBM/Fermi and BAT/Swift is the theme approached in this work. The LF is a strong statistical tool to extract useful information from astrophysical samples, and the key point of this statistical analysis is in the detector sensitivity, where we have performed careful analysis. We produced, by LF statistics, the GRB predicted distributions of: peak ux N(Fpk), redshift N(z) and peak luminosity N(Lpk). We also used different GRB rates. We performed a comparison between the distributions predicted and observed (with and without redshifts), where we had to build a list with more then 250 GRBs with known redshifts. We estimated the effects of the Malmquist bias in all samples, and we looked for a correlation between the isotropic luminosity and the Band peak spectral energy.

  4. 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.

  5. Luminosity Functions Of Xxl Clusters Galaxies

    NASA Astrophysics Data System (ADS)

    Ricci, Marina; Maurogordato, Sophie; Benoist, Christophe; XXL Consortium

    2017-06-01

    The galaxy luminosity function (LF) is a powerful statistical tool to investigate galaxy evolution. In particular the study of cluster galaxies LFs gives information about environmental effects and how galaxies populate their parent dark matter halos. In this poster we present our work on the galaxy LF of X-ray detected galaxy clusters from the XXL survey. The sample consists of 173 galaxy groups/clusters spanning a wide range in both mass (M500 from 1013 to 1015 solar masses ) and redshit (0.03 < z < 1.22). The main goal is to investigate the effect of evolution and cluster masses on the luminosity distribution of cluster galaxies.

  6. The DA{phi}NE luminosity monitor

    SciTech Connect

    Di Pirro, G.; Drago, A.; Ghigo, A.; Mazzitelli, G.; Preger, M.; Sannibale, F.; Serio, M.; Vignola, G.; Cervelli, F.; Lomtadze, T.

    1998-12-10

    DA{phi}NE, the Frascati {phi}-factory, is an e{sup +}/e{sup -} collider with 2 interaction points (IPs). The center of mass energy is 1020 MeV and the design luminosity 4.2x10{sup 30} cm{sup -2} s{sup -1} in single bunch mode and 5x10{sup 32} cm{sup -2} s{sup -1} in multibunch mode. Between the possible electromagnetic reactions at the interaction point, single bremsstrahlung (SB) has been selected for the luminosity measurement. The SB high counting rate allows real-time monitoring, which is very useful during machine tune-up and moreover the narrow peak of the SB angular distribution makes the counting rate almost independent from the beam position at the IP. A description of the experimental set-up, calibration results and luminosity measurements is presented.

  7. 21 CFR 1313.34 - Distribution of the international transaction declaration.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Distribution of the international transaction declaration. 1313.34 Section 1313.34 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE... International Transactions Involving Listed Chemicals § 1313.34 Distribution of the international...

  8. 21 CFR 1313.34 - Distribution of the international transaction declaration.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Distribution of the international transaction... IMPORTATION AND EXPORTATION OF LIST I AND LIST II CHEMICALS Transshipments, In-Transit Shipments and International Transactions Involving Listed Chemicals § 1313.34 Distribution of the international transaction...

  9. 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).

  10. Measuring the Average Evolution of Luminous Galaxies at z < 3: The Rest-Frame Optical Luminosity Density, Spectral Energy Distribution, and Stellar Mass Density

    NASA Astrophysics Data System (ADS)

    Rudnick, Gregory; Labbé, Ivo; Förster Schreiber, Natascha M.; Wuyts, Stijn; Franx, Marijn; Finlator, Kristian; Kriek, Mariska; Moorwood, Alan; Rix, Hans-Walter; Röttgering, Huub; Trujillo, Ignacio; van der Wel, Arjen; van der Werf, Paul; van Dokkum, Pieter G.

    2006-10-01

    We present the evolution of the volume-averaged properties of the rest-frame optically luminous (LV>3×1010 h-270 Lsolar) galaxy population to z~3, determined from four disjoint deep fields. We characterize their rest-frame UV through optical properties via the mean SED. To measure evolution, we apply the selection criteria to a sample of galaxies from the SDSS and COMBO-17 survey. The mean rest-frame 2200 Å through V-band SED becomes steadily bluer with increasing redshift, but at all redshifts z<3 the mean SED falls within the range defined by ``normal'' galaxies in the nearby universe. We measure the mean stellar mass-to-light ratios (M*/L) and stellar mass densities (ρ*) by fitting models to the mean rest-frame UV-optical SEDs. The ρ* in galaxies selected at a fixed luminosity has increased by a factor of 3.5-7.9 from z=3 to 0.1. If we instead use our observed M*/LV evolution to select galaxies at a fixed mass, ρ* evolves by a factor of 5.3-16.7. After correcting to total, the measured ρ* at z<2 lie below the integral of the star formation rate density as a function of redshift as derived from UV-selected samples after a standard correction for extinction. We find large discrepancies between recent model predictions for the evolution of ρ* and our results, even when our observational selection is applied to the models. Finally, we determine that distant red galaxies (selected to have Js-Ks>2.3) in our LrestV-selected samples contribute 30% and 64% of the stellar mass budget at z~2 and z~2.8, respectively. These galaxies are largely absent from UV surveys, and this result highlights the need for mass selection of high-redshift galaxies. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555. Also based on observations collected at the European Southern Observatories on

  11. Different Luminosity Correlation of GRBs

    NASA Astrophysics Data System (ADS)

    Zhang, Z. B.; Liu, H. C.; Jiang, L. Y.; Chen, D. Y.

    2014-09-01

    We report our recent understanding about a tight correlation between relative spectral lag and luminosity (or redshift) for γ-ray bursts. The latest investigations indicate that the empirical correlations got from BATSE bursts also exist for Swift/BAT ones. The special luminosity-lag correlation is much similar to that of the luminosity with pulse number proposed by Schaefer (2003), but largely different from most of others ever discovered. Note that our newly built luminosity-lag correlation predicts that luminosity should evolve with cosmological redshift as L p ∝ (1 + z)2.4±0.7 that is excellently confirmed by Salvaterra et al. (2012) and Geng & Huang (2013). In addition, it is also surprisingly found that the luminosity-lag correlation can account for both long and short Swift/BAT bursts, which might be an evidence of the same radiation mechanism for diverse burst groups.

  12. 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.

  13. 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

  14. 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.

  15. The Herschel Orion Protostar Survey: Luminosity and Envelope Evolution

    NASA Astrophysics Data System (ADS)

    Fischer, William J.; Megeath, S. Thomas; Furlan, Elise; Ali, Babar; Stutz, Amelia M.; Tobin, John J.; Osorio, Mayra; Stanke, Thomas; Manoj, P.; Poteet, Charles A.; Booker, Joseph J.; Hartmann, Lee; Wilson, Thomas L.; Myers, Philip C.; Watson, Dan M.

    2017-05-01

    The Herschel Orion Protostar Survey obtained well-sampled 1.2-870 μm spectral energy distributions (SEDs) of over 300 protostars in the Orion molecular clouds, home to most of the young stellar objects (YSOs) in the nearest 500 pc. We plot the bolometric luminosities and temperatures for 330 Orion YSOs, 315 of which have bolometric temperatures characteristic of protostars. The histogram of the bolometric temperature is roughly flat; 29% of the protostars are in Class 0. The median luminosity decreases by a factor of four with increasing bolometric temperature; consequently, the Class 0 protostars are systematically brighter than the Class I protostars, with a median luminosity of 2.3 L⊙ as opposed to 0.87 L⊙. At a given bolometric temperature, the scatter in luminosities is three orders of magnitude. Using fits to the SEDs, we analyze how the luminosities corrected for inclination and foreground reddening relate to the mass in the inner 2500 au of the best-fit model envelopes. The histogram of the envelope mass is roughly flat, while the median-corrected luminosity peaks at 15 L⊙ for young envelopes and falls to 1.7 L⊙ for late-stage protostars with remnant envelopes. The spread in luminosity at each envelope mass is three orders of magnitude. Envelope masses that decline exponentially with time explain the flat mass histogram and the decrease in luminosity, while the formation of a range of stellar masses explains the dispersion in luminosity.

  16. STS atmospheric luminosities

    NASA Technical Reports Server (NTRS)

    Mende, S. B.

    1984-01-01

    During the STS-8 space shuttle mission special photographic and TV operations were carried out to record the properties of the spacecraft induced luminosities. One of these luminous phenomena is the quiescent vehicle glow which was photographed during the STS-8 mission with an image intensified photographic camera, with and without an objective grating. During the latter part of the mission the altitude of the shuttle was relatively low (120 n.m. = 222 km) and unprecedentedly high intensity of the glow was observed. The crew reported that the glow was easily visible to the naked eye. The proper orientation of the shuttle with respect to the velocity vector and the objective grating permitted the exposure of good objective spectrum of the glow in the visible region. From the results it is clear that the spectrum appears to be a continuum as observed by the image intensifier objective grating camera. Qualitative examination of the data shows that there is very tail little glow ion the wavelength range of 4300 to about 5000 angstroms. Above 5000 angstroms the glow becomes stronger towards the red and then it falls off towards higher wavelength and of the spectrum presumably because of the responsivity of the device.

  17. The luminosity structure and objective classification of galaxies

    NASA Technical Reports Server (NTRS)

    Han, Mingshen

    1995-01-01

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

  18. 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.

  19. On the luminosity of black hole cluster model of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Stoeger, W. R.; Pacholczyk, A. G.; Stepinski, T. F.

    1992-01-01

    The luminosity of a nuclear cluster of accreting black holes and other objects is discussed in terms of two accretion regimes: external supply of gas from outside the cluster and internal supply resulting from tidal disruption and capture of stars within the cluster. The external supply regime results in radiation being emitted from the innermost parts of the cluster while internal supply can efficiently feed the holes in the outer parts of the cluster as long as it is not too compact cluster and is embedded in a distribution of stars with a density larger than 10 exp 7 solar masses/cu pc.

  20. A jet-dominated model for a broad-band spectral energy distribution of the nearby low-luminosity active galactic nucleus in M94

    NASA Astrophysics Data System (ADS)

    van Oers, Pieter; Markoff, Sera; Uttley, Phil; McHardy, Ian; van der Laan, Tessel; Donovan Meyer, Jennifer; Connors, Riley

    2017-06-01

    We have compiled a new multiwavelength spectral energy distribution (SED) for the closest obscured low-ionization emission-line region active galactic nucleus (AGN), NGC 4736, also known as M94. The SED comprises mainly high-resolution (mostly sub-arcsecond, or, at the distance to M94, ≲23 pc from the nucleus) observations from the literature, archival data, as well as previously unpublished sub-millimetre data from the Plateau de Bure Interferometer (PdBI) and the Combined Array for Research in Millimeter-wave Astronomy, in conjunction with new electronic MultiElement Radio Interferometric Network (e-MERLIN) L-band (1.5 GHz) observations. Thanks to the e-MERLIN resolution and sensitivity, we resolve for the first time a double structure composed of two radio sources separated by ˜1 arcsec, previously observed only at higher frequency. We explore this data set, which further includes non-simultaneous data from the Very Large Array, the Gemini telescope, the Hubble Space Telescope and the Chandra X-ray observatory, in terms of an outflow-dominated model. We compare our results with previous trends found for other AGN using the same model (NGC 4051, M81*, M87 and Sgr A*), as well as hard- and quiescent-state X-ray binaries. We find that the nuclear broad-band spectrum of M94 is consistent with a relativistic outflow of low inclination. The findings in this work add to the growing body of evidence that the physics of weakly accreting black holes scales with mass in a rather straightforward fashion.

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. The High Luminosity LHC Project

    NASA Astrophysics Data System (ADS)

    Rossi, Lucio

    The High Luminosity LHC is one of the major scientific project of the next decade. It aims at increasing the luminosity reach of LHC by a factor five for peak luminosity and a factor ten in integrated luminosity. The project, now fully approved and funded, will be finished in ten years and will prolong the life of LHC until 2035-2040. It implies deep modifications of the LHC for about 1.2 km around the high luminosity insertions of ATLAS and CMS and relies on new cutting edge technologies. We are developing new advanced superconducting magnets capable of reaching 12 T field; superconducting RF crab cavities capable to rotate the beams with great accuracy; 100 kA and hundred meter long superconducting links for removing the power converter out of the tunnel; new collimator concepts, etc... Beside the important physics goals, the High Luminosity LHC project is an ideal test bed for new technologies for the next hadron collider for the post-LHC era.

  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. 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.

  8. Masses, luminosities and dynamics of galactic molecular clouds

    NASA Technical Reports Server (NTRS)

    Solomon, P. M.; Rivolo, A. R.; Mooney, T. J.; Barrett, J. W.; Sage, L. J.

    1987-01-01

    Star formation in galaxies takes place in molecular clouds and the Milky Way is the only galaxy in which it is possible to resolve and study the physical properties and star formation activity of individual clouds. The masses, luminosities, dynamics, and distribution of molecular clouds, primarily giant molecular clouds in the Milky Way are described and analyzed. The observational data sets are the Massachusetts-Stony Brook CO Galactic Plane Survey and the IRAS far IR images. The molecular mass and infrared luminosities of glactic clouds are then compared with the molecular mass and infrared luminosities of external galaxies.

  9. 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.

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

    PubMed

    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. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. 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

  12. 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…

  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. Linear Colliders: Achieving High Luminosity

    NASA Astrophysics Data System (ADS)

    Dugan, Gerald

    2002-04-01

    Four styles of linear collider are under active consideration by the high energy physics community as candidates for the next machine at the energy frontier. The four concepts (CLIC, the C-band linear collider, NLC/JLC and TESLA) differ widely in technology but share similar goals for energy and luminosity. The luminosity goal is more than three orders of magntiude larger than what has been acheived at the SLC. Nevertheless, as a result of many years of world-wide accelerator R&D efforts, feasible designs now exist for machines capable of reaching this goal. This talk will review the methods proposed by each linear collider concept to attain its luminosity goal. The most challenging issues facing each concept will be outlined and compared, and the areas requiring further R&D efforts will be noted.

  16. 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.

  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. The faint quasar luminosity function

    NASA Technical Reports Server (NTRS)

    Kron, Richard G.; Bershady, Matthew A.; Munn, Jeffrey A.; Smetanka, John J.; Majewski, Steven; Koo, David C.

    1991-01-01

    Preliminary results of an expanded program to determine the faint-quasar luminosity function are described. Quasars have been selected in four fields totaling 1.2 sq deg from four-band photometry. Out of a total of 130 quasars with good spectroscopy, 37 have J greater than 21.5 and 46 have F greater than 21.0. The spectroscopic sample is representative of all of the color-selected candidates. An estimate of the luminosity function as a function of redshift is derived.

  19. UPGRADING RHIC FOR HIGHER LUMINOSITY.

    SciTech Connect

    MACKAY,W.; BEN-ZVI,I.; BRENNAN,J.M.; HARRISON,M.; KEWISCH,J.; PEGGS,S.; ROSER,T.; TRBOJEVIC,D.; PARKHOMCHUK,V.

    2001-06-18

    While RHIC has only just started running for its heavy ion physics program, in the first run last summer, we achieved 10% of the design luminosity. In this paper we discuss plans for increasing the luminosity by a factor of 35 beyond the nominal design. A factor of 4 should be straightforward by doubling the number of bunches per ring and squeezing the {beta}* from 2 to 1 m at selected interaction points. An additional factor of 8 to 10 could be possible by using electron cooling to counteract intrabeam scattering and reduce emittances of the beams.

  20. 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.

  1. 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.

  2. 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.

  3. The white dwarf luminosity function

    NASA Astrophysics Data System (ADS)

    García-Berro, Enrique; Oswalt, Terry D.

    2016-06-01

    White dwarfs are the final remnants of low- and intermediate-mass stars. Their evolution is essentially a cooling process that lasts for ∼ 10 Gyr. Their observed properties provide information about the history of the Galaxy, its dark matter content and a host of other interesting astrophysical problems. Examples of these include an independent determination of the past history of the local star formation rate, identification of the objects responsible for the reported microlensing events, constraints on the rate of change of the gravitational constant, and upper limits to the mass of weakly interacting massive particles. To carry on these tasks the essential observational tools are the luminosity and mass functions of white dwarfs, whereas the theoretical tools are the evolutionary sequences of white dwarf progenitors, and the corresponding white dwarf cooling sequences. In particular, the observed white dwarf luminosity function is the key manifestation of the white dwarf cooling theory, although other relevant ingredients are needed to compare theory and observations. In this review we summarize the recent attempts to empirically determine the white dwarf luminosity function for the different Galactic populations. We also discuss the biases that may affect its interpretation. Finally, we elaborate on the theoretical ingredients needed to model the white dwarf luminosity function, paying special attention to the remaining uncertainties, and we comment on some applications of the white dwarf cooling theory. Astrophysical problems for which white dwarf stars may provide useful leverage in the near future are also discussed.

  4. 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.

  5. 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,...

  6. The cosmological evolution and luminosity function of X-ray selected active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Maccacaro, T.; Gioia, I. M.; Avni, Y.; Giommi, P.; Griffiths, R. E.; Liebert, J.; Stocke, J.; Danziger, J.

    1983-01-01

    The cosmological evolution and the X-ray luminosity function of X-ray selected active galactic nuclei (AGNs) are derived and discussed. The sample used consists of 31 AGNs extracted from a fully identified sample of X-ray sources from the Einstein Observatory Medium Sensitivity Survey and is therefore exclusively defined by its X-ray properties. The distribution in space is found to be strongly nonuniform. The amount of cosmological evolution required by the X-ray data is derived in the framework of pure luminosity evolution and is found to be smaller than the amount determined from optically selected samples. The X-ray luminosity function is derived. It can be satisfactorily represented by a single power law only over a limited range of absolute luminosities. Evidence that the luminosity function flattens at low luminosity or steepens at high luminosity, or both, is presented and discussed.

  7. 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)

  8. Dependence of the radon emanation coefficient on radium distribution and internal structure of the material

    NASA Astrophysics Data System (ADS)

    Morawska, L.; Phillips, Colin R.

    1993-04-01

    The mechanisms of escape of radon from the solid structure of a particle to the free pore space are examined. According to the present state of knowledge, the most important factors affecting the radon emanation coefficient are the distribution of the parent radium atoms and the internal structure of the material. In early studies of the radon emanation coefficient, it was usually assumed that the material under investigation was homogeneous in radium distribution and in internal structure. It is now known that these assumptions are often not justified for real materials. In consequence, models based on these assumptions may not be useful in explaining the emanation process. The importance of radium distribution and internal structure is explained here, and an analysis made of differences in the internal structure of various natural and man-made materials. The analysis is then developed in order to identify the effect of different models of radium atom distribution on the emanation coefficient. Four models of radium atom distribution are presented, together with mathematical approaches for developing and finding numerical solutions for equations leading to determination of the emanation coefficient for each model.

