Research Articles (Statistics & Population Studies): Recent submissions

Now showing items 81-100 of 162

    • An exploratory look at associated factors of poverty on educational attainment in Africa and in-depth multilevel modelling for Namibia. 

      Adegboye, Oyelola A.; Kotze, Danelle (BER, 2013)
      This study examines several indicator variables related to education and poverty in Africa from the Demographic and Health Surveys (DHS). Many have described income and education as one of the fundamental determinants ...

    • Two new pulsating hot subdwarf stars from the Edinburgh-Cape survey 

      Kilkenny, David; O'Donoghue, D.; Crause, L.; Engelbrecht, C.; Hambly, N.; MacGillivray, H. (Oxford University Press, 2009)
      We report the discovery of very rapid pulsations in two hot subdwarf stars from the Edinburgh- Cape blue object survey. The short periods, small amplitudes and multiperiodicity establish these stars as members of the ...

    • Trends and risk factors for childhood diarrhea in sub-Saharan countries (1990 2013): assessing the neighborhood inequalities 

      Bado, Aristide R.; Appunni, Sathiya Susuman; Nebie, Eric I. (Co-Action Publishing, 2016)
      BACKGROUND: Diarrheal diseases are a major cause of child mortality and one of the main causes of medical consultation for children in sub-Saharan countries. This paper attempts to determine the risk factors and neighborhood ...

    • Long-term eclipse timing of white dwarf binaries: an observational hint of a magnetic mechanism at work 

      Bours, M.C.P.; Kilkenny, David (Oxford University Press, 2016)
      We present a long-term programme for timing the eclipses of white dwarfs in close binaries to measure apparent and/or real variations in their orbital periods. Our programme includes 67 close binaries, both detached and ...

    • The effect of weak lensing on distance estimates from supernovae 

      Smith, Mathew (American Astronomical Society, 2013)
      Using a sample of 608 Type Ia supernovae from the SDSS-II and BOSS surveys, combined with a sample of foreground galaxies from SDSS-II, we estimate the weak lensing convergence for each supernova line of sight. We find ...

    • Maths4Stats: Opleiding vir onderwysers 

      Blignaut, Renette; Luus, Retha; Lombard, Ronell; Latief, Abduraghiem; Kotze, Danelle (AOSIS, 2013)
      Maths4Stats: Educating teachers. The inadequate nature of the education infrastructure in South Africa has led to poor academic performance at public schools. Problems within schools such as under-qualified teachers and ...

    • A qualitative study of referring agents’ perceptions of access barriers to inpatient substance abuse treatment centres in the Western Cape 

      Isobell, Deborah; Kamaloodien, Kamal; Savahl, Shazly (BioMed Central, 2015)
      Background: Despite empirical support for the individual and public health benefits of treating substance use disorders (SUDs) , access to these services is impeded by several barriers. Although many studies on access ...

    • Herschel-ATLAS: A binary HyLIRG pinpointing a cluster of starbursting protoellipticals 

      Ivison, R.J.; Swinbank, A.M.; Jarvis, Matt (American Astronomical Society, 2013)
      Panchromatic observations of the best candidate hyperluminous infrared galaxies from the widest Herschel extragalactic imaging survey have led to the discovery of at least four intrinsically luminous z = 2.41 galaxies across ...

    • Herschel*-ATLAS: correlations between dust and gas in local submm-selected galaxies 

      Dunne, L.; Bourne, N.; Bendo, G.J.; Smith, M.W.L.; Clark, C.J.R.; Smith, Daniel J.B.; Rigby, E.E.; Baes, M.; Leeuw, L.L.; Maddox, S.J.; Thompson, M.A.; Bremer, M.N.; Cooray, Asantha; Dariush, A.; de Zotti, G.; Dye, S.; Eales, S.; Hopwood, R.; Ibar, Edo; Ivison, R.J.; Jarvis, Matt; Michalowski, M.J.; Rowlands, K.; Valiante, E. (2013)
      We present an analysis of CO molecular gas tracers in a sample of 500 μ m-selected Herschel -ATLAS galaxies at z < 0 . 05 ( cz < 14990 km s − 1 ). Using 22 − 500 μ m photom- etry from WISE , IRAS an ...