  9. Modelling the luminosities and sizes of radio sources: radio luminosity function at z = 6

    NASA Astrophysics Data System (ADS)

    Saxena, A.; Röttgering, H. J. A.; Rigby, E. E.

    2017-08-01

    We present a model to predict the luminosity function for radio galaxies and their linear size distribution at any redshift. The model takes a black hole mass function and Eddington ratio distribution as input and tracks the evolution of radio sources, taking into account synchrotron, adiabatic and inverse Compton energy losses. We first test the model at z = 2 where plenty of radio data are available and show that the radio luminosity function (RLF) is consistent with observations. We are able to reproduce the break in luminosity function that separates locally the Fanaroff-Riley class I and Fanaroff-Riley class I radio sources. Our prediction for linear size distribution at z = 2 matches the observed distribution too. We then use our model to predict an RLF and linear size distribution at z = 6, as this is the epoch when radio galaxies can be used as probes of reionization. We demonstrate that higher inverse Compton losses lead to shorter source lifetimes and smaller sizes at high redshifts. The predicted sizes are consistent with the generally observed trend with redshift. We evolve the z = 2 RLF based on observed quasar space densities at high redshifts, and show that our RLF prediction at z = 6 is consistent. Finally, we predict the detection of 0.63, 0.092 and 0.0025 z ≥ 6 sources deg2 at flux density limits of 0.1, 0.5 and 3.5 mJy. We assess the trade-off between coverage area and depth and show that LOFAR surveys with flux density limits of 0.1 and 0.5 mJy are the most efficient at detecting a large number of z ≥ 6 radio sources.

  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. 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.

  12. 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.

  13. 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…

  14. 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…

  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. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. Luminosity Dependence and Search Doppler

    NASA Technical Reports Server (NTRS)

    VanParadijs, Johannes A.

    1998-01-01

    The research supported by this grant covered two projects: (1) a study of the luminosity dependence of the properties of atoll sources; and (2) a search for Doppler shifts in the pulse arrival times of the anomalous pulsar 4U 0142+61. Following the discovery of kilohertz quasi-periodic oscillations (QPOS) in Sco X-1 studies of the X-ray properties of atoll sources have been dominated by searches for these QPOS, and the study of their dependence on other source properties, such as X-ray luminosity and spectral state. In the project supported by grant NAG5-3269 we have detected kHz QPOs for several atoll sources. The physical interpretation of these QPO is as yet unclear, but simple models (such as the Keplerian beat frequency model) can probably be excluded. The results of this research have been reported. We have studied the X-ray pulsations of the anomalous X-ray pulsar 4U 0142+61 using the Rossi XTE. A detailed search for Doppler shifts did not lead to a positive detection. The upper limits exclude almost all types of possible companion stars, except white dwarfs. However, the latter can be excluded since anomalous X-ray pulsars are very young objects. We therefore conclude that anomalous X-ray pulsars are single neutron stars.

  9. 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.

  10. 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.

  11. 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

  12. Waiting time distribution revealing the internal spin dynamics in a double quantum dot

    NASA Astrophysics Data System (ADS)

    Ptaszyński, Krzysztof

    2017-07-01

    Waiting time distribution and the zero-frequency full counting statistics of unidirectional electron transport through a double quantum dot molecule attached to spin-polarized leads are analyzed using the quantum master equation. The waiting time distribution exhibits a nontrivial dependence on the value of the exchange coupling between the dots and the gradient of the applied magnetic field, which reveals the oscillations between the spin states of the molecule. The zero-frequency full counting statistics, on the other hand, is independent of the aforementioned quantities, thus giving no insight into the internal dynamics. The fact that the waiting time distribution and the zero-frequency full counting statistics give a nonequivalent information is associated with two factors. Firstly, it can be explained by the sensitivity to different timescales of the dynamics of the system. Secondly, it is associated with the presence of the correlation between subsequent waiting times, which makes the renewal theory, relating the full counting statistics and the waiting time distribution, no longer applicable. The study highlights the particular usefulness of the waiting time distribution for the analysis of the internal dynamics of mesoscopic systems.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Luminosity from thermal neutron counting with MPX detectors and relation to ATLAS reference luminosity at √s= 8 TeV proton-proton collisions

    NASA Astrophysics Data System (ADS)

    Sopczak, A.; Ali, B.; Asbah, N.; Bergmann, B.; Bekhouche, K.; Caforio, D.; Campbell, M.; Heijne, E.; Leroy, C.; Lipniacka, A.; Nessi, M.; Pospíšil, S.; Seifert, F.; Şolc, J.; Soueid, P.; Suk, M.; Tureček, D.; Vykydal, Z.

    2017-09-01

    A luminosity determination based on thermal neutron counting with six MPX silicon pixel devices installed in the ATLAS cavern is presented. Recently, the ATLAS Collaboration published final √s=8 TeV luminosity results. This made possible to perform a detailed comparison and verify the potential of the thermal neutron counting as a novel method for luminosity measurements to supplement the well-established presently used procedures. This measurement is unique to the MPX network and has the advantage that the neutrons, which pass the MPX devices, cannot result from activation processes of material nearby. Good agreement is found between the MPX neutron counting results and the ATLAS reference luminosity. The differences between the ATLAS and MPX luminosity measurements are described by a Gaussian distribution with width of 1.5%.

  18. Stereotactic model of the electrical distribution within the internal globus pallidus during deep brain stimulation.

    PubMed

    Vasques, Xavier; Cif, Laura; Hess, Olivier; Gavarini, Sophie; Mennessier, Gerard; Coubes, Philippe

    2009-02-01

    Deep brain stimulation (DBS) of the internal globus pallidus (GPi) is an established surgical technique for the treatment of movement disorders. The objective of this study was to propose a computational stereotactic model of the electrical distribution around the electrode within the targeted GPi in order to optimize parameter adjustment in clinical practice. The outline of the GPi can be defined precisely by using stereotactic magnetic resonance imaging (MRI) and from this it is possible to model its three-dimensional structure. The electrode and the distribution of the patient-specific parameters can then be co-registered with the GPi volume. By using this methodology, it is possible to visualize and measure the relationship between the electrical distribution of patient-specific parameters and the morphology of the GPi. The model could be applied in clinical practice to help determine the threshold for achieving a therapeutic effect and consequently may aid in optimizing parameter settings for individual patients.

  19. 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.

  20. 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.

  1. The faint end of the galaxy luminosity function

    NASA Technical Reports Server (NTRS)

    Treyer, Marie A.; Silk, Joseph

    1994-01-01

    The evolution of the B- and K-band luminosity functions of galaxies is inferred in a relatively model-independent way from deep spectroscopic and photometric surveys. We confirm earlier evidence by Eales for an increase in the amplitude of the B-band galaxy luminosity function at modest redshift (z less than or approx. 0.2). We find in addition that the slope of the faint end of the luminosity function must systematically steepen and progress toward more luminous galaxies with increasing lookback time, assuming that the galaxy redshift distribution may be smoothly extrapolated 2 mag fainter than observed, as suggested by recent gravitational lensing studies. This evolution is shown to be color-dependent, and we predict the near-infrared color distribution of faint galaxies. The luminosity function of blue (B - K less than or approx. 4) galaxies in the range 0.2 less than or approx. z less than or approx. 1 can be represented by a Schechter function with characteristic light density phi(sup *) L(sup *) comparable to that of present-day late-type galaxies, but with a steeper faint end slope alpha approx. 1.4.

  2. Optimizing integrated luminosity of future hadron colliders

    NASA Astrophysics Data System (ADS)

    Benedikt, Michael; Schulte, Daniel; Zimmermann, Frank

    2015-10-01

    The integrated luminosity, a key figure of merit for any particle-physics collider, is closely linked to the peak luminosity and to the beam lifetime. The instantaneous peak luminosity of a collider is constrained by a number of boundary conditions, such as the available beam current, the maximum beam-beam tune shift with acceptable beam stability and reasonable luminosity lifetime (i.e., the empirical "beam-beam limit"), or the event pileup in the physics detectors. The beam lifetime at high-luminosity hadron colliders is largely determined by particle burn off in the collisions. In future highest-energy circular colliders synchrotron radiation provides a natural damping mechanism, which can be exploited for maximizing the integrated luminosity. In this article, we derive analytical expressions describing the optimized integrated luminosity, the corresponding optimum store length, and the time evolution of relevant beam parameters, without or with radiation damping, while respecting a fixed maximum value for the total beam-beam tune shift or for the event pileup in the detector. Our results are illustrated by examples for the proton-proton luminosity of the existing Large Hadron Collider (LHC) at its design parameters, of the High-Luminosity Large Hadron Collider (HL-LHC), and of the Future Circular Collider (FCC-hh).

  3. The Consequences of Internal Waves for Phytoplankton Focusing on the Distribution and Production of Planktothrix rubescens

    PubMed Central

    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. 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

  5. "internal Tide Pools" and Their Influence on the Distribution of Hypoxia in the Kelp Forest

    NASA Astrophysics Data System (ADS)

    Leary, P.; Squibb, M. E.; Woodson, C. B.; Denny, M.; Micheli, F.; Monismith, S. G.

    2016-02-01

    In coastal upwelling systems, severe hypoxic pulses occur often on the inner shelf. The primary driver of coastal hypoxic events in Monterey Bay is internal wave transport of upwelled cold oxygen depleted water from within Monterey canyon. Most research on internal waves has been conducted over smooth bottoms, and interaction with complex topographies such as kelp forests/rocky reef systems has been largely unstudied. Previously, we have shown that spatial dissolved oxygen variability at small (10m) scales is strongly influenced by phasing with local internal wave activity, and hypothesized that the observed variability is a consequence of flow-reef interactions. Here we present evidence for an "internal tide pool" phenomenon, where the relaxation of internal waves leaves pools of dense hypoxic water retained in depressions in the subtidal reef. We show that following an internal wave event, the recovery dissolved oxygen and temperature within these depressions to pre-event levels, can be delayed by 6+ hours behind the water column as a whole, during which, oxygen and temperature inside the pool may differ from surrounding areas by 5mg/L and 3°C respectively. This delay is strongest in areas of greatest concavity ("bowl-shaped"). Further, we show that this delay, is a direct result of "pooling" of dense hypoxic, water within these depressions, i.e. salinity and flow patterns indicate that upwelled water settles within topographical depressions and slowly drains along topographic contours. Finally we show that the diversity of pooling topographies within a small area creates a highly "patchy" dissolved oxygen landscape following a water column hypoxic event, where, across a small spatial scale, individual depressions in the reef may vary widely in their instantaneous oxygen and temperature content, which is likely to impact the habitat quality and distributions of local species.

  6. 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

  7. The internal density distribution of comet 67P/C-G based on 3D models

    NASA Astrophysics Data System (ADS)

    Jorda, Laurent; Faurschou Hviid, Stubbe; Capanna, Claire; Gaskell, Robert W.; Gutiérrez, Pedro; Preusker, Frank; Scholten, Frank; Rodionov, Sergey; OSIRIS Team

    2016-10-01

    The OSIRIS camera aboard the Rosetta spacecraft observed the nucleus of comet 67P/C-G from the mapping phase in summer 2014 until now. The images have allowed the reconstruction in three-dimension of nucleus surface with stereophotogrammetry (Preusker et al., Astron. Astrophys.) and stereophotoclinometry (Jorda et al., Icarus) techniques. We use the reconstructed models to constrain the internal density distribution based on: (i) the measurement of the offset between the center of mass and the center of figure of the object, and (ii) the assumption that flat areas observed at the surface of the comet correspond to iso-gravity surfaces. The results of our analysis will be presented, and the consequences for the internal structure and formation of the nucleus of comet 67P/C-G will be discussed.

  8. The internal density distribution of comet 67P/C-G based on 3D models

    NASA Astrophysics Data System (ADS)

    Jorda, Laurent; Hviid, Stubbe; Capanna, Claire; Gaskell, Robert; Gutierrez, Pedro; Preusker, Frank; Rodionov, Sergey; Scholten, Frank

    2016-04-01

    The OSIRIS camera aboard the Rosetta spacecraft observed the nucleus of comet 67P/C-G from the mapping phase in summer 2014 until now. The images have allowed the reconstruction in three-dimension of nucleus surface with stereophotogrammetry (Preusker et al., Astron. Astrophys.) and stereophotoclinometry (Jorda et al., submitted to Icarus) techniques. We use the reconstructed models to constrain the internal density distribution based on: (i) the measurement of the offset between the center of mass and center of figure of the object, and (ii) the assumption that flat areas observed at the surface of the comet correspond to iso-gravity surfaces. The results of our analysis will be presented, and the consequences for the internal structure and formation of the nucleus of comet 67P/C-G will be discussed.

  9. Parallel glide: flow of dislocations with internal stress source/sink distribution

    PubMed Central

    Raić, Karlo T

    2008-01-01

    The unexpected glide of dislocations on a plane parallel to the film/substrate interface in ultrathin copper films, which has been called parallel glide (Balk et al 2003 Acta Metall. 51 447), is described using an analytical model. The phenomenon is observed as a problem involving inlet/outlet flow from different positions of a grain boundary into the grain channel. In this sense, parallel glide is presented as the flow of dislocations with an internal stress source/sink distribution. PMID:27877945

  10. Temperature distribution in internally heated walls of heat exchangers composed of nonnuclear flow passages

    NASA Technical Reports Server (NTRS)

    Eckert, E R G; Low, George M

    1951-01-01

    In the walls of heat exchangers composed of noncircular passages, the temperature varies in the circumferential direction because of local variations of the heat-transfer coefficients. A prediction of the magnitude of this variation is necessary in order to determine the region of highest temperature and in order to determine the admissible operating temperatures. A method for the determination of these temperature distributions and of the heat-transfer characteristics of a special type of heat exchanger is developed. The heat exchanger is composed of polygonal flow passages and the passage walls are uniformly heated by internal heat sources. The coolant flow within the passages is assumed to be turbulent. The circumferential variation of the local heat-transfer coefficients is estimated from flow measurements made by Nikuradse, postulating similarity between velocity and temperature fields. Calculations of temperature distributions based on these heat-transfer coefficients are carried out and results for heat exchangers with triangular and rectangular passages are presented.

  11. 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.

  12. Modelling the internal field distribution in human erythrocytes exposed to MW radiation.

    PubMed

    Sebastián, J L; Muñoz San Martín, S; Sancho, M; Miranda, J M

    2004-08-01

    This paper studies the internal electric field distribution in human erythrocytes exposed to MW radiation. For this purpose, an erythrocyte cell model is exposed to linearly polarized electromagnetic (EM) plane waves of frequency 900 MHz and the electric field within the cell is calculated by using a finite element (FE) technique with adaptive meshing. The results obtained show the dependence of the induced electric field distribution on the main modelling parameters, i.e., the electrical properties (permittivity and conductivity) of the membrane and cytoplasm and the orientation of the cell with respect to the applied field. It is found that for certain orientations, the field amplification within the membrane of the erythrocyte shape cell can be higher than the one observed in an equivalent simple spheroidal geometry cell, commonly used in bioelectromagnetism. The present work shows that a better insight of the interaction of electromagnetic fields with basic biological structures is obtained when the most possible realistic cell shape is used.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. Applying the luminosity function statistics in the fireshell model

    NASA Astrophysics Data System (ADS)

    Rangel Lemos, L. J.; Bianco, C. L.; Ruffini, R.

    2015-12-01

    The luminosity function (LF) statistics applied to the data of BATSE, GBM/Fermi and BAT/Swift is the theme approached in this work. The LF is a strong statistical tool to extract useful information from astrophysical samples, and the key point of this statistical analysis is in the detector sensitivity, where we have performed careful analysis. We applied the tool of the LF statistics to three GRB classes predicted by the Fireshell model. We produced, by LF statistics, predicted distributions of: peak ux N(Fph pk), redshift N(z) and peak luminosity N(Lpk) for the three GRB classes predicted by Fireshell model; we also used three GRB rates. We looked for differences among the distributions, and in fact we found. We performed a comparison between the distributions predicted and observed (with and without redshifts), where we had to build a list with 217 GRBs with known redshifts. Our goal is transform the GRBs in a standard candle, where a alternative is find a correlation between the isotropic luminosity and the Band peak spectral energy (Liso - Epk).

  19. 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.

  20. The luminosity function of galactic X-ray sources - A cutoff and a 'standard candle'

    NASA Technical Reports Server (NTRS)

    Margon, B.; Ostriker, J. P.

    1973-01-01

    Analysis of the 2- to 10-kev luminosity distribution of 36 X-ray sources in the Local Group having known or estimated distances, showing that there exists a luminosity cutoff of approximately 10 to the 37.7th ergs/sec in agreement with the theoretical (Eddington) limit for the luminosity of an approximately 1 solar mass star. Furthermore, among the complete sample of high-luminosity sources, there appears to be a statistically significant group of X-ray 'standard candles' at (within less than 0.8 mag) the critical luminosity. This finding (which is in agreement with the self-consistent mass flow accretion models) presents the possibility that X-ray sources may be used as extragalactic distance indicators in the next generation of X-ray astronomy experiments.

  1. Influence of Transformation Plasticity on the Distribution of Internal Stress in Three Water-Quenched Cylinders

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Qin, Shengwei; Zhang, Jiazhi; Wang, Ying; Rong, Yonghua; Zuo, Xunwei; Chen, Nailu

    2017-10-01

    Based on the hardenability of three medium carbon steels, cylinders with the same 60-mm diameter and 240-mm length were designed for quenching in water to obtain microstructures, including a pearlite matrix (Chinese steel mark: 45), a bainite matrix (42CrMo), and a martensite matrix (40CrNiMo). Through the combination of normalized functions describing transformation plasticity (TP), the thermo-elasto-plastic constitutive equation was deduced. The results indicate that the finite element simulation (FES) of the internal stress distribution in the three kinds of hardenable steel cylinders based on the proposed exponent-modified (Ex-Modified) normalized function is more consistent with the X-ray diffraction (XRD) measurements than those based on the normalized functions proposed by Abrassart, Desalos, and Leblond, which is attributed to the fact that the Ex-Modified normalized function better describes the TP kinetics. In addition, there was no significant difference between the calculated and measured stress distributions, even though TP was taken into account for the 45 carbon steel; that is, TP can be ignored in FES. In contrast, in the 42CrMo and 40CrNiMo alloyed steels, the significant effect of TP on the residual stress distributions was demonstrated, meaning that TP must be included in the FES. The rationality of the preceding conclusions was analyzed. The complex quenching stress is a consequence of interactions between the thermal and phase transformation stresses. The separated calculations indicate that the three steels exhibit similar thermal stress distributions for the same water-quenching condition, but different phase transformation stresses between 45 carbon steel and alloyed steels, leading to different distributions of their axial and tangential stresses.

  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. 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.

  4. 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.

  5. Dynamics of spherical distributions of charge with small internal dipolar motion

    NASA Astrophysics Data System (ADS)

    Flammer, P. D.

    2016-04-01

    This paper extends the Lorentz-Abraham model of an electron (i.e., the equations of motion for a small spherical shell of charge, which is rigid in its proper frame) to treat a small, spherically symmetric charge distribution, allowing for small internal dipolar motion. This is done by dividing the distribution into thin spherical shells (in the continuum limit), and tracking the interactions between shells. Dipolar motion of each constituent spherical shell is allowed along the net dipole moment, but higher-order multipole moments are ignored. The amplitude of dipolar motion of each spherical shell is assumed to be linearly proportional to the net dipole moment. Under these assumptions, low-velocity equations of motion are determined for both the center-of-mass motion and net dipolar motion of the distribution. This is then generalized to arbitrary (relativistic) center-of-mass velocity and acceleration, assuming the motion of individual shells is completely in phase or out of phase with the net dipole moment.

  6. 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.

  7. 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

  8. The correlations of multi-wave band luminosity and BLR luminosity in Fermi 2LAC blazars

    NASA Astrophysics Data System (ADS)

    Wang, Zerui; Xue, Rui; Xie, Zhaohua; Du, Leiming; Yi, Tingfeng; Xu, Yunbing; Liu, Wenguang

    2017-10-01

    We collect a sample of 78 Fermi detected blazars with broad line region (BLR) data and the quasi-simultaneous multi-wave band data. By analyzing the sample, we find: (1) For whole blazar sample, there exist significant correlations between radio, γ-ray luminosity and BLR luminosity. The slope of the best-fit linear regression equation is close to the theoretical value 1. Our results provided another support of jet-disk symbiosis. (2) For FSRQ sample, we find a significant correlation between radio luminosity and optical luminosity, and weaker correlations between X-ray luminosity and radio, optical luminosity. It indicates that the X-ray band radiation mechanism is slightly different from radio and optical bands. The X-ray emission is diluted by inverse Compton scattering (IC). There is a significant correlation between BLR luminosity and γ-ray luminosity, but no correlations between X-ray luminosity and BLR, γ-ray luminosity, which suggests that the seed soft photons are different for IC process. From these results we suggest that the X-ray band emission is diluted by synchrotron self-Compton (SSC) process, γ-ray band emission is produced by external Compton (EC) process.

  9. The histology of ovarian cancer: worldwide distribution and implications for international survival comparisons (CONCORD-2).

    PubMed

    Matz, Melissa; Coleman, Michel P; Sant, Milena; Chirlaque, Maria Dolores; Visser, Otto; Gore, Martin; Allemani, Claudia

    2017-02-01

    Ovarian cancers comprise several histologically distinct tumour groups with widely different prognosis. We aimed to describe the worldwide distribution of ovarian cancer histology and to understand what role this may play in international variation in survival. The CONCORD programme is the largest population-based study of global trends in cancer survival. Data on 681,759 women diagnosed during 1995-2009 with cancer of the ovary, fallopian tube, peritoneum and retroperitonum in 51 countries were included. We categorised ovarian tumours into six histological groups, and explored the worldwide distribution of histology. During 2005-2009, type II epithelial tumours were the most common. The proportion was much higher in Oceania (73.1%), North America (73.0%) and Europe (72.6%) than in Central and South America (65.7%) and Asia (56.1%). By contrast, type I epithelial tumours were more common in Asia (32.5%), compared with only 19.4% in North America. From 1995 to 2009, the proportion of type II epithelial tumours increased from 68.6% to 71.1%, while the proportion of type I epithelial tumours fell from 23.8% to 21.2%. The proportions of germ cell tumours, sex cord-stromal tumours, other specific non-epithelial tumours and tumours of non-specific morphology all remained stable over time. The distribution of ovarian cancer histology varies widely worldwide. Type I epithelial, germ cell and sex cord-stromal tumours are generally associated with higher survival than type II tumours, so the proportion of these tumours may influence survival estimates for all ovarian cancers combined. The distribution of histological groups should be considered when comparing survival between countries and regions. Copyright © 2016. Published by Elsevier Inc.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. Internal charge distribution of iodine adatoms on silicon and silicon oxide investigated with alkali ion scattering

    NASA Astrophysics Data System (ADS)

    Yang, Ye; Yarmoff, Jory A.

    2004-12-01

    Time-of-flight spectra were collected for low energy 7Li + and 23Na + ions backscattered from Si(1 1 1) surfaces covered with sub-monolayers of iodine. Li ions singly scattered from the iodine adatoms have consistently larger neutralization probabilities than those scattered from the silicon substrate, and the neutralization decreases with off-normal emission. This indicates that the internal charge distribution of the iodine adatoms is not uniform, presumably due to attraction of electron density to the positively charged bonding Si atom. Photoelectron spectroscopy shows that iodine adsorbed on pre-oxidized Si bonds through the oxygen atom, forming hypoiodite (-OI) moieties. The neutralization of 23Na + backscattered from such iodine adatoms is independent of the emission angle, indicating that there is less charge rearrangement than for iodine bonded directly to Si.

  15. 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

  16. Providing International Research Experiences in Water Resources Through a Distributed REU Program

    NASA Astrophysics Data System (ADS)

    Judge, J.; Sahrawat, K.; Mylavarapu, R.

    2012-12-01

    Research experiences for undergraduates offer training in problem solving and critical thinking via hands-on projects. The goal of the distributed Research Experience for Undergraduates (REU) Program in the Agricultural and Biological Engineering Department (ABE) at the University of Florida (UF) is to provide undergraduate students a unique opportunity to conduct research in water resources using interdisciplinary approaches, integrating research and extension, while the cohort is not co-located. The eight-week REU Program utilizes the extensive infrastructure of UF - Institute of Food and Agricultural Sciences (IFAS) through the Research and Education Centers (RECs). To provide international research and extension experience, two students were located at the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), in India. Prior to the beginning of the Program, the students worked closely with their research mentors at University of Florida and ICRISAT to develop a project plan for understanding the water quality issues in two watersheds. The students were co-located during the Orientation week at the University of Florida. During the Program, they achieved an enriching cohort experience through social networking, daily blogs, and weekly video conferences to share their research and other REU experiences. The group meetings and guest lectures are conducted via synchronously through video conferencing. The students who were distributed across Florida benefited from the research experiences of the students who were located in India, as their project progressed. They described their challenges and achievements during the group meetings and in the blogs. This model of providing integrated research and extension opportunities in hydrology where not all the REU participants are physically co-located, is unique and can be extended to other disciplines.

  17. 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.

  18. Internal wave generation by tidal flow over periodically and randomly distributed seamounts

    NASA Astrophysics Data System (ADS)

    Zhang, Likun; Buijsman, Maarten C.; Comino, Eva; Swinney, Harry L.

    2017-06-01

    We examine numerically the conversion of barotropic tidal energy into internal waves by flow over an isolated seamount and over systems of periodically and randomly distributed 1100 m tall seamounts with Gaussian profiles. The simulations use the Massachusetts Institute of Technology general circulation model (MITgcm) to calculate for an infinitely deep ocean the dependence of the energy conversion on seamount slope, seamount separation, tidal direction, and the size and aspect ratio of the simulation domain. For neighboring seamounts with a slope greater than the internal wave beam slope, wave interference reduces the conversion relative to that calculated for an isolated seamount, and relative to that predicted by linear theory for a seamount of slope less than the beam slope. The conversion by an individual seamount in a system of random seamounts separated by an average distance of 18 km is found to be suppressed by 16% relative to the conversion by an isolated seamount. This study provides insight into tidal conversion by ocean seamounts modeled as Gaussian mountains with slopes both smaller and larger than the beam slope. We conclude that the total energy conversion by all seamounts (peak height ≥1000 m) and knolls (peak height 500-1000 m), taking into account interference affects, is of the order of 1% of the total barotropic to baroclinic energy conversion in the oceans, which is about twice as large as previous estimates.

  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. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  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

    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.

  7. 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.

  8. 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

  9. International.

    ERIC Educational Resources Information Center

    Hoover, Linn

    1979-01-01

    The International Geological Correlation Project has attained scientific maturity and broad support and participation by geologists world wide. Its purpose is to provide a mechanism for international cooperation and information exchange about geological problems that transcend national boundaries. (Author/BB)

  10. The nature of very low luminosity objects (VeLLOs)

    NASA Astrophysics Data System (ADS)

    Vorobyov, Eduard I.; Elbakyan, Vardan; Dunham, Michael M.; Guedel, Manuel

    2017-03-01

    Aims: The nature of very low luminosity objects (VeLLOs) with the internal luminosity Lobj ≤ 0.1 L⊙ is investigated by means of numerical modeling coupling the core collapse simulations with the stellar evolution calculations. Methods: The gravitational collapse of a large sample of model cores in the mass range 0.1-2.0 M⊙ is investigated. Numerical simulations were started at the pre-stellar phase and terminated at the end of the embedded phase when 90% of the initial core mass had been accreted onto the forming protostar plus disk system. The disk formation and evolution was studied using numerical hydrodynamics simulations, while the formation and evolution of the central star was calculated using a stellar evolution code. Three scenarios for mass accretion from the disk onto the star were considered: hybrid accretion in which a fraction of accreted energy absorbed by the protostar depends on the accretion rate, hot accretion wherein a fraction of accreted energy is constant, and cold accretion wherein all accretion energy is radiated away. Results: Our conclusions on the nature of VeLLOs depend crucially on the character of protostellar accretion. In the hybrid accretion scenario, most VeLLOs (90.6%) are expected to be the first hydrostatic cores (FHSCs) and only a small fraction (9.4%) are true protostars. In the hot accretion scenario, all VeLLOs are FHSCs due to overly high photospheric luminosity of protostars. In the cold accretion scenario, on the contrary, the majority of VeLLOs belong to the Class I phase of stellar evolution. The reason is that the stellar photospheric luminosity, which sets the floor for the total internal luminosity of a young star, is lower in cold accretion, thus enabling more VeLLOs in the protostellar stage. VeLLOs are relatively rare objects occupying 7%-11% of the total duration of the embedded phase and their masses do not exceed 0.3 M⊙. When compared with published observations inferring a fraction of VeLLOs in the

  11. 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

  12. 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

  13. Internalized racism, body fat distribution, and abnormal fasting glucose among African-Caribbean women in Dominica, West Indies.

    PubMed Central

    Butler, Cleve; Tull, Eugene S.; Chambers, Earle C.; Taylor, Jerome

    2002-01-01

    The current study examined the relationship of internalized racism to glucose intolerance in a population of Afro-Caribbean women aged 18 to 55. Also of interest was whether this relationship would be differentially influenced by the type of body fat distribution or confounded by the level of hostility. A total of 244 women were selected from a systematic sample of households on the island of Dominica, West Indies. Demographic data together with information on internalized racism were collected by questionnaire. Anthropometric information and fasting blood glucose were also measured. Women with high levels of internalized racism exhibited an increased risk of elevated fasting glucose compared to those with low levels of internalized racism (odds ratio (OR) = 2.4; 95% confidence interval (CI) = 1.1-5.5). There was no difference in mean body mass index (BMI) by level of internalized racism. However those with high internalized racism had a significantly larger waist circumference after adjusting for age, education, hostility, and elevated fasting glucose status. In multivariate analyses controlling for age, education, hostility, and either weight or BMI, internalized racism remained independently associated with elevated fasting glucose. However, once waist circumference was included in the model, the relationship of internalized racism to elevated fasting glucose was not statistically significant. This study demonstrates a significant relationship between internalized racism and abnormal levels of fasting glucose which may be mediated through abdominal fat. The exact nature of the relationship of internalized racism to glucose intolerance may be an important area of future study. PMID:11918383

  14. Internalized racism, body fat distribution, and abnormal fasting glucose among African-Caribbean women in Dominica, West Indies.

    PubMed

    Butler, Cleve; Tull, Eugene S; Chambers, Earle C; Taylor, Jerome

    2002-03-01

    The current study examined the relationship of internalized racism to glucose intolerance in a population of Afro-Caribbean women aged 18 to 55. Also of interest was whether this relationship would be differentially influenced by the type of body fat distribution or confounded by the level of hostility. A total of 244 women were selected from a systematic sample of households on the island of Dominica, West Indies. Demographic data together with information on internalized racism were collected by questionnaire. Anthropometric information and fasting blood glucose were also measured. Women with high levels of internalized racism exhibited an increased risk of elevated fasting glucose compared to those with low levels of internalized racism (odds ratio (OR) = 2.4; 95% confidence interval (CI) = 1.1-5.5). There was no difference in mean body mass index (BMI) by level of internalized racism. However those with high internalized racism had a significantly larger waist circumference after adjusting for age, education, hostility, and elevated fasting glucose status. In multivariate analyses controlling for age, education, hostility, and either weight or BMI, internalized racism remained independently associated with elevated fasting glucose. However, once waist circumference was included in the model, the relationship of internalized racism to elevated fasting glucose was not statistically significant. This study demonstrates a significant relationship between internalized racism and abnormal levels of fasting glucose which may be mediated through abdominal fat. The exact nature of the relationship of internalized racism to glucose intolerance may be an important area of future study.

  15. 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

  16. 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.

  17. Updating quasar bolometric luminosity corrections - III. [O iii] bolometric corrections

    NASA Astrophysics Data System (ADS)

    Pennell, Alison; Runnoe, Jessie C.; Brotherton, M. S.

    2017-06-01

    We present quasar bolometric corrections using the [O III] λ 5007 narrow emission line luminosity based on the detailed spectral energy distributions of 53 bright quasars at low to moderate redshift (0.0345 < z < 1.0002). We adopted two functional forms to calculate Liso, the bolometric luminosity determined under the assumption of isotropy: {L_{iso}}=A {L_{[O III]}} for comparison with the literature and {log(L_{iso})}=B+C log(L_{[O III]}), which better characterizes the data. We also explored whether 'Eigenvector 1 (EV1)', which describes the range of quasar spectral properties and quantifies their diversity, introduces scatter into the L_{[O III]}-Liso relationship. We found that the {[O III]} bolometric correction can be significantly improved by adding a term including the equivalent width ratio R_{Fe II} ≡ EW_{{Fe II}}/EW_{Hβ }, which is an EV1 indicator. Inclusion of R_{Fe II} in predicting Liso is significant at nearly the 3σ level and reduces the scatter and systematic offset of the luminosity residuals. Typically, {[O III]} bolometric corrections are adopted for Type 2 sources where the quasar continuum is not observed and in these cases, R_{Fe II} cannot be measured. We searched for an alternative measure of EV1 that could be measured in the optical spectra of Type 2 sources but were unable to identify one. Thus, the main contribution of this work is to present an improved {[O III]} bolometric correction based on measured bolometric luminosities and highlight the EV1 dependence of the correction in Type 1 sources.

  18. 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.

  19. Liners and Low Luminosity AGN in the ROSAT Database

    NASA Technical Reports Server (NTRS)

    Elvis, Martin; West, Donald K. (Technical Monitor)

    2003-01-01

    This program has led to a series of papers being written and published in the Astrophysical Journal. Together these papers try to explain major parts of the LINER and low luminosity AGN puzzle. One paper ('Accretion Disk Instabilities, Cold Dark Matter Models, and Their Role in Quasar Evolution', Hatziminaoglou E., Siemiginowska A., & Elvis M., 2001, ApJ, 547, 90) describes an analytical model for the evolution of the quasar luminosity function. By combining the Press-Schechter formalism for the masses of initial structures with the luminosity distribution for a population of single mass black holes given by an unstable accretion disk an almost complete end-to-end physics-based model of quasar evolution is produced. In this model black holes spend 75% of their time in a low accretion state (at L(Edd)). This low state population of black holes is likely to be observed as the LINER and low luminosity AGNs in the local universe. Another paper ('Broad Emission Line Regions in AGN: the Link with the Accretion Power', Nicastro F., 2000, ApJ Letters, 530, L65) gives a physical basis for why low state black holes appear as LINERS. By linking the Lightman-Eardley instability in an accretion disk to the ori.gin of a wind that contains the broad emission line cloud material this model explains the large widths seen in these lines as being the Keplerian velocity of the disk at the instability radius. For LINERS the key is that below an accretion rate of 10(exp -3)M(sub Edd)the Lightman-Eardley instability falls within the innermost stable orbit of the disk, and so leaves the entire disk stable. No wind occurs, and so no broad emission lines are seen. Most LINERS are likely to be black holes in this low state. Tests of this model are being considered.

  20. Correlation function of the luminosity distances

    NASA Astrophysics Data System (ADS)

    Biern, Sang Gyu; Yoo, Jaiyul

    2017-09-01

    We present the correlation function of the luminosity distances in a flat ΛCDM universe. Decomposing the luminosity distance fluctuation into the velocity, the gravitational potential, and the lensing contributions in linear perturbation theory, we study their individual contributions to the correlation function. The lensing contribution is important at large redshift (z gtrsim 0.5) but only for small angular separation (θ lesssim 3°), while the velocity contribution dominates over the other contributions at low redshift or at larger separation. However, the gravitational potential contribution is always subdominant at all scale, if the correct gauge-invariant expression is used. The correlation function of the luminosity distances depends significantly on the matter content, especially for the lensing contribution, thus providing a novel tool of estimating cosmological parameters.

  1. Apparent luminosity of solar power satellites

    NASA Technical Reports Server (NTRS)

    Livingston, L. E.

    1980-01-01

    The objective of this investigation was a quantitative characterization of solar power satellite luminosity as seen from the earth. The reflective characteristics of the reference photovoltaic satellite configurations are defined. Diffuse reflection from a single satellite will, at maximum, fall between magnitudes -4 and -5. A 60-satellite fleet will have a maximum total luminosity equivalent to a single object of magnitude -9. Specular reflections from the array and antenna will be of magnitude -12 to -15, but visible only occasionally for about 2 minutes at a given location. Methods of preventing specular reflections from striking the earth are presented. Thermal cycle power conversion systems are discussed qualitatively as a means of reducing diffuse luminosity.

  2. 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.

  3. 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.

  4. Radius-luminosity and mass-luminosity relationships for active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Koratkar, Anuradha P.; Gaskell, C. Martin

    1991-01-01

    Broad-line region (BLR) sizes derived from spectral variability and BLR line widths are used to directly derive the mass (M) of the central objects of ten active galactic nuclei (AGNs) in a uniform manner. It is shown that the luminosity-weighted C IV 1549-emitting BLR radius (R) correlates with the bolometric luminosity L(Bol) and is consistent with R about sq rt L(Bol). The measurements also permit a verification of the Dibai mass-luminosity (M-L) relationship (previously derived indirectly). It is found that L(Bol) is proportional to M exp (1.1 + or - 0.3). It is found that the efficiency factor epsilon, defined as the ratio of L(Bol) to the Eddington luminosity increases from 0.03 in the low-luminosity Seyferts up to 0.06 in the most luminous objects in the sample.

  5. 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.

  6. 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.

  7. 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.