    • The Herschel* view of the environment of the radio galaxy 4C+41.17 at z = 3.8 

      Wylezalek, D.; Vernet, J.; De Breuck, C.; Stern, D.; Galametz, A.; Seymour, N.; Jarvis, Matt; Barthel, P.; Drouart, G.; Rottgering, H.J.A.; Greve, T.R.; Haas, M.; Hatch, N.; Ivison, R.J.; Lehnert, M.; Meisenheimer, K.; Miley, G.; Nesvadba, N.; Stevens, J.A. (Oxford University Press, 2013)
      We present Herschel observations at 70, 160, 250, 350 and 500 μm of the environment of the radio galaxy 4C+41.17 at z = 3.792. About 65 per cent of the extracted sources are securely identified with mid-infrared sources ...

    • Herschel PEP/HerMES: the redshift evolution of dust attenuation and of the total (UV+IR) star formation rate density 

      Burgarella, D.; Buat, V.; Gruppioni, C.; Cucciati, O.; Heinis, S.; Berta, S.; Bethermin, M.; Bock, J.; Cooray, Asantha; Dunlop, J.S.; Farrah, D.; Franceschini, Alberto; Le Floch, E.; Lutz, D.; Magnelli, B.; Nordon, R.; Oliver, S.J.; Page, Matthew J.; Popesso, P.; Pozzi, F.; Riguccini, L.; Vaccari, M.; Viero, M. P. (EDP Sciences, 2013)
      Using new homogeneous luminosity functions (LFs) in the far-ultraviolet (FUV) from VVDS and in the far-infrared (FIR) from Herschel/PEP and Herschel/HerMES, we studied the evolution of the dust attenuation with redshift. ...

    • HerMES: The far-infrared emission from dust-obscured galaxies 

      Calanog, J.A.; Wardlow, Julie L.; Fu, Hai; Cooray, Asantha; Assef, R.J.; Bock, J.; Casey, C.M.; Conley, A.; Farrah, D.; Ibar, Edo; Kartaltepe, J.; Magdis, G.; Marchetti, L.; Oliver, S.J.; Perez-Fournon, I.; Riechers, D.; Rigopoulou, D.; Roseboom, I.G.; Schulz, B.; Scott, Douglas; Symeonidis, Myrto; Vaccari, M.; Viero, M. P.; Zemcov, M. (American Astronomical Society, 2013)
      The far-infrared (far-IR) luminosities of luminous infrared galaxies (LIRGs) and ultra-LIRGs (ULIRGs) are dominated by reprocessed thermal dust emission, due to a combination of star formation and active galactic nucleus ...

    • Hermes: Cosmic infrared background anisotropies and the clustering of dusty star-forming galaxies 

      Viero, M. P.; Wang, L.; Zemcov, M.; Addison, G.; Amblard, A.; Arumugam, V.; Aussel, H.; Bethermin, M.; Bock, J.; Boselli, A.; Buat, V.; Burgarella, D.; Casey, C.M.; Clements, D.L.; Conley, A.; Conversi, L.; Cooray, Asantha; de Zotti, G.; Dowell, C.D.; Farrah, D.; Franceschini, Alberto; Glenn, J.; Griffin, M.; Hatziminaoglou, Evanthia; Heinis, S.; Ibar, Edo; Ivison, R.J.; Lagache, G.; Levenson, L.; Marchetti, L.; Marsden, G.; Nguyen, H.T.; OHalloran, B.; Oliver, S.J.; Omont, A.; Page, Matthew J.; Papageorgiou, A.; Pearson, C.P.; Perez-Fournon, I.; Pohlen, M.; Rigopoulou, D.; Roseboom, I.G.; Rowan-Robinson, M.; Schulz, B.; Scott, Douglas; Seymour, N.; Shupe, D.L.; Smith, A.J.; Symeonidis, Myrto; Vaccari, M.; Valtchanov, I.; Vieira, J.D.; Wardlow, Julie L.; Xu, C.K. (American Astronomical Society, 2013)
      Star formation is well traced by dust, which absorbs the UV/optical light produced by young stars in actively starforming regions and re-emits the energy in the far-infrared/ submillimeter (FIR/submm; e.g., Savage & ...