  8. Direct measurement of solar luminosity variation.

    PubMed

    Willson, R C; Duncan, C H; Geist, J

    1980-01-11

    Two rocket flights of an absolute pyrheliometer, separated by 30 months, indicate an increase in solar luminosity (solar constant) of 0.4 percent. The significance of this result is considered in light of the instrument performance during the rocket flights and of pre- and postflight intercomparisons with independently maintained pyrheliometers. There is a high probability that the measured difference is real. Additional observations are required to determine whether the difference results from random fluctuations in solar luminosity, a nonrandom change of short duration, or a sustained change that has climatological significance.

  9. 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.

  10. 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.

  11. Offline Software for the PANDA Luminosity Detector

    NASA Astrophysics Data System (ADS)

    Karavdina, A.; Denig, A.; Feldbauer, F.; Jasinski, P.; Leithoff, H.; Michel, M.; Motzko, C.; Pflüger, S.; Weber, T.; Fritsch, M.

    2014-06-01

    In 2018 data taking for hadronphysics facility PANDA is planned to commence. It will be build at the antiproton accelerator HESR, which itself is a part of the FAIR complex (GSI, Darmstadt, Germany). The luminosity at PANDA will be measured by a dedicated sub-detector, which will register scattered antiproton tracks from pp elastic scattering. From a software point of view, the Luminosity Detector is a tracking system. Therefore the most of its offline software parts are typical for a track reconstruction. The basic concept and Monte Carlo based performance studies of each reconstruction step is presented in this paper.

  12. Consistency between the luminosity function of resolved millisecond pulsars and the galactic center excess

    NASA Astrophysics Data System (ADS)

    Ploeg, Harrison; Gordon, Chris; Crocker, Roland; Macias, Oscar

    2017-08-01

    Fermi Large Area Telescope data reveal an excess of GeV gamma rays from the direction of the Galactic Center and bulge. Several explanations have been proposed for this excess including an unresolved population of millisecond pulsars (MSPs) and self-annihilating dark matter. It has been claimed that a key discriminant for or against the MSP explanation can be extracted from the properties of the luminosity function describing this source population. Specifically, is the luminosity function of the putative MSPs in the Galactic Center consistent with that characterizing the resolved MSPs in the Galactic disk? To investigate this we have used a Bayesian Markov Chain Monte Carlo to evaluate the posterior distribution of the parameters of the MSP luminosity function describing both resolved MSPs and the Galactic Center excess. At variance with some other claims, our analysis reveals that, within current uncertainties, both data sets can be well fit with the same luminosity function.

  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. 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.

  15. Review and Content Analysis of the "International Review of Research in Open and Distance/Distributed Learning" (2000-2015)

    ERIC Educational Resources Information Center

    Zawacki-Richter, Olaf; Alturki, Uthman; Aldraiweesh, Ahmed

    2017-01-01

    This paper presents a review of distance education literature published in the "International Review of Research in Open and Distance/Distributed Learning" (IRRODL) to describe the status thereof and to identify gaps and priority areas in distance education research based on a validated classification of research areas. All articles (N =…

  16. 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.

  17. Assessing Faculty Experiences with and Perceptions of an Internal Quality Assurance Process for Undergraduate Distributed Learning Courses: A Pilot Study

    ERIC Educational Resources Information Center

    Rucker, Ryan; Edwards, Karen; Frass, Lydia R.

    2015-01-01

    To ensure that online courses match traditional classes' quality, some institutions are implementing internal standards for online course design and quality review. The University of South Carolina created the Distributed Learning Quality Review program, based on "Quality Matters'" standards. It was designed to be faculty-guided, as…

  18. 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.

  19. Summary of symposium: Low luminosity sources

    NASA Technical Reports Server (NTRS)

    Shu, Frank H.

    1987-01-01

    The author summarized certain aspects of the conference. He shares this task with another colleague thereby breaking the task into more manageable proportions. The author covers the low luminosity sources. He begins his review with a summary of some major themes of the conference and ends with a few speculations on possible theoretical mechanisms.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. BOSS Great Wall: morphology, luminosity, and mass

    NASA Astrophysics Data System (ADS)

    Einasto, Maret; Lietzen, Heidi; Gramann, Mirt; Saar, Enn; Tempel, Elmo; Liivamägi, Lauri Juhan; Montero-Dorta, Antonio D.; Streblyanska, Alina; Maraston, Claudia; Rubiño-Martín, José Alberto

    2017-06-01

    Context. Galaxy superclusters are the largest systems in the Universe that can give us information about the formation and evolution of the cosmic web. Aims: We study the morphology of the superclusters from the BOSS Great Wall (BGW), a recently discovered very rich supercluster complex at the redshift z = 0.47. Methods: We have employed the Minkowski functionals to quantify supercluster morphology. We calculate supercluster luminosities and masses using two methods. Firstly, we used data about the luminosities and stellar masses of high stellar mass galaxies with log (M∗/h-1M⊙) ≥ 11.3. Secondly, we applied a scaling relation that combines morphological and physical parameters of superclusters to obtain supercluster luminosities, and obtained supercluster masses using the mass-to-light ratios found for local rich superclusters. Results: The BGW superclusters are very elongated systems, with shape parameter values of less than 0.2. This value is lower than that found for the most elongated local superclusters. The values of the fourth Minkowski functional V3 for the richer BGW superclusters (V3 = 7 and 10) show that they have a complicated and rich inner structure. We identify two Planck SZ clusters in the BGW superclusters, one in the richest BGW supercluster, and another in one of the poor BGW superclusters. The luminosities of the BGW superclusters are in the range of 1-8 × 1013h-2L⊙, and masses in the range of 0.4-2.1 × 1016h-1M⊙. Supercluster luminosities and masses obtained with two methods agree well. Conclusions: The BGW is a complex of massive, luminous and large superclusters with very elongated shape. The search and detailed study, including the morphology analysis of the richest superclusters and their complexes from observations and simulations can help us to understand formation and evolution of the cosmic web.

  5. Precision Luminosity of LHC Proton-Proton Collisions at 13 TeV Using Hit Counting With TPX Pixel Devices

    NASA Astrophysics Data System (ADS)

    Sopczak, André; Ali, Babar; Asawatavonvanich, Thanawat; Begera, Jakub; Bergmann, Benedikt; Billoud, Thomas; Burian, Petr; Caicedo, Ivan; Caforio, Davide; Heijne, Erik; Janeček, Josef; Leroy, Claude; Mánek, Petr; Mochizuki, Kazuya; Mora, Yesid; Pacík, Josef; Papadatos, Costa; Platkevič, Michal; Polanský, Štěpán; Pospíšil, Stanislav; Suk, Michal; Svoboda, Zdeněk

    2017-03-01

    A network of Timepix (TPX) devices installed in the ATLAS cavern measures the LHC luminosity as a function of time as a stand-alone system. The data were recorded from 13-TeV proton-proton collisions in 2015. Using two TPX devices, the number of hits created by particles passing the pixel matrices was counted. A van der Meer scan of the LHC beams was analyzed using bunch-integrated luminosity averages over the different bunch profiles for an approximate absolute luminosity normalization. It is demonstrated that the TPX network has the capability to measure the reduction of LHC luminosity with precision. Comparative studies were performed among four sensors (two sensors in each TPX device) and the relative short-term precision of the luminosity measurement was determined to be 0.1% for 10-s time intervals. The internal long-term time stability of the measurements was below 0.5% for the data-taking period.

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. Luminosity with more bunches in PEP

    SciTech Connect

    Corbett, W.J.

    1990-12-01

    The near term accelerator physics program for PEP includes experiments in a collider mode with up to 9 bunches in each beam. In this memo, luminosity data from the 3 {times} 3 configuration is first used to calculate vertical beam size, emittance and tune shift as a function of current. The data is then used to extrapolate to the case with either 6 {times} 6 or 9 {times} 9 bunches colliding in PEP. Vertical emittance growth from the separated bunch optics and dispersion at the IP are included in the calculations. The conclusion is that given a 90 mA current drive limitation in PEP, operating with 6 {times} 6 bunches yields the maximum luminosity. 9 refs., 6 figs.

  11. 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.

  12. 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.

  13. 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.

  14. Avoiding Spurious Breaks in Binned Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Cara, M.; Lister, M. L.

    2008-10-01

    We show that using either the method of Page & Carrera or the well-known 1/Va method to construct the binned luminosity function (LF) of a flux limited sample of active galactic nuclei (AGNs) can produce an artificial flattening (or steepening in the case of negative evolution) of the binned LF for bins intersected by the flux cutoff of the sample. This effect is more pronounced for samples with steep and strongly evolving parent LFs but is still present even for non-evolving LFs. As a result of this distortion of the true LF, fitting a model LF to binned data may lead to errors in the estimation of the parameters and may even prompt the erroneous use of broken power-law functions. We compute the expected positions of apparent breaks in the binned LF. We show that these spurious breaks in the binned LFs can be avoided if the binning is done in the flux-redshift plane instead of the typically used luminosity-redshift plane. Binning in the flux-redshift plane can be used in conjunction with the binning in the luminosity-redshift plane to test for real breaks in the binned LFs and to identify the features that are the result of binning biases. We illustrate this effect for most typical forms of luminosity dependence and redshift evolution and show how the proposed method helps address this problem. We also apply this method to the MOJAVE AGN sample and show that it eliminates an apparent break in the binned LF.

  15. 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.

  16. Generalized Tests for Eight GRB Luminosity Relations

    NASA Astrophysics Data System (ADS)

    Schaefer, Bradley E.; Collazzi, Andrew C.

    2007-02-01

    Long-duration gamma-ray bursts (GRBs) have eight luminosity relations where observable burst properties can yield the burst luminosity and hence distance. This turns GRBs into useful tools of cosmology. Recently, two tests have been proposed (by Nakar & Piran and by Li) for which one of the eight relations is claimed to have significant problems. In this Letter, we generalize these tests and apply them to all eight GRB luminosity relations. (1) All eight relations pass the Nakar & Piran test after accounting for the uncertainties on the data and the dispersions of the correlations. (2) All eight relations are good when the GRB redshifts are known, for example, for calibration of the relations and for GRB Hubble diagram purposes. (3) We confirm the earlier results that the Eγ,iso-Epeak Amati relation must produce very large error bars whenever an unknown redshift being sought is >~1.4. (4) The Eγ-Epeak relation of Ghirlanda et al. must produce very large error bars whenever an unknown redshift being sought is >~3.4. (55) The other six relations have no problem at all from the ambiguity test of Li.

  17. Internal electric-field-lines distribution in CdZnTe detectors measured using X-ray mapping

    SciTech Connect

    Bolotnikov,A.E.; , .; Camarda, G.S.; Cui, Y.; Hossain, A.; Yang, G.; Yao, H.W.; James, R.B.

    2009-10-19

    The ideal operation of CdZnTe devices entails having a uniformly distributed internal electric field. Such uniformity especially is critical for thick long-drift-length detectors, such as large-volume CPG and 3-D multi-pixel devices. Using a high-spatial resolution X-ray mapping technique, we investigated the distribution of the electric field in real devices. Our measurements demonstrate that in thin detectors, <5 mm, the electric field-lines tend to bend away from the side surfaces (i.e., a focusing effect). In thick detectors, >1 cm, with a large aspect ratio (thickness-to-width ratio), we observed two effects: the electric field lines bending away from or towards the side surfaces, which we called, respectively, the focusing field-line distribution and the defocusing field-line distribution. In addition to these large-scale variations, the field-line distributions were locally perturbed by the presence of extended defects and residual strains existing inside the crystals. We present our data clearly demonstrating the non-uniformity of the internal electric field.

  18. 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.

  19. New calibrators for the Cepheid period-luminosity relation

    NASA Technical Reports Server (NTRS)

    Evans, Nancy R.

    1992-01-01

    IUE spectra of six Cepheids have been used to determine their absolute magnitudes from the spectral types of their binary companions. The stars observed are U Aql, V659 Cen, Y Lac, S Nor, V350 Sgr, and V636 Sco. The absolute magnitude for V659 Cen is more uncertain than for the others because its reddening is poorly determined and the spectral type is hotter than those of the others. In addition, a reddening law with extra absorption in the 2200 A region is necessary, although this has a negligible effect on the absolute magnitude. For the other Cepheids, and also Eta Aql and W Sgr, the standard deviation from the Feast and Walker period-luminosity-color (PLC) relation is 0.37 mag, confirming the previously estimated internal uncertainty. The absolute magnitudes for S Nor from the binary companion and from cluster membership are very similar. The preliminary PLC zero point is less than 2 sigma (+0.21 mag) different from that of Feast and Walker. The same narrowing of the instability strip at low luminosities found by Fernie is seen.

  20. Exposure to smoking in internationally distributed American movies and youth smoking in Germany: a cross-cultural cohort study.

    PubMed

    Hanewinkel, Reiner; Sargent, James D

    2008-01-01

    Studies of US adolescents have linked exposure to movie smoking with smoking behavior. It is unclear whether European adolescents are also responsive to movie tobacco imagery. A longitudinal study was conducted to assess exposure to movie smoking in 2711 German never-smokers (aged 10 to 16 years). Movie smoking exposure was estimated by asking adolescents if they had seen movies from a list of 50 movie titles, randomly selected for each adolescent from 398 internationally distributed movies released between 1994 and 2004 that became box-office hits in Germany. These films were reviewed for smoking content. Adolescents were resurveyed 12 to 13 months later to determine smoking status, and results were compared with a similarly designed survey of 2603 white US adolescents. We hypothesized replication of the main effect of the exposure on trying smoking, and an interaction, with a significantly larger response among adolescents whose parents did not smoke. The 398 internationally distributed movies represented 80% of the German box-office hits within this time frame, with the majority (388) produced and/or distributed internationally by US companies. Smoking was present in 74% of the movies. Overall, 503 (19%) of the students tried smoking during the follow-up period. The incidence of trying smoking was associated with increased exposure to movie smoking. The form of the dose-response was similar to the US sample, with the strongest response to movies seen in the lower 2 quartiles of exposure. After controlling for baseline covariates, exposure to movie smoking remained a significant predictor of trying smoking in German adolescents, and the effect was significantly stronger in adolescents whose parents did not smoke. Smoking in internationally distributed US movies predicts trying smoking among German adolescents, closely replicating findings from a longitudinal study of white US adolescents. Smoking in these movies could have important worldwide public health

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Electromagnetic luminosity function of superconducting cosmic string loops

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Pijushpani

    1988-08-01

    The luminosity function (LF) of electromagnetically radiating closed loops of superconducting cosmic strings (SCS) is calculated in a cosmological context. The LF has a peak as a function of luminosity and a cutoff at the low-luminosity end, and increases with increasing redshift. Some questions concerning a hypothetical model of quasars in which SCS loops act as the ``central engines'' are discussed.

  7. NLC Luminosity as a Function of Beam Parameters

    NASA Astrophysics Data System (ADS)

    Nosochkov, Y.

    2002-06-01

    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.

  8. 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.

  9. 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.

  10. The luminosity function of the CfA Redshift Survey

    NASA Technical Reports Server (NTRS)

    Marzke, R. O.; Huchra, J. P.; Geller, M. J.

    1994-01-01

    We use the CfA Reshift Survey of galaxies with m(sub z) less than or equal to 15.5 to calculate the galaxy luminosity function over the range -13 less than or equal to M(sub z) less than or equal to -22. The sample includes 9063 galaxies distributed over 2.1 sr. For galaxies with velocities cz greater or equal to 2500 km per sec, where the effects of peculiar velocities are small, the luminosity function is well represented by a Schechter function with parameters phi(sub star) = 0.04 +/- 0.01 per cu Mpc, M(sub star) = -18.8 +/- 0.3, and alpha = -1.0 +/- 0.2. When we include all galaxies with cz greater or equal to 500 km per sec, the number of galaxies in the range -16 less than or equal to M(sub z) less than or equal to -13 exceeds the extrapolation of the Schechter function by a factor of 3.1 +/- 0.5. This faint-end excess is not caused by the local peculiar velocity field but may be partially explained by small scale errors in the Zwicky magnitudes. Even with a scale error as large as 0.2 mag per mag, which is unlikely, the excess is still a factor of 1.8 +/- 0.3. If real, this excess affects the interpretation of deep counts of field galaxies.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Observed variability of the solar luminosity

    NASA Astrophysics Data System (ADS)

    Hudson, H. S.

    Data on solar luminosity variations are compiled in graphs and analyzed, with a focus on the SMM satellite bolometric measurements and other observations made since 1983. Consideration is given to total irradiance measurements in integrated light; emission-line variability in the visible, UV, and IR; mechanisms contributing to the solar variability (sunspots, faculae, rotation, oscillations, granulation, and active networks); the role of the solar magnetic cycle; and other observable parameters indicating variability. Also discussed are the effects of solar variations on the earth climate and the implications of the observations for theoretical models of convective-envelope processes (thermal diffusion near the surface and magnetic pressure in the interior).

  16. 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).

  17. The Distribution of Talent and the Pattern and Consequences of International Trade

    ERIC Educational Resources Information Center

    Grossman, Gene M.

    2004-01-01

    The author studies the interaction between imperfect labor contracts and international trade in a setting in which workers have private information about their own abilities. When an individual's contribution to firm output can be measured accurately in some activities but not in others, the most able workers select occupations in which their pay…

  18. 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,…

  19. 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.

  20. 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.

  1. 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.

  2. Simulation Model of Microsphere Distribution for Selective Internal Radiation Therapy Agrees With Observations.

    PubMed

    Högberg, Jonas; Rizell, Magnus; Hultborn, Ragnar; Svensson, Johanna; Henrikson, Olof; Mölne, Johan; Gjertsson, Peter; Bernhardt, Peter

    2016-10-01

    To perform a detailed analysis of microsphere distribution in biopsy material from a patient treated with (90)Y-labeled resin spheres and characterize microsphere distribution in the hepatic artery tree, and to construct a novel dichotomous bifurcation model for microsphere deposits and evaluate its accuracy in simulating the observed microsphere deposits. Our virtual model consisted of arteries that successively branched into 2 new generations of arteries at 20 nodes. The artery diameter exponentially decreased from the lowest generation to the highest generation. Three variable parameters were optimized to obtain concordance between simulations and measure microsphere distributions: an artery coefficient of variation (ACV) for the diameter of all artery generations and the microsphere flow distribution at the nodes; a hepatic tree distribution volume (HDV) for the artery tree; and an artery diameter reduction (ADR) parameter. The model was tested against previously measured activity concentrations in 84 biopsies from the liver of 1 patient. In 16 of 84 biopsies, the microsphere distribution regarding cluster size and localization in the artery tree was determined via light microscopy of 30-μm sections (mean concentration, 14 microspheres/mg; distributions divided into 3 groups with mean microsphere concentrations of 4.6, 14, and 28 microspheres/mg). Single spheres and small clusters were observed in terminal arterioles, whereas large clusters, up to 450 microspheres, were observed in larger arterioles. For 14 microspheres/mg, the optimized parameter values were ACV=0.35, HDV = 50 cm(3), and ADR=6 μm. For 4.6 microspheres/mg, ACV and ADR decreased to 0.26 and 0 μm, respectively, whereas HDV increased to 130 cm(3). The opposite trend was observed for 28 microspheres/mg: ACV = 0.49, HDV = 20 cm(3), and ADR = 8 μm. Simulations and measurements reveal that microsphere clusters are larger and more common in volumes with high microsphere concentrations

  3. Application of mercury isotopes for tracing trophic transfer and internal distribution of mercury in marine fish feeding experiments.