    • HerMES: Candidate gravitationally lensed galaxies and lensing statistics at submillimeter wavelengths 

      Wardlow, Julie L.; Cooray, Asantha; De Bernardis, Francesco; Amblard, A.; Arumugam, V.; Aussel, H.; Baker, A.J.; Bethermin, M.; Blundell, R.; Bock, J.; Boselli, A.; Bridge, C.; Buat, V.; Burgarella, D.; Bussmann, R.S.; Cabrera-Lavers, A.; Calanog, J.A.; Carpenter, J.M.; Casey, C.M.; Castro-Rodríguez, N.; Cava, A.; Chanial, P.; Chapin, E.; Chapman, S.C.; Clements, D.L.; Conley, A.; Cox, P.; Dowell, C.D.; Dye, S.; Eales, S.; Farrah, D.; Ferrero, P.; Franceschini, Alberto; Frayer, D.T.; Frazer, C.; Fu, Hai; Gavazzi, R.; Glenn, J.; González Solares, E.A.; Griffin, M.; Gurwell, M.A.; Harris, A.I.; Hatziminaoglou, Evanthia; Hopwood, R.; Hyde, A.; Ibar, Edo; Ivison, R.J.; Kim, S.; Lagache, G.; Levenson, L.; Marchetti, L.; Marsden, G.; Martinez-Navajas, P.; Negrello, M.; Neri, R.; Nguyen, H.T.; OHalloran, B.; Oliver, S.J.; Omont, A.; Page, Matthew J.; Panuzzo, P.; Papageorgiou, A.; Pearson, C.P.; Perez-Fournon, E.; Pohlen, M.; Riechers, D.; Rigopoulou, D.; Roseboom, I.G.; Rowan-Robinson, M.; Schulz, B.; Scott, Douglas; Scoville, N.; Seymour, N.; Shupe, D.L.; Smith, A.J.; Streblyanska, A.; Strom, A.; Symeonidis, Myrto; Trichas, M.; Vaccari, M.; Vieira, J.D.; Viero, M. P.; Wang, L.; Xu, C.K.; Zemcov, M.; Yan, L. (American Astronomical Society, 2013)
      Gravitational lensing increases the angular size and integrated flux of affected sources. It is exploited to investigate the mass distribution of the foreground lensing structures and the properties of the background lensed ...

    • HerMES: The contribution to the cosmic infrared background from galaxies selected by mass and redshift 

      Viero, M. P.; Monclesi, L.; Quadri, L.F.; Arumugam, V.; Assef, R.J.; Bethermin, M.; Bock, J.; Bridge, C.; Casey, C.M.; Conley, A.; Cooray, Asantha; Farrah, D.; Glenn, J.; Heinis, S.; Ibar, Edo; Ikarashi, S.; Ivison, R.J.; Kohno, K.; Marsden, G.; Oliver, S.J.; Roseboom, I.G.; Schulz, B.; Scott, Douglas; Serra, P.; Vaccari, M.; Vieira, J.D.; Wang, L.; Wardlow, Julie L.; Wilson, G.W.; Yun, M.S.; Zemcov, M. (American Astronomical Society, 2013)
      The cosmic infrared background (CIB), discovered in Far Infrared Absolute Spectrophotometer (FIRAS) data from the Cosmic Background Explorer (COBE; Puget et al. 1996; Fixsen et al. 1998), originates from thermal ...

    • The analysis of indexed astronomical time series – XII. The statistics of oversampled Fourier spectra of noise plus a single sinusoid 

      Koen, Chris (Oxford University Press, 2015)
      With few exceptions, theoretical studies of periodogram properties focus on pure noise time series. This paper considers the case in which the time series consists of noise together with a single sinusoid, observed at ...

    • The analysis of indexed astronomical time series – XI. The statistics of oversampled white noise periodograms 

      Koen, Chris (Oxford University Press, 2015)
      The distribution of the maxima of periodograms is considered in the case where the time series is made up of regularly sampled, uncorrelated Gaussians. It is pointed out that if there is no oversampling, then for large ...

    • A search for p-mode pulsations in white dwarf stars using the Berkeley Visible Imaging Tube detector 

      Kilkenny, David; Welsh, B.Y.; Koen, Chris; Gulbis, A.A.S.; Kotze, M.M. (Oxford University Press, 2014)
      We present high-speed photometry (resolution 0.1 s) obtained during the commissioning of the Berkely Visible Imaging Tube system on the Southern African Large Telescope (SALT). The observations were an attempt to search ...

    • An O−C (and light travel time) method suitable for application to large photometric databases 

      Koen, Chris (Oxford University Press, 2014)
      The standard method of studying period changes in variable stars is to study the timing residuals or O−C values of light-curve maxima or minima. The advent of photometric surveys for variability, covering large parts of ...

    • Multicolour time series photometry of the T Tauri star CVSO 30 

      Koen, Chris (Oxford University Press, 2015)
      Five consecutive runs of at least five hours, and two shorter runs, of V(RI)C time series photometry of CVSO 30 are presented. No evidence could be seen for planetary transits, previously claimed in the literature for ...