    PubMed

    Kwon, Sae Yun; Blum, Joel D; Chirby, Michelle A; Chesney, Edward J

    2013-10-01

    Feeding experiments were performed to investigate mercury (Hg) isotope fractionation during trophic transfer and internal distribution of total Hg (THg) in marine fish on exposure to natural seafood. Young-of-the-year amberjack (Seriola dumerili) were fed with either blackfin tuna (Thunnus atlanticus; 2647 ng/g THg) or brown shrimp (Farfantepenaeus aztecus; 25.1 ng/g THg) for 80 d or 50 d, respectively, and dissected for muscle, liver, kidney, brain, and blood. After 30 d of tuna consumption, Hg isotopes (δ(202) Hg and Δ(199)Hg) of the amberjack organs shifted to the tuna value (δ(202)Hg = 0.55‰, Δ(199)Hg = 1.54‰,), demonstrating the absence of Hg isotope fractionation. When amberjack were fed a shrimp diet, there was an initial mixing of the amberjack organs toward the shrimp value (δ(202)Hg = -0.48‰, Δ(199)Hg = 0.32‰), followed by a cessation of further shifts in Δ(199)Hg and a small shift in δ(202)Hg. The failure of Δ(199)Hg to reach the shrimp value can be attributed to a reduction in Hg bioaccumulation from shrimp resulting from feeding inhibition and the δ(202)Hg shift can be attributed to a small internal fractionation during excretion. Given that the feeding rate and Hg concentration of the diet can influence internal Hg isotope distribution, these parameters must be considered in biosentinel fish studies. © 2013 SETAC.

  4. 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.

  5. 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.

  6. 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

  7. Solar luminosity variations in solar cycle 21

    NASA Technical Reports Server (NTRS)

    Willson, Richard C.; Hudson, H. S.

    1988-01-01

    Long-term variations in the solar total irradiance found in the ACRIM I experiment on the SMM satellite have revealed a downward trend during the declining phase of solar cycle 21 of the sunspot cycle, a flat period between mid-1095 and mid-1987, and an upturn in late 1987 which suggests a direct correlation of luminosity and solar active region population. If the upturn continues into the activity maximum of solar cycle 22, a relation between solar activity and luminosity of possible climatological significance could be ascertained. The best-fit relationship for the variation of total irradiance S with sunspot number Rz and 10-cm flux F(10) are S = 1366.82 + 7.71 x 10 to the -3rd Rz and S = 1366.27 + 8.98 x 10 to the -3rd F(10)(W/sq m). These findings could be used to approximate total irradiance variations over the periods for which these indices have been compiled.

  8. 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.

  9. 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.

  10. 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.

  11. Maximum likelihood random galaxy catalogues and luminosity function estimation

    NASA Astrophysics Data System (ADS)

    Cole, Shaun

    2011-09-01

    We present a new algorithm to generate a random (unclustered) version of an magnitude limited observational galaxy redshift catalogue. It takes into account both galaxy evolution and the perturbing effects of large-scale structure. The key to the algorithm is a maximum likelihood (ML) method for jointly estimating both the luminosity function (LF) and the overdensity as a function of redshift. The random catalogue algorithm then works by cloning each galaxy in the original catalogue, with the number of clones determined by the ML solution. Each of these cloned galaxies is then assigned a random redshift uniformly distributed over the accessible survey volume, taking account of the survey magnitude limit(s) and, optionally, both luminosity and number density evolution. The resulting random catalogues, which can be employed in traditional estimates of galaxy clustering, make fuller use of the information available in the original catalogue and hence are superior to simply fitting a functional form to the observed redshift distribution. They are particularly well suited to studies of the dependence of galaxy clustering on galaxy properties as each galaxy in the random catalogue has the same list of attributes as measured for the galaxies in the genuine catalogue. The derivation of the joint overdensity and LF estimator reveals the limit in which the ML estimate reduces to the standard 1/Vmax LF estimate, namely when one makes the prior assumption that the are no fluctuations in the radial overdensity. The new ML estimator can be viewed as a generalization of the 1/Vmax estimate in which Vmax is replaced by a density corrected Vdc, max.

  12. Relativistic cosmology number densities and the luminosity function

    NASA Astrophysics Data System (ADS)

    Iribarrem, A. S.; Lopes, A. R.; Ribeiro, M. B.; Stoeger, W. R.

    2012-03-01

    Aims: This paper studies the connection between the relativistic number density of galaxies down the past light cone in a Friedmann-Lemaître-Robertson-Walker spacetime with non-vanishing cosmological constant and the galaxy luminosity function (LF) data. It extends the redshift range of previous results presented in Albani et al. (2007, ApJ, 657, 760), where the galaxy distribution was studied out to z = 1. Observational inhomogeneities were detected at this range. This research also searches for LF evolution in the context of the framework advanced by Ribeiro and Stoeger (2003, ApJ, 592, 1), further developing the theory linking relativistic cosmology theory and LF data. Methods: Selection functions are obtained using the Schechter parameters and redshift parametrization of the galaxy LF obtained from an I-band selected dataset of the FORS deep field galaxy survey in the redshift range 0.5 ≤ z ≤ 5.0 for its blue bands and 0.75 ≤ z ≤ 3.0 for its red ones. Differential number counts, densities and other related observables are obtained, and then used with the calculated selection functions to study the empirical radial distribution of the galaxies in a fully relativistic framework. Results: The redshift range of the dataset used in this work, which is up to five times larger than the one used in previous studies, shows an increased relevance of the relativistic effects of expansion when compared to the evolution of the LF at the higher redshifts. The results also agree with the preliminary ones presented in Albani et al., suggesting a power-law behavior of relativistic densities at high redshifts when they are defined in terms of the luminosity distance.

  13. Kinematics of nearby subdwarfs and the luminosity function of the Galactic thick disk

    NASA Astrophysics Data System (ADS)

    Arifyanto, Mochamad Ikbal

    2005-12-01

    We present an analysis of the space motions of 740 subdwarf stars based on the sample stars of Carney et al. (1994; CLLA). Hipparcos parallaxes and proper motion and Tycho2 proper motions were combined with radial velocities and metallicities from CLLA. The kinematical behavior is discussed in particular in relation to their metallicities. For stars with metallicity -1.0<[Fe/H]<-0.4, the velocity distribution represent the thick disk population. We derived the luminosity function of thick disk using 1/Vmax method. We found that the luminosity function in absolute magnitude of MV = 4 - 5 mag, agree well with the Luminosity function derived from the stellar initial function (Reyle & Robin 2001). We analayzed the kinematics in our thick disk sample and found substructure in the thick disk population.

  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. 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.

  16. Detailed Shape and Evolutionary Behavior of the X-Ray Luminosity Function of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Miyaji, T.; Hasinger, G.; Salvato, M.; Brusa, M.; Cappelluti, N.; Civano, F.; Puccetti, S.; Elvis, M.; Brunner, H.; Fotopoulou, S.; Ueda, Y.; Griffiths, R. E.; Koekemoer, A. M.; Akiyama, M.; Comastri, A.; Gilli, R.; Lanzuisi, G.; Merloni, A.; Vignali, C.

    2015-05-01

    We construct the rest-frame 2-10 keV intrinsic X-ray luminosity function (XLF) of active galactic nuclei (AGNs) from a combination of X-ray surveys from the all-sky Swift BAT survey to the Chandra Deep Field South. We use ˜3200 AGNs in our analysis, which covers six orders of magnitude in flux. The inclusion of XMM and Chandra COSMOS data has allowed us to investigate the detailed behavior of the XLF and evolution. In deriving our XLF, we take into account realistic AGN spectrum templates, absorption corrections, and probability density distributions in photometric redshift. We present an analytical expression for the overall behavior of the XLF in terms of the luminosity-dependent density evolution, smoothed two-power-law expressions in 11 redshift shells, three-segment power-law expression of the number density evolution in four luminosity classes, and binned XLF. We observe a sudden flattening of the low luminosity end slope of the XLF slope at z ≳0.6. Detailed structures of the AGN downsizing have also been revealed, where the number density curves have two clear breaks at all luminosity classes above log {{L}X}\\gt 43. The two-break structure is suggestive of two-phase AGN evolution, consisting of major merger triggering and secular processes.

  17. MIR Luminosity Function of Galaxies in the Nep-Wide Field

    NASA Astrophysics Data System (ADS)

    Kim, Seong Jin; Lee, Hyung Mok; Jeong, Woong-Seob; NEP Team

    2017-03-01

    We present the mid-infrared (MIR) luminosity function (LF) of local (z < 0.3) star-forming (SF) galaxies in the North Ecliptic Pole (NEP) field. This work is based on the NEP-Wide point source catalogue and the spectroscopic redshift (z) data for ∼1700 galaxies obtained by the optical follow-up survey with MMT/Hectospec and WIYN/Hydra. The AKARI's continuous 2-24 μm coverage and the spectroscopic redshifts enable us to determine the spectral energy distribution (SED) in the mid-infrared and derive the luminosity functions of galaxies. Our 8 μm LF finds good agreements with the results from SWIRE field over the wide luminosity range, while showing significant difference from the NOAO deep data in the faint end. The comparison with higher-z sample shows significant luminosity evolution from z > 0.3 to local universe. 12 μm LF also shows a clear indication of luminosity evolution.

  18. 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.

  19. 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.

  20. Fluctuations of Internal Transmittance in Security of Measurement-Device-Independent Quantum Key Distribution with an Untrusted Source*

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Bao, Wan-Su; Chen, Rui-Ke; Zhou, Chun; Jiang, Mu-Sheng; Li, Hong-Wei

    2017-08-01

    Measurement-device-independent quantum key distribution (MDI-QKD) is immune to detector side channel attacks, which is a crucial security loophole problem in traditional QKD. In order to relax a key assumption that the sources are trusted in MDI-QKD, an MDI-QKD protocol with an untrusted source has been proposed. For the security of MDI-QKD with an untrusted source, imperfections in the practical experiment should also be taken into account. In this paper, we analyze the effects of fluctuations of internal transmittance on the security of a decoy-state MDI-QKD protocol with an untrusted source. Our numerical results show that both the secret key rate and the maximum secure transmission distance decrease when taken fluctuations of internal transmittance into consideration. Especially, they are more sensitive when Charlie’s mean photon number per pulse is smaller. Our results emphasize that the stability of correlative optical devices is important for practical implementations.

  1. 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%.

  2. Internal energy distribution of carboxylate negative-ions of the herbicide diclofop acid in the gas-phase

    NASA Astrophysics Data System (ADS)

    Headley, J. V.; Peru, K. M.

    1997-11-01

    Unimolecular dissociations of diclofop acid and three of its esters were studied using electron capture negative-ion mass spectrometry, to determine to what extent the gas-phase chemistry correlated with transformation products reported for the herbicide in soils and microbial biofilms. Electron capture of the trimethylsilyl (TMS) and pentafluorobenzyl (PFB) esters along with H+ abstraction of diclofop acid were used to form the carboxylate ion at m / z 325. The degree of dissociation of this ion was strongly dependent on the relative distribution of internal energies, chemical nature and size of the ester group. For carboxylate ions formed with relatively low distribution of internal energies (PFB ester), elimination of HCl only was the preferred pathway. In contrast, m / z 325 from the TMS ester and diclofop acid, underwent loss of Cl, followed by loss of HCl to give m / z 254 with some direct loss of HCl for the TMS ester. For carboxylate ions formed with little or no internal energy under electrospray ionization, no unimolecular dissociations were observed. However, a wide range of product-ions were observed for the latter using collision-induced dissociations. For the methyl ester there was a preponderance for initial formation of a chlorodibenzofuran oxide ion (m / z 217) instead of electron attachment on the carbonyl function. The ion (m / z 217) was also prevalent for fragmentation of m / z 253 produced directly by electron capture of diclofop acid and the TMS ester. In general, the gas-phase ion chemistry correlated well with the distribution of some transformation products reported in the literature for the herbicide in soils and microbial biofilms.

  3. 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. Copyright © 2011

  4. Theoretical Models for Classical Cepheids. II. Period-Luminosity, Period-Color, and Period-Luminosity-Color Relations

    NASA Astrophysics Data System (ADS)

    Bono, Giuseppe; Caputo, Filippina; Castellani, Vittorio; Marconi, Marcella

    1999-02-01

    We present and discuss theoretical predictions concerning the pulsational properties of classical Cepheids. Masses and luminosities provided by stellar evolutionary calculations are used as input parameters of nonlinear, nonlocal, and time-dependent convective pulsating models, and accurate determinations of both the blue and red edge of the instability strip are derived, together with theoretical light curves for a suitable grid of models. The computations have been performed for three different chemical compositions (Y=0.25, Z=0.004; Y=0.25, Z=0.008; Y=0.28, Z=0.02), taken as representative of Cepheids in the Magellanic Clouds (MCs) and in the Galaxy. Bolometric light curves have been transformed into visual and near-infrared magnitudes, and the intensity-weighted mean magnitudes of the pulsators over a full pulsation cycle ( and , respectively) have been derived. We obtain that both in the log P- and in the log P- planes the predicted edges of instability strip are in excellent agreement with the observed distribution of Galactic and Magellanic Cepheids, providing a preliminary estimate of the distance to these galaxies. Moreover, we show that the models are in agreement with several empirical period-luminosity (PL) relations given in the literature, even though the theoretical distribution in the log P- plane is better represented by a quadratic PL relation. We also show that both the zero point and the slope of the predicted PL relations are significantly dependent on metallicity, with the amplitude of the metallicity effect decreasing at the longer wavelength. At variance with several empirical suggestions appeared in the literature, we find that at fixed period the metal-rich pulsators should be fainter than the metal-poor ones. Tight period-luminosity-color (PLC) relations are derived for both visual and near-infrared photometric bands. Also in this case the effect of metallicity decreases with increased wavelength. By applying our

  5. Galaxy luminosity functions in WINGS clusters

    NASA Astrophysics Data System (ADS)

    Moretti, A.; Bettoni, D.; Poggianti, B. M.; Fasano, G.; Varela, J.; D'Onofrio, M.; Vulcani, B.; Cava, A.; Fritz, J.; Couch, W. J.; Moles, M.; Kjærgaard, P.

    2015-09-01

    Aims: Using V band photometry of the WINGS survey, we derive galaxy luminosity functions (LF) in nearby clusters. This sample is complete down to MV = -15.15, and it is homogeneous, thus facilitating the study of an unbiased sample of clusters with different characteristics. Methods: We constructed the photometric LF for 72 out of the original 76 WINGS clusters, excluding only those without a velocity dispersion estimate. For each cluster we obtained the LF for galaxies in a region of radius = 0.5 × r200, and fitted them with single and double Schechter's functions. We also derive the composite LF for the entire sample, and those pertaining to different morphological classes. Finally, we derive the spectroscopic cumulative LF for 2009 galaxies that are cluster members. Results: The double Schechter fit parameters are correlated neither with the cluster velocity dispersion nor with the X-ray luminosity. Our median values of the Schechter's fit slope are, on average, in agreement with measurements of nearby clusters, but are less steep that those derived from large surveys, such as the SDSS. Early-type galaxies out number late-types at all magnitudes, but both early and late types contribute equally to the faint end of the LF. Finally, the spectroscopic LF is in excellent agreement with the one derived for A2199, A85 and Virgo, and with the photometric LF at the bright magnitudes (where both are available). Conclusions: There is a large spread in the LF of different clusters, however, this spread is not caused by correlation of the LF shape with cluster characteristics such as X-ray luminosity or velocity dispersions. The faint end is flatter than previously derived (αf = -1.7), which is at odds with that predicted from numerical simulations. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile. Progs. ID 67.A-0030, 68.A-0139, and 69.A-0119.Table 1 and full Fig. 1 (Fig. A.1) are available in

  6. 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.

  7. 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.

  8. 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.

  9. The Planetary Nebula Luminosity Function at the dawn of Gaia

    NASA Astrophysics Data System (ADS)

    Ciardullo, Robin

    2012-09-01

    The [O iii] λ5007 Planetary Nebula Luminosity Function (PNLF) is an excellent extragalactic standard candle. In theory, the PNLF method should not work at all, since the luminosities of the brightest planetary nebulae (PNe) should be highly sensitive to the age of their host stellar population. Yet the method appears robust, as it consistently produces ≲10 % distances to galaxies of all Hubble types, from the earliest ellipticals to the latest-type spirals and irregulars. It is therefore uniquely suited for cross-checking the results of other techniques and finding small offsets between the Population I and Population II distance ladders. We review the calibration of the method and show that the zero points provided by Cepheids and the Tip of the Red Giant Branch are in excellent agreement. We then compare the results of the PNLF with those from Surface Brightness Fluctuation measurements, and show that, although both techniques agree in a relative sense, the latter method yields distances that are ˜15 % larger than those from the PNLF. We trace this discrepancy back to the calibration galaxies and argue that, due to a small systematic error associated with internal reddening, the true distance scale likely falls between the extremes of the two methods. We also demonstrate how PNLF measurements in the early-type galaxies that have hosted Type Ia supernovae can help calibrate the SN Ia maximum magnitude-rate of decline relation. Finally, we discuss how the results from space missions such as Kepler and Gaia can help our understanding of the PNLF phenomenon and improve our knowledge of the physics of local planetary nebulae.

  10. 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.

  11. 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).

  12. 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.

  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. Lyman-Break Galaxies at z>~4 and the Evolution of the Ultraviolet Luminosity Density at High Redshift

    NASA Astrophysics Data System (ADS)

    Steidel, Charles C.; Adelberger, Kurt L.; Giavalisco, Mauro; Dickinson, Mark; Pettini, Max

    1999-07-01

    We present initial results of a survey for star-forming galaxies in the redshift range 3.8<~z<~4.5. This sample consists of a photometric catalog of 244 galaxies culled from a total solid angle of 0.23 deg2 to an apparent magnitude of IAB=25.0. Spectroscopic redshifts in the range 3.61<=z<=4.81 have been obtained for 48 of these galaxies; their median redshift is =4.13. Selecting these galaxies in a manner entirely analogous to our large survey for Lyman-break galaxies at smaller redshift (2.7<~z<~3.4) allows a relatively clean differential comparison between the populations and integrated luminosity density at these two cosmic epochs. Over the same range of UV luminosity, the spectroscopic properties of the galaxy samples at z~4 and z~3 are indistinguishable, as are the luminosity function shapes and the total integrated UV luminosity densities [ρUV(z=3)/ρUV(z=4)=1.1+/-0.3]. We see no evidence at these bright magnitudes for the steep decline in the star formation density inferred from fainter photometric Lyman-break galaxies in the Hubble deep field (HDF). The HDF provides the only existing data on Lyman-break galaxy number densities at fainter magnitudes. We have reanalyzed the z~3 and z~4 Lyman-break galaxies in the HDF using our improved knowledge of the spectral energy distributions of these galaxies, and we find, like previous authors, that faint Lyman-break galaxies appear to be rarer at z~4 than z~3. This might signal a large change in the faint-end slope of the Lyman-break galaxy luminosity function between redshifts z~3 and z~4, or, more likely, be due to significant variance in the number counts within the small volumes probed by the HDF at high redshifts (~160 times smaller than the ground-based surveys discussed here). If the true luminosity density at z~4 is somewhat higher than implied by the HDF, as our ground-based sample suggests, then the emissivity of star formation as a function of redshift would appear essentially constant for all z>1

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. Effect of long-term intensity variations on pulsar searches and the pulsar luminosity function

    NASA Technical Reports Server (NTRS)

    Krishnamohan, S.

    1981-01-01

    Long-term intensity data for five pulsars are used to obtain the probability density distribution of intensities for each pulsar, and it is found that they are described satisfactorily by chi-squared distributions. Based on these distributions, the number of new pulsars expected to be found on repeatedly searching the same region of the sky with the same sensitivity is given. Nearly 25 percent more new pulsars are expected to be found on the first repeat search. It is also shown that the luminosity function deduced from either a single survey or surveys with very different sensitivities is not affected by the omission of flux density variations in the calculation of selection effects. Finally, a method is proposed for deriving the luminosity function by combining the different searches of a given area on the basis of a probabilistic approach to the evaluation of selection effects.

  20. On estimators of the jet bolometric luminosity of Fermi 2LAC blazars

    NASA Astrophysics Data System (ADS)

    Wang, Zerui; Xue, Rui; Du, Leiming; Xie, Zhaohua; Xiong, Dingrong; Yi, Tingfeng; Xu, Yunbing; Liu, Wenguang

    2017-10-01

    Bolometric luminosity is a basic physical parameter that is widely used in the study of blazars. Due to the lack of simultaneous full wavelength data, several estimators of the bolometric luminosity are being used in practice. In this paper, we study and evaluate the reliability and significance of six estimators, the 5GHz luminosity, the 1keV luminosity, the γ-ray luminosity, the 5GHz luminosity + the 1keV luminosity, the 5GHz luminosity + the γ-ray luminosity and the 1keV luminosity + the γ-ray luminosity, by analyzing the linear correlations between the integrated bolometric luminosity and them. Our main results are as follows. (i) All the six estimators are reliable in the sense that they are all significant correlated with the bolometric luminosity. (ii) Ranking from the higher significance of the reliability to lower one the six estimators are the 5GHz luminosity + the γ-ray luminosity, the 1keV luminosity + the γ-ray luminosity, γ-ray luminosity, the 5GHz luminosity + the 1keV luminosity, the 5GHz luminosity and the 1keV luminosity. (iii) We suggest that the bolometric luminosity can be well estimated by the γ-ray luminosity using the best linear equation that given in this paper for Fermi FSRQs. (iv) According to the linear regressions obtained in the analysis, we provide calibration for each estimator.

  1. 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.

  2. 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.

  3. 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.

  4. The distribution of cigarette prices under different tax structures: findings from the International Tobacco Control Policy Evaluation (ITC) Project.

    PubMed

    Shang, Ce; Chaloupka, Frank J; Zahra, Nahleen; Fong, Geoffrey T

    2014-03-01

    The distribution of cigarette prices has rarely been studied and compared under different tax structures. Descriptive evidence on price distributions by countries can shed light on opportunities for tax avoidance and brand switching under different tobacco tax structures, which could impact the effectiveness of increased taxation in reducing smoking. This paper aims to describe the distribution of cigarette prices by countries and to compare these distributions based on the tobacco tax structure in these countries. We employed data for 16 countries taken from the International Tobacco Control Policy Evaluation Project to construct survey-derived cigarette prices for each country. Self-reported prices were weighted by cigarette consumption and described using a comprehensive set of statistics. We then compared these statistics for cigarette prices under different tax structures. In particular, countries of similar income levels and countries that impose similar total excise taxes using different tax structures were paired and compared in mean and variance using a two-sample comparison test. Our investigation illustrates that, compared with specific uniform taxation, other tax structures, such as ad valorem uniform taxation, mixed (a tax system using ad valorem and specific taxes) uniform taxation, and tiered tax structures of specific, ad valorem and mixed taxation tend to have price distributions with greater variability. Countries that rely heavily on ad valorem and tiered taxes also tend to have greater price variability around the median. Among mixed taxation systems, countries that rely more heavily on the ad valorem component tend to have greater price variability than countries that rely more heavily on the specific component. In countries with tiered tax systems, cigarette prices are skewed more towards lower prices than are prices under uniform tax systems. The analyses presented here demonstrate that more opportunities exist for tax avoidance and brand

  5. The distribution of cigarette prices under different tax structures: findings from the International Tobacco Control Policy Evaluation (ITC) Project

    PubMed Central

    Shang, Ce; Chaloupka, Frank J; Zahra, Nahleen; Fong, Geoffrey T

    2013-01-01

    Background The distribution of cigarette prices has rarely been studied and compared under different tax structures. Descriptive evidence on price distributions by countries can shed light on opportunities for tax avoidance and brand switching under different tobacco tax structures, which could impact the effectiveness of increased taxation in reducing smoking. Objective This paper aims to describe the distribution of cigarette prices by countries and to compare these distributions based on the tobacco tax structure in these countries. Methods We employed data for 16 countries taken from the International Tobacco Control Policy Evaluation Project to construct survey-derived cigarette prices for each country. Self-reported prices were weighted by cigarette consumption and described using a comprehensive set of statistics. We then compared these statistics for cigarette prices under different tax structures. In particular, countries of similar income levels and countries that impose similar total excise taxes using different tax structures were paired and compared in mean and variance using a two-sample comparison test. Findings Our investigation illustrates that, compared with specific uniform taxation, other tax structures, such as ad valorem uniform taxation, mixed (a tax system using ad valorem and specific taxes) uniform taxation, and tiered tax structures of specific, ad valorem and mixed taxation tend to have price distributions with greater variability. Countries that rely heavily on ad valorem and tiered taxes also tend to have greater price variability around the median. Among mixed taxation systems, countries that rely more heavily on the ad valorem component tend to have greater price variability than countries that rely more heavily on the specific component. In countries with tiered tax systems, cigarette prices are skewed more towards lower prices than are prices under uniform tax systems. The analyses presented here demonstrate that more opportunities

  6. 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.

  7. 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.

  8. Internally ratiometric fluorescent sensors for evaluation of intracellular GTP levels and distribution.

    PubMed

    Bianchi-Smiraglia, Anna; Rana, Mitra S; Foley, Colleen E; Paul, Leslie M; Lipchick, Brittany C; Moparthy, Sudha; Moparthy, Kalyana; Fink, Emily E; Bagati, Archis; Hurley, Edward; Affronti, Hayley C; Bakin, Andrei V; Kandel, Eugene S; Smiraglia, Dominic J; Feltri, Maria Laura; Sousa, Rui; Nikiforov, Mikhail A

    2017-10-01

    GTP is a major regulator of multiple cellular processes, but tools for quantitative evaluation of GTP levels in live cells have not been available. We report the development and characterization of genetically encoded GTP sensors, which we constructed by inserting a circularly permuted yellow fluorescent protein (cpYFP) into a region of the bacterial G protein FeoB that undergoes a GTP-driven conformational change. GTP binding to these sensors results in a ratiometric change in their fluorescence, thereby providing an internally normalized response to changes in GTP levels while minimally perturbing those levels. Mutations introduced into FeoB to alter its affinity for GTP created a series of sensors with a wide dynamic range. Critically, in mammalian cells the sensors showed consistent changes in ratiometric signal upon depletion or restoration of GTP pools. We show that these GTP evaluators (GEVALs) are suitable for detection of spatiotemporal changes in GTP levels in living cells and for high-throughput screening of molecules that modulate GTP levels.

  9. 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.

  10. The Low-luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    We present an updated and revised analysis of the relationship between the Hβ 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 Hβ time lag, which is assumed to yield the average Hβ 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 BLR-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of \\alpha = 0.533^{+0.035}_{-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 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.

  11. The Low-Luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Bentz, Misty C.; Denney, K.; Grier, C.; Barth, A. J.; Peterson, B. M.; Vestergaard, M.

    2014-01-01

    We present an updated and revised analysis of the relationship between the Hβ 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 Hβ time lag, which is assumed to yield the average Hβ 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-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of α = 0.533^{+0.035}_{-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-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.

  12. 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.

  13. 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.

  14. 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).

  15. 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.

  16. 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.

  17. Slope error tolerance analysis for candela distribution of total-internal-reflection collimating lens

    NASA Astrophysics Data System (ADS)

    Luo, Tao; Wang, Gang

    2016-10-01

    This paper presented a general concentration standard index (GCSI) for 3D TIR lenses, which is introduced as a metric for analyzing the luminous intensity at certain angle, both locally and globally. A Three- Dimensional (3D) slope error tolerance model for TIR lens is constructed and the slope error sensitivities for luminous intensity for different angels are derived. How the slope error impact on the angular candela distribution is obtained with calculation of the slope error impact on the Beam angle (the Full Width at Half Maximum luminous intensity (FWHM)) and the Filed Angle (the Full Width at 10% Maximum luminous intensity). The results revealed that the Beam Angle is decreased at first and then increased with the increased slope error, whereas the Filed angle is monotonically increasing with the slope errors. According theory has been well demonstrated with Monte Carlo ray tracing due to RMS uniformity as low as 1.8% for Beam angle and 2.23% for Filed angle.

  18. 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.

  19. 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).

  20. Distribution of fat, non-osseous lean and bone mineral mass in international Rugby Union and Rugby Sevens players.

    PubMed

    Higham, D G; Pyne, D B; Anson, J M; Dziedzic, C E; Slater, G J

    2014-06-01

    Differences in the body composition of international Rugby Union and Rugby Sevens players, and between players of different positions are poorly understood. The purpose of this study was to examine differences in the quantity and regional distribution of fat, non-osseous lean and bone mineral mass between playing units in Rugby Union and Rugby Sevens. Male Rugby Union (n=21 forwards, 17 backs) and Rugby Sevens (n=11 forwards, 16 backs) players from the Australian national squads were measured using dual-energy X-ray absorptiometry. The digital image of each player was partitioned into anatomical regions including the arms, legs, trunk, and android and gynoid regions. Compared with backs, forwards in each squad were heavier and exhibited higher absolute regional fat (Union 43-67%; ±~17%, range of % differences; ±~95% confidence limits (CL); Sevens 20-26%; ±~29%), non-osseous lean (Union 14-22%; ±~5.8%; Sevens 6.9-8.4%; ±~6.6%) and bone mineral (Union 12-26%; ±~7.2%; Sevens 5.0-11%; ±~7.2%) mass. When tissue mass was expressed relative to regional mass, differences between Rugby Sevens forwards and backs were mostly unclear. Rugby Union forwards had higher relative fat mass (1.7-4.7%; ±~1.9%, range of differences; ±~95% CL) and lower relative non-osseous lean mass (-4.2 to -1.8%; ±~1.8%) than backs in all body regions. Competing in Rugby Union or Rugby Sevens characterized the distribution of fat and non-osseous lean mass to a greater extent than a player's positional group, whereas the distribution of bone mineral mass was associated more with a player's position. Differences in the quantity and distribution of tissues appear to be related to positional roles and specific demands of competition in Rugby Union and Rugby Sevens. © Georg Thieme Verlag KG Stuttgart · New York.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. GALAXY CLUSTERING IN THE COMPLETED SDSS REDSHIFT SURVEY: THE DEPENDENCE ON COLOR AND LUMINOSITY

    SciTech Connect

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

    2011-07-20

    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 w{sub p} (r{sub p}) of volume-limited samples, extracted from the parent sample of {approx}700,000 galaxies over 8000 deg{sup 2}, extending up to redshift of 0.25. We interpret our measurements using halo occupation distribution (HOD) modeling assuming a {Lambda}CDM cosmology (inflationary cold dark matter with a cosmological constant). The amplitude of w{sub p} (r{sub p}) grows slowly with luminosity for L < L{sub *} and increases sharply at higher luminosities, with a large-scale bias factor b(> L) x ({sigma}{sub 8}/0.8) = 1.06 + 0.21(L/L{sub *}){sup 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 r{sub p} < 1 h{sup -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 w{sub p} (r{sub p}). The large-scale clustering of red galaxies shows little luminosity dependence until a sharp increase at L > 4 L{sub *}, but the lowest luminosity red galaxies (0.04-0.25 L{sub *}) show very strong clustering on small scales (r{sub p} < 2 h{sup -1} Mpc). Most of the observed trends can be naturally understood within the {Lambda}CDM+HOD framework. The growth of w{sub p} (r{sub p}) 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

  6. 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

  7. 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…

  8. 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.

  9. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. CO{sub 2} ICE TOWARD LOW-LUMINOSITY EMBEDDED PROTOSTARS: EVIDENCE FOR EPISODIC MASS ACCRETION VIA CHEMICAL HISTORY

    SciTech Connect

    Kim, Hyo Jeong; Evans, Neal J. II; Dunham, Michael M.; Lee, Jeong-Eun; Pontoppidan, Klaus M.

    2012-10-10

    We present Spitzer IRS spectroscopy of CO{sub 2} ice bending mode spectra at 15.2 {mu}m toward 19 young stellar objects (YSOs) with luminosity lower than 1 L{sub Sun} (3 with luminosity lower than 0.1 L{sub Sun }). Ice on dust grain surfaces can encode the history of heating because pure CO{sub 2} ice forms only at elevated temperature, T > 20 K, and thus around protostars of higher luminosity. Current internal luminosities of YSOs with L < 1L{sub Sun} do not provide the conditions needed to produce pure CO{sub 2} ice at radii where typical envelopes begin. The presence of detectable amounts of pure CO{sub 2} ice would signify a higher past luminosity. Many of the spectra require a contribution from a pure, crystalline CO{sub 2} component, traced by the presence of a characteristic band splitting in the 15.2 {mu}m bending mode. About half of the sources (9 out of 19) in the low-luminosity sample have evidence for pure CO{sub 2} ice, and 6 of these have significant double-peaked features, which are very strong evidence of pure CO{sub 2} ice. The presence of the pure CO{sub 2} ice component indicates that the dust temperature, and hence luminosity of the central star/accretion disk system, must have been higher in the past. An episodic accretion scenario, in which mixed CO-CO{sub 2} ice is converted to pure CO{sub 2} ice during each high-luminosity phase, explains the presence of pure CO{sub 2} ice, the total amount of CO{sub 2} ice, and the observed residual C{sup 18}O gas.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. On the influence of a hybrid thermal-non-thermal distribution in the internal shocks model for blazars

    NASA Astrophysics Data System (ADS)

    Rueda-Becerril, J. M.; Mimica, P.; Aloy, M. A.

    2017-06-01

    Internal shocks occurring in blazars may accelerate both thermal and non-thermal electrons. While the non-thermal tail fills the higher end of the electron energy distribution (EED), thermal electrons populate the lowest energies of the shock-accelerated particles. In this paper, we examine the consequences that such a hybrid (thermal-non-thermal) EED has on the spectrum of blazars. Since the thermal component of the EED may extend to very low energies, the synchrotron emission of ultrarelativistic electrons may not be sufficiently accurate to compute blazar spectra. Thus, we replace the standard synchrotron process by the more general magneto-bremsstrahlung (MBS) mechanism encompassing the discrete emission of harmonics in the cyclotron regime, the transition from the discrete to continuum and the continuum emission in the synchrotron realm. In the γ-ray band, an EED of mostly thermal particles displays significant differences with respect to the one dominated by non-thermal particles. A thermally dominated EED produces a synchrotron self-Compton (SSC) peak extending only up to a few MeV, and the valley separating the MBS and the SSC peaks is much deeper than if the EED is dominated by non-thermal particles. The combination of these effects modifies the Compton dominance of a blazar, suggesting that the vertical scatter in the distribution of FSRQs and BL Lacs in the peak synchrotron frequency-Compton dominance parameter space could be attributed to different proportions of thermal/non-thermal particles in the EED of blazars.

  2. A period-luminosity-colour relation for Mira variables

    NASA Astrophysics Data System (ADS)

    Feast, M. W.; Glass, I. S.; Whitelock, P. A.; Catchpole, R. M.

    1989-11-01

    Time-averaged J, H, K and m(bot) magnitudes are given for 29 O-rich and 20 C-rich Mira variables in the LMC. PL and PC relations are derived. The PL relations for O-Miras and C-Miras are very similar at K. For the O-Miras the residuals from the PL and PC relations are correlated showing the existence of PLC relations. Such relations are derived and compared with the theoretical pulsation equation. Data are also given for six variables with periods greater than 420 days. These are brighter by 0.7 mag than expected from extrapolations of the PL or PLC relations. Using Miras in galactic globular clusters to estimate the cluster distances (from the PLC relation) gives a mean horizontal branch luminosity of +0.71 + or - 0.09 (internal standard error) at Fe/H = -0.58, in good agreement with that derived in other ways. For the C-Miras, a significant color term is estimated for the PLC relation at J. There is, however, little evidence for a significant color term at K and the evidence for one in m(bot) is marginal.

  3. 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.

  4. 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.

  5. 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.

  6. Distribution

    Treesearch

    John R. Jones

    1985-01-01

    Quaking aspen is the most widely distributed native North American tree species (Little 1971, Sargent 1890). It grows in a great diversity of regions, environments, and communities (Harshberger 1911). Only one deciduous tree species in the world, the closely related Eurasian aspen (Populus tremula), has a wider range (Weigle and Frothingham 1911)....

  7. 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…

  8. 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.

  9. 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.

  10. The Effect of Variability on X-Ray Binary Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Binder, Breanna A.; Gross, Jacob; Williams, Benjamin F.; Eracleous, Michael; Gaetz, Terrance J.; Plucinsky, Paul P.; Skillman, Evan D.

    2017-08-01

    X-ray binaries are inherently variable X-ray sources, particularly at low luminosities (<1036 erg s-1). Despite this intrinsic variability, the resulting X-ray luminosity functions of X-ray binary populations in star-forming galaxies are remarkably stable across galaxies and across multiple epochs in time. We have obtained three epochs of Chandra ACIS-I observations (totaling ~184 ks) of the nearby spiral galaxy NGC 300 to study the logN-logS distributions of its X-ray point-source population down to 0.35-8 keV luminosities of ~1036 erg s-1. The individual epoch differential logN-logS distributions are best described as the sum of a component made up of background active galactic nuclei (AGN), a simple power law, and a broken power law.We find the shape of the logN-logS distributions sometimes varies between observations. The simple power law and AGN components produce a good fit for “persistent” sources (i.e., with fluxes that remain constant within a factor of ~2). The power-law index of ~1.2 and high fluxes suggest that the persistent sources intrinsic to NGC 300 are dominated by Roche-lobe-overflowing low-mass X-ray binaries. The variable X-ray sources are described by a broken power law, with a faint-end power-law index of ~1.7, a bright-end index of ~2.8-4.9, and a break luminosity of ~4 × 1036 erg s-1. This suggests that these variable sources are mostly outbursting, wind-fed high-mass X-ray binaries, although the logN-logS distribution of variable sources likely also contains low-mass X-ray binaries. We generate model logN-logS distributions for synthetic X-ray binaries and constrain the distribution of maximum X-ray fluxes attained during outburst. Our observations suggest that the majority of X-ray binaries outburst at sub-Eddington luminosities, where mass transfer likely occurs through direct wind accretion at ~1%-3% of the Eddington rate.

  11. 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.

  12. 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.

  13. Seeking the Epoch of Maximum Luminosity for Dusty Quasars

    NASA Astrophysics Data System (ADS)

    Vardanyan, Valeri; Weedman, Daniel; Sargsyan, Lusine

    2014-08-01

    Infrared luminosities νL 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 ν(7.8 μm) >~ 1047 erg s-1 luminosity functions show one quasar Gpc-3 having νL ν(7.8 μm) > 1046.6 erg s-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 ν(0.25 μm), have the largest values of the ratio νL ν(0.25 μm)/νL 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.

  14. 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.

  15. 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°.

  16. 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.

  17. Infall-driven protostellar accretion and the solution to the luminosity problem

    SciTech Connect

    Padoan, Paolo; Haugbølle, Troels; Nordlund, Åke

    2014-12-10

    We investigate the role of mass infall in the formation and evolution of protostars. To avoid ad hoc initial and boundary conditions, we consider the infall resulting self-consistently from modeling the formation of stellar clusters in turbulent molecular clouds. We show that infall rates in turbulent clouds are comparable to accretion rates inferred from protostellar luminosities or measured in pre-main-sequence stars. They should not be neglected in modeling the luminosity of protostars and the evolution of disks, even after the embedded protostellar phase. We find large variations of infall rates from protostar to protostar, and large fluctuations during the evolution of individual protostars. In most cases, the infall rate is initially of order 10{sup –5} M {sub ☉} yr{sup –1}, and may either decay rapidly in the formation of low-mass stars, or remain relatively large when more massive stars are formed. The simulation reproduces well the observed characteristic values and scatter of protostellar luminosities and matches the observed protostellar luminosity function. The luminosity problem is therefore solved once realistic protostellar infall histories are accounted for, with no need for extreme accretion episodes. These results are based on a simulation of randomly driven magnetohydrodynamic turbulence on a scale of 4 pc, including self-gravity, adaptive-mesh refinement to a resolution of 50 AU, and accreting sink particles. The simulation yields a low star formation rate, consistent with the observations, and a mass distribution of sink particles consistent with the observed stellar initial mass function during the whole duration of the simulation, forming nearly 1300 sink particles over 3.2 Myr.

  18. 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.

  19. Current status of luminosity measurement with the CMD-3 detector

    NASA Astrophysics Data System (ADS)

    Ryzhenenkov, A. E.; Akhmetshin, R. R.; Amirkhanov, A. N.; Anisenkov, A. V.; Aulchenko, V. M.; Banzarov, V. Sh.; Bashtovoy, N. S.; Berkaev, D. E.; Bondar, A. E.; Bragin, A. V.; Eidelman, S. I.; Epifanov, D. A.; Epshteyn, L. B.; Erofeev, A. L.; Fedotovich, G. V.; Gayazov, S. E.; Grebenuk, A. A.; Gribanov, S. S.; Grigoriev, D. N.; Ignatov, F. V.; Ivanov, V. L.; Karpov, S. V.; Kazanin, V. F.; Kasaev, A. S.; Koop, I. A.; Korobov, A. A.; Kozyrev, A. N.; Kozyrev, E. A.; Krokovny, P. P.; Kuzmenko, A. E.; Kuzmin, A. S.; Logashenko, I. B.; Lysenko, A. P.; Lukin, P. A.; Mikhailov, K. Yu.; Okhapkin, V. S.; Pestov, Yu. N.; Perevedentsev, E. A.; Popov, A. S.; Razuvaev, G. P.; Rogovsky, Yu. A.; Ruban, A. A.; Ryskulov, N. M.; Shatunov, Yu. M.; Shebalin, V. E.; Shemyakin, D. N.; Shwartz, B. A.; Shwartz, D. B.; Sibidanov, A. L.; Solodov, E. P.; Titov, V. M.; Talyshev, A. A.; Vorobiov, A. I.; Yudin, Yu. V.

    2017-07-01

    The CMD-3 detector has begun to take data at the electron-positron collider VEPP-2000 since december 2010. The collected data sample corresponds to an integrated luminosity of 60 pb-1 in the c.m. energy range from 0.32 up to 2 GeV and about 50pb-1 for RUN2017. The integrated luminosity was measured by counting e+e- → e+e- and e+e- → γγ events, allowing additional photons in the final state. Preliminary results of the luminosity measurement are presented for various energy ranges and its accuracy is estimated to be 1%.

  20. Internal energy distributions from nitrogen dioxide fluorescence. 4. Variable-wavelength photodissociation of ClNO[sub 2] and HONO[sub 2

    SciTech Connect

    Miller, C.E.; Johnston, H.S. Lawrence Berkeley Lab., CA )

    1993-09-30

    The cumulative sum spectroscopy method is used to derive internal energy distributions for the fluorescing NO[sub 2] ensembles from ClNO[sub 2] and HONO[sub 2] photodissociations as a function of the photolysis wavelength. The fluorescing NO[sub 2] ensemble internal energy distribution, NO[sub 2]* P(E[sub int]), for ClNO[sub 2] evolves from distributions peaked at 25 130 cm[sup [minus]1] to those having a majority of the NO[sub 2]* components with internal energies less than 15 000 cm[sup [minus]1] as the energy available to the photofragments decreases from 30 000 to 20 000 cm[sup [minus]1]. The NO[sub 2]* P(E[sub int]) distributions derived for HONO[sub 2] are dominated by components with energies less than 15 000 cm[sup [minus]1], and only for photolysis wavelength shorter than 255 nm do the distributions have significant contributions from NO[sub 2]* components approaching the maximum available energy. The PIF P(E[sub int]) derived from 308-nm ClNO[sub 2] photodissociation is compared to the P(E[sub T]) distribution derived from time-of-flight experiments, and the HONO[sub 2] PIF P(E[sub int]) distributions are compared to energy-partitioning measurements made after 241- and 280-nm photolysis. 19 refs., 20 figs.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Improvement to the D0 luminosity monitor constant

    SciTech Connect

    Bantley, J.

    1996-03-01

    The D0 experiment has previously calculated its luminosity using the visible cross section (luminosity monitor constant) for its Level 0 trigger, {sigma}{sub L0} = 48.2 mb, based on the world average {ovr p}p inelastic cross sections at {radical}s = 1.8 TeV. The error on luminosity had been set at 12%. Recent studies using the MBR and DTUJET Monte Carlo event generators and unbiased D0 data samples have resulted in a more precise determination of the D0 luminosity monitor constant. The result, {sigma}{sub L0} = 46.7 {+-} 2.5 mb, lowers the central value by 3.1% and reduces the error to 5.4%. 12 refs., 7 figs., 9 tabs.

  8. Producing ultra high energy cosmic rays from AGN magnetic luminosity

    NASA Astrophysics Data System (ADS)

    Coimbra-Araújo, Carlos H.; Anjos, Rita C.

    The present work proposes a method to calculate the AGN magnetic luminosity fraction to be converted into ultra high energy cosmic rays (UHECRs) luminosities for nine UHECR AGN Seyfert sources based on the respective observation of gamma ray upper limits. The motivation for such calculation comes attached to the fact that a fraction of the magnetic luminosity (L B ) produced by Kerr black holes in some AGNs can produce the necessary energy to accelerate UHECRs beyond the GZK limit, observed, e.g., by the Auger experiment. Nevertheless, the direct detection of those UHECRs has a lack of information about the direction of the source from where those cosmic rays are coming, since charged particles are deflected by the intergalactic magnetic field. Such problem arises alternative methods to evaluate the luminosity of UHECRs from the observation of upper limits during the propagation.

  9. 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.

  10. 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.

  11. 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.

  12. The luminosity function for different morphological types in the CfA Redshift Survey

    NASA Technical Reports Server (NTRS)

    Marzke, Ronald O.; Geller, Margaret J.; Huchra, John P.; Corwin, Harold G., Jr.

    1994-01-01

    We derive the luminosity function for different morphological types in the original CfA Redshift Survey (CfA1) and in the first two slices of the CfA Redshift Survey Extension (CfA2). CfA1 is a complete sample containing 2397 galaxies distributed over 2.7 steradians with m(sub z) less than or equal 14.5. The first two complete slices of CfA2 contain 1862 galaxies distributed over 0.42 steradians with m(sub z)=15.5. The shapes of the E-S0 and spiral luminosity functions (LF) are indistinguishable. We do not confirm the steeply decreasing faint end in the E-S0 luminosity function found by Loveday et al. for an independent sample in the southern hemisphere. We demonstrate that incomplete classification in deep redshift surveys can lead to underestimates of the faint end of the elliptical luminosity function and could be partially responsible for the difference between the CfA survey and other local field surveys. The faint end of the LF for the Magellanic spirals and irregulars is very steep. The Sm-Im luminosity function is well fit by a Schechter function with M*=-18.79, alpha=-1.87, and phi*=0.6x10(exp -3) for M(sub z) less than or equal to -13. These galaxies are largely responsible for the excess at the faint end of the general CfA luminosity function. The abundance of intrinsically faint, blue galaxies nearby affects the interpretation of deep number counts. The dwarf population increases the expected counts at B=25 in a no-evolution, q(sub 0)=0.05 model by a factor of two over standard no-evolution estimates. These dwarfs change the expected median redshift in deep redshift surveys by less than 10 percent . Thus the steep Sm-Im LF may contribute to the reconciliation of deep number counts with deep redshift surveys.

  13. The Cosmic-Ray Luminosity of the Galaxy

    NASA Astrophysics Data System (ADS)

    Dogiel, V. A.; Schönfelder, V.; Strong, A. W.

    2002-06-01

    The total cosmic-ray luminosity of the Galaxy is one of the main parameters that strongly constrain possible models of the origin of cosmic rays. Recently, Dar & De Rújula suggested a luminosity that is 2 orders of magnitude larger than the standard estimate. If this estimate were correct, it would completely change our conception of the origin of cosmic rays. From a number of different arguments, however, we show that the estimate of Dar & Rújula is too high.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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…

  1. 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.

  2. 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…

  3. 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…

  4. Gamma-Ray Burst Host Galaxies Have "Normal" Luminosities.

    PubMed

    Schaefer

    2000-04-10

    The galactic environment of gamma-ray bursts can provide good evidence about the nature of the progenitor system, with two old arguments implying that the burst host galaxies are significantly subluminous. New data and new analysis have now reversed this picture: (1) Even though the first two known host galaxies are indeed greatly subluminous, the next eight hosts have absolute magnitudes typical for a population of field galaxies. A detailed analysis of the 16 known hosts (10 with redshifts) shows them to be consistent with a Schechter luminosity function with R*=-21.8+/-1.0, as expected for normal galaxies. (2) Bright bursts from the Interplanetary Network are typically 18 times brighter than the faint bursts with redshifts; however, the bright bursts do not have galaxies inside their error boxes to limits deeper than expected based on the luminosities for the two samples being identical. A new solution to this dilemma is that a broad burst luminosity function along with a burst number density varying as the star formation rate will require the average luminosity of the bright sample (>6x1058 photons s-1 or>1.7x1052 ergs s-1) to be much greater than the average luminosity of the faint sample ( approximately 1058 photons s-1 or approximately 3x1051 ergs s-1). This places the bright bursts at distances for which host galaxies with a normal luminosity will not violate the observed limits. In conclusion, all current evidence points to gamma-ray burst host galaxies being normal in luminosity.

  5. Empirical Approach to Cepheid Period-Luminosity-Color and Period-Luminosity Relations by Surface Brightness

    NASA Astrophysics Data System (ADS)

    di Benedetto, G. P.

    1995-10-01

    Empirical period-luminosity-color and period-luminosity (PLC [V, B-V] and PL[V] relations according to Stefan's law are derived for Cepheid variables by applying thermal scales of nonvariable giant and supergiant stars established by modern observational interferometry. Intrinsic surface brightnesses are predicted by the apparent color index V - K as fiducial reference unbiased by metallicity and gravity effects, along with current optical absorption data. Linear radii are inferred from periods through the period-radius relation, assumed to be insensitive to abundance and brightness variations. The dependence of PLC and PL zero points to abundance effects is further investigated. I compare current Cepheid data from our metal- normal Galaxy (GAL) with those in the Magellanic Clouds (LMC and SMC) of poorer metal content. The major achievement is that the PL(V) relations are found to be severely biased by metallicity, whereas the PLC(V, B- V) relations turn out to be much less affected by abundances than previously expected. The new PLC and PL relations calibrated on fundamental quantities are compared with those from the classical zero-age main-sequence (ZAMS) fitting empirical approach. It is shown that all metal-normal equations lead to remarkably consistent luminosities of GAL Cepheids, to within +/- 0.05 mag (PL) and +/- 0.02 mag (PLC), whereas metal-poor LMC and SMC results appear to be significantly discrepant. It is emphasized that theoretical thermal scales applied for the derivation of ZAMS metal- corrected relations, either explicit or implicit, are mainly responsible for such observed discrepancies. The actual empirical approach appears to overcome most of the previous difficulties closely related to the poor knowledge of Cepheid thermal properties. Theoretical Cepheid thermal scales are critically reviewed. It is found that recent metal-normal color-brightness relations lead to results remarkably consistent with those from observational scales, whereas

  6. X-ray selected quasars and Seyfert galaxies - Cosmological evolution, luminosity function, and contribution to the X-ray background

    NASA Technical Reports Server (NTRS)

    Maccacaro, T.; Gioia, I. M.; Stocke, J. T.

    1984-01-01

    The cosmological evolution and the X-ray luminosity function of quasars and Seyfert galaxies (active galactic nuclei /AGNs/) are derived and discussed. The sample used consists of 56 objects extracted from the expanded Einstein Observatory Medium Sensitivity Survey, and it is exclusively defined by its X-ray properties. The distribution in space of X-ray selected AGNs is confirmed to be strongly nonuniform; the amount of cosmological evolution required by the data is in agreement with a previous determination based on a smaller sample of objects. The X-ray luminosity function (XLF) is derived. The high-luminosity part of the XLF is satisfactorily described by a power law of slope gamma approximately 3.6. A significant flattening is observed at low luminosities. The simultaneous determination of the cosmological evolution and of the X-ray luminosity function of AGNs is then used to estimate the contribution to the extragalactic diffuse X-ray background. Using the best fit values for the evolution of AGNs and for their volume density, it is found that they contribute approximately 80 percent of the 2 keV diffuse X-ray background. Uncertainties in this estimate are still rather large; however, it seems difficult to reconcile the data with a contribution much less than 50 percent.

  7. Luminosity and Stellar Mass Functions of Local Star-forming Galaxies

    NASA Astrophysics Data System (ADS)

    Pérez-González, Pablo G.; Gallego, Jesús; Zamorano, Jaime; Alonso-Herrero, Almudena; Gil de Paz, Armando; Aragón-Salamanca, Alfonso

    2003-04-01

    We present the optical and near-infrared luminosity and mass functions of the local star-forming galaxies in the Universidad Complutense de Madrid (UCM) Survey. A bivariate method that explicitly deals with the Hα selection of the survey is used when estimating these functions. Total stellar masses have been calculated on a galaxy-by-galaxy basis taking into account differences in star formation histories. The main difference between the luminosity distributions of the UCM sample and the luminosity functions of the local galaxy population is a lower normalization (φ*), indicating a lower global volume density of UCM galaxies. The typical near-infrared luminosity (L*) of local star-forming galaxies is fainter than that of normal galaxies. This is a direct consequence of the lower stellar masses of our objects. However, at optical wavelengths (B and r), the luminosity enhancement arising from the young stars leads to M* values that are similar to those of normal galaxies. The fraction of the total optical and near-infrared luminosity density in the local universe associated with star-forming galaxies is 10%-20%. Fitting the total stellar mass function using a Schechter parameterization, we obtain α=-1.15+/-0.15, logM*=10.82+/-0.17 Msolar, and logφ*=-3.04+/-0.20 Mpc-3. This gives an integrated total stellar mass density of 107.83+/-0.07 Msolar Mpc-3 in local star-forming galaxies (H0=70 km s-1 Mpc-1, ΩM=0.3, and Λ=0.7). The volume-averaged burst strength of the UCM galaxies is b=0.04+/-0.01, defined as the ratio of the mass density of stars formed in recent bursts (with an age of <10 Myr) to the total stellar mass density in UCM galaxies. Finally, we derive that in the local universe, 13%+/-3% of the total baryon mass density in the form of stars is associated with star-forming galaxies.

  8. 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.

  9. 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.

  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. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. The impact of dust in host galaxies on quasar luminosity functions

    NASA Astrophysics Data System (ADS)

    Shirakata, Hikari; Okamoto, Takashi; Enoki, Motohiro; Nagashima, Masahiro; Kobayashi, Masakazu A. R.; Ishiyama, Tomoaki; Makiya, Ryu

    2015-06-01

    We have investigated effects of dust attenuation on quasar luminosity functions at z ˜ 2 using a semi-analytic galaxy formation model combined with a large cosmological N-body simulation. We estimate the dust attenuation of quasars self-consistently with that of galaxies by considering the dust in their host bulges. We find that the luminosity of the bright quasars is strongly dimmed by the dust attenuation, ˜2 mag in the B-band. Assuming the empirical bolometric corrections for active galactic nuclei (AGNs) by Marconi et al., we find that this dust attenuation is too strong to explain the B-band and X-ray quasar luminosity functions simultaneously. We consider two possible mechanisms that weaken the dust attenuation. As such a mechanism, we introduce a time delay for AGN activity, that is, gas fuelling to a central black hole starts sometime after the beginning of the starburst induced by a major merger. The other is the anisotropy in the dust distribution. We find that in order to make the dust attenuation of the quasars negligible, either the gas accretion into the black holes has to be delayed at least three times the dynamical time-scale of their host bulges or the dust covering factor is as small as ˜0.1.

  17. 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.

  18. Regulation of the X-ray luminosity of clusters of galaxies by cooling and supernova feedback.

    PubMed

    Voit, G M; Bryan, G L

    2001-11-22

    Clusters of galaxies are thought to contain about ten times as much dark matter as baryonic matter. The dark component therefore dominates the gravitational potential of a cluster, and the baryons confined by this potential radiate X-rays with a luminosity that depends mainly on the gas density in the cluster's core. Predictions of the X-rays' properties based on models of cluster formation do not, however, agree with the observations. If the models ignore the condensation of cooling gas into stars and feedback from the associated supernovae, they overestimate the X-ray luminosity because the density of the core gas is too high. An early episode of uniformly distributed supernova feedback could rectify this by heating the uncondensed gas and therefore making it harder to compress into the core, but such a process seems to require an implausibly large number of supernovae. Here we show how radiative cooling of intergalactic gas and subsequent supernova heating conspire to eliminate highly compressible low-entropy gas from the intracluster medium. This brings the core entropy and X-ray luminosities of clusters into agreement with the observations, in a way that depends little on the efficiency of supernova heating in the early Universe.

  19. 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).

  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. 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}.

  2. 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.

  3. 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.

  4. 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.; hide

    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).

  5. X-ray constraints on the fraction of obscured active galactic nuclei at high accretion luminosities

    NASA Astrophysics Data System (ADS)

    Georgakakis, A.; Salvato, M.; Liu, Z.; Buchner, J.; Brandt, W. N.; Ananna, T. Tasnim; Schulze, A.; Shen, Yue; LaMassa, S.; Nandra, K.; Merloni, A.; McGreer, I. D.

    2017-08-01

    The wide-area XMM-XXL X-ray survey is used to explore the fraction of obscured active galactic nuclei (AGNs) at high accretion luminosities, LX(2-10 keV) ≳ 1044 erg s - 1, and out to redshift z ≈ 1.5. The sample covers an area of about 14 deg2 and provides constraints on the space density of powerful AGNs over a wide range of neutral hydrogen column densities extending beyond the Compton-thick limit, NH ≈ 1024 cm - 2. The fraction of obscured Compton-thin (NH = 1022-1024 cm - 2) AGNs is estimated to be ≈0.35 for luminosities LX(2-10 keV) > 1044 erg s - 1, independent of redshift. For less luminous sources, the fraction of obscured Compton-thin AGNs increases from 0.45 ± 0.10 at z = 0.25 to 0.75 ± 0.05 at z = 1.25. Studies that select AGNs in the infrared via template fits to the observed spectral energy distribution of extragalactic sources estimate space densities at high accretion luminosities consistent with the XMM-XXL constraints. There is no evidence for a large population of AGNs (e.g. heavily obscured) identified in the infrared and missed at X-ray wavelengths. We further explore the mid-infrared colours of XMM-XXL AGNs as a function of accretion luminosity, column density and redshift. The fraction of XMM-XXL sources that lie within the mid-infrared colour wedges defined in the literature to select AGNs is primarily a function of redshift. This fraction increases from about 20-30 per cent at z = 0.25 to about 50-70 per cent at z = 1.5.

  6. The luminosity calibration of SNe Ia: present status.

    NASA Astrophysics Data System (ADS)

    Tammann, G. A.; Reindl, B.

    Blue supernovae of type Ia (SNe Ia) have become the most important objects in cosmology being of exceptionally uniform luminosity. Used as relative distance indicators they map deviations from pure Hubble flow and determine the cosmological constant Λ. Once their absolute magnitude is determined they provide the best estimate of the large-scale value of the Hubble constant H0. An HST project is reviewed where Cepheid distances are used for the luminosity calibration of SNe Ia. The mean luminosity of 8 SNe Ia is MB(max) = -19.47±0.07, MV(max) = -19.48±0.07, corresponding - after small corrections for second parameters - to H0(cosmic) = 59±5.

  7. The luminosity function of galaxies in compact groups

    NASA Technical Reports Server (NTRS)

    Ribeiro, A. L. B.; De Carvalho, R. R.; Zepf, S. E.

    1994-01-01

    We use counts of faint galaxies in the regions of compact groups to extend the study of the luminosity function of galaxies in compact groups to absolute magnitudes as faint as M(sub B) = -14.5 + 5 log h. We find a slope of the faint end of the luminosity function of approximately alpha = -0.8, with a formal uncertainty of 0.15. This slope is not significantly different from that found for galaxies in other environments. Our results do not support previous suggestions of a dramatic underabundance of intrinsically faint galaxies in compact groups, which were based on extrapolations from fits at brighter magnitudes. The normal faint-end slope of the luminosity function in compact groups is in agreement with previous evidence that most galaxies in compact groups have not been dramatically affected by recent merging.

  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. Solar Luminosity on the Main Sequence, Standard Model and Variations

    NASA Astrophysics Data System (ADS)

    Ayukov, S. V.; Baturin, V. A.; Gorshkov, A. B.; Oreshina, A. V.

    2017-05-01

    Our Sun became Main Sequence star 4.6 Gyr ago according Standard Solar Model. At that time solar luminosity was 30% lower than current value. This conclusion is based on assumption that Sun is fueled by thermonuclear reactions. If Earth's albedo and emissivity in infrared are unchanged during Earth history, 2.3 Gyr ago oceans had to be frozen. This contradicts to geological data: there was liquid water 3.6-3.8 Gyr ago on Earth. This problem is known as Faint Young Sun Paradox. We analyze luminosity change in standard solar evolution theory. Increase of mean molecular weight in the central part of the Sun due to conversion of hydrogen to helium leads to gradual increase of luminosity with time on the Main Sequence. We also consider several exotic models: fully mixed Sun; drastic change of pp reaction rate; Sun consisting of hydrogen and helium only. Solar neutrino observations however exclude most non-standard solar models.

  11. 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.

  12. Change to the D0 luminosity monitor constant

    SciTech Connect

    Amos, N.; Bantly, J.; Brandt, A.; Demina, R.; Goldschmidt, A.; Partridge, R.; Paterno, L.; Puseljic, D.; Thompson, J.

    1995-01-01

    The D0 experiment has previously calculated its luminosities using a visible cross section (luminosity monitor constant) for its Level 0 trigger, {sigma}{sub L0} = 42.9 mb based on the E710 inelastic cross section measurements. Recently, CDF has also published inelastic cross section measurements markedly different from E710. The D0 experiment has moved to world average inelastic cross sections at {radical}s = 1.8 TeV. The result changes the D0 visible cross section to {sigma}{sub L0} = 48.2 mb which is an increase of 12.4% in the visible cross section value. The error on luminosity has been left unchanged at 12%.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. Modeling the Red Sequence: Hierarchical Growth yet Slow Luminosity Evolution

    NASA Astrophysics Data System (ADS)

    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 ~ 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 ~ 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 ~ 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.

  20. A new universal photon energy-luminosity relationship for GRBs

    SciTech Connect

    Willingale, Dick; O'Brien, Paul; Goad, Mike; Osborne, Julian; Page, Kim; Tanvir, Nial

    2008-05-22

    We define a new characteristic photon energy for the Band function, E{sub wz}, and describe a new way of estimating the peak luminosity of the prompt emission from GRBs, L{sub iso}, which is not dependent on the time binning. We show that E{sub wz} and L{sub iso} are correlated for all bursts, long and short. The new photon energy-luminosity relationship gives us a strong indication that the underlying process responsible for the prompt GRB emission is thermal.

  1. 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.

  2. 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.

  3. Surface brightness and intrinsic luminosity of ellipticals

    NASA Astrophysics Data System (ADS)

    Dhar, Barun Kumar; Williams, Liliya L. R.

    2012-11-01

    shallow-cusp galaxies. This indicates a universality in the functional form describing the 3D density distribution of light in galaxies and dark matter in Λ cold dark matter (ΛCDM) N-body haloes. Finally, planetary nebulae and strong-lensing observations, and the Einasto index n of ΛCDM dark matter haloes, indicate that our result - the outer component of the surface brightness profiles of massive galaxies has 5 ≲ n ≲ 8 - could imply (i) a common feature of collisionless systems; and (ii) that galaxies with such n for their outer component are dark matter dominated.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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

  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. 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…

  11. 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…

  12. Upgrading Luminosity from the Tevatron Through the LHC

    NASA Astrophysics Data System (ADS)

    Peggs, Stephen

    2005-04-01

    Very soon the LHC will push the high energy frontier from 1 TeV to 7 TeV, well beyond present operating experience with the Tevatron. The LHC (with 2 rings) is also expected to raise proton luminosities by about two orders of magnitude, to about 10^34 cm-2sec-1 in its initial configuration. This extrapolation leads to a new regime of Accelerator Physics and Technology challenges. The stored energy in the nominal LHC beam is almost 3 orders of magnitude larger than in the Tevatron. Efficient acceleration up the energy ramp is more difficult and more important. Long range beam-beam collisions become more severe. Luminosity debris power becomes a significant constraint. The U.S. LHC Accelerator Research Program (LARP) is a collaboration of BNL, FNAL, LBNL, and SLAC, working with CERN to address these frontier issues. LARP is also working with CERN on an LHC Interaction Region upgrade, through which the luminosity may be increased even further, to about 10^35cm-2sec-1. This paper discusses the technical issues in extrapolating the energy and luminosity from the Tevatron to the LHC, and describes the programs in place to address them.

  13. Gauge-invariance and infrared divergences in the luminosity distance

    NASA Astrophysics Data System (ADS)

    Biern, Sang Gyu; Yoo, Jaiyul

    2017-04-01

    Measurements of the luminosity distance have played a key role in discovering the late-time cosmic acceleration. However, when accounting for inhomogeneities in the Universe, its interpretation has been plagued with infrared divergences in its theoretical predictions, which are in some cases used to explain the cosmic acceleration without dark energy. The infrared divergences in most calculations are artificially removed by imposing an infrared cut-off scale. We show that a gauge-invariant calculation of the luminosity distance is devoid of such divergences and consistent with the equivalence principle, eliminating the need to impose a cut-off scale. We present proper numerical calculations of the luminosity distance using the gauge-invariant expression and demonstrate that the numerical results with an ad hoc cut-off scale in previous calculations have negligible systematic errors as long as the cut-off scale is larger than the horizon scale. We discuss the origin of infrared divergences and their cancellation in the luminosity distance.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. The luminosity function at z ∼ 8 from 97 Y-band dropouts: Inferences about reionization

    SciTech Connect

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

    2014-05-01

    We present the largest search to date for Y-band dropout galaxies (z ∼ 8 Lyman break galaxies, LBGs) based on 350 arcmin{sup 2} 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 arcmin{sup 2} 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 ≤ m{sub J} ≤ 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{sup ⋆}=−20.15{sub −0.38}{sup +0.29}, a faint-end slope of α=−1.87{sub −0.26}{sup +0.26}, and a number density of log{sub 10} ϕ{sup ⋆}[Mpc{sup −3}]=−3.24{sub −0.24}{sup +0.25}. Integrated down to M = –17.7, this luminosity function yields a luminosity density log{sub 10} ϵ[erg s{sup −1} Hz{sup −1} Mpc{sup −3}]=25.52{sub −0.05}{sup +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

  3. 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

  4. 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

  5. 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

  6. SN 2008ha: AN EXTREMELY LOW LUMINOSITY AND EXCEPTIONALLY LOW ENERGY SUPERNOVA

    SciTech Connect

    Foley, Ryan J.; Kirshner, Robert P.; Challis, Peter J.; Friedman, Andrew S.; Chornock, Ryan; Filippenko, Alexei V.; Ganeshalingam, Mohan; Li, Weidong; Cenko, S. Bradley; Modjaz, Maryam; Silverman, Jeffrey M.; Wood-Vasey, W. Michael

    2009-08-15

    We present ultraviolet, optical, and near-infrared photometry as well as optical spectra of the peculiar supernova (SN) 2008ha. SN 2008ha had a very low peak luminosity, reaching only M{sub V} = -14.2 mag, and low line velocities of only {approx}2000 km s{sup -1} near maximum brightness, indicating a very small kinetic energy per unit mass of ejecta. Spectroscopically, SN 2008ha is a member of the SN 2002cx-like class of SNe, a peculiar subclass of SNe Ia; however, SN 2008ha is the most extreme member, being significantly fainter and having lower line velocities than the typical member, which is already {approx}2 mag fainter and has line velocities {approx}5000 km s{sup -1} smaller (near maximum brightness) than a normal SN Ia. SN 2008ha had a remarkably short rise time of only {approx}10 days, significantly shorter than either SN 2002cx-like objects ({approx}15 days) or normal SNe Ia ({approx}19.5 days). The bolometric light curve of SN 2008ha indicates that SN 2008ha peaked at L {sub peak} = (9.5 {+-} 1.4) x 10{sup 40} erg s{sup -1}, making SN 2008ha perhaps the least luminous SN ever observed. From its peak luminosity and rise time, we infer that SN 2008ha generated (3.0 {+-} 0.9) x 10{sup -3} M {sub sun} of {sup 56}Ni, had a kinetic energy of {approx}2 x 10{sup 48} erg, and ejected 0.15 M {sub sun} of material. The host galaxy of SN 2008ha has a luminosity, star formation rate, and metallicity similar to those of the Large magellanic Cloud. We classify three new (and one potential) members of the SN 2002cx-like class, expanding the sample to 14 (and one potential) members. The host-galaxy morphology distribution of the class is consistent with that of SNe Ia, Ib, Ic, and II. Several models for generating low-luminosity SNe can explain the observations of SN 2008ha; however, if a single model is to describe all SN 2002cx-like objects, deflagration of carbon-oxygen white dwarfs, with SN 2008ha being a partial deflagration and not unbinding the progenitor star, is

  7. 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.

  8. Cosmic Evolution of Long Gamma-Ray Burst Luminosity

    NASA Astrophysics Data System (ADS)

    Deng, Can-Min; Wang, Xiang-Gao; Guo, Bei-Bei; Lu, Rui-Jing; Wang, Yuan-Zhu; Wei, Jun-Jie; Wu, Xue-Feng; Liang, En-Wei

    2016-03-01

    The cosmic evolution of gamma-ray burst (GRB) luminosity is essential for revealing the GRB physics and for using GRBs as cosmological probes. We investigate the luminosity evolution of long GRBs with a large sample of 258 Swift/BAT GRBs. By describing the peak luminosity evolution of individual GRBs as {L}{{p}}\\propto \\text{}{(1+z)}k, we get k=1.49+/- 0.19 using the nonparametric τ statistics method without considering observational biases of GRB trigger and redshift measurement. By modeling these biases with the observed peak flux and characterizing the peak luminosity function of long GRBs as a smoothly broken power law with a break that evolves as {L}{{b}}\\propto {(1+z)}{k{{b}}}, we obtain {k}{{b}}={1.14}-0.47+0.99 through simulations based on the assumption that the long GRB rate follows the star formation rate incorporating the cosmic metallicity history. The derived k and kb values are systematically smaller than those reported in previous papers. By removing the observational biases of the GRB trigger and redshift measurement based on our simulation analysis, we generate mock complete samples of 258 and 1000 GRBs to examine how these biases affect the τ statistics method. We get k=0.94+/- 0.14 and k=0.80+/- 0.09 for the two samples, indicating that these observational biases may lead to overestimating the k value. With the large uncertainty of kb derived from our simulation analysis, one cannot even convincingly argue for a robust evolution feature of the GRB luminosity.

  9. 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.

  10. Understanding The Time Evolution Of Luminosity And Associated Accretion Structures In X-Ray Pulsars

    NASA Astrophysics Data System (ADS)

    Laycock, Silas

    We propose to analyze the large archive of RXTE, XMM-Newton and Chandra observations of X-ray Binary Pulsars in the Magellanic Clouds and Milky Way. There are some 2000 individual RXTE PCA pointings on the SMC spanning 15 years, and a smaller number on the LMC. Each PCA observation covers a large fraction of the whole SMC (or LMC) population, and we are able to deconvolve the sometimes simultaneous signals to create an unrivaled record of pulsar temporal behavior. More than 200 XMM- Newton and Chandra observations of the SMC/LMC and individual Galactic pulsars provide information at lower luminosity levels. Together, these datasets cover the entire range of variability timescales and accretion regimes in High Mass X-ray Binaries. We will produce a comprehensive library of energy- resolved pulse profiles covering the entire luminosity and spin-period parameter space, and make this available to the community. We will then model these pulse profiles using state of the art techniques to parameterize the morphology, and publish the resulting data-cube. This result will include for example the distribution of offsets between magnetic and spin axes. These products are needed for the next generation of advances in neutron star theory and modeling. The unique dataset will also enable us to determine the upper and lower limits of accretion powered luminosity in a large statistically complete sample of neutron stars, and hence make several direct tests of fundamental NS parameters and accretion physics. In addition the long-duration of the dataset and "whole-galaxy" nature of the SMC sample make possible a new statistical approach to uncover the duty-cycle distribution and hence population demographics of transient High Mass X-ray Binary (HMXB) populations.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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…

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. The most powerful astrophysical events: Gravitational-wave peak luminosity of binary black holes as predicted by numerical relativity

    NASA Astrophysics Data System (ADS)

    Keitel, David; Forteza, Xisco Jiménez; Husa, Sascha; London, Lionel; Bernuzzi, Sebastiano; Harms, Enno; Nagar, Alessandro; Hannam, Mark; Khan, Sebastian; Pürrer, Michael; Pratten, Geraint; Chaurasia, Vivek

    2017-07-01

    For a brief moment, a binary black hole (BBH) merger can be the most powerful astrophysical event in the visible Universe. Here we present a model fit for this gravitational-wave peak luminosity of nonprecessing quasicircular BBH systems as a function of the masses and spins of the component black holes, based on numerical relativity (NR) simulations and the hierarchical fitting approach introduced by X. Jiménez-Forteza et al. [Phys. Rev. D 95, 064024 (2017)., 10.1103/PhysRevD.95.064024]. This fit improves over previous results in accuracy and parameter-space coverage and can be used to infer posterior distributions for the peak luminosity of future astrophysical signals like GW150914 and GW151226. The model is calibrated to the ℓ≤6 modes of 378 nonprecessing NR simulations up to mass ratios of 18 and dimensionless spin magnitudes up to 0.995, and includes unequal-spin effects. We also constrain the fit to perturbative numerical results for large mass ratios. Studies of key contributions to the uncertainty in NR peak luminosities, such as (i) mode selection, (ii) finite resolution, (iii) finite extraction radius, and (iv) different methods for converting NR waveforms to luminosity, allow us to use NR simulations from four different codes as a homogeneous calibration set. This study of systematic fits to combined NR and large-mass-ratio data, including higher modes, also paves the way for improved inspiral-merger-ringdown waveform models.

  3. 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

  4. 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}⊙ . 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.

  5. 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.

  6. 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